Spatial and Temporal Variability of Macroinvertyebrate Communities in Vernal Pools on the Coastal Plain of Virginia PDF Download
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Author: Shrijeeta Ganguly Publisher: ISBN: Category : Languages : en Pages :
Book Description
Vernal pools are often defined as seasonal pools that typically are inundated beginning in the winter and then drying out completely in summer. Though evidence of spatial and temporal variability in the macroinvertebrate communities of vernal pools has been found in previous studies, it has not been studied extensively. The primary objective of this study was to determine the extent of variability in the macroinvertebrate communities within vernal pools closely situated in a forested landscape. An effort was made to explain this variability with respect to certain physiochemical environmental variables of the pools. Significant variability was observed in the macroinvertebrate communities within the vernal pools both spatially and temporally. Water temperature, as an indicator of seasonal changes, was strongly correlated with the observed variations. Higher species richness and diversity were observed in the pools in winter than in spring 2007. Chironomidae was the most diverse family (8 genera) occurring in these vernal pools. At the beginning of inundation, amphipods and copepods were more abundant. ß-diversity was low in both winter and spring 2007; a-diversity in winter was high and low in spring 2007.
Author: Shrijeeta Ganguly Publisher: ISBN: Category : Languages : en Pages :
Book Description
Vernal pools are often defined as seasonal pools that typically are inundated beginning in the winter and then drying out completely in summer. Though evidence of spatial and temporal variability in the macroinvertebrate communities of vernal pools has been found in previous studies, it has not been studied extensively. The primary objective of this study was to determine the extent of variability in the macroinvertebrate communities within vernal pools closely situated in a forested landscape. An effort was made to explain this variability with respect to certain physiochemical environmental variables of the pools. Significant variability was observed in the macroinvertebrate communities within the vernal pools both spatially and temporally. Water temperature, as an indicator of seasonal changes, was strongly correlated with the observed variations. Higher species richness and diversity were observed in the pools in winter than in spring 2007. Chironomidae was the most diverse family (8 genera) occurring in these vernal pools. At the beginning of inundation, amphipods and copepods were more abundant. ß-diversity was low in both winter and spring 2007; a-diversity in winter was high and low in spring 2007.
Author: Virginia C. Meyer Publisher: ISBN: 9781267240637 Category : Languages : en Pages :
Book Description
Vernal pools are ephemeral wetlands that form in depressions underlain with soils that include a water-restricting horizon. These depressions fill with water during the winter in Mediterranean-type climates, and then rapidly dry during the late spring. Vernal pools are diminished in California, due to habitat loss from land-use conversion. The biota endemic to vernal pool habitats includes many rare and endangered species. Creation of vernal pools has been used as mitigation since the mid 1980s. Whether creation can reliably result in vernal pools with the range of biotic characteristics found in natural vernal pools remains unclear. Evaluation of created vernal pool attributes that reflect ecological function over the long-term is needed to inform management of existing mitigation projects and the planning of future projects. The vegetation, hydrology, soils, and plant communities of created vernal pools were compared with natural vernal pools at three mitigation sites in the Great Valley of California that differed in climate and substrate. Vegetation attributes and parameters of hydrologic regime were measured in the first years following construction, and again when the created pools at each site were 12-14 years old. Soil samples were taken during the last year of the study to assess basic soil characteristics. Finally, plant communities of created vernal pools were identified during the last two years of the study period and compared with natural vernal pool communities. The values of vernal pool species attributes increased with increasing maximum water depth and period of inundation. Fluctuations and downward trends in the values of vernal pool species attributes correlated with increased exotic species cover, and exotic species cover was highest in years of lowest annual precipitation. Trends of decreasing maximum water depth, inundation period, and vernal pool species cover, as well as increasing exotic species cover, correlated with release from cattle grazing at two sites. At a third site where light-to-moderate grazing occurred, vernal pools species attributes of created pools matched or were higher than those of natural pools, and maximum water depth was higher in created than in natural pools throughout the study period. Thus, grazing may be of primary importance in the ability of created vernal pools to maintain hydrologic function and vernal pool species attributes over the long-term. Soil texture, color, bulk density, and redox concentrations did not differ between created and natural pools. However, differences in soil pH and depth to hardpan were found between created and natural vernal pools. Natural vernal pool plant communities were found in created pools at two sites, but were those of deeper, longer-inundated habitats compared to the natural pools on-site. This may lead to a greater proportion of deeper, longer-inundated vernal pool habitats over time with continued use of creation as mitigation. Only one natural vernal pool community was identified at one site, where most created pools supported exotics-dominated, non-wetland communities. Site characteristics and management practices of mitigation projects lead to differences in outcomes in ecological function in created vernal pools.
Author: Michael A. Plenzler Publisher: ISBN: Category : Forest canopies Languages : en Pages : 159
Book Description
Vernal pools are temporary wetlands and local-scale biodiversity hot spots for a variety of amphibians, macroinvertebrates, and plants because their seasonal drying prevents the establishment of predatory fish populations. Vernal pools are often of conservation concern because of the amphibian populations; however, the emphasis on these organisms often eclipses the macroinvertebrates, which are important predators, prey, and nutrient cyclers in wetlands and the surrounding habitat. Hydroperiod and water chemistry are thought to be the primary regulators of vernal pool macroinvertebrates, but the surrounding habitat also affects these organisms. Specifically, canopy cover and forest composition can alter the autochthonous and allochthonous carbon sources for wetland food webs. My research objectives were to understand how variations in these factors affect macroinvertebrate diversity and community composition. In 2009, I conducted a field survey of fifteen vernal pools that varied in area, depth, hydroperiod, canopy and surrounding land use. I measured several habitat conditions, assessed the biotic communities of these wetlands, and found that canopy cover influenced bottom-up productivity and macroinvertebrate diversity. I used the results of this study to determine how known macroinvertebrate communities respond to variation in canopy cover in mesocosm wetlands. The low canopy treatments sustained the highest macroinvertebrate abundance, family richness, and Shannon diversity, as greater algal productivity increased resources available to support the macroinvertebrate communities. I conducted a second mesocosm experiment to explore how variation in canopy cover (low or high) and litter species (oak, maple, or a mixture of the two litters) affect vernal pool macroinvertebrates. Macroinvertebrate abundance and family richness were greater under low canopy and with oak litter, but the effects of canopy often depended on litter species. Canopy limits the amount of light that reaches a wetland, but litter and its impact on dissolved organic carbon (DOC) limit light transmittance and producer communities. Because forest composition and structure are changing from anthropogenic activities, these results suggest they will also alter the food webs of vernal pools. However, as some organisms utilize pools considered to be low quality for macroinvertebrates, vernal pools should be protected in a variety of habitat contexts to preserve regional species diversity.
Author: Shrijeeta Ganguly
Author: Shrijeeta Ganguly
Author: Leonard Sandin
Author: Jeff A. Yockey
Author: Anne Boschen Wright
Author: Betsy Ray Leppo
Author: Heikki Mykrä
Author: Virginia C. Meyer
Author: Rosemary E. Laird
Author: Michael A. Plenzler
Author: Holly S. Houtz, 1981-