دانلود رایگان مقاله تاثیر تنوع سالانه آب و هوا در وفور گیاهان آبگیر بهاری

Abstract

Vernal pools, also termed temporary wetlands, promote key ecosystem services such as floodwater retention and provide unique habitat for many organisms. Despite their ecological value, vernal pools are declining worldwide. Because vernal pools are strongly influenced by variation in annual precipitation that fills the pools, climate change and alterations in precipitation regimes could drastically alter these fragile communities. To understand how annual variation in precipitation and temperature affect vernal pool plant community composition, we examined vernal pool vegetation data collected over a 10 year period. We used native and non-native plant frequencies to explore the dynamics between species frequency and weather variability. We further analyzed fine-scale site topography to explore the effects of spatial variability on ponding.We identified key differences between native and non-native plant species’ responses to weather variability and ponding. Over all, most native species tended to respond positively to precipitation accumulations in the early growing season, but some native species frequencies were negatively associated with precipitation accumulations in the late growing season. Some non-native species were negatively associated with increases in precipitation in either the early or late growing season. Inundation appears to act as an ecological filter, impairing the establishment of some non-native species. In addition, elevation was a predictor of ponding—lower elevation pools tended to have higher clay concentrations and promote greater ponding depths, which could enhance the effects of the inundation filter. Together, these findings will assist conservation and management efforts in understanding the climatic and physical factors that influence vernal pool plant community ecology.

5. Conclusion

The currentunderstanding of vernalpoolplant species’ response to weather variability is limited within the scientific community. We have identified key trends between native and non-native plant species found in constructed vernal pools in response to weather variability. Our analyses reveal an overall trend for many native focal species: a positive response to precipitation accumulations, especially in the early growing season. No such trend was found among the non-native focal species. Inundation acts as an ecological filter impairing the establishment of some non-native species. The Gerhardt and Collinge (2007) study concurs with these results, suggesting that inundation exerts an abiotic pressure that acts to impair the establishment of non-native species in the pools. Lower elevation pools promote deeper ponding and may be more amenable to native species that can tolerate greater inundation depths. As climate change intensifies, precipitation shifts will likely affect vernal pool hydrology and potentially reshape plant community structure. However, this study may help inform land managers of the appropriate timing of vernal pool restoration efforts in relation to the timing of precipitation events and ideal pool location in relation to site specific topography.