Spatial variation in catchment response to climate change depends on lateral moisture transport and nutrient dynamics

C. M. Stephens, L. A. Marshall, F. M. Johnson, H. Ajami, L. Lin, L. E. Band

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Future shifts in rainfall, temperature and carbon dioxide (CO2) will impact hydrologic and ecosystem behavior. These changes are expected to vary in space because water and nutrient availability vary with terrain and soil properties, with feedbacks on vegetation and canopy adjustment. However, within-basin patterns and spatial dependencies of ecohydrologic dynamics have often been ignored in future scenario modeling. We used a distributed process-based ecohydrologic model, the Regional Hydro-Ecological Simulation System, as a virtual catchment to examine spatial and temporal variability in climate change response. We found spatial heterogeneity in Leaf Area Index, transpiration and soil saturation trends, with some scenarios even showing opposite trends in different locations. For example, in a drying scenario, decreased vegetation productivity in water-limited upslope areas enhanced downslope nutrient subsidies so that productivity increased in the nutrient-limited riparian zone. In scenarios with both warming and rising CO2, amplifying feedbacks between mineralization, vegetation water use efficiency and litter fall led to large increases in growth that were often strongest in the riparian area (depending on the coincident rainfall change). Modeled transpiration trends were determined by the competing effects of vegetation growth and changing water use efficiency. Overall, the riparian zone experienced substantially different (and even opposing) ecohydrologic trends compared to the rest of the catchment, which is important because productive riparian areas often contribute a disproportionate amount of vegetation growth, transpiration and nutrient consumption to catchment totals. Models that are spatially lumped, lack key ecosystem-driving dynamics, or ignore lateral transport could misrepresent the complex ecohydrologic changes catchments could experience in the future.
Original languageEnglish
Article numbere2021WR030577
Number of pages20
JournalWater Resources Research
Volume58
Issue number10
DOIs
Publication statusPublished - 2022

Open Access - Access Right Statement

© 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited

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