Effect of prescribed fire on plant a- and beta-diversity and regulating role of soil in mesquite-oak savanna

Authors: JAIME, XAVIER - Texas A&M University; Angerer, Jay; FUHLENDORF, SAMUEL - Oklahoma State University; WALKER, JOHN - Texas A&M Agrilife; Yang, Chenghai; TOLLESON, DOUG - Texas A&M Agrilife; WU, X.BEN - Texas A&M University

Submitted to: Landscape Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fire plays a vital role in the ecosystems of the North American Great Plains, especially in rangelands. Research shows that fire, combined with grazing, creates a variety of plant communities across the land. These dynamic patterns are crucial for maintaining the health and diversity of tall-grass prairies. However, in the drier savanna areas of the Southern Great Plains, fires tend to burn unevenly because of the way vegetation grows. How these patchy fires impact plant diversity and overall biodiversity in savanna ecosystems is still not fully understood. This study focused on how controlled burns, also known as prescribed fires, affect plant diversity in a mesquite-oak savanna within the Edwards Plateau region of Texas, USA. Data were collected on plant species and abundance from 288 plots in a 447 acre area before and after the fires. Satellite images were also used to map the areas that burned. The results showed that burned areas had higher local plant diversity (alpha diversity) compared to unburned areas, but this was influenced by soil conditions and rainfall patterns. On the other hand, fire reduced differences in plant communities between areas (beta diversity), making the burned landscapes more uniform. The changes in plant diversity were tied to shifts in the types and amounts of grasses and forbs, along with grazing patterns after the fire. These changes show how fire can shape the landscape. The study also found that the way fires burn across a patchy environment directly affects patterns of plant diversity. This highlights the need to consider factors like soil, moisture, and weather when planning controlled burns. For farmers, ranchers, and land managers, understanding these effects can help improve strategies for using fire as a tool to manage land and support healthy ecosystems in savanna areas. By considering how fires interact with the natural landscape, more informed decisions can be made to preserve biodiversity and promote sustainable land use.

Technical Abstract: Fire is a fundamental ecological process in North American Great Plains rangelands. Studies show that dynamic mosaics created by fire and grazing, areas burned at different times with distinct plant community structures, are essential for maintaining biodiversity in tall-grass prairie landscapes. In more arid savanna landscapes of the Southern Great Plains, vegetation is highly heterogeneous and fire tends to burn in a patchy manner. The influence of the spatial heterogeneity in vegetation and fire behavior on plant diversity within burn units remains poorly understood, as do the broader implications for biodiversity of these savanna landscapes. In this study, we investigated the effect of prescribed fires on plant alpha and beta diversity and their spatial pattern in a mesquite-oak savanna landscape in the Edwards Plateau. In a 181-ha study area, we sampled 288 randomly located 1-m2 plots during prefire and postfire seasons and collected data on plant species composition and abundance, and mapped areas burned using remote sensing imagery. Our results show that the prescribed fire promoted alpha diversity in burned areas compared to unburned areas, and fire effect was modulated by moisture regime shaped by soil properties and precipitation pattern. Fire had a significant negative effect on plant ß-diversity. Differential changes in species composition and relative abundance of forbs and grasses in response to fire and postfire grazing and homogenization of plant communities in burned areas contributed to reductions in both incidence- and abundance-based beta diversity. Significant associations between the spatial patterns of the burn and postfire alpha and beta diversity underscores the role of fire heterogeneity in shaping the spatial pattern of plant diversity. These findings highlight the need to consider both biophysical heterogeneity and weather patterns when evaluating fire effects on plant diversity. Understanding these interactions is essential for developing ecologically informed fire and land management strategies in these heterogeneous savanna landscapes.