Abstract
Soil moisture resources are highly spatially and temporally heterogeneous. Although temporal heterogeneous water conditions have a more common impact on plants than spatial heterogeneous conditions, very few studies have been conducted to investigate how plants respond to existing temporally heterogeneous water conditions. To address this issue, we adopted three species with different habitat ranges, including a karst-endemic species of Kmeria septentrionalis (growing in karst habitats only), a karst-suitable species of Celtis sinensis (occur in both habitats) and a non-karst species of Lithocarpus glaber (found in normal habitats only), and conducted a greenhouse experimental study at Guizhou University, Guiyang, China. This study explored the response ability and coping strategies of seedlings from various habitats by comparing the differences in growth of biomass, and physiological traits of the three species in response to temporally heterogeneous water (alternating drought and waterlogging) and temporally homogeneous water (constant moist) treatments. Compared with constant moist treatment, the first round of temporally heterogeneous water treatment reduced the growth of leaf, root, and total biomass increased the contents of osmoregulation substances, malondialdehyde, and antioxidant enzyme activities. However, the third round of temporally heterogeneous water treatment improved their late growth of biomass, and the content of physiological traits was also significantly decreased. K. septentrionalis showed a higher compensation effect in late growth by early heterogeneous experience. Typical karst species may be more able to benefit from early experience with temporally heterogeneous environments, due to long-term adaptation to karst habitats of great heterogeneity and low resource availability. The temporally heterogeneous water conditions can induce plants to produce a higher physiological response, and inhibit the current growth of plants, but can enhance the adaptability of plants to similar stress events in the later period. The ability of species to respond to temporally heterogeneous water treatment may be related to their habitat range.
