Impact of Eastern Redcedar Proliferation on Water Resources in the Great Plains USA—Current State of Knowledge

Abstract

In the Great Plains of the central United States, water resources for human and aquatic life rely primarily on surface runoff and local recharge from rangelands that are under rapid transformation to woodland by the encroachment of Eastern redcedar (redcedar; Juniperus virginiana) trees. In this synthesis, the current understanding and impact of redcedar encroachment on the water budget and water resources available for non-ecosystem use are reviewed. Existing studies concluded that the conversion from herbaceous-dominated rangeland to redcedar woodland increases precipitation loss to canopy interception and vegetation transpiration. The decrease of soil moisture, particularly for the subsurface soil layer, is widely documented. The depletion of soil moisture is directly related to the observed decrease in surface runoff, and the potential of deep recharge for redcedar encroached watersheds. Model simulations suggest that complete conversion of the rangelands to redcedar woodland at the watershed and basin scale in the South-central Great Plains would lead to reduced streamflow throughout the year, with the reductions of streamflow between 20 to 40% depending on the aridity of the climate of the watershed. Recommended topics for future studies include: (i) The spatial dynamics of redcedar proliferation and its impact on water budget across a regional hydrologic network; (ii) the temporal dynamics of precipitation interception by the herbaceous canopy; (iii) the impact of redcedar infilling into deciduous forests such as the Cross Timbers and its impact on water budget and water availability for non-ecosystem use; (iv) land surface and climate interaction and cross-scale hydrological modeling and forecasting; (v) impact of redcedar encroachment on sediment production and water quality; and (vi) assessment and efficacy of different redcedar control measures in restoring hydrological functions of watershed.

Stand-Level Transpiration Increases after Eastern Redcedar (Juniperus virginiana L.) Encroachment into the Midstory of Oak Forests

“…Woody plant encroachment is transforming the southern Great Plains of the USA, which has significant implications for ecosystem carbon and water dynamics (e.g., [1,2]). The Cross-Timbers is an ecoregion historically composed of a mosaic of open prairie, oak savannas, and oak-dominated forests extending from Kansas to Texas [3,4].…”

“…However, fire exclusion has increased woody species density and richness and allowed eastern redcedar (Juniperus virginiana L., redcedar), a native, evergreen conifer, to encroach the prairie and infill the oak-dominated areas [5][6][7], which affects a large number of ecosystem services [8][9][10]. Encroachment of redcedar into grasslands increases ecosystem-level water use, resulting in a reduction of runoff and groundwater recharge potential [1,[11][12][13]. However, the effect of redcedar encroachment and infilling into the oak forest on water use and ecosystem-level water budgets remains unknown.…”

Spatial Imaging and Screening for Regime Shifts

“…Cheatgrass invasion and regional dominance led to surprising changes in wildfire behavior and occurrence, heightened exposure of urban populations to smoke and air pollution, and cascading impacts to endemic wildlife (D'Antonio and Vitousek, 1992;Balch et al, 2013;Chambers et al, 2014). Juniper displacement of prairie ecosystems in the Great Plains is now linked to concerning impacts on water resources (Zou et al, 2018), public school funding (Lally et al, 2016), wildfire suppression potential, and collapses in pastoral agricultural revenue and rural livelihoods (Twidwell et al, 2013a). Erosion and desertification has been a notorious regime shift that has been actively avoided since the tragedy of the Dust Bowl (Wallace and Silcox, 1936), which was driven in part by human conversion of rangeland to cropland.…”

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

“…The south-central Great Plains of the USA relies heavily on groundwater in the form of aquifers [41] and surface water in the form of impoundments and reservoirs for irrigation, municipal water supplies, and the oil and gas industry [42,43]. With climate change and the concurring increase in population, water demand is projected to increase drastically.…”