6.1 Context

Pennsylvania’s conservation future for the 21st century must take account of the past, because historic human imprints have played a major role in conditioning contemporary habitats. Pennsylvania has experienced successive waves of deforestation, and even devastation. After the first waves of lumbering and clearing for settlement, many areas suffered virtual denudation either directly by mining activities or for charcoal in conjunction with mining. Each new wave of deforestation contributed a legacy of soil erosion on uplands and sediment deposition in lowlands and waters. Widespread filling of wetlands compounded impacts of sedimentation. Waters were impounded, dredged, navigated, bordered by canals, diverted, and polluted from both point sources and non-point sources. The assault on waters continues today from acid mine drainage, acidic deposition, and non-point contributions from agriculture, transportation, and human habitation.

Pennsylvania’s substantial complement of rugged topography has been unforgiving with regard to land uses that involve absence of forest cover, to the degree that unsustainable human occupancy was eventually abandoned in favor of those involving more naturalistic cover. Fortunately, Pennsylvania’s climate is conducive to reforestation. Oak stumps remaining on the uplands sprouted vigorously, and other forests were restored through planting by the former Civilian Conservation Corps and Bureau of Reclamation. Reclamation of strip mines has given rise to substantial areas of grassy habitat that were not formerly available. Physical degradation has been considerably reduced on lands that are sufficiently stable to accommodate maintenance of open conditions. Thus, Pennsylvania had a resurgence of terrestrial habitats that are largely a result of either natural resilience or human restoration.

The situation has not been as forgiving, however, for wetlands and waters. Wetlands that were filled have been lost completely (about 56% loss in the state). Development continues to intensify along watercourses, and grazing of animals in riparian areas contributes to stream degradation in rural areas. Natural wetlands are replaced by compensatory created wetlands to make way for development. Intensive use of agricultural and landscaping chemicals places both toxic substances and excess nutrients in wetlands and waters. Thus, the story for many aquatic habitats has been one of progressive degradation.

Terrestrial forest fauna also face increasing competition from humans for use of the forest as living space. The Governor’s 21st Century Environment Commission has flagged residential development in rural (often forested) areas as a major environmental issue. Unlike the former waves of deforestation, this sort of incursion can persist indefinitely through clever engineering and landscape architecture. It nevertheless contributes to forest fragmentation, increases numbers of exotic plants, and otherwise degrades habitat for many animal species.

Degradations also arise from imbalances among fauna associated with elimination of predators and overly aggressive management of game species. Pennsylvania is notable in this regard because of the heavy impact on vegetation from browsing due to over-abundance of deer.

What has been most lacking in Pennsylvania’s modern context is a landscape perspective, whereby the cumulative impacts of incremental alterations in land-use can be gauged appropriately and steps taken to promote cooperative counter-measures. Interactions across landscapes must be better and more widely appreciated, particularly with respect to effects of land-based activities on aquatic habitats and also with regard to fragmentation of naturalistic cover. The Pennsylvania GAP Project can help to provide the needed landscape perspective.

6.2 Landscape Integrity

The dual scale approach to Pennsylvania gap analysis shows that the state has substantial landscape integrity, with 69% being dominated by forest cover at the 100-ha scale. Furthermore, there is relative continuity of this forested landscape matrix over approximately 65% of the Commonwealth, spanning the state from south to north and covering much of northcentral Pennsylvania. Therefore, Pennsylvania constitutes an important bridge of habitats for dispersal and gene flow between New York and New England to the north and West Virginia to the south. Thus, Pennsylvania’s designation as the “Keystone State” is merited even with regard to habitat conservation.

Pennsylvania is approximately 65% forested at a finer (2-ha) scale, with deciduous species predominating. State and federal inventories show oak-hickory types as primary forest cover over much of the Commonwealth, with species composition changing according to elevation and aspect. Mixed northern hardwoods comprise most forests in the northern Plateau areas. There are radical differences, however, in the condition of Pennsylvania landscapes between ecoregions.

Forest cover is lacking at both broad and fine scales over much of the Piedmont in southeastern Pennsylvania, as well as most of the larger valleys in the adjoining Ridge & Valley region. Forests in the Pittsburgh Low Plateau and Glaciated Pittsburgh Plateau of western Pennsylvania are quite fragmented. Integrity has been compromised in these landscapes to the degree that conservation stewardship areas are small and scattered.

Mapping of urban and suburban areas shows that 95% of Pennsylvania has rural land-use patterns involving forests and agriculture. Rural landscapes with predominantly herbaceous cover occupy approximately 25% of Pennsylvania. Intensive agriculture is particularly concentrated in the Piedmont and the broad valleys of the Ridge & Valley Region. Urbanization in the other 5% of Pennsylvania shows two patterns. One is expansion of suburban areas outward from urban cores. This pattern occurs around most of the major urban areas in Pennsylvania. The second pattern is one of residential and recreational developments in areas known for their forested environments and scenic quality. This pattern is especially evident in certain regions of northeastern Pennsylvania like the Poconos, but is also penetrating the forest in other areas as well.

Even though breakdowns by tree species composition are not provided, the Pennsylvania GAP land-cover maps should be of particular utility for incorporating conservation and maintenance of landscape integrity as considerations for regional planning and likewise for cooperative watershed stewardship. Given the problematic circumstances of Pennsylvania’s aquatic environments and the difficulty of establishing formal conservation areas in economic growth regions, cooperative watershed stewardship may be one of the better hopes for conserving aquatic biota and species having a strong habitat affinity for wetlands and water.

6.3 Conservation Stewardship Lands

Western Pennsylvania is notably under-represented with respect to conservation stewardship lands. This includes the Pittsburgh Low Plateau, the Glaciated Pittsburgh Plateau, and the Erie Lake Plain. The heavily developed Piedmont region in southeastern Pennsylvania likewise has a dearth of conservation stewardship lands. Conservation lands are also sparse over much of Glaciated Low Plateau region in northeastern Pennsylvania. In short, the corners of Pennsylvania are largely lacking in conservation stewardship lands. Since these are also areas of intensifying development, it becomes increasingly problematic to find substantial tracts that can serve as reserves. Thus, these are regions in which collaboration among conservation-minded landowners may be the best hope for maintenance of natural diversity.

Of the several categories of public land, national forest and the state forests have greatest regional concentration. State parks are intended to have a broad geographic dispersion across the Commonwealth so that they serve all of its citizens. State gamelands are also quite dispersed for similar reasons. Sites in the National Parks System have an irregular distribution, being mostly either recreational or cultural/historical in nature.

National forest, state forests, and state parks all have special areas dedicated primarily to conservation. These natural areas and wild areas represent most of Pennsylvania’s GAP status 1 lands, encompassing less than 1% of the entire Commonwealth.

Pennsylvania’s extensive state forests have recently undergone Green Certification for sustainability, and ecosystem management is emphasized in the new cycle of management planning. Pennsylvania’s state parks emphasize naturalistic cover and serve recreational rather than extractive purposes. Pennsylvania’s state gamelands exist to provide habitat that will support wildlife populations sufficient for hunting. Therefore, all of these lands have been ascribed GAP stewardship status 2. Such lands comprise approximately 80% of conservation stewardship area in the state, and slightly more than 12% of the entire Commonwealth.

Undesignated national forest land and national parks have both been assigned to GAP status 3 in Pennsylvania. This is because undesignated national forest lands have a rather broad management purview, and habitat is often incidental to stewardship of national parks. These lands comprise 14% of conservation stewardship lands in Pennsylvania, and a bit more than 2% of the state as a whole.

Conservancy lands have been treated as either GAP status 1 or status 2, depending upon the terms of land tenure.

6.4 Considerations for Conservation in the Commonwealth

The findings of the Pennsylvania GAP Project regarding vertebrate habitats are summarized first for taxonomic groups and then collectively. The “gaps” being studied in gap analysis are situations where landscapes containing important habitats are under-represented with regard to conservation stewardship areas. Nevertheless, there also emerge implications for conservation that are broader than the circumstances of particular gaps.

6.4.1 Mammals:

Since major conservation stewardship areas are predominantly in the upper quartile (top quarter) of our regional habitat importance index (RHII) for mammals, they are seen to be well located with regard to conserving this faunal component. This conclusion is reinforced by the upper quartile pattern outside the stewardship areas, being situated adjacent to and as connectors between the stewardship areas. This is consistent with the capability of most mammals to disperse over time, whereby the more ecologically sensitive species typically find habitat and refuge in large tracts of forest cover where fragmentation is minimal.

The leading landscapes for mammals likewise emerge as extensions of existing conservation stewardship areas or connectors between them. Improving conservation status of these leading landscapes would help to ensure the maintenance of habitat connectivity across substantial regions.

Ordination of mammal species according to RHII lends emphasis to eastern spotted skunk, evening bat, least shrew, rock vole, Indiana myotis, elk, Appalachian cottontail, northern water shrew, fisher, river otter, fox squirrel, least weasel, Allegheny woodrat, and snowshoe hare. From a purely spatial standpoint, the eastern mole is also highlighted; however, the latter species would not generally be deemed to merit special attention since its situation involves natural confinement by barriers of inhospitable soil. It is also doubtful whether the eastern spotted skunk actually remains a viable element of Pennsylvania’s mammalian fauna, and it would be an unlikely prospect for reintroduction. Elk, fisher, and otter have already become subjects of reintroduction programs. Therefore, Pennsylvania reveals no major gaps with respect to mammalian fauna, except for the need to protect the habitats supporting rare occurrences of species such as federally endangered Indiana myotis, evening bat, rock vole, and least shrew.

6.4.2 Birds:

The picture for avifauna is not nearly as simple as for mammals. The RHII approach tends to focus attention most strongly on areas having wetlands. It is noteworthy that the existing stewardship lands favor area-sensitive species because of the landscape matrix being predominantly intact forest habitat. Leading landscapes (outside current conservation areas) for birds emphasize regions containing wetlands, and particularly those associated with major river systems and large expanses of emergent wetlands.

Due to the much larger number of species and greater habitat specialization, the species ordination of birds with respect to RHII is too lengthy for listing in this summary and reference should be made to Table 5.2 in Chapter 5. The black-necked stilt at the top of the ordination is anomalous because it represents only a single pair known to nest regularly around a sewage treatment facility in southeastern Pennsylvania. The mute swan was analyzed as a regular breeder, but is not a component of natural diversity since it is an introduced species. It is notable that the majority of species in the upper quartile have a wetland affiliation of some kind. There are also several species associated with grassland habitats. Thus, it would seem that further conservation focus is warranted for avifauna in these landscape settings. This is consistent with the current listings of bird species of concern in Pennsylvania.

6.4.3 Amphibians:

The major concentration of stewardship lands in the northcentral portion of the state does not fit well with the distribution of crucial amphibian habitats as determined by the RHII approach, since the upper quartile of RHII is largely absent from that region. The Pittsburgh Low Plateau in southwestern Pennsylvania exhibits special importance for amphibians. This is also an area where human influence has become dominant at a broad landscape scale, but considerable localized naturalistic cover still remains. Since amphibians do not have a capacity for rapid long-distance dispersal, this is a region where collaborative conservation efforts can have an important role. This is also true for several other less expansive sectors in southcentral and southeastern Pennsylvania, as well as for an area near Lake Erie and another in the Glaciated Low Plateau region of the northeast.

Ordination of amphibian species with respect to RHII draws attention to the eastern mud salamander, southern leopard frog, green salamander, eastern spadefoot toad, ravine salamander, northern cricket frog, mudpuppy salamander, mountain chorus frog, and Appalachian seal salamander. These species should be accorded special emphasis in fostering conservation of wetlands and their environs.

6.4.4 Turtles:

For turtles, the RHII approach puts major emphasis on southeastern Pennsylvania along with portions of the Ridge & Valley. The western part of the state including the Pittsburgh Low Plateau, Glaciated Pittsburgh Plateau, and Erie Lake Plain is also important. Northeastern Pennsylvania also has two areas of emphasis with more limited extent. As with amphibians, the main body of stewardship lands in the northcentral area is not of particular significance for turtles. Ordination of turtle species with respect to RHII focuses on the map turtle, bog turtle, and eastern spiny softshell turtle. These species should be given careful consideration in promoting conservation of their respective environments.

6.4.5 Snakes and Lizards:

Conservation geography for snakes and lizards has a different pattern than for other groups of terrestrial vertebrates. Large areas of existing stewardship lands in the High Plateau and Deep Valleys regions have high RHII. Several existing stewardship areas in southcentral Pennsylvania also have emphasis in terms of RHII. Major portions of habitat emphasis areas, however, lie outside existing stewardship areas. In the central portion of the state, these leading landscapes tend to connect existing stewardship areas. In contrast, extensive leading landscapes in the Pittsburgh Low Plateau, Piedmont, and northeastern glaciated plateaus are set apart from substantial stewardship areas. Ordination of snake and lizard species in terms of RHII places emphasis on the broadhead skink, Kirtland’s snake, rough green snake, eastern massasauga, and eastern worm snake.

6.4.6 Fishes:

Even more so than for amphibians and turtles, the large body of stewardship lands in northcentral Pennsylvania is not located strategically with respect to fishes that are most in need of conservation attention. Some portions of the Allegheny National Forest are above average in this respect, but more are below. Likewise, most of the stewardship lands in southcentral Pennsylvania lack emphasis in terms of RHII. Importantly, the limited stewardship lands in the northwestern part of the state are better situated.

The Erie and Ohio River basins along with the eastern part of the Allegheny River basin are important areas with regard to conservation of fishes. Proximal watersheds for other major rivers like the Susquehanna are noteworthy as well. Western Pennsylvania takes precedence over the rest of the state with respect to leading landscapes for fishes. It comes as no surprise to those involved in fish conservation efforts that the French Creek drainage in northwestern Pennsylvania is a premier area. The ordination of fishes by RHII features many species at risk, with important elements appearing even halfway through the ranks of species (see Table 5.6).

6.4.7 Coincidence Among Leading Landscapes:

Mapping the number of groups with leading landscapes in a cell provides an overall indication of conservation importance for vertebrates in the local environment. This coincidence among leading landscapes (CALL) constitutes our first-order indicator of conservation relevance for landscapes of Pennsylvania. In other words, they are the primary gaps for Pennsylvania gap analysis. Areas of leading landscape for multiple groups should receive special consideration with respect to natural diversity. Figure 6.1 is a coincidence map of leading landscapes with boundaries of ecoregions and counties superimposed. It is noteworthy that major CALL areas tend to be situated along ecoregion boundaries where habitat diversity, speciation, and range limitation are likely to occur. By definition, leading landscapes are outside existing conservation stewardship areas.

A notable area of multiple leading landscapes occurs in the Western Allegheny Mountain region of the Appalachian Plateau in Westmoreland County. This area also has the ecological advantage of being proximate to existing conservation stewardship lands, thus, presenting an opportunity to help secure landscape integrity for the region. It consists primarily of lands on or adjacent to a ridge parallel to a more protected ridge to the east.

A pair of similarly advantageous areas having multiple leading landscapes is situated along opposite sides of the Great Valley on the borders of Cumberland County. Each of these areas would serve to extend existing conservation stewardship lands, thereby helping to secure landscape integrity for the region.

Another important case of compound leading landscapes adjacent to existing conservation stewardship area is found in Crawford County on the Glaciated Pittsburgh Plateau. This area is special for its inclusion of relevance to fishes. Important compound leading landscapes in this regard also occur on the Erie Lake Plain and in Butler and Allegheny Counties on the Pittsburgh Low Plateau.

Still other areas of strong coincidence among leading landscapes occur in Wyoming and Lackawanna Counties on the Glaciated Low Plateau, and in Montgomery and Bucks Counties on the Gettysburg-Newark Lowland of the Piedmont. The maps reveal other instances as well, such as that shared by York and Lancaster Counties on the Piedmont Upland.

The map depictions here are all at very small scale, making leading landscapes appear to be solid. Mapping at larger (more detailed) scale would show the leading landscapes to be quite perforated in many cases. Since this is a landscape level approach rather than a site approach, it may be appropriate to use GIS for putting a one-kilometer buffer on the leading landscapes as recorded in the PAKAGE database. The PAKAGE database is available through PASDA (http://www.pasda.psu.edu).


6.5 Landscape Perspectives for Conservation Stewardship Lands

Whereas the “leading landscapes” are defined to be outside existing conservation stewardship areas, buffered versions of the composite RHII layers used in determination of leading landscapes should also be informative for purposes of conservation planning inside stewardship areas. These layers are also incorporated in the PAKAGE database. Conservation planners have traditionally operated in terms of sites, whereas we contend that a landscape approach is also necessary to complement site-based work at broader scales. These layers can provide the conservation planner with a first approximation to the more important landscape sectors over which integrity must be preserved in the course of resource management.

The ordination of species based on RHII when used in conjunction with the maps should also alert resource managers to species that may deserve special accommodation within the scope of operations for Pennsylvania’s working landscapes. These two new informational resources from gap analysis should also serve to signal where coordination is needed between neighboring stewards of current or prospective conservation lands.

6.6 Looking Ahead

We feel that this gap analysis undertaking can contribute substantially to furtherance of habitat conservation in Pennsylvania if the informational resources generated will become part of the natural resource manager’s toolkit. We have not, however, provided corresponding support toward conservation of Pennsylvania’s flora in circumstances where human disturbance is sufficiently muted for natural communities to be expressed. This must become the next priority for continuing to broaden conservation perspectives at landscape scales. Our experience has shown that this would be a very expensive and arduous undertaking if done by mapping actual species composition of the vegetation canopy with reasonable accuracy. Given Pennsylvania’s strong physiographic influences, however, there is every reason to believe that suitability models could be formulated for plant communities in much the same manner as we have done for vertebrate species. Such strategy is under study in Wyoming GAP research. To help provide background in this regard, the Pennsylvania GAP Project has cooperated in landscape level ecological mapping of state forests (Myers 2000). The Bureau of Forestry has also undertaken direct mapping of plant community types (Fike 1999) on state forests through a combination of aerial photography and field reconnaissance. When these major endeavors are coupled with more ready access to U.S. Forest Service FIA data collected on an annual basis, the stage should be set for plant community modeling on a statewide basis.