1 CHAPTER I

Literature Review

The Ouachita Mountains and the Ozark Plateau compose a unique isolated upland area known as the Interior Highlands (Atwood 1940). The region consists of over 80,000 km2 of mountainous relief, which is topographically and geologically similar to the Appalachian Mountains (Dowling 1956). The Ouachita Mountains are made up of a series of east- west trending ridges and valleys that lie between the Gulf Coastal Plain to the south and the broad Arkansas River valley to the north. This portion of the uplift averages 80-90 km in width and is more than 300 km long, extending from Atoka County, Oklahoma, to near Little Rock, Arkansas (Fig. 1). Elevations range from 150 to 760 m. The Ouachitas are made up mostly of sedimentary rocks: sandstone, limestone, and conglomerate, along with metamorphic rocks such as shale and chert (Mohlenbrock 1993). Soils are predominately silty clay and silty loam and are very shallow and stony on the ridgetops, becoming progressively deeper downslope. These soils are of medium texture and are moderately permeable (Reagan 1974).

Climate

Historically, climate has played an important role in the maintenance of faunal assemblages in the Interior Highlands. In the past, dry cycles have dominated the southwestern United States, but they have been moderate in this region due to its relief and geographic proximity to northern glaciers (Dowling 1956). Presently the Ouachita Mountains receive >127 cm of annual precipitation (Webb 1970). Average daily temperature in the region is near 15o C (United States Department of Agriculture 1982).

Biogeography

Several factors contribute to the unique fauna and flora of the Interior Highlands. (1) Unlike the southwestern United States, the Interior Highlands were not covered by shallow inland seas during the Cretaceous period (Dowling 1956) and served as an island refuge for species. (2) The 2 region also may have served as a refuge for plants and animals during the Pleistocene epoch when glaciers covered adjacent northern regions (Dowling 1956). (3) During the late Cenozoic era, sediments that were deposited by inland seas were eroded, further defining boundaries and isolating the uplift. (4) Finally, during the Pleistocene, the river systems were formed (Dowling 1956). The formation of the Arkansas River divided the region into the Ozark Mountains to the north and the Ouachitas to the south. The Ozarks are drained by the Fourche Maline-Poteau River of the Arkansas drainage and the Ouachitas are drained by the Kiamichi River of the Red River drainage. The topographic and climatic situation that exists in the Ouachita uplift has created a unique habitat which supports a rich flora, including more than a dozen endemic plant species (Mohlenbrock 1993). The herpetofauna is likewise rich with high species densities of both reptiles and amphibians (Kiester 1971). Most reptile species are less confined by ecological factors than some other taxa. For this reason, reptile faunal assemblages are more or less representative of adjacent regions and no endemic species are found within the uplift. Frogs and toads, which are relatively mobile, also are not represented by endemic forms. Salamanders, however, are represented by five or more endemic species, and several distinct endemic subspecies (Connant and Collins 1991). Many of the endemic species that are found in the Ouachitas are relatively uncommon and in some cases are considered threatened due to their limited distributions or low population densities. The following species likely to be found in the region are considered by Ashton (1976), Black (1977) and Reagan (1974) to be rare or threatened:

Amphiuma tridactylum, three-toed amphiuma Ambystoma annulatum, ringed salamander Ambystoma talpoideum, mole salamander Plethodon ouachitae, Rich Mountain salamander Plethodon caddoensis, Caddo Mountain salamander Hyla avivoca, bird-voiced tree frog Cemophora coccinea, scarlet snake Terapene ornata, ornate box turtle

Silvicultural Effects 3

Topography in the mountainous areas of the Ouachitas is often too steep for intensive agricultural use. This has led to a local economy which is heavily reliant upon livestock, poultry production, and a large timber industry. Even-aged silviculture employing clearcutting, site preparation, and planting of pines has been the primary method of pine regeneration on southern national forests for the last 25 years. Although young pine plantations provide excellent habitat for many wildlife species adapted to early successional stages (such as deer, rabbits, and quail), even-aged management on short rotations, as typically practiced by the forest industry, is generally detrimental to those species that require an abundance of snags and cavity trees, hardwoods, hard mast, large down woody material, and other mature forest habitat features (Thill 1990). It has been shown that some reptiles, and especially amphibians, require these habitat components; e.g., oak-hickory habitats supported greater numbers of amphibians than nearby managed pine habitats in South Carolina (Bennett et al. 1980). Similarly, Enge and Marion (1986) found that clearcutting and site preparation in Florida had a negative overall impact on reptile and amphibian numbers and on reptile species richness. The decrease in numbers of amphibians in heavily treated areas was primarily due to reduced reproductive success in certain species such as Scaphiopus spp., Rana sphenocephala and Gastrophryne carolinensis. A low number of young-of- the-year were noted during the study, which may have been due to the early disappearance of standing water in clearcut areas before young anurans could metamorphose. In another study, occurrence and longevity of intermittent ponds and streams during winter strongly affected presence and numbers of amphibians in managed stands (Whiting et al. 1987). Clearcutting causes changes in soil structure, hydrology, and both horizontal and vertical vegetation structure that subsequently affect temperature and moisture regimes. These altered characteristics in turn affect microhabitats that are important to amphibians (Ash 1988; Bury 1983; Heatwole and Lim 1961; Heatwole 1962; Matlack 1994; Pechman et al. 1991; Pough et al. 1987). Also, the water quality of streams may be degraded by increased sedimentation. These changes in microclimatic conditions on the forest floor and the erosion of stream quality are in part facilitated by canopy removal, elimination of the moisture-retaining forest 4 floor litter, and soil compaction (Bratton 1994; Bury 1983; Raymond and Hardy 1991). Contemporary logging practices have also altered the spatial and temporal disturbance regimes of forest ecosystems (Bratton 1994). Pough et al. (1987) suggested that small scale modifications to a forest may have little effect on salamander populations; after clearcutting, however, return of Plethodon cinereus was slow due to inadequate litter accumulation, which appeared to be a prerequisite for colonization. In general, deciduous leaf litter seems to be a very important habitat requirement for many terrestrial salamander species. Deciduous leaf litter retains moisture that plays a significant role in the distribution and activity patterns of terrestrial salamanders (Jaeger 1971). Pure stands of conifers are generally unsuitable for salamanders in the eastern and central United States (Bennett et al. 1980; Pough et al. 1987; Williams and Mullin 1987). In loblolly-shortleaf pine (Pinus taeda and P. echinata) stands of east Texas, Whiting et al. (1987) found that understory development and the degree of deciduous litter accumulation strongly influenced herpetofaunal communities. Petranka et al. (1993) compared clearcuts <5 years old with mature stands >80 years old and found that terrestrial salamanders were completely eliminated or reduced to very low numbers after the mature forest was cut. Petranka et al. estimated that 75-80% of salamanders from a variety of taxonomic groups are lost following timber harvest by clearcutting. Furthermore, it is estimated to require a century or more for populations to return to predisturbance levels following clearcutting (Petranka et al. 1994). There is concern that this reduction could produce population bottlenecks that result in decreased genetic diversity. In some cases local populations may be prone to extinction. On a regional scale, survival of a reduced population depends upon recolonization through immigration from undisturbed areas (Fahrig and Merriam 1994). Constraints on such immigration, however, are that (1) salamanders generally only migrate under a narrow set of environmental conditions, (2) migrating individuals may have difficulty establishing territories in new areas due to interspecific competition with other herps, and (3) adult salamanders are often strongly philopatric (Petranka et al. 1993; Petranka 1994). As a result of these factors, recolonization of heavily disturbed areas is slow. As with amphibians, differences in reptile species richness and 5 community composition have been observed between different age stands (Enge and Marion 1986; Whiting et al. 1987). These differences can in part be attributed to the disappearance of three arboreal lizard species following clearcutting. Furthermore, reduction of these three species, Anolis carolinensis, Eumeces fasciatus, and Eumeces laticeps, was thought to have diminished the foodbase available to certain snakes (Enge and Marion 1986), negatively affecting the snakes. Populations of some reptiles increase in response to clearcutting. This may be due to increased abundance of certain types of prey as well as the creation of favorable microhabitats or refugia (Enge and Marrion 1986). Cnemidophorus sexlineatus, a cursorial lizard that prefers open sandy areas, was favored in the most intensively-treated clearcut sites (Enge and Marion 1986). Several grassland species also seemed to favor very young plantations (Whiting et al. 1987): Thamnophis proximus, Masticophis flagellum, Lampropeltis calligaster, and L. getula. Evidence suggests that clearcutting is followed by increases in small mammal densities and community diversity (Atkinson and Johnson 1979; Kirkland 1977; Kirkland 1990). This may in turn provide a greater food base for snake species that feed primarily on small rodents. In summary, various factors have a major influence on reptile and amphibian community composition and relative abundances. For amphibians, availability of water and ground cover seem to be the most important; however, these factors are not independent of other habitat characteristics such as overstory composition. Reptile community composition is reliant on understory and overstory development as well as the presence of large down woody material. Some reptile species also seem to be particularly dependent upon the presence of various prey, which are indirectly affected by other habitat characteristics. All of the habitat characteristics that determine herpetofaunal community composition are ultimately dependent upon the age of the forest and the degree of disturbance to which it has been subjected. Reptiles and amphibians are important components of the food chain and contribute a surprising amount of biomass to the community (Burton and Likens 1975; Pough et al. 1987). For example, population densities of Plethodon cinereus in the deciduous forests of the eastern United States have been recorded as high as 0.9-2.2 individuals/m2 (Heatwole 1962; Jaeger 1980). Furthermore, because amphibians are often habitat specialists with restricted distributions, they may be valuable indicator species to reveal the 6 overall health and stability of the ecosystem. Despite the evidence that reptiles and amphibians are important components in many ecosystems, these groups continue to be neglected by land managers (Pough et al. 1987). Some management plans may even promote mid-successional stages to maximize alpha diversity of other taxa at the cost of sensitive reptile and amphibian species (Faaborg 1980; Sampson and Knopf 1982). Recently, public awareness of the importance of the wildlife community as a whole has lead to the concern for nongame wildlife and their habitats (Jones 1986).

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