Loss of Playa Wetlands Caused by Reclassification and Remapping of Hydric Soils on the Southern High Plains

Abstract

Historically, playas in the Southern High Plains (SHP) were identified by the presence of hydric soils. The United States Department of Agriculture (USDA) has begun a reclassification and remapping of upland and depressional soils for the playa region of Texas. For eight counties in Texas, we compared the occurrence of playas, as indicated by soils designated as hydric in original soil surveys, to designations in remapped soil surveys. We estimate a 65% decrease in playa numbers and 50% decrease in area as defined by the presence of hydric soil. Anthropogenic impacts, resulting in an altered hydrology and masking of hydric soil are proposed as primary factors responsible for reduction in playa numbers. Other potential factors include current USDA methodology and correction of historical survey errors. Playas on the SHP being considered for inclusion under USDA conservation programs must be individually and independently assessed on-site for wetland criteria, rather than reliance on revised USDA-NRCS Soil Survey maps. During on-site evaluations, effects of anthropogenic alterations on the playa soil to develop and maintain hydric characteristics must be considered. Until completion of the remapping effort, confusion will ensue with the use of the online USDA-NRCS Soil Survey maps during interpretation by those unfamiliar with the status of soil survey reports for the Texas SHP.

Modeling sediment accumulation in North American playa wetlands in response to climate change, 1940–2100

“…Wetland-dependent plant richness is reduced by loss of wetland volume and presence of upland agriculture (Tsai et al 2012). Further, sediments can also mask underlying hydric soils, compromising wetland delineation efforts and thus environmental protection, leaving more playas vulnerable to development (Johnson et al 2011a).…”

Land Use and Conservation Reserve Program Effects on the Persistence of Playa Wetlands in the High Plains

“…It is through watershed runoff that the bulk of sediments are deposited in playa basins. 10 Johnson et al 23 highlighted the loss of playas from the landscape due to reclassification of soils, a condition facilitated by burying playas under eroded upland soils. Playas are a primary source of surface water in the western High Plains; 24 thus, losses in water storage capabilities due to soil erosion can be detrimental to dependent biota.…”

Using Remotely Sensed Imagery to Document How Land Use Drives Turbidity of Playa Waters in Texas

“…Because hydric soils can be buried by sediments, some playas have also been "lost" due to soil reclassification [29]. The presence of such sediments can cause the basins to no longer pond water (the sediments displace water as well as absorb water), but reclassification reflects a semantic loss in playa numbers that can preclude legal wetland protection or allocation of funds for wetland conservation or restoration [7].…”

“…The presence of such sediments can cause the basins to no longer pond water (the sediments displace water as well as absorb water), but reclassification reflects a semantic loss in playa numbers that can preclude legal wetland protection or allocation of funds for wetland conservation or restoration [7]. Playa loss rates range from 17% to 85.7% [17,28,29], with this wide range reflecting differences in methodology and region. For example, Johnson et al [28] compared historic (~1970) and more recent (2008) aerial imagery for 602 playas in Texas and New Mexico to estimate that~17% of basins in the southern Great Plains were filled entirely (no depression remaining) and~60% no longer held water despite the presence of a depression.…”