Multi-species habitat suitability models to enhance oak species regeneration in the lower mississippi alluvial valley

Abstract

Understanding species-habitat relationships is critical for successful conservation and restoration of ecologically important tree species. Bottomland hardwood forests in the Lower Mississippi Alluvial Valley (LMAV) are diverse ecosystems that continue to be threatened by changing flooding regimes and higher temperatures due to global climate change. Restoration of native oak species in these ecosystems is essential but challenging given the complex and changing environmental conditions within the region. This study aimed to identify: (1) suitable habitat and ecoregions for eight oak species in the LMAV, and (2) the key habitat drivers that influence the distribution of oak species in the region. We modeled the habitat suitability and ecological niches of eight native oak species in the LMAV using an ensemble approach. Habitat suitability models, validated with Forest Inventory and Analysis data, identified substantial suitable areas for Nuttall's oak (Quercus texana), cherrybark oak (Quercus pagoda), white oak (Quercus alba), and other oaks. However, suitable habitat was reduced compared to historical levels. Niche overlap analysis revealed similarities among species at the ecosystem level but niche differentiation within ecoregions. Summer temperature, isothermality, flooding frequency, and soil pH emerged as key drivers of oak species distributions. Response curves highlighted potential vulnerabilities to climate change. Our findings emphasize the need for adaptive, ecoregion-specific restoration strategies and the integration of oak restoration into climate mitigation efforts. This study provides a robust foundation for guiding oak conservation and management in the LMAV and underscores the importance of considering species-habitat relationships, niche differentiation, and anthropogenic pressures in restoration planning.