Hydrology and Biogeochemistry of Semiarid and Arid Regions

Abstract

Arid and semi-arid areas with more than 30% of the world’s land surface are characterized by low and sporadic moisture availability and sparse or discontinuous vegetation, both spatially and temporally. Vegetation, water, and nutrients are intimately coupled in the arid environments with strong feedbacks and interactions occurring across fine to coarse scales. This chapter reviews and synthesizes recent advances in ecohydrology and biogeochemistry in arid and semiarid regions and discusses future research needs and directions. Four connections are needed in future studies: (1) connecting hydrology and biogeochemistry with other two new emerging interdisciplinary fields of hydropedology and ecohydrology to understand a complex network of interaction and feedbacks between vegetation, hydrology, and biogeochemical cycling; (2) connecting aboveground and belowground processes to investigate how canopies redistribute rainfall and nutrient and their impact on subsurface flow, and to integrate landscape connectivity through recharge and discharge dynamics; (3) connecting individual plant, patch, slope and watershed scales to identify key variables, nonlinearities and linkages for interacting hydrological and biogeochemical processes between different spatial scales; (4) connecting vegetation perturbation (degradation) and recovery to understand how anthropogenic changes in landscape heterogeneity and watershed processes alter the dynamic regimes of the coupled hydrological-biogeochemical systems at different scales.