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HomeMy WebLinkAboutAgenda - 09-29-1999 - 9e0 SUBJECT: ORANGECOUNTY BOARD OF COMMISSIONERS ACTION AGENDA ITEM ABSTRACT Meeting Date: September 21, 1999 1 Action Agenda Item #-9-e ADVERTISEMENT FOR JOINT PLANNING PUBLIC HEARING - OCTOBER 13, 1999 DEPARTMENT: PLANNING PUBLIC HEARING Yes x No ATTACHMENT(S): INFORMATION CONTACT: - Proposed Legal Notice Craig Benedict Extension 2592 - Proposed Amendments to Joint Planning Agreement Gene Bell Extension 2589 TELEPHONE NUMBERS: Hillsborough- 732 -8181 Durham - 688 -7331 PURPOSE: BACKGROUND: FINANCIAL IMPACT: RECOMMENDATION: h: \jpa \jpa3not.doc \9- 10 -99 \gb Mebane -227 -2031 Chapel Hill - 967 -9251 To consider the legal notice for items to be presented at the Joint Planning Area public hearing scheduled for October 13, 1999. A Joint Planning Area public hearing, involving Orange County and the Towns of Chapel Hill and Carrboro, has been scheduled for October 13, 1999. The Board of Commissioners reviews proposals to be considered at public hearing for consistency with general County policy and presentation format. The following item is proposed for consideration at the October 13, 1999, public hearing. Amendment to the Joint PlanningA¢reement Orange County proposes amendments to the Joint Planning Agreement to establish consistent review time limits. The Joint Planning Agreement addresses intergovernmental review of proposed ordinance amendments in the Transition Areas and Rural Buffer and establishes time frames for review. Review times vary from ten (10) days (with the concurrence of the Orange County Manager) to thirty (30) days. Proposed amendments to the Joint Planning Agreement would establish a consistent time of sixty (60) days throughout. This amendment requires the approval of the governing boards of Orange County, Chapel Hill, and Carrboro. None. The Administration recommends approval of the Notice of Public Hearing for October 13, 1999. 2 NOTICE OF PUBLIC HEARING ON PROPOSED AMENDMENTS TO THE ORANGE COUNTY /CHAPEL HILL/CARRBORO JOINT PLANNING AGREEMENT Pursuant to the requirements of the General Statutes of North Carolina, Chapter 153A, 240, 323, and 343; Articles 20.5, 20.6, 2.2.12 and 2.2.13 of the Orange County Zoning Ordinance; and Article 2 of a Joint Planning Agreement between Orange County and the Towns of Chapel Hill and Carrboro, notice is hereby given that a public hearing will be held at the Southern Human Services Center, 2505 Homestead Road, Chapel Hill, NC, on October 13, 1999. at 7:30 PM for the purpose of giving all interested citizens an opportunity to speak for or against the following items: JOINT PLANNING AGREEMENT 1. Orange County proposes amendments to the Joint Planning Agreement to establish consistent review time limits. The Joint Planning Agreement addresses intergovernmental review of proposed ordinance amendments in the Transition Areas and Rural Buffer and establishes time frames for review. Review times vary from ten (10) days (with the concurrence of the Orange County Manager) to thirty (30) days. Proposed amendments to the Joint Planning Agreement would establish a consistent time of sixty (60) days throughout. This amendment requires the approval of the governing boards of Orange County, Chapel Hill, and Carrboro. All interested citizens are invited to attend this hearing and be heard. Public comment will be received during the public hearing. Following the close of the public hearing, only evidence received in writing by the date of the Orange County Planning Board meeting following the public hearing will be considered by the Board of Commissioners for decision. Changes may be made in the advertised proposals which reflect debate, objections and discussion at the hearing. Questions regarding the proposals may be directed to the Orange County Planning Department located in the Planning and Agricultural Center, 306F Revere Road, Hillsborough, North Carolina. Office hours are from 8:00 a.m. to 5:00 p.m., Monday through Friday. You may also call 732 -8181 (Hillsborough), 688 -7331 (Durham) or 967 -9251 (Chapel Hill - Carrboro). When prompted for an extension number, please enter 2589. Craig Benedict, Planning Director PUBLISH: September 29, 1999 October 6, 1999 Proposed Amendments to the Joint Planning Agreement Concerning Review Time Limits The Joint Planning Agreement addresses intergovernmental review of proposed ordinance amendments in the Transition Areas and Rural Buffer and establishes time frames for review to occur. Review times vary from ten (10) days (with the concurrence of the Orange County Manager) to thirty (30) days. Proposed amendments to the Joint Planning Agreement would establish a consistent time of sixty (60) days throughout. Proposed text revisions affecting review times are printed below with text proposed for deletion shown in str-ileethfeugh and that for addition in bold underline. Section 2.6 Teat and Map Amendments A. Proposed amendments to the Joint Planning Area Land Use Plan and/or the Joint Planning Area Land Use Map may be initiated by (i) Orange County or (ii) the Towns or any other party by filing a request for such an amendment with Orange County. Any petition or request to amend the Joint Planning Area Land Use Plan received by the County shall be referred to the respective Towns. No such amendment may become effective until after it has been adopted by Orange County, Chapel Hill and Carrboro following a joint public hearing by all three governing bodies. B. Except as provided herein, proposed amendments to the text of the Orange County Zoning and Subdivision Ordinances that are applicable within the Rural Buffer as well as proposed changes in zoning district classifications (i.e., zoning map changes) that affect property within the Rural Buffer shall be initiated and adopted in accordance with the procedures set forth in those County ordinances. All such proposals that affect the CHJDA shall be referred to Chapel Hill for review and recommendation, and all such proposed amendments that affect the CJDA shall be referred to Carrboro for review and recommendation. Orange County may not adopt such proposed amendments until the respective Towns have made their recommendations, or until the expiration of thifty (30) six 60 days following such referral, whichever occurs first. C. Whenever Chapel Hill proposes to amend the text of its Land Development Ordinance, and whenever Carrboro proposes to amend the text of its Land Use Ordinance, the respective towns shall deliver a copy of the full text of the proposed amendment to Orange County not later than thift (30) six 60 days before the date of the public hearing on any such amendment. Howevef, vMh the written eensent e the Orange Geunty Manager of: his designate, this thifty (30) day per-ied nmy be fedueed te net less than ten (10) days- Unless Orange County files with the respective towns a written objection on or before the date of the public hearing on the proposed ordinance amendment, then adoption of the amendment by the respective town shall automatically effect a corresponding amendment to the applicable ordinance adopted by reference by Orange County as provided in Section 2.1C. Any such objection shall be based on a determination by Orange County that the proposed amendment is inconsistent with the adopted Joint Planning Area Land Use Plan. If a town adopts an amendment despite Orange County's objection, then it shall refer such amendment to Orange County with a request that the County make corresponding changes as expeditiously as reasonably possible so that the town may continue to enforce within its portion of the Transition area the same standards that it enforces within its own planning jurisdiction. In the event of objection by Orange County as provided herein, no such amendment shall be effective within the Joint Planning Area until it is adopted by Orange County. hAjpa \60days.doc \8- 27 -99 \gb 2 n ORANGE COUNTY BOARD OF COMMISSIONERS ACTION AGENDA ITEM ABSTRACT Meeting Date: September 21, 1999 Action Agenda Item No. /o -A SUBJECT: Triangle Land Conservancy Report: A Landscape with Wildlife, Part II DEPARTMENT: Environment and Resource PUBLIC HEARING: (Y /N) No Conservation ATTACHMENT(S): TLC Report (previously provided) -INFORMATION CONTACT: David Stancil, ext 2590 TELEPHONE NUMBERS: Hillsborough 732 -8181 Chapel Hill 968 -4501 Durham 688 -7331 Mebane 336- 227 -2031 PURPOSE: To receive a report from representatives of Triangle Land Conservancy entitled "Rating Land In Orange County By Its Wildlife Value; A Landscape with Wildlife for Orange County, Part II." BACKGROUND: In 1996, with funding from Orange County, the Triangle Land Conservancy (TLC) developed "A Landscape With Wildlife for Orange County, Part I." This report identified important prime forest areas in the County and their overland connectors, and assessed the loss of forest land that had occurred in the previous decade. TLC previously authored the County's "Inventory of Natural Areas and Wildlife Habitat' in 1988, also with funding from the County. In 1998, the County asked TLC to continue its work on prime forests with a follow -up report. This report, "Rating Land by Its Wildlife Value" was received in July. The report uses a formula approach to identify and evaluate the most significant prime hardwood forests in the County. There are a number of recommendations in the report on ways to use the formula. The authors of the report, Haven Wiley and Livy Ludington, will be present to present the findings. FINANCIAL IMPACT: None at this time. Some of the recommendations of the report call for acquisition of key prime forest areas for preservation. RECOMMENDATION(S): The Manager recommends that the Board receive the report and refer it to the Commission for the Environment and Environment and Resource Conservation staff, for evaluation and incorporation into the upcoming Orange Lands Legacy program. J To purchase copies of this report, or the first report, A Landscape with Wildlife Orange County, or Inventory of the Natural Areas and Wildlife Habitats of Orange County, please contact: TRIANGLE LAND CONSERVANCY PO Box 13031 Research Triangle Park, NC 27709-3031 919-833-3662 RATING LAND IN ORANGE COUNTY BY ITS WILDLIFE VALUE A Landscape With Wildlife: Part 2 Haven Wiley Livy Ludington Steve Hall TRIANGLE LAND CONSERVANCY 1999 � 'if1 WV' MMA W his report provides a way to evaluate land as habitat for native wildlife in Orange County. The objective is to introduce a general method for comparing tracts of land by how much they contribute to habitat for native wildlife. The habitat for most of the native species of wildlife in Orange County is mature forest. How much native wildlife a forest can support depends in part on its own features (area, matu- rity of forest, level of human disturbance, edgi- ness, and presence of water or inventoried natural areas) and in part on its context in a landscape. A context with other forest nearby allows the exchange of individuals, reduces the, chances of random local extinctions, and avoids the low genetic variability that develops in isolat- ed populations. These features are included in RECOMMENDATIONS separate Intrinsic and Contextual Ratings for the wildlife value of each tract of forest in Orange County (Maps 1 and 2). These ratings are also combined into a Total Rating (Map 3). These ratings can help planners and resource conservationists to (1) identify the most crucial forests for protection, (2) monitor Orange County's overall value for wildlife, (3) evaluate the impacts of development on nearby natural areas, (4) assess proposals for mitigation of adverse influences on wildlife habitats. Saving isolated areas is not enough to assure that Orange County can keep most of its native wildlife in the coming decades. We also need to think about preserving a Landscape with Wildlife. In particular, we need to preserve forests, including large forests, and their connections. USE BOTH INTRINSIC AND CONTEXTUAL RATINGS of land for wildlife, along with direct surveys, to: PRESERVE AND RESTORE LARGE TRACTS of forest and other wildlife habitats. PRESERVE AND RESTORE CONNECTIONS between forests or other wildlife habitats (including eliminating barriers to movements of wildlife such as those created by highways). IDENTIFY AND PRESERVE AREAS FOR WILDLIFE within any proposed development. MINIMIZE IMPACTS OF DEVELOPMENT on nearby protected natural areas. REQUIRE MITIGATION for major losses of forests for wildlife. MONITOR PROGRESS in maintaining a Landscape for Wildlife by using up -to -date aerial photographs to determine Orange Countys overall Total Rating for wildlife every decade. PROMOTE A REGIONAL PLAN for a Landscape with Wildlife. INTRODUCTION he objective of this report is to help citi- zens of Orange County make decisions about habitats for native wildlife. Most of these species depend on forests, the habitat that covered most of Orange County until two hundred years ago. A report on the first phase of this project, Landscape With Wildlife for Orange County (1997), accompanied a series of maps of the County's forests and emphasized the impor- tance of these forests for native wildlife. The present report, the second phase of this project, describes a way to rate the forests of Orange County by their predicted values for wildlife and presents a series of maps with these ratings for the County's remaining forests. The first part of this report reviews some characteristics of forests important for native wildlife. The next part explains a way to rate tracts of forest by the presence or absence of these important characteristics. The final part suggests some ways these ratings can help to preserve the forests of Orange County and their native wildlife. Barred c 3 NATIVE WILDLIFE AND HUMAN ACTIVITIES he previous report described characteris- tic species of native wildlife: Box Turtles, Spotted Salamanders, Scarlet Tanagers, Wild Turkeys, Red- shouldered Hawks, Bobcat, and others. These species and many others depend on forest and thus raise concerns about their future when forests are steadily converted to other uses. Only a few species of native wildlife have adjusted to environments created by human activities: Gray Squirrels, Raccoons, White - tailed Deer, and Carolina Chickadees, for instance. Several other species that did not orig- inally inhabit this area have moved in during the last century or so: House Sparrows, Starlings,. House Wrens, Brown - headed Cowbirds, ', most recently, douse Finches. n 1s their names uggest, these opportunists do well near humans. In contrast, most of our native wildlife disap- ,ears when the riginal forests disappear. Un- less we take action to protect species will ; reise. FOREST MATURITY IS IMPORTANT FOR NATIVE WILDLIFE Of the characteristics of forests important for native wildlife, maturity is among the most important. Mature forest is the primary habitat for most of the native wildlife in Orange County. It is the habitat that covered most of Orange County until two hundred years ago. Native wildlife and mature forests are inseparable: these species will disappear if these forests disappear and will prosper if these forests flourish. The first phase of this project produced a complete map of the forests of Orange County, now available in the County Planning Office and the new Department of Environment and Resource Conservation. All tracts of forest at least 40 acres in size were classified from aerial photographs by the composition of the canopy (more than 50% pine, 50 -90% hardwoods, more than 90% hardwoods) and by the degree of human disturbance by small roads and other openings (none, slight, moderate, heavy). The resulting maps of forests can be combined with other maps, such as those showing recent building permits or the natural areas described in the Inventory of Natural Areas in On nge Gounty (1988). The proportion of hardwoods in the canopy of a forest indicates the maturity of the forest. Abandoned fields develop through a predictable series of changes in vegetation, called succession. In abandoned fields of upland areas in Orange County, the first trees to grow are pines. In this stage, most of the trees are one species, the loblolly pine. Within twenty years or so, if the forest is left undisturbed, hardwoods like maples, sweetgum, oaks, and hickories, have begun to grow underneath the pines. Eventually these hardwoods become tall enough to reach the canopy, and the shade - intolerant pines die. Aker 100 -150 years most of the pines have fallen. The remaining forest has a canopy with a variety of hardwoods and an understory of shade - tolerant shrubs and herbs, as well as seedlings and saplings of the hardwoods in the canopy. When trees in the canopy die or are blown over by storms, these saplings from the understory respond to the additional light and grow to fill the gap. The prevalence of pines in the forests of Hickory leaves Orange County is a result of human intervention and thus is a rela- tively new feature of our forests. As a consequence, most of our native species of wildlife have adapted for life in hardwood forests and only a few make much use of young forests of pine. During the summer of 1998, a preliminary study of birds in Orange County forests confirmed that mature hardwood forests harbor more species of our native birds than other habi- tats (Appendix D. Birds are an easy group of species to survey and provide a convenient assay for the quality of habitats for wildlife in general. SIZE OF A FOREST IS IMPORTANT The importance of a forest as a habitat for wildlife increases disproportionately with its size. Studies throughout eastern North America have repeatedly confirmed that many forest- inhabiting species do not inhabit tracts of forest below a certain size. Species vary in their sensitivity to forest area. In Maryland, for instance, the chance of finding a Pileated Woodpecker at a randomly chosen point in a forest is greatest for forests over 3000 hectares in size (7000 .� a.a�A .'.a - Red - Shoudered Hawk acres). This 1•' study includedY 3 16 species of birds that are known to be sensitive to the area of forests and that also occur in Orange County (Table 1). Eight of these 16 species are most likely to be encountered in forests over 7000 acres in size. Biologists do not completely understand the reasons why each of these species is sensitive to the area of forests. The explanations probably differ from species to species. In some species, the minimal size of a forest needed for breeding is larger than the area that one nesting pair usually occupies. Possibly the edges of a forest do not provide the habitats that these species need. Edges might have more human disturbance and more small predatory mammals and birds (raccoons, crows, jays) or nest parasites (brown - headed cowbirds which lay their eggs in other species' nests). A small forest has a greater proportion of its total area near an edge than does a large forest. Consequently, species that avoid edges would have more individuals for a given acreage of forest in larger tracts. In other words, forest - interior species are often also area - sensitive species. Usually only so many individuals of one 5 These figures are from a study of the probabilities of detecting birds at random points in forests of different sizes and degrees of isolation in Maryland.The probabili- ty of detecting a bird at a random point is equivalent to the density of individuals in the forest.The table includes all area- sensitive species breeding in Maryland that also breed in Orange County. COLUMN I shows the area for which the probability of detecting each species is a maximum. It indicates that for many species the density of individuals reaches a maximum only in very large forests. COLUMN 2 shows the area for which the probability of detecting each species is reduced by half. Eight of these species require forests at least 12 hectares (30 acres) in size to have half the maximal densities of individuals. COLUMN 3 provides an indication of the smallest isolated forest in which each species might ever occur. Most forests of these sizes would not have the species. The species with the smallest minimal areas (Tufted Titmouse, Great Crested Flycatcher, Wood Thrush) are ones that sometimes occur in wooded residential areas. Source: Robbins, C. S., D K Dawson, and B.A Dowell (1989). Habitat area requirements of breeding forest birds of the middle Atlantic states.Wildlife Monographs 103: 1 -34. Table THREE MEASURES OF THE SENSITIVITY OF FOREST-NESTING BIRDS TO THE SIZES OF FORESTS Area for which Area for which Median area probability is a probability is of three smallest maximum reduced by 50% forests Louisiana Waterthrush 3000+ 350 24.7 Red- shouldered Hawk 3000 225 40.5 Pileated Woodpecker 3000+ 165 64.3 Summer Tanager 3000+ 40 47.8 Blue -gray Gnatcatcher 3000+ 15 10.1 Acadian Flycatcher 3000+ 15 2.6 Scarlet Tanager 3000+ 12 3.2 Red -eyed Vireo 3000+ 2.5 0.5 Wood Thrush 500 1 0.8 Ovenbird 450 6 1.2 Kentucky Warbler 300 17 10.4 White- breasted Nuthatch 300 3.0 3.0 Hairy Woodpecker 200 6.8 16.1 Red- bellied Woodpecker 85 0.3 1.6 Great Crested Flycatcher 72 0.3 0.8 Tufted Titmouse 52 0.5 0.6 These figures are from a study of the probabilities of detecting birds at random points in forests of different sizes and degrees of isolation in Maryland.The probabili- ty of detecting a bird at a random point is equivalent to the density of individuals in the forest.The table includes all area- sensitive species breeding in Maryland that also breed in Orange County. COLUMN I shows the area for which the probability of detecting each species is a maximum. It indicates that for many species the density of individuals reaches a maximum only in very large forests. COLUMN 2 shows the area for which the probability of detecting each species is reduced by half. Eight of these species require forests at least 12 hectares (30 acres) in size to have half the maximal densities of individuals. COLUMN 3 provides an indication of the smallest isolated forest in which each species might ever occur. Most forests of these sizes would not have the species. The species with the smallest minimal areas (Tufted Titmouse, Great Crested Flycatcher, Wood Thrush) are ones that sometimes occur in wooded residential areas. Source: Robbins, C. S., D K Dawson, and B.A Dowell (1989). Habitat area requirements of breeding forest birds of the middle Atlantic states.Wildlife Monographs 103: 1 -34. species can occupy a limited area of habitat. Sometimes there is not enough food or other necessities for more individuals to exist there; sometimes each individual defends some or all of the area it occupies against others of the same species. Either way, the larger an area the larger the number of individuals that can live and reproduce there. This limitation on the number of individu- als that an area can support exposes a frequent misunderstanding about wildlife. When a forest is cut, the animals living there cannot usually go somewhere else to live. Everywhere else already has a full population of individuals. When wildlife habitat is destroyed, the displaced indi- viduals have lost their livelihood. There are no refugees following loss of habitat for wildlife. The only way to assure that wildlife survives is to preserve their habitats. CONNECTIONS ARE IMPORTANT Large size of forests is important for another reason as well, one that might apply more to wildlife other than birds. Small tracts of forest inevitably include only a few individuals of each species. If these individuals cannot move around as easily as birds, each tract of forest becomes an isolated "island". For Box Turtles and Spotted Salamanders, for instance, few individuals or in some cases none can make the trek from one patch of forest inhospitable areas. Some of the intervening areas are potentially deadly as a result of automobiles on roads. Just as important is exposure to preda- tors or dessication in the open. In addition, some intervening areas, like riprap around bridges across streams, are physically impossible for some animals to cross. Many animals simply will not venture into such inhospitable habitats. Small isolated patches of forest contain small isolated populations of animals and plants. Biologists have repeatedly documented the consequences of small sizes for populations. Over generations, small populations lose genetic vari- ability. They thus lose flexibility in adapting to variations and changes in habitats. In addition, unpredictable fluctuations in the numbers of individuals in a small population are more likely to lead to a population of zero individuals — in other words, to local extinction. Local extinction of a species in an isolated island of habitat is ly to be reversed by immigrants from other ces. So small populations disappear one by one as each takes an unpredicted hit. The best way to avoid these conse- quences of small populations is to maintain large tracts of suitable habitat. The second best way is to preserve connections or corridors between Is of suitable habitat. These connections 7 need not provide all of the conditions needed for long -term survival and successful reproduction, but they must provide adequate conditions to allow individuals to make the journey. Like the tracts of forest themselves, the effec- tiveness of a connection depends on its size. Like other kinds of conduits, the shorter and wider a connection between habitats is, the more wildlife can pass through it. So to increase the interchanges of individuals between otherwise isolated patches of forest, the broader the connection the better. Biologists know little about what makes a connection effective for any one species. No doubt, just as for the sizes of forests, the answer differs from species to species. Although broader, shorter, less disturbed connections are probably always better, some species can make do with connections that other species cannot. 8 i OTHER CONSIDERATIONS FOR WILDLIFE Each species of native animal and plant has its .own specific requirements. In most cases, we do not yet know exactly what these requirements are. Some native species require highly specific habitats. The distinctive communities of plants and animals, that occur on steep north - facing slopes along Morgan Creek, New Hope Creek, and Eno River are good examples. Many such cases are documented in the 1988 Inventory of Natural Areas in Orange County. The presence of natural bodies of water (streams, rivers, vernal pools, seasonally inundat- ed floodplains) augments the diversity of habi- tats within forests. Partly for this reason, mature forests on floodplains include the greatest diver- sity of wildlife species of any habitat in Orange County. In general, forested areas that include or are adjacent to natural water courses often harbor more species and individuals of native wildlife than those that do not. The presence of rare or threatened species often indicates an area with a long history of ecological integrity. In Orange County most areas with these characteristics were mapped in the 1988 Inventory of Natural Areas in Orange County. These identified natural areas are thus important as indica- tors of especially rich habitats for wildlife. Green Heron NEED FORA WAY TO EVALUATE FORESTS FO R WI LD LI FE here are two motivations for attempting to evaluate habitats for their contribu- tions to populations of wildlife. First, there is the question of which tracts of habitat are currently the most important for wildlife. Second, there is the question of the best use for a particular tract of land. Wildlife does not care whether its habitat is privately or publicly owned. Nor' does the wildlife of Orange County change much as some forests are cut while others mature. The problem is the progressive disappearance of forest as a result of its loss for either private or public alter- natives, either subdivisions or highways, timber- ing or reservoirs. To reduce these pressures on forests, it would help to know the value of a forest for wildlife. Yet, it is difficult, perhaps impossible, to place a dollar value on a forest as a habitat for native wildlife. In the end, reducing homes, reservoirs, and wildlife to a common currency might never reach a consensus. Homes, reservoirs, and timber have an advantage over wildlife in part because there are ways to compare the value of different tracts of land for housing, water, or timber, but not for wildlife. Wildlife would fare better at the negotiating table if there were also ways to compare different tracts of land by their value for wildlife. We need to know which of two tracts is more valuable for wildlife, how much a proposed change in use of a tract affects its value for wildlife, or how much an increase in value for wildlife in one place can mitigate a loss in another place. Only then can we minimize adverse consequences for wildlife and negotiate mitigation for the benefit of wildlife. Only then can we know whether Orange County is maintaining its value as a Landscape with Wildlife. EVALUATING ORANGE COUNTY'S FORESTS There are two ways to evaluate forests as habi- tats for wildlife: direct and indirect. Direct methods, such as scientific surveys, provide the most accurate information. Because of the time and expense required, however, it is seldom prac- tical to obtain surveys for every tract of habitat in an area as large as Orange County. Furthermore, surveys inevitably focus on a 9 particular set of species. Indirect methods of evaluation, on the other hand, can be applied to large areas and broad categories of species. The direct and indirect approaches comple- ment each other. For instance, direct methods, like the preliminary surveys described in Appendix I, serve to refine more comprehensive indirect methods. For this reason alone, Orange County needs more surveys of its forests and wildlife. The following sections develop the broad view afforded by an indirect approach, as a way to promote thinking about a Landscape with Wildlife. The procedure we propose consists of a rating system that takes into account the size, maturity, disturbance by human activities, and "edginess" of forests. It also takes into account special habitats recognized by the 1988 Inventory of Natural Areas in Orange County and bodies of water such as streams or rivers. The procedure also includes the importance of connections between forests. The value of a forest for wildlife depends not only on its own, intrinsic features but also on the surrounding area, its contextual features. Forests with other forests nearby offer possibilities for ` movements of individuals between patches of forest. For any tract of forest we thus need separate intrinsic and contextual ratings for its contributions to landscape with wildlife. 10 We first propose ratings for tracts of forest, such as those defined by the forest cover map of Orange County. These ratings can serve to iden- tify the most important tracts of forest remain- ing in Orange County. They can provide an index of progress in maintaining Orange County as a Landscape with Wildlife. They can also be used to assess the consequences of changes in one forested tract on the value for wildlife of nearby tracts. Tracts defined by types of forest do not usually correspond to those defined by property boundaries. Consequently, we also show how the ratings can be applied to tracts defined by prop- erty boundaries. This application can indicate how a proposed use of a particular property will affect wildlife in the County and how it will affect the value of nearby tracts for wildlife. White Oak INTRINSIC RATING (IR) OF A TRACT OF FOREST The IR provides a measure of the value of a tract of forest for wildlife based solely on the features of the forest itself. To obtain a simple yet reasonable index, we have focused on six features of a forest important for wildlife, as described previously and in Table 2.. For each feature, we have assigned a numerical weight or value to each possible condition. For instance, one important feature of a forest is its maturity. The forest maps show four stages of maturity: forests that are mostly pine (more than 50% of the canopy); forests that are mostly but not entirely hardwoods (50 -90% of the canopy); and forests that are almost entirely or entirely hardwoods (more than 90% of the canopy). These three types of forest are rated 1, 2, and 3, respectively, for maturity. Areas with no tall forest receive a rating of 0 for this feature. See Table 2 for our methods of scoring five other features of forests. The Intrinsic Rating (IR) of a tract of forest is obtained by multiplying the six numbers together: IR= AxMxDxExSxI with A = acreage, M = maturity, D = distur- bance, E = edginess, S = stream, I = inventoried natural area. Each number is explained further in Table 2 and in the following paragraphs. In calculating the IR, the basic feature of a forest is its area or acreage (A). As we have seen the size of a forest is the primary determinant of how many individuals of each species it can contain. The other five numbers serve to adjust the rating based on the acreage. For instance, mature forests (almost entirely hardwoods) have three times the rating of predominantly pine forests (M). Forests with no human disturbance of the canopy have twice the rating of those with a lot of disturbance (D). Forests with a high propor- tion of edge to area have ratings that are decreased proportionately (E). Forests that overlap areas with inventoried natural areas (I) of regional or state -wide significance '(as classified by the N. C. Natural Heritage Program) have ratings 2 and 3 times as high, respectively, as otherwise comparable areas with special signifi- cance. Forests that include streams or other known bodies of water (S) have ratings that are twice as high as areas without those features. A large, mature, undisturbed, compact forest that includes a stream and an inventoried natural area has a very high rating. The highest IR for a single tract of forest in Orange County is 48,260. In contrast, a small disturbed patch of pines with an irregular shape and no water or inventoried natural area has a very low rating. The Intrinsic Ratings of tracts of forest in Orange County in 1988 appear in Map 1. Bobcats Table 2 N FEATURES OF FORESTS USED TO CALCULATE THE INTRINSIC RATING FORA TRACT Area (A) the size in acres of a tract of forest Maturity (M) 3 — more than 90% hardwoods in the canopy 2 — 50 -90% hardwoods in the canopy 1 — less than 50% hardwoods (more than 50% pines) in the canopy 0 — no closed canopy of full -grown trees) Disturbance (absence oo (D) 3 — no breaks in the canopy for small roads or buildings 2 — few breaks in canopy 1 — many breaks in canopy Edginess (minimization ofl (E) the perimeter of the tract divided by the circumference of a circle of equal area. (A circular disc has the shortest edge in relation to its area. The longer, narrower, and more convoluted a tract is, the greater is its perimeter in relation to its area. So E equals 1 for a circular tract and decreases toward 0 as a tract becomes narrower and more convoluted in shape.) Inventoried natural areas (1) 3 — tract overlaps or includes an inventoried natural area of state -wide significance 2 — tract overlaps or includes an area of regional significance 1 — tract does not overlap or include an area of state -wide or regional significance Stream present (S) 2 — a mapped stream, river, vernal pool, or lake within or adjoining the tract 1— no known body of water INTRINSIC RATING FOR WILDLIFE (IR) =A x M x D x E x S x CONTEXTUAL RATING (CR) OFATRACT OF FOREST The value of a forest also depends on its context in a landscape and especially on possible connections and corridors to other tracts of forest. We need a way to evaluate the contribution of the context of a forest to its value for wildlife. A simple procedure is to consider several zones at different distances from the "target" tract. To calculate a Contextual Rating for a particular target tract of forest, we chose zones extending from 0 to 0.5 miles, 0.5 to 1.0 miles, and 1.0 to 2.0 miles around the tract. We then calculated the average Intrinsic Rating for each acre in each of these doughnut - shaped zones (some details of this calculation are explained in Appendix II). The average IR/acre for each zone' (AVIR1, AVIR2, and AVIR3) tells us what an individual animal migrating outward from the target tract can expect to find in each of the zones around its origin. A dispersing individual is more likely to move a shorter distance than a longer one (if only because an animal must first cross the nearer zone before reaching the farther one). Consequently, in calculating the Contextual Rating for the target tract, we gave the nearer zones heavier weight. The average IR/acre for the closest zone (AVIRI) was multiplied by 4, that for the middle zone (AVIR2) by 2, and that for the farthest zone (AVIR3) by 1. We added the three resulting numbers together to obtain a Contextual Rating (CR) for the target tract: CR = (AVIRi x 4) + (AVIR2 x 2) + (AVIR3 x 1) This rating indicates the chance that an animal dispersing from the target tract will find suit- able habitat nearby. As emphasized above, little is known about the ways animals move between patches of habitat. Of course, different species have very different chances of moving to any particular distance. It is only necessary to think about a Box Turtle and a Pileated Woodpecker to realize these differences between species. Nevertheless, any animal is more likely to move a shorter distance than a longer distance. In addition, a dispersing animal is more likely to find suitable habitat when there is on average more suitable habitat in the surrounding zones. Thus this Contextual Rating incorporates the basic features that might influence these movements. The Contextual Rating is incomplete near the boundaries of the County, because parts of the three zones fall outside the County. The County's maps of forests in Orange County extend far enough over the boundaries to allevi- ate this problem. Regional efforts to plan for preservation of forest would eliminate this problem altogether. Contextual Ratings for tracts of forest in Orange County in 1988 appear in Map 2. COMBINING INTRINSIC RATING AND CONTEXTUAL RATING INTO A TOTAL RATING (TR) The Contextual and Intrinsic Ratings for a tract of land can be combined into a Total Rating by adding 1 to the Contextual Rating and then multiplying the two ratings together: Total Rating = IR x (CR + 1) The Contextual Rating, after all three zones are combined, is a weighted average rating per acre. Like the maturity of a forest or its degree of "edginess ", the context of a forest multiplies the overall value of the tract for wildlife. 13 The Contextual Rating would have a maximal value of about 42 in the extreme case of a tract entirely surrounded by undisturbed hard- wood forest (see Appendix II). It would have a value of 0 in the other extreme case of a tract entirely surrounded by unforested land to a distance of 2 miles in all directions. By adding 1 to the. CR, the target tract in this latter case would have a Total Rating equal to its Intrinsic Rating: when CR = 0, TR = IR x (CR + 1) = IR. Thus when CR = 0, it has no effect on the Total Rating. Total Ratings for tracts of forest in Orange County in 1988 appear in Map 3, and the sites with the highest Total Ratings are presented in Map 4. HOW RATINGS HAVE CHANGED IN THE PAST DECADE The aerial photos used for mapping the forests in Orange County date from 1988, the most recent available. In the past decade the Intrinsic Ratings of some tracts of forest have probably increased and others have decreased. Undisturbed forests have continued to mature, so some have changed from predomi- nantly pine to predominantly hardwood and thus have higher Intrinsic Ratings. Other forests include properties that have been timbered or for which building permits have been issued in the past decade. Although a building permit does not necessarily mean that all forest on the property has been cleared, some clearing is usually the case. These tracts would now have lower Intrinsic Ratings. To estimate the consequences of recent building for the wildlife value of forests, we have recalculated the ratings after subtracting all properties for which building permits were issued between 1988 and 1998 (except those 14 tracts in the Chapel Hill Planning District, for which information on building permits was not available). The resulting ratings appear in Maps 5 -8. Some statistics for these ratings before and after subtracting properties with building permits appear in Table 3. It is important to emphasize that the statis- tics in Table 3 for forests in 1998 are based on incomplete information: they do not include the effects of timbering, the progressive maturity of undisturbed forests, nor the actual effects of building permits. Accurate assessment of the County's current forests will require an analysis of recent aerial photographs. Male (bottom) and Female Pileated Woodpeckers RATINGS FORTRACTS DETERMINED BY PROPERTY BOUNDARIES T he preceding sections have applied these ratings to tracts of forest. Usually these tracts do not correspond to property boundaries, but no special problems arise in applying the IR and CR to parcels defined by property boundaries. A parcel of land would usually include several different tracts of forest or parts of tracts. To i calculate an Intrinsic Rating for the entire parcel, we could recompute areas (GIS polygons) by using both the boundaries of forest tracts and the property boundaries in question. Then we could find the IR for each polygon included within the property boundaries and sum them to obtain a total IR for the property. To obtain the Contextual Rating for the proper- ty, we could then follow the procedures described previously without modification. The Total Rating for the property would equal the product of IR and (1 + CR), as described above. Table 3 STATISTICS FOR RATINGS OF FOREST FOR WILDLIFE YEAR 1988* INTRINSIC RATINGS Median (50th percentile) 803 Maximum 48260 Overall Sum 941,547 Number of tracts over 15,000 7 1999** 713 40510 789,077 5 CONTEXTUAL RATINGS Median (50th percentile) 22.3 25.6 Maximum 147 145 `., TOTAL RATINGS Median (50th percentile) 19045 14788 Maximum 1,385,000 1,098,000 Overall Sum 30,129,000 23,273,000 Number of tracts over 300,000 14 12 *Based on 1988 Aerial Photographs (689 tracts of forest over 40 acres) **After subtracting properties with building permits issued 1988 -1998 (653 remaining tracts of forest over 40 acres) IS USING RATINGS FOR WILDLIFE WAYS WILDLIFE RATINGS CAN HELP PLANNERS AND CONSERVATIONISTS Preserve and restore large tracts of forest and other wildlife habitats. These areas make such important contributions to a Landscape with Wildlife that they merit acquisition for perma- nent protection. Map 8 shows the areas in Orange County with the highest Total Ratings after subtracting properties with recent building permits. Important priorities include both those areas that have high Intrinsic Ratings and those with high Contextual Ratings. Preserve and restore connections between forests or other wildlife habitats. Contextual, Ratings of forests are important because they indicate the opportunities for dispersal of animals between patches of habitat. These ratings can thus help to preserve the connections between forests. Especially important are areas that have large influences on the Contextual Ratings of nearby natural areas In Orange County. Several impor- tant natural areas are already protected by public or ` institutional ownership. Nevertheless, even these areas can lose some of their value for native wildlife by changes in land use nearby. In order to retain our native wildlife, we must maintain the Contextual Ratings of important natural areas. Thus land within two miles of important natural areas requires special attention in planning. Identify and preserve areas for wildlife within any proposed development. On a small as well as large scale, it is important to identify which land to set aside for wildlife. Within any one development, some areas are identified for active recreation and other community space. L Y fa Developments should also plan to reserve areas for wildlife, particularly those areas with high Intrinsic and Contextual Ratings. Subdivision of land for homes can lead to extreme fragmentation of forests. To minimize the effects of fragmentation on wildlife, it is impor- tant to keep the remaining forests as large and as close together as possible and to provide connec- tions between forests. Hence the Contextual as well as the Intrinsic Ratings of forests are impor- tant in identifying land to set aside for wildlife. Nkdmize impacts of development on nearby protected natural areas. The importance of natural areas for wildlife does not depend entirely on their intrinsic features. Turning a natural area into an isolated "island" diminishes its value for wildlife. In evaluating plans for development or public facilities, it is thus important to consider any changes in the Contextual Ratings of nearby protected areas. When considering proposals for changes in land use, we routinely consider the consequences for neighboring land — not only for its property value but also for its water quality, noise, odor, traffic, schools, and other values. We should also consider changes in the wildlife value of nearby land. To do so, we can compute the changes expected in the Contextual Ratings of these areas for wildlife. Require mitigation for major losses of forests for wildlife. Without planning, the proportion of land left for wildlife diminishes steadily. A solution is to negotiate mitigation for losses. Imagine a proposal to develop a tract of land in a way that decreases its Intrinsic Rating for wildlife or decreases the Contextual Rating of a nearby protected area. The County might require the developer or agency to protect land with equal ratings elsewhere. A requirement of this sort would also create an incentive to mini- mize any decrease in wildlife ratings for the property under development. For successful. mitigation, we do not have to put a dollar value on the consequences for wildlife. Instead, it is enough to determine whether a decrease in value for wildlife in one place is matched by an increase somewhere else. For this purpose, we can use a wildlife value, such as the Total Rating for wildlife, rather than a dollar value. Monitor how Orange County measures up as a Landscape for Wildlife. We can compute the grand total of the Total Ratings for all forests in Orange County. This grand total is an index of the County's overall suitability for native wildlife. The grand total changes over time as the forested areas of Orange County and their arrangement change. If we subtract all forested tracts for which building permits were issued between 1988 and 1998, Orange County's overall Total Rating for wildlife decreases from 30,130,000 to 23,273,000 — over 25% (see Table 3). As explained above in the section, How Ratings Have Changed in the Past Decade, it is not clear that the actual decrease is this large. An accurate measure of changes in the Countys forests will require analysis of a new set of aerial photographs. It would take a person about one month, full-time, to identify and digitize the forests of the entire County. Eventually satellite photogra- phy might become detailed enough to permit this sort of mapping automatically, but the reso- lution of satellite photos is not high enough at the present time. By obtaining up -to -date infor- mation every decade, the County could identify developing problems and monitor its progress in maintaining a Landscape with Wildlife. Promote a regional plan for a Landscape with Wildlife. A regional assessment of habitats for native wildlife, including large tracts of forest, will help Orange County to understand its own place in a Landscape with Wildlife. As described in the next section, some important wildlife areas in Orange County lie near county bound- aries. Much of the Contextual Ratings for these areas will depend on land in adjacent counties. Without a regional perspective, these areas are in danger of falling between the cracks in planning for a Landscape with Wildlife. CARE IS NECESSARY IN APPLYING WILDLIFE RATINGS The ratings we have proposed represent a first step in evaluating land for wildlife. The ratings include those features of natural habitats that current evidence suggests are important for many kinds of native wildlife and for which we had information. Different kinds of wildlife have different requirements, and different tracts of land have special features. Any one rating system cannot apply equally well to all. We have proposed ratings in the conviction that the time to start thinking about the value of land for wildlife is now. In using these ratings, it is important to keep several issues in mind. 17 Confirmation in the field. Any application of the ratings we have proposed to particular circumstances should always follow confirmation of the ratings by field work. For instance, identi- fying land for preservation or for mitigation of development should always include an assess- ment on the ground. There is no substitute for direct field studies in particular cases. The ratings we propose can help planners make initial decisions about the value of land for wildlife, but these decisions always need confir- mation in specific cases. Artificial barriers affect the movement of wildlife. Our ratings do not take account of every influence on the suitability of forests for native wildlife. An example of a factor not included in these ratings is the presence nearby of an absolute barrier to movements of animals. Barriers such as fenced and heavily traveled high- ways, railroad tracks, or causeways lined with riprap can completely block some animals' move- ments. A large mature forest nearby would make little difference to a dispersing Box Turtle if it lay on the far side of a major highway. The Contextual Ratings presented here do not take these barriers into consideration. As new information becomes available, it will allow development of better ratings in the future. Even so, to assure the continued presence of a full range of native wildlife, we must not ignore the special requirements of each species. County boundaries affect wildlife ratings. As already mentioned, the Contextual Ratings of tracts near the edge of the County are too low because we currently lack maps of forests in adjacent counties. For instance, the Mason Farm Biological Reserve in the southeastern corner of Orange County would have higher Contextual and Total Ratings if we could include the influence of the extensive forests 18 along the floodplain of Morgan Creek in Durham and Chatham Counties. Also the presence of flood - plains, which are often rich wildlife habitats, are not included in our ratings. The artificiality of political boundaries for wildlife can only be resolved by a regional effort. Regional planning would improve our understand- ing of Orange County as a Landscape with Wildlife. Wildlife ratings depend on the arrangement of forests. Because the Total Rating for each tract of land depends in part on the features of neighbor- ing tracts, the sum of the Total Ratings over any large area inevitably depends on the arrangement of tracts. In this respect, wildlife values calculated from our Total Ratings are like real estate proper- ty values. Both depend on intrinsic and contex- tual features of properties, and both consequent- ly depend on the arrangement of properties. OTHERVALUES FOR FOREST The forests which once covered most of Orange County, and still cover nearly a third, have other advantages as well. They provide important benefits for water quality. Forests behave both like sponges and like filters. By absorbing rainfall and releasing it slowly into streams, they dampen floods and droughts. By removing most pollutants and silt from water flowing into streams, the soils of forests provide us with clean water. Forests also provide much of the natural appeal of the landscapes of Orange County. Forests on rolling hills are what make the land- scapes of the Piedmont distinctive. We have focused here on the importance of forests for native wildlife. To protect our wildlife we must protect our forests, but if we protect our forests we will have protected much more as well. APPENDIX I PRELIMINARY SURVEYS OF BIRDS IN ORANGE COUNTY FORESTS During the summer of 1998, Susan Campbell, an ornithologist who works for the N. C. State Museum of Natural Sciences, surveyed birds in forests in several areas of Orange County. The intent was to determine the species breeding in the different types of forest identified on the maps of forest in Orange County. There are nine such categores: hardwood, mixed, and pine forests, each undisturbed, slightly disturbed, and strongly disturbed by human activities. PROCEDURES The areas easily accesible for this work were, Moorefields Estate, Occoneechee Mountain, Duke Forest (Durham and Korstian Divisions), Pickard's Mountain, Cane Creek Reservoir, University Lake, and Mason Farm Biological Reserve. In each of these areas, she received enthusiastic cooperation from the resident owners or managers. Occurrence of birds was recorded during "point counts ", a standard procedure for assess- ing the occurrence and density of birds. During each point count, the observer recorded all birds seen or heard within 50 meters of an arbitrarily selected point located as much as possible within a larger area of one type of forest. Points were never closer than 100 meters apart, to avoid overlap in individuals recorded. All counts were conducted during the morning between 6:00 and 11:00 a.m. Altogether 84 point counts were obtained in May and June. The areas available for surveys provided fewer opportunities for studying disturbed forests than undisturbed ones. Consequently, most counts were obtained in undisturbed hardwood (31 counts), mixed (21), and pine (14 counts); there were 15 counts in slightly disturbed forests, and only 4 in strongly disturbed forests. Only the counts in undisturbed hardwood and mixed forests adequately sampled the birds. Most of the censuses in undisturbed pine forests were conducted in Duke Forest, where most tracts of uniform forest are small. Consequently, the counts in these forests often included some species from adjacent hardwood forests. There were too few counts in disturbed forests for firm conclusions. The data for these counts is on file in the office of the Triangle Land Conservancy. A summary of the results is presented here. GENERAL OBSERVATIONS It became clear that the County must update its maps of forests periodically. Campbell's notes repeatedly refer to recent loss of forest in the County. The maps do not reflect clearing for building since 1988 (although information about recent building permits indicates where such clearing has probably occurred). The maps also do not reflect clearing for timber sales. The State has information about timber sales in ArcInfo format, but the County has not yet been able to obtain this information. In addition, some areas designated on the maps as Mixed Forests are now nearly pure Hardwood. Campbell noted that Hurricane Fran had blown down pines in some areas of Mixed Forest and thus accelerated the final stage of succession to Hardwood Forest. Of course, some Mixed Forests on the maps just missed the crite- rion for Hardwood Forests in 1988 and subse- 19 20 quently have lost enough of the last pines to have qualified as Hardwood Forests today. BREEDING BIRDS IN ORANGE COUNTY FORESTS The 84 point counts revealed a total of 72 species of birds that normally breed in Orange County. Some of these species do not usually use forests for nesting or feeding and were noted only while flying overhead or at the edges of the count areas in habitats other than forest. Species that normally nest or feed in forests, or in the air above forests, totaled 51. Some nocturnal species (Whip- poor -will, Eastern Screech -Owl, Great Horned Owl) were no doubt also present but not detected in these counts. Among these 51 species, those that live entirely inside forests during the breeding season totaled 23 (Table A -1). Table A -2 presents a summary of the numbers of birds found in different kinds of Orange County forests. Table A- BIRDS RECORDED IN ORANGE COUNTY FORESTS - 1998 The name of each species is followed by a standardized four- letter abbreviation and then two letters that indicate its habitat: F - regularly nests or feeds in forests (some also nest elsewhere); FI - nests only inside forests (with canopy mostly closed) 1 Sharp - shinned Hawk SSHA F FI 37 Tufted Titmouse ETTI F 2 Red - shouldered Hawk RSHA F FI 38 Brown - headed Nuthatch BHNU F 3 Barred Owl BAOW F FI 39 Carolina Wren CARW F 4 Yellow- billed Cuckoo YBCU F FI 40 Blue -gray Gnatcatcher BGGN F 5 Hairy Woodpecker HAWO F FI 41 American Robin AMRO F 6 Pileated Woodpecker PIWO F FI 42 Gray Catbird GRCA F 7 Eastern Wood -Pewee EWPE F FI 43 Brown Thrasher BRTH F 8 Acadian Flycatcher ACFL F FI 44 White -eyed Vireo WEVI F 9 Great Crested Flycatcher GCFL F FI 45 Summer Tanager SUTA F 10 White- breasted Nuthatch WBNU F FI 46 Northern Cardinal NOCA F 11 Wood Thrush WOTH F FI 47 Rufous -sided Towhee RSTO F 12 Solitary Vireo SOVI F FI 48 Common Grackle COGR F 13 Red -eyed Vireo REVI F FI 49 Brown- headed Cowbird BHCO F 14 Northern Panda NOPA F FI 50 Canada Goose CAGO 15 Pine Warbler PIWA F FI 51 Mallard MALL 16 Black- and -white Warbler BAWW F FI 52 Killdeer KILL 17 American Redstart AMRE F FI 53 Chimney Swift CHSW 18 Worm - eating Warbler WEWA F FI 54 Eastern Phoebe EAPH 19 Ovenbird OVEN F FI 55 Eastern Kingbird EAKI 20 Louisiana Waterrhrush LOWA F FI 56 Purple Martin PUMA 21 Kentucky Warbler KEWA F FI 57 Northern Rough- winged Swallow NRWS 22 Hooded Warbler HOWA F FI 58 Cliff Swallow CLSW 23 Scarlet Tanager SCTA F FI 59 Bam Swallow BASW 24 Green Heron GRHE F 60 Fish Crow FICR 25 Turkey Vulture TUVU F 61 Eastern Bluebird EABL 26 Red- tailed Hawk RTHA F 62 European Starling EUST 27 Northern Bobwhite NOBO F 63 Prairie Warbler PRWA 28 Mourning Dove MODO F 64 Common Yellowthroat COYE 29 Ruby- throated Hummingbird RTHU F 65 Yellow- breasted Chat YBCH 30 Belted Kingfisher BEKI F 66 Blue Grosbeak BLGR 31 Red - bellied Woodpecker RBWO F 67 Indigo Bunting INBU 32 Downy Woodpecker DOWO F 68 Chipping Sparrow CHSP 33 Northern Flicker YSFL F 69 Field Sparrow FISP 34 Blue Jay BLJA F 70 Red winged Blackbird RWBL 35 American Crow AMCR F 71 House Finch HOFI 36 Carolina Chickadee CACH F 72 American Goldfinch AMGO 21 Table A -2 BIRDS RECORDED IN HARDWOOD, MIXED,AND PINE FORESTS OF ORANGE COUNTY (UNDISTURBED, SLIGHTLY DISTURBED,AND DISTURBED BY HUMAN ACTIVITIES) HARDWOOD HARDWOOD MIXED MIXED MIXED PINE PINE UNDISTURBED SLIGHTLY UNDISTURBED SLIGHTLY DISTURBED UNDISTURBED DISTURBED DISTURBED DISTURBED 1.2 REVI POINTS 31 9 21 6 2 14 2 SPECIES 39 33 38 28 18 31 17 INDIVIDUALS (ALL SPECIES) ETTI 1.5 ETTI 424 146 285 110 32 183 32 INDIVIDUALS/POINT REVI 1.5 BLJA 13.7 16.2 13.6 18.3 16 13.1 16 INDIVIDUALS /POINT FOR EACH SPECIES * CARW 1.5 CARW 2.0 CARW 1.6' CARW 1.8 NOCA 2.0 NOCA 1.3 NOCA 2.0 REVI 1.2 REVI 1.6 REVI 1.0 NOCA 1.7 AMRE 1.5 CARW 1.2 ETTI 1.5 ETTI 1.0 NOCA 1.6 NOCA 1.0 REVI 1.5 BLJA 1.0 REVI 1.0 PIWA 1.5 CACH 0.9 ETTI 1.4 ETTI 0.9 WOTH 1.3 AMCR 1.0 CACH 0.9 DOWO 1.0 OVEN 0.9 ACFL 0.9 OVEN 0.8 OVEN 1.2 CACH 1.0 PIWA 0.9 BLJA 1.0 NOCA 0.9 AMCR 0.9 WOTH 0.8 ETTI 1.0 CARW 1.0 AMCR 0.8 CACH 1.0 DOWO 0.7 CACH 0.9 ACFL 0.7 RBWO 0.8 WOTH 1.0 BGGN 0.6 CARW 1.0 ACFL 0.7 BLJA 0.8 SUTA 0.7 CACH 0.8 BRTH 1.0 DOWO 0.6 WOTH 1.0 BLJA 0.6 BGGN 0.8 CACH 0.6 SUTA 0.8 REVI 1.0 ACFL 0.5 REVI 1.0 SUTA 0.6 WOTH 0.6 RBWO 0.5 ACFL 0.7 PIWA 1.0 ETTI 0.5 OVEN 1.0 WOTH 0.5 NOPA 0.6 DOWO 0.4 BLJA 0.7 SCTA 1.0 BLJA 0.4 RSTO 1.0 RBWO 0.4 RBWO 0.4 BLJA 0.4 BGGN 0.7 RBWO 0.5 OVEN 0.4 AMCR 0.5 BGGN 0.4 DOWO 0.4 BGGN 0.4 PIWA 0.7 DOWO 0.5 COYE 0.4 WBNU 0.5 SCTA 0.4 PIWA 0.3 SCTA 0.4 SCTA 0.7 ETTI 0.5 SCTA 0.4 GRCA 0.5 BHCO 0.4 OVEN 0.3 MODO 0.3 BHCO 0.7 BGGN 0.5 RSTO 0.4 COYE 0.5 NOPA 0.3 COYE 0.3 YBCU 0.3 DOWO 0.5 NOPA 0.5 PRAW 0.4 SUTA 0.5 YBCU 0.3 MODO 0.2 BHCO 0.3 AMCR 0.5 COYE 0.5 WOTH 0.3 SCTA 0.5 HAWO 0.3 SUTA 0.2 NOPA 0.2 MODO 0.3 SUTA 0.5 MODO 0.2 SSHA 0.0 AMCR 0.2 SCTA 0.2 RTHU 0.2 RTHU 0.3 SSHA 0.0 YBCU 0.2 RSHA 0.0 WBNU 0.2 RSTO 0.2 PIWO 0.2 COGR 0.3 RSHA 0.0 EAWP 0.2 RTHA 0.0 COYE 0.2 BHCO 0.2 EAWP 0.2 HAWO 0.2 RTHA 0.0 SUTA 0.2 MODO 0.0 HOWA 0.2 RSHA 0.1 AMCR 0.2 YSFL 0.2 MODO 0.0 COGR 0.2 BAOW 0.0 WP SP. 0.2 RTHU 0.1 PIWA 0.2 EAWP 0.2 BAOW 0.0 RBWO 0.1 YBCU 0.0 MODO 0.1 YSFL 0.1 LOWA 0.1 GRCA 0.2 YBCU 0.0 PIWO 0.1 RTHU 0.0 EAWP 0.1 PIWO 0.1 KEWA 0.1 SOVI 0.2 RTHU 0.0 AMRO 0.1 RBWO 0.0 PIWA 0.1 EAWP 0.1 COPE 0.1 NOPA .0.2 HAWO 0.0 BHCO 0.1 HAWO 0.0 YSFL 0.1 GCFL 0.1 COGR 0.1 LOWA 0.2 YSFL 0.0 RTHA 0.1 YSFL 0.0 PIWO 0.1 WBNU 0.1 WBNU 0.1 RSTO 0.2 PIWO 0.0 HAWO 0.1 PIWO 0.0 GCFL 0.1 WEVI 0.1 HOWA 0.1 SSHA 0.0 WP SP. 0.0 WP SP. 0.1 WP SP. 0.0 RTHA 0.1 LOWA 0.1 RSTO 0.1 RSHA 0.0 EAWP 0.0 NOPA 0.1 EAWP 0.0 YTWA 0.1 KEWA 0.1 SSHA 0.0 RTHA 0.0 ACFL 0.0 HOWA 0.1 ACFL 0.0 COGR 0.1 HOWA 0.1 RSHA 0.0 BAOW 0.0 GCFL 0.0 SSHA 0.0 GCFL 0.0 RSHA 0.0 COGR 0.1 BAOW 0.0 YBCU 0.0 WBNU 0.0 RSHA 0.0 BHNU 0.0 RTHU 0.0 SSHA 0.0 YSFL 0.0 PIWO 0.0 BHNU 0.0 BAOW 0.0 BGGN 0.0 AMRO 0.0 RTHA 0.0 GCFL 0.0 WP SP. 0.0 AMRO 0.0 RTHU 0.0 AMRO 0.0 WEWA 0.0 BAOW 0.0 BAWW 0.0 GCFL 0.0 GRCA 0.0 YSFL 0.0 BRTH 0.0 LOWA 0.0 YBCU 0.0 AMRE 0.0 WBNU 0.0 SOVI 0.0 GCFL 0.0 SOVI 0.0. KEWA 0.0 HAWO 0.0 WEWA 0.0 BHNU 0.0 WEVI 0.0 WBNU 0.0 WEVI 0.0 RSTO 0.0 WP SP. 0.0 RTHA 0.0 AMRO 0.0 YTWA 0.0 BHNU 0.0 NOPA 0.0 SSHA 0.0 BHNU 0.0 HAWO 0.0 BRTH 0.0 PRAW 0.0 GRCA 0.0 YTWA 0.0 BAOW 0.0 AMRO 0.0 WP SP. 0.0 WEVI 0.0 BAWW 0.0 BRTH 0.0 PRAW 0.0 BHNU 0.0 GRCA 0.0 BHNU 0.0 YTWA 0.0 WEWA 0.0 SOVI 0.0 BAWW 0.0 GRCA 0.0 BRTH 0.0 AMRO 0.0 PRAW 0.0 OVEN 0.0 WEVI 0.0 AMRE 0.0 BRTH 0.0 SOVI 0.0 GRCA 0.0 BAWW 0.0 LOWA 0.0 YTWA 0.0 WEWA 0.0 SOVI 0.0 YTWA 0.0 BRTH 0.0 AMRE 0.0 KEWA 0.0 BAWW 0.0 LOWA 0.0 WEVI 0.0 PRAW 0.0 SOVI 0.0 WEWA 0.0 HOWA 0.0 AMRE 0.0 KEWA OA PRAW 0.0 BAWW 0.0 WEVI 0.0 KEWA 0.0 RSTO 0.0 WEWA 0.0 HOWA 0.0 BAWW 0.0 AMRE 0.0 YTWA 0.0 COYE 0.0 COGR 0.0 LOWA 0.0 COGR 0.0 AMRE 0.0 WEWA 0.0 PRAW 0.0 HOWA 0.0 BHCO 0.0 KEWA 0.0 BHCO 0.0 *LIMITED TO 49 SPECIES THAT NEST OR FEED INSIDE FORESTS (SOME ALSO OCCUR OUTSIDE FORESTS). EACH SPECIES IS INDICATED BY ITS FOUR - LETTER ABBREVIATION (SEE TABLE A -1). APPENDIX II CALCULATING THE CONTEXTUAL RATING FOR A TARGET TRACT BY MEANS OF THREE BUFFER ZONES AROUND THE TRACT The procedure we suggest here is easy to calculate in ArcInfo and produces an intuitively under- standable rating for the context of a target tract of forest. THREE BUFFERS AROUND THE TARGET TRACT First, ArcInfo finds three buffer zones around a target tract. These three buffers extend outward 0.5, 1, and 2 miles from the target tract. Within each buffer, we consider all tracts of forest and non - forest (non - forest is a tract with a Maturity value of 0, as explained in Table 2). The IR for each tract is computed, the resulting numbers are summed, and the sum is divided by the total acreage in the buffer. The result is an average IR for each acre in each buffer. Notice that the IR for each tract in a buffer includes the acreage of the tract. When we divide by the total acreage in the buffer, we end up with an average IR for the buffer or an IR per acre in the buffer. To visualize what an average IR means, consider an extreme case. If a buffer were completely forested with undisturbed Hardwood Forest, with no bodies of water or inventoried natural areas, the average IR in the zone would equal about 6 (3 for Hardwood Forest, times 2 for no disturbance). TWO COMPLICATIONS There are two complications when ArcInfo calcu- lates an average IR in this way. First, ArcInfo can 24 quickly identify buffers around a target tract, but it cannot quickly identify concentric doughnut - shaped zones. A buffer with a narrower width is thus completely included within a buffer with a wider width. We actually want the information for concentric doughnut - shaped zones, rather than for buffers. This problem is easily solved. The average IR of a doughnut - shaped zone is quickly obtained by subtracting the values for a narrower buffer from the values for a ' wider buffer. For instance, the average IR for the zone from 1.0 to 2.0 miles from a target tract equals �y (total IR for 2 -mile -wide buffer) - (total IR for I -mile -wide buffer) (total area for 2- mile -wide buffer) - (total area for I -mile -wide buffer) There is a second complication. ArcInfo can easily determine the set of all polygons that overlap a buffer, but it cannot easily determine the set that are entirely included within a buffer. Consequently, in computing the average IR for any buffer, we have included tracts that overlap that buffer. The buffer "gets credit" for some forest outside the buffer. Tracts of forest that overlap two doughnut- shaped zones get "counted" in the nearer zone. This problem, in most cases, is not a large one. In examing the maps of Contextual Ratings for Orange County forests, we have not noticed distortions in ratings as a result of this complica- ton. From a biological point of view, this situa- tion is not unreasonable. Once an animal finds a patch of suitable habitat, it might easily move throughout it. Although more complicated calcu- lations could remove this problem, they do not seem justified on the basis of our present knowl- edge. THE CONTEXTUAL RATING (CR) After summing the results for each of the three doughnut - shaped zones, with their respective weights, the maximal value of the Contextual Rating for a target tract is about 42. This value is 6 x 4 for the innermost zone, plus 6 x 2 for the middle zone, plus 6 x I. for the outer zone. The minimal value of the Contextual Rating is 0, when there is no forest within 2 miles of the target tract in any direction. The Contextual Rating we present here thus combines the advantages of (1) agreement with general features of biological dispersal between patches of habitat, (2) intuitively understandable results, and (3) easy computation by Ardnfo. 25 ACKNOWLEDGMENTS Susan Campbell, N. C. State Museum of Natural Sciences, conducted the surveys of birds in forests of Orange County and prepared a database with the results. Stephanie Wilds, Blue Star Consulting, Inc., prepared the maps and transferred the ARCINFO files and programs to the Orange County Planning Department. Beth Young, Orange County Planning Department, provided the ARCINFO files of forests in Orange County (those prepared by the first phase of this project) and printed the maps for the present report. We thank them all for their enthusiastic participation in this project. 26 0 Al A-7i .07 4 a 99 C, Z *6f Cal Ilk UK F'1 rl;_;- I gg - posgIm. .11 "1 lwl� Me sk M Wildlife Ratings for Orange County Forests (Based on 1988 Aerial Photographs) Areas with the Highest Ratings Highest Rad 0 50,000 - 199,999 ® 200,000 - 349,999 350,000 - 1,384,523 N E S 2 0 2 4 6 8 10 Miles 1999 Blue Star Consulting /' ' VL 01( Pd t q_ L-M At , mv M6A Al IN