Comparison of Vertebrate Communities of Coralville Reservoir and Cone Marsh, Iowa

The vertebrates in communities comprising a habitat with unpredictable water levels (the Coralville Reservoir) were compared to those present in communities comprising a habitat without severely fluctuating water levels (Cone Marsh). From data on the species of vertebrates and their relative abundance, it was determined that extensive ecosystem simplification had occurred in communities along the Coralville Reservoir. The major characteristics of this simplification were the following: 1) several species with similar modes of feeding were present at Cone Marsh but only species with generalized food habits were present along the Coralville Reservoir; 2) species at the top of food chains often were very rare or absent in communities along the Coralville Reservoir flood plain, and 3) food chains that were dominant at Cone Marsh often were less important on the Coralville Reservoir flood plain. On these characteristics is based the following hypothesis of ecosystem simplification: 1) a massive trophic simplification and reduction in the number of species present; 2) alterations in the trophic structure so that major food chains are different; 3) the replacement of specialized species by more generalized species capable of adapting to the environmental stresses imposed; and 4) severe reductions in, or elimination of, top trophic levels, which eliminates a mechanism for binding together communities in the same habitat

The Vertebrate Fauna of the Cayler Prairie Preserve, Dickinson County, Iowa

The vertebrate fauna of the Cayler Prairie Preserve, Dickinson County, Iowa, has been compiled from field observations and study between 1971 and 1974. Seventy-two species, including four amphibians, seven reptiles, 35 birds, and 26 mammals, were recorded. The diverse fauna results from the variety of habitats contained in the preserve, as well as the size of the preserve. One key member of the fauna is the badger (Taxidea taxus), which creates microhabitats favorable for small vertebrates while digging for ground squirrels. Few adventive vertebrates have successfully invaded the prairie, and the fauna represents a sizable fragment (larger vertebrates are absent) of the fauna typically associated with tall-grass prairies

Predicting severe wildfire years in the Florida Everglades

© 2003 The Ecological Society of America. Wildfires result in important ecological benefits to many ecosystems, but have costs associated with fire fighting and property loss. Accurate, timely forecasts of the severity of upcoming wildfire seasons could facilitate wildfire management, limiting the most destructive aspects of fires, while preserving their ecological benefits. We demonstrate an approach where time series models are used to predict the severity of the wildfire season in Everglades National Park in southern Florida 3 months and 1 year beforehand. Model predictions contained all obserations within a 90% credible interval and also anticipated severe wildfire seasons. These models may be used to implement more ecologically sound wildfire management

Conservation and restoration of the Pinus palustris ecosystem

The well-documented decline of the Pinus palustris ecosystem has resulted from several anthropogenic influences, such as forest clearing (e.g. pine plantation forestry, agriculture) and urban development, both of which are closely related to increases in human populations. Other impacts have arisen from alterations in disturbance regimes responsible for maintaining the structure and function of these ecosystems. Restoration and management of degraded pine savanna ecosystems is critical. Identification of ecological processes that determine the structure and function of the intact system are important because successful restoration efforts should be based on sound scientific understanding. In this paper, we introduce this special issue on the ecology, conservation, and restoration of the Pinus palustris ecosystem. Some global climate change scenarios have suggested that future changes may occur that alter frequency and severity of disturbances such as fires and hurricanes. Such changes may have large effects on pine stands, and ultimately entire Pinus palustris savanna ecosystems, thus presenting further challenges to their sustainable management

Short-Term Effects of Shrew Predation Upon Invertebrate Prey Sets in Prairie Ecosystem

During August of 1971, the effects of different densities of shrews (Sorex cinereus) upon the density and species composition of invertebrate prey sets on two prairies in northwestern Iowa were studied. Invertebrates were sampled using pitfall traps set on areas containing known shrew densities. In general, different levels of shrew predation produced certain differences in the prey sets. Increased shrew density was associated with the following prey set characteristics: 1) decreased numerical densities, but not the total biomass of prey sets; 2) decreased species dominance of prey sets; and 3) increased species diversity of the largest prey size subsets of the total prey set. These observed effects of shrew predation are short-term effects which are typical of keystone predators

Small-scale fuel variation alters fire intensity and shrub abundance in a pine savanna

Small-scale variation in fire intensity and effects may be an important source of environmental heterogeneity in frequently burned plant communities. We hypothesized that variation in fire intensity resulting from local differences in fuel loads produces heterogeneity in pine savanna ground cover by altering shrub abundance. To test this hypothesis, we experimentally manipulated prefire fuel loads to mimic naturally occurring fuel-load heterogeneity associated with branch falls, needle fall near large pines, and animal disturbances in a frequently burned longleaf pine (Pinus palustris) savanna in Louisiana, USA. We applied one of four fuel treatments (unaltered control, fine-fuel removal, fine-fuel addition, wood addition) to each of 540 (1-m2) quadrats prior to growing-season prescribed fires in each of two years (1999 and 2001). In both years fuel addition increased (and fuel removal decreased) fuel consumption and maximum fire temperatures relative to unaltered controls. Fuel addition, particularly wood, increased damage to shrubs, increased shrub mortality, and decreased resprout density relative to controls. We propose that local variation in fire intensity may contribute to maintenance of high species diversity in pine savannas by reducing shrub abundance and creating openings in an otherwise continuous ground cover. © 2006 by the Ecological Society of America

Fuel composition influences fire characteristics and understorey hardwoods in pine savanna

Fuels in the groundcover of frequently burned south-eastern pine savannas include shed leaves of trees. Flammable needles of longleaf pine (Pinus palustris) potentially increase maximum fire temperatures and durations of heating, negatively affecting other trees within the groundcover. Less flammable leaves that accumulate around the bases of understorey stems of hardwood trees such as mockernut hickories (Carya alba) in the fall potentially depress maximum fire temperatures and durations of heating, enhancing post-fire recovery. We experimentally manipulated amounts of pine and hickory leaves beneath understorey hickory stems in a pine savanna, measured temperatures during prescribed fires and assessed combustion of fuels and survival and regrowth of hickory stems. Pine needles increased fire temperatures and durations of heating relative to herbaceous fuels and increased combustion of hickory leaves. Hickory leaves, however, neither increased nor decreased fire characteristics relative to herbaceous fuels. All hickories survived fire by resprouting. When pine needles were absent, most hickories resprouted from buds located above-ground along the stem at heights inversely related to temperature increase. In contrast, resprouting occurred only from underground root crowns when pine needles were present. Such differences in locations of resprouts influenced sizes of stems at the end of the growing season. Synthesis. Groundcover fuels containing flammable leaves shed by pyrogenic species of savanna trees affect local fire characteristics and resprouting of non-pyrogenic understorey trees. Thus, local variation in flammable fuels produced by pyrogenic species can engineer landscape dynamics of other trees in savannas. © 2012 The Authors. Journal of Ecology © 2012 British Ecological Society

A climate-based approach to the restoration of fire-dependent ecosystems

Recurrent fires are integral to the function of many ecosystems worldwide. The management of fire-frequented ecosystems requires the application of fire at the appropriate frequency and seasonally, but establishing the natural fire regime for an ecosystem can be problematic. Historical records of fires are often not available, and surrogates for past fires may not exist. We suggest that the relationship between climate and fire can provide an alternative means for inferring past fire regimes in some ecosystems. © 2005 Society for Ecological Restoration International