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University of New Mexico (2019)

Riparian vegetation in the face of environmental variability

Steinberg, Kelly A.

Titre : Riparian vegetation in the face of environmental variability

Auteur : Steinberg, Kelly A.

Université de soutenance : University of New Mexico

Grade : Master of Science in Biology 2019

Riparian ecosystems are among the most highly disturbed ecosystems globally, over the past century dryland riparian forests have become less likely to flood, removing the largest historical disturbance. Yet these provide many essential ecosystem services. Climate change adds further change and uncertainty to the future of these ecosystems. In the southwestern United States, climate models predict changes in the mean and variance of temperature and precipitation. Determining the ecological consequences of interactions between slow changes in long-term climate means and amplified variability in climate is an important research frontier in plant ecology. We used long-term plant cover, groundwater and precipitation datasets from the Middle Rio Grande Valley in New Mexico to explore the relationships between riparian plants and environmental variability We explored the relationships between the riparian plant community and climate factors (temperature, precipitation, water availability and variability) The sensitivity of riparian vegetation to climate and other abiotic factors will depend on the interaction between properties of the ecosystem, such as flood regime, and characteristics of plant species, like structure, and provenance. We found that the strength and direction of the relationships between diversity or plant cover and abiotic factors changed with flood regime. To understand environmental variability on individual species, we combined the recent approach of climate sensitivity functions with the revised ‘bucket model’ to improve predictions on how plant species will respond to future changes in both the mean and variance of groundwater resources. Webuilt the first groundwater sensitivity functions (GSFs) for common plant species of dryland riparian corridors. Riparian plant species differed in sensitivity to both the mean and variance in groundwater levels. Rio Grande cottonwood (Populus deltoidesssp.wislizeni) cover was predicted to decline with greater interannual variance in groundwater, especially during warmer periods, while coyote willow (Salix exigua)was predicted to benefit from greater variance. Non-native species, including Russian olive (Elaeagnus angustifolia)and tamarisk (Tamarix) were insensitive to groundwater variability. Altogether, our results indicate that changes in groundwater variability as well as mean may alter riparian plant communities.

Mots clés : Climate variability, cottonwood, riparian plants, Rio Grande


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