Woody Plant Encroachment Impacts on Groundwater Recharge: A Review

Abstract

Woody plant encroachment has profound impacts on the sustainable management of water resources in water-limited ecosystems. However, our understanding of the effects of this global phenomenon on groundwater recharge at local and regional scales is limited. Here, we reviewed studies related to (i) recharge estimation methods; (ii) mechanisms by which woody plants impact groundwater recharge; (iii) impacts of woody plant on recharge across different soil and geology; (iv) hydrological repercussions of woody plant removal; and (v) research gaps and needs for groundwater studies. We identified six different methods: water balance, water table, isotopes, chloride mass balance, electrical geophysical imaging, and modeling were used to study the impact of woody encroachment on groundwater. Woody plant encroachment could alter soil infiltration rates, soil water storage, transpiration, interception, and subsurface pathways to affect groundwater recharge. The impact is highly variable, with the extent and the magnitude varying across the soil, substrate, plant cover, and topographic locations. Our review revealed mixed effects of woody plant removal on groundwater recharge. Studies of litter interception, root water uptake, soil moisture dynamics, and deep percolation along with the progression of woody plant encroachment are still limited, warranting further experimental studies focusing on groundwater recharge. Overall, information about woody plant encroachment impacts on groundwater resources across a range of scales is essential for long-range planning of water resources.

Multiple trade‐offs regulate the effects of woody plant removal on biodiversity and ecosystem functions in global rangelands

“…We also failed to detect any signal of hydrological recovery or soil carbon reduction following woody plant removal, consistent with previous studies (Acharya, Kharel, Zou, Wilcox, & Halihan, ; Huxman et al, ). Rather, the response was highly variable, reinforcing our view that woody removal produces context‐dependent results.…”

“…Thus, different roots’ distributions could produce varied effects on infiltration. At landscape scales, dense woody encroachment could reduce hydrological function by altering the downward flux of water and therefore recharge rates (Acharya et al, ) or reduce surface and subsurface flows (Qiao, Zou, Stebler, & Will, ). Although we found no evidence for a direct effect of woody plants on soil carbon, our STEs suggest a general depression, particularly for burning (Figure d).…”

Interactive Effect of Meteorological Drought and Vegetation Types on Root Zone Soil Moisture and Runoff in Rangeland Watersheds

“…where ω 0 = aω [1] and t = η/a [1], respectively, are dimensionless frequency and dimensionless time, η is the time parameter [T], ω is the frequency parameter [1/T] [32]. The continuous wavelet transform (CWT) of a time series x n , n = 1, 2, .…”

“…The parameters a[T] and n [1] are a scale expansion factor and a time shift factor, respectively, to adjust the scale and location of the wavelet in the time-frequency domain [32].…”

“…Root zone soil moisture is positively correlated with streamflow potential in semiarid and subhumid rangelands [1][2][3]. For these rangelands, streamflow is an important ecosystem service dominated by surface runoff generated from infiltration excess or saturation excess overland flow [4,5].…”