Measuring plant water use in wet places: paradoxical or paramount?
Abstract
Plant water-use measurements are critical for understanding vegetation responses to water inputs, catchment water-balance and global cycling. But measurements of water use in wet places (e.g., humid tropics, wet temperate forests, wetlands, or floods during extreme wet conditions) could be considered less critical than for comparatively drier environments. Given that water limitation factors motivate much work in the field of ecohydrology, either from the vantage point of vegetation growth or water supplies for downstream use, it could be argued that the rationale for measuring plant water-use in wet places is weaker, or even paradoxical! After all, when and where rainfall is abundant, plant transpiration tends to be a smaller fraction of the water budget. Further, in the absence of soil water stress, net evapotranspiration is readily modeled using basic climate data (e.g. Penman-Monteith).
On the other hand, it could be argued that measuring plant water-use in wet places is paramount to advancing the field of ecohydrology. Wet tropical evapotranspiration drives rainwater recycling over large scales. Such areas may be sensitive to climate change in ways we do not fully understand. For example, reduced rainfall in extreme wet environments where energy is limited may actually enhance ecosystem productivity. Alternatively, elevated rainfall and flooding due to extreme climate events may inhibit plant growth under waterlogged soil conditions. These factors add complexity to models that use soil moisture as the primary driver. Additional drivers of vegetation water-use dynamics that warrant further study in wet places include leaf wetness, canopy temperature, and vapor pressure deficit. Using examples from the Oregon cascades, tropical montane cloud forests, bottomland hardwood wetlands, and areas flooded by Hurricane Harvey (Texas, USA), we provide a rationale for measuring plant water-use that advances understanding of the mechanisms controlling evapotranspiration in wet places. Moreover, lessons learned in wet environments complement our understanding of vegetation responses across contrasting climates.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H52E..04M
- Keywords:
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- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 1807 Climate impacts;
- HYDROLOGY;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1899 General or miscellaneous;
- HYDROLOGY