Effects of Wetland Spatial Patterns and Human Activities on Wetland Habitat Quality

Wetlands are transitional ecosystems between aquatic and terrestrial ecosystems. They are among the most productive and diverse ecosystems and make a critical part of larger ecosystems. Functional wetlands provide numerous significant environmental, social, and economic benefits and services. However, wetlands are probably the most threatened ecosystems on Earth. The ability of wetlands to function is increasingly threatened by the direct and indirect impacts of human disturbances. From the mid-1950s to the mid-1970s, agricultural drainage of wetlands was responsible for 87 percent of the United States' wetland losses. Since 1780, Florida lost more wetland acreages than any other state.This dissertation research investigated the association between Wetland Habitat Quality (WHQ), wetland patterns, and anthropogenic disturbances from the landscape ecology perspective. Statistical and spatial models are used to analyze these associations and to predict WHQ. The study area is a landscape typical of Florida's wetland and agriculture interface that is also subject to mining activities. The first chapter of this study is a literature review of fundamental concepts such as wetland (definition, importance, function, ecological services, their condition in the world and the United States), landscape ecology (island biogeography, landscape mosaic, and landscape patterns), habitat quality, and anthropogenic disturbances (agricultural activities and roads). Furthermore, this chapter explores how the spatial configuration of the most common human disturbances influences the habitat quality of the nearby wetlands in a landscape of wetland-farmland interface. The second chapter explores two objectives of this research on how wetlands spatial patterns (measured by selected landscape pattern metrics) and the landscape matrix composition influence WHQ. The first Objective results show that WHQ is strongly associated with some spatial characteristics of wetland patches, such as area. Some other spatial characteristics that were expected to be strongly associated with individual patches WHQ showed a small to no meaningful association. The results of multiple variable stepwise analysis showed that the best subset of available data explaining the variation of WHQ is wetland type, core area index, and the contiguity index. The second objective's results show that local adjacency and distance to anthropogenic disturbances (or natural and semi-natural landcovers) significantly impact WHQ. Overall, chapter two shows the significant impact of landscape's spatial configurations on wetland habitat conditions. However, these impacts are widely overlooked in Florida's environmental policies and regulations. The third chapter aims to develop a predictive WHQ model called WPM (Wetland Habitat Quality Predictive Model) based on a combination of landscape patterns and projection of nearby developed lands anthropogenic disturbance intensity. The proposed WPM can serve as a US Environmental Protection Agency (EPA) National Wetland Condition Assessment (NWCA) Level I Landscape Assessment tool. WPM uses a thermodynamic base approach in a sense that human disturbance intensity is mainly inferred by the nonrenewable energy consumption rate to maintain a specific type of human activity. The model was built by interpolating the disturbances imposed on wetlands from nearby human disturbances and based on the wetland’s shapes and distance to the sources of disturbances, where the previous chapter supported the selection of variables. The model was built using cokriging geostatistical interpolation methods. The results showed that WPM provides a more accurate prediction of WHQ compare to the traditional thermodynamic methods used by Florida’s environmental agencies for decades. Overall, the entire dissertation work enriches the research on modeling and predicting wetland qualities using landscape ecology measures as well as other spatially calculated indicators, as mentioned in the last conclusive chapter. This study bridges the two relatively separated research fields, one being landscape ecology at the broader spatial scale and the other precision habitat evaluation at the micro-scale. For the latter, the novel WHQ dataset used in this study consists of a high-quality ecological field study of 899 wetlands collected and confirmed by expert wetland biologists and ecologists. Such datasets have been rarely used in conjunction with pattern metrics usually applied to broader-scale landscape patterns. This interdisciplinary study is unique in terms of the integration of knowledge gained in physical geography, biology, ecology, information sciences, and environmental administration. Environmental managers and policymakers benefit from quantitative assessment of habitat quality, which provides a knowledge base for managing or conserving wetland habitats. The accuracy and precision of the landscape-level wetland assessment method proposed in this research is significantly better than the methods traditionally used in Florida. This Research’s results are beneficial to environmental managers as a decision support tool for the numerical evaluation of different anthropogenic disturbances scenarios based on the spatial configuration of human-nature systems. Scholars and environmental managers can use this study's numerical models as an extra layer of information for investigating habitat connectivity and land suitability models.