Considerable variation in embolism resistance in a temperate forest driven by anatomy

Embolism resistance is a key trait that determines plant survival during drought. While much attention has been directed toward understanding embolism resistance within individual species, researchers have rarely assessed the variation in this trait within a plant community. Here, using the optical method, we investigated stem and leaf embolism resistance in 14 deciduous tree species native to the central hardwood forest of North America. We sought to test whether vulnerability segmentation between leaves and stems was common in this plant community and to determine if key anatomical traits correlated with embolism resistance. We compared these results with published datasets that report significant correlations between embolism resistance and anatomy in other similar communities. We found considerable variation in embolism resistance and anatomy across the species in this community, with minimal vulnerability segmentation between leaf and stem. In contrast to previous studies, ring-porous species were significantly more embolism resistant than diffuse-porous species and had larger stomatal safety margins. Across species, P50 was best predicted by xylem connectivity and the xylem to leaf area ratio, whereas vessel diameter and lumen fraction showed no relationship with P50. Across all species, stomatal safety margin was strongly correlated with leaf P50, whereas turgor loss point showed minimal variation across species. A broad variation in embolism resistance, correlated with xylem anatomy, suggests the potential for P50 to drive localized ecological differentiation within communities.