Ecosystem management

In recent decades, ecohydrology has received renewed attention because of the impacts of groundwater withdrawal on ecosystems. Growing population and urban expansion in Palm Beach County, FL. place pressure to eradicate natural areas, such as Florida scrub habitats, and increase groundwater withdrawal. This study presents preliminary results of soil and hydrological characterization of an ecological preserve surrounded by changing land use. Soil moisture and water levels were monitored to assess the effects of precipitation as influenced by plants and soil analysis determined the suitability of current soil conditions for hosting native vegetation habitats. Hydrologic and soil conditions on the preserve fall within values expected for native Florida scrub habitats. Hydrologic response to precipitation varied due to factors including antecedent conditions and vegetation types. These results provide a better understanding of the interactions between soil proper ties, hydrologic cycle, and plants, and assist with establishing a baseline to monitor changes over time.

Shortened periods of inundation due to water management have led to the encroachment and expansion of Carolina willow (Salix caroliniana) in sawgrass (Cladium jamaicense) marsh communities. Morphologic and physiologic differences between sawgrass and willow have potential consequences for microhabitat conditions and ecosystem function such as a reduction in temperatures and light availability and changes in primary productivity. Since it is a woody shrub, willow is often assumed to exhibit higher rates of transpiration than non woody plants, which in turn can affect photosynthesis and carbon exchange and ultimately wetland water management. In this study willow was found to have higher rates of stomatal conductance (gs) and photosynthesis (Anet) than sawgrass. However, sawgrass had greater intrinsic water use efficiency (WUE) than willow. This suggests that willow is capable of greater gas exchange and carbon assimilation than sawgrass but requires more water. Understanding the implications of willow expansion will improve landscape models of wetland water and carbon exchange and inform water management decisions.

Changes in vegetation may influence the quality and quantity of the underlying
organic peat soils and have impacts on faunal populations. My goal was to determine
whether shifts from native slough communities to invasive cattail in the Florida
Everglades could affect peat characteristics that could cascade to impact the dry season
survival of crayfish (Procambarus fallax). I contrasted peat soils from native slough and
cattail-invaded sites as alternative dry-season burrowing substrates for crayfish. Cattail
peat had higher average bulk density and inorganic content within the first ten
centimeters of the soil profile. Crayfish showed marginally greater initial burrowing
success in slough peat than in cattail peat but survival was equivalent in both peat soils
and high overall. Understanding these indirect linkages between vegetation and crayfish
populations in the Everglades can provide insight on the consequences of plant invasion
on ecosystem trophic dynamics.

The viability of the eastern oyster, Crassostrea virginica, is designated as an ecological performance measure for the management of freshwater inflows to the St. Lucie Estuary, Florida. Thus, oysters derived from the St. Lucie Estuary were tested for their physiological response to stress, measured as altered condition index and RNA/DNA ratios, resulting from changes in salinity and infection by the protozoan parasite Perkinsus marinus, the agent of Dermo, a common oyster disease. Pilot studies consisted of the development of a real-time PCR-based assay for P. marinus infection, procedures to infect oysters with the pathogen by injection method and procedures for the measurement of RNA/DNA ratios. The general experimental design was to assess the response of non-injected and injected C. virginica to low salinity challenges. Two scenarios for salinity stress were tested: one in which oysters were subjected to a single reduction in salinity and one in which an initial reduction in salinity was followed by a recovery phase and then subjected to a second challenge of reduced salinity. Condition index was more responsive to changes in salinity regimes than to P. marinus infection. Changes in the RNA/DNA ratio were responsive to the infection status, but not changes in salinity; the pattern of change in the RNA/DNA ratio generally followed changes in the measured levels of infection. The lack of mortalities showed that these oysters were able to tolerate short periods of reduced salinity.

Old World Climbing Fern, Lygodium microphyllum is an aggressive nonindigenous plant that is on the verge of becoming a major ecological threat in South Florida. Currently, specific habitat characteristics that contribute to success or failure of its establishment are unknown. I studied the pattern of distribution of the fern in Florida's Big Cypress Swamp. Two similar forested wetland sites with high incidence of L. microphyllum infestation were assessed in order to identify broad-scale hydrological and physiographic conditions that may favor high susceptibility to L. microphyllum invasion. On each site, species richness, abundance and distribution of herbs, shrubs and trees were characterized. In addition, several parameters including elevation, substrate depth, percentage substrate water content, percentage substrate organic content, substrate texture, and photosynthetically active radiation were quantified. The patterns of distribution of L. microphyfum indicated that presence of the fern was dependent on relatively low elevation, relatively deep substrate and moderately high substrate water content.

The Regeneration of Nature: an alternative to ecological restoration is an exploration of the human response to alterations society has imposed on natural ecosystems. Ecological restoration is the dominant response to these degraded systems that has emerged within Western, empirical thought. Restoration as it is characteristically practiced in the United States attempts to reverse human impact by returning an ecosystem to an earlier state of existence; its so called pre-disturbance condition. However, I argue that ecological restoration does not adequately address degraded ecosystems dominating today's landscape primarily because it excludes humans as an integrated part of ecosystems and it ignores the dynamic characteristics of nature. Despite the dichotomy embedded in the restoration view, humans and nature are best understood as interdependent. Therefore, those working on urban environmental issues must develop integrated solutions in which both society and nature benefit without creating negative impacts on each other. In The Regeneration of Nature: an alternative to ecological restoration , I show how the connections between science, society, and nature can be recognized as an integrated view to establish a new paradigm for positive change within communities, both natural and human. The new paradigm, which I entitle ecological regeneration, extends the interdisciplinary style of environmental research as it calls for the development, adoption, and dissemination of a truly integrated and dynamic socio-ecological model to replace the static and reductionist view that prevails within the ecological restoration model. Where restoration treats the human and natural environments as mutually exclusive, regeneration recognizes the necessity of integrating human built systems within nature and nature within built systems. By examining conceptual and practical problems within ecological restoration, my goal is to offer an ecological regeneration framework leading to theoretically better solutions with respect to society's impact on natural ecosystems. The vision I offer here of regenerating nature within the built environment is intended to help fellow scientists, non-scientists, and the general public pursue an environmentally accountable and socially responsible prospect.

Pixel based and object based vegetation community classification methods were performed using 30 meter spatial resolution Landsat satellite imagery of the Arthur R. Marshall Loxahatchee National Wildlife Refuge (Refuge), a remnant of the northern Everglades. Supervised classification procedures using maximum likelihood and parallelepiped algorithms were used to produce thematic maps with the following vegetation communities : wet prairie, sawgrass, cattail, tree island, brush, aquatic/open water. Spectral data, as well as NDVI, texture and principal component data were used to produce vegetation community classification maps. The accuracy levels of the thematic maps produced were calculated and compared to one another. The pixel based approach using the parallelepiped classification algorithm on the spectral and NDVI dataset had the highest accuracy level. A generalized form of this classification using only three vegetation communities (all wet prairie, tree island/brush and aquatic/open water) was compared to a previously published classification which used 1987 SPOT imagery in order to extract information on possible vegetation community transitions that are occurring within the Refuge. Results of the study indicate that 30 meter spatial resolution may be useful for understanding broad vegetation community trends but not species level trends. Pixel based procedures provide a more accurate classification than object based procedures for this landscape when using 30 meter imagery. Lastly, since 1987 there may be a trend of tree island/brush communities replacing wet prairie communities in the northern part of the Refuge and a transition to wet prairie communities in place of tree island/brush communities in the southern portion of the Refuge.

Oyster reefs are biodiverse communities that provide many ecological and commercial benefits. However, oyster reefs have declined around the world from human activities. Oyster reef restoration programs have begun to limit some of the decline, but the need for determining the success of a program has been problematic. Passive acoustic techniques can use naturally occurring sounds produced by organisms to assess biodiversity. Passive acoustics was utilized to compare the sounds in natural and restored oyster reefs, with special attention on snapping shrimp (Alpheus spp.) snap sounds, in the St. Lucie Estuary, Florida over a one year period. Season, estuary region, habitat and day period had an effect on sound production. Passive acoustic monitoring of snapping shrimp sound production may be a useful non-destructive technique for monitoring the progress of oyster reef restoration projects once further correlations are established between environmental effects and sound production.

Shrimp mariculture expansion in developing countries has been criticized for its ecological destruction and the resulting social conflicts. In Ecuador, shrimp pond development particularly affects rural, coastal communities. This study addresses the environmental and social effects of shrimp farming in two Ecuadorian villages, Muisne and Bunche. Interview and survey responses indicate that locals have an overall negative view of the industry. In some instances, such as increased class marginalization through reduced access to subsistence collection areas, shrimp farming directly results in conflict. However, the data also demonstrates that ponds are only one of various stressors on mangrove ecosystems. Furthermore, mariculture provides benefits to the community, including increasing employment opportunities, the local economy, and shrimp availability. In spite of these benefits, local negative perception suggests modifications to existing regulations and educational programs are necessary to minimize impacts and help the community understand the multiple factors affecting their ecosystem and livelihoods.

The Florida Fish and Wildlife Conservation Commission lacks a viable method for monitoring woody vegetation in expansive wetland communities, such as the Florida Everglades. This study used aerial photographs of Rotenberger Wildlife Management Area in southeastern Palm Beach County, Florida to develop techniques for remotely monitoring changes in woody vegetation. Imagery from 2006, 2008, and 2010 were classified into woody and non-woody categories using Adobe Photoshop's Magic Wand Tool. Selection was performed with a bias toward over classification, as project objectives required identifying as many trees as possible. Classified pixels in Time 1 within 4 feet (2 pixels) of classified pixels from Time 2 were considered the same canopy. Overall accuracy for the study was 98%.