Topography strongly affects drought stress and xylem embolism resistance in woody plants from a karst forest in Southwest China

Abstract

Xylem resistance to drought‐induced embolism is an important trait determining plant distribution. In the karst hills of Southwest China, with a relatively small variation in altitude, soil depth and water availability strongly decrease from the foot towards the top, and woody plant species display distinct spatial distribution. For testing the hypothesis that embolism resistance of leaf and stem xylem reflects the spatial distribution across species along a topographical gradient of the karst hills, we measured the xylem water potential in the dry season, vulnerability to drought‐induced embolism in stems and leaves, and relevant anatomical traits in 17 evergreen species with a different topographical distribution. We found that from the foot towards the hill top, plant water potential sharply decreased, and both stem and leaf xylem showed increasing resistance to hydraulic dysfunction and drought‐resistant anatomical characteristics, but non‐significant variation in specific hydraulic conductivity. Also, hydraulic safety margins increased with relative altitude and thus increasing hydraulic safety. Hydraulic safety underlies the local distribution of the species, but does not come at the cost of hydraulic efficiency. Our results demonstrate that plant hydraulic safety largely shape the niche differentiation and hence community assembly in highly heterogeneous and water‐limited landscapes. A free Plain Language Summary can be found within the Supporting Information of this article.

Arbuscular mycorrhizal fungi improve the growth and drought tolerance of Cinnamomum migao by enhancing physio‐biochemical responses

“…Karst lands, which are fragile ecological environments, are characterized by slow soil formation, shallow and discontinuous soil, low water holding capacity, low vegetation coverage, high soil erosion, and even serious rock desertification (Wang, Zhang et al, 2019; Zhang et al, 2021). They account for approximately 10% of the world's land surface (Hartmann et al, 2014).…”

Variations in leaf water status and drought tolerance of dominant tree species growing in multi-aged tropical forests in Thailand

“…In contrast, species with limiting soil water, e.g., I. chevalieri which occupied in a hilly slope, showed relatively less vulnerable to embolism compared to the rest of the species. Consistent with this finding, Zhang et al 64 and Zhu et al 38 found a wide range of P 50 in tropical karst forests, in which species existing in the middle to top of hilly areas were more resistant to embolism than species dominated in lowlands or valleys, resulting from soil water gradient. Nevertheless, further investigations on hydraulic architecture, sapwood water storage capacity, and rooting depth should be performed to confirm such findings.…”

Exposed Rock Reduces Tree Size, but Not Diversity

“…Many species in karst habitats exhibit a set of mechanisms that are adaptive within particular environments. For example, species may be rupicolous, or exhibit drought tolerance (with respect to photosynthetic performance, xylem hydraulic characteristics, osmotic regulation, antioxidant enzymes, or leaf structure ( Liu et al, 2010 ; Vilhar et al, 2010 ; Geekiyanage et al, 2018 ; Zhang et al, 2020a ), barren tolerance ( Peng et al, 2012 ; Zhu et al, 2017 ), leaf shed during the dry season ( Felfili et al, 2007 ), reduced growth or dwarfing ( Felfili et al, 2007 ; Liu et al, 2018 ; Zhang et al, 2020b ), or improved root–shoot ratios ( Ni et al, 2015 ). We also found that some species (e.g., P. strobilacea and R. chinensis ) maintain their dominance and increase their probability of regeneration through high seed production.…”

“…They have also focused on the correlations between soil characteristics and non-spatial aspects of tree community structure (e.g., diameter at breast height, DBH; tree height, TH; basal area, BA; and crown width; Peng et al, 2012 ; Guo et al, 2016 ). Other studies have explored the relationships of topographic factors (e.g., slope, elevation, convexity, aspect, and degree of rock exposure) with species distribution, community composition, and biomass ( Zhang et al, 2010 , 2020a ; Peng et al, 2012 ; Guo et al, 2017 ; Su et al, 2017 ). Moreover, some studies have compared the species compositions between sites on exposed rocks and sites on soil ( Porembski et al, 1996 , 1998 ; Nie et al, 2018 ).…”