Phreatophytic vegetation and groundwater fluctuations: a review of current research and application of ecosystem response modeling with an emphasis on great basin vegetation.

Although changes in depth to groundwater occur naturally, anthropogenic alterations may exacerbate these fluctuations and, thus, affect vegetation reliant on groundwater. These effects include changes in physiology, structure, and community dynamics, particularly in arid regions where groundwater can be an important water source for many plants. To properly manage ecosystems subject to changes in depth to groundwater, plant responses to both rising and falling groundwater tables must be understood.

Short-term light and leaf photosynthetic dynamics affect estimates of daily understory photosynthesis in four tree species.

Instantaneous measurements of photosynthesis are often implicitly or explicitly scaled to longer time frames to provide an understanding of plant performance in a given environment. For plants growing in a forest understory, results from photosynthetic light response curves in conjunction with diurnal light data are frequently extrapolated to daily photosynthesis (A(day)), ignoring dynamic photosynthetic responses to light. In this study, we evaluated the importance of two factors on A(day) estimates: dynamic physiological responses to photosynthetic photon flux density (PPFD); and time-resolution of the PPFD data used for modeling.

Modeling dynamic understory photosynthesis of contrasting species in ambient and elevated carbon dioxide.

Dynamic responses of understory plants to sunflecks have been extensively studied, but how much differences in dynamic light responses affect daily photosynthesis (A ) is still the subject of active research. Recent models of dynamic photosynthesis have provided a quantitative tool that allows the critical assessment of the importance of these sunfleck responses on A . Here we used a dynamic photosynthesis model to assess differences in four species that were growing in ambient and elevated CO.