How disturbing: humans are intertwined with ecosystem health. A study of the effects of human disturbance on soil health, aboveground biomass, and species community makeup in tropical and subtropical systems
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2024
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Anthropogenic, or human, disturbances have shaped the way the natural world functions for thousands of years. Today, climate is changing faster than ever before, global biodiversity is declining at an alarming rate, and our natural resources are depleting. While we still need to feed the growing population, we also need to conserve and restore the land to coexist with all other species. Is there an achievable balance between both of these objectives? Here I tested a community ecology concept, applying the intermediate disturbance hypothesis (IDH) to understand how soil health, tree and shrub community makeup and aboveground biomass shifted with anthropogenic disturbance across land use types. I measured the level of anthropogenic disturbance within each land use type to better understand how our actions differ across thelandscape and affect these outcomes. I developed an anthropogenic disturbance index that could be applied to the land use types at our study sites including Maui, Hawaiʻi, Puerto Rico, and Pohnpei, Federated States of Micronesia. I first identified indicators of disturbance in categories of geomorphology, biota, hydrology, atmosphere, and culture. We used questionnaires, field measurements, and online GIS databases to determine Anthropogenic Disturbance Index (ADI)
scores for each. Next, I ranked and compared disturbance levels within each land use and across all sites on a continuous scale, rather than categorizing each land use as a specific disturbance level. Disturbance levels were dependent on land use type (p<.001); however, ADI scores overlapped between them. We found that the IDH did not apply to our sites but that there was instead a threshold of ADI scores from 35-55% where soil health scores dramatically decreased overall. While biomass did not have any significant factors found to influence amounts, species richness and diversity changed with ADI scores. We may use this to advise land managers to incorporate low disturbance conservation practices such as the addition of perennials in their systems. Our disturbance practices may not only establish resiliency and safeguard the soil and plants we work with from the effects of climate change but also the ecosystem services soil health can support, such as nutrient cycling and carbon sequestration.
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Natural resource management, Agriculture, Soil sciences, agriculture, agroecology, biomass, human disturbance, land use, soil health
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152 pages
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