Haukos David A, Johnson Lacrecia A, Smith Loren M, McMurry Scott T
U.S. Fish and Wildlife Service, Department of Natural Resources Management, Texas Tech University, Lubbock, TX 79409, USA.
Department of Natural Resources Management, Texas Tech University, Lubbock, TX 79409, USA.
J Environ Manage. 2016 Oct 1;181:552-562. doi: 10.1016/j.jenvman.2016.07.011. Epub 2016 Aug 5.
Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30-60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands.
普拉亚湿地是美国半干旱高平原地区主要的水文特征，提供着关键的生态系统服务。由于短草草原景观的人为改变，这些湿地正在消失并退化。导致普拉亚湿地消失的主要过程是，通过周围耕种流域降水侵蚀和输送的土壤堆积，使湿地被填满。我们评估了普拉亚湿地周围植被缓冲带在去除降水径流中的金属、养分以及溶解/悬浮沉积物方面的有效性。在三种缓冲带类型（原生草、休耕农田和保护储备计划）中，每隔10米收集一次雨水径流。缓冲带类型在植物组成上有所不同，但在污染物的最大去除百分比方面没有差异。在距耕地最初的60米范围内，所有类型的植被缓冲带去除了所有测量污染物的50%以上，包括83%的总悬浮固体（TSS）和58%的总溶解固体（TDS）。缓冲带平均去除了70%的磷和78%的氮，以减少进入普拉亚湿地的养分。金属的平均最大去除百分比范围从钠的56%到铬的87%。最大去除率通常出现在缓冲带宽度为50米处。TSS的测量值与除氮以外的所有金属和养分测量值相关，氮与TDS相关。任何植被覆盖率超过80%且宽度为30 - 60米的缓冲带类型，都能在确保普拉亚湿地继续发挥水文功能以提供生态系统服务的同时，最大限度地去除降水径流中的污染物。流域管理以尽量减少侵蚀并创建植被缓冲带，对于普拉亚湿地来说可能是经济有效的保护工具。
