Department of Natural Resources Management, Texas Tech University, Lubbock, TX 79409, USA.
J Environ Manage. 2012 Dec 15;112:275-83. doi: 10.1016/j.jenvman.2012.07.014. Epub 2012 Aug 28.
Playas are the primary wetland system in the Southern Great Plains (SGP) of North America providing critical stopover habitats for migratory birds in the Western Hemisphere. Collectively, these wetlands form the keystone ecosystem in this region supporting biodiversity for North America and provide habitat for native plants and animals that are essential for maintenance of international biological diversity along with other local and regional ecological services. Large-scale landscape changes in this region, primarily as a result of agriculturally-based anthropogenic impacts, threaten playas with functional loss and physical extinction. These impacts are not considered in current estimates of the number of extant functional playas, leading to biased estimates by groups or agencies extrapolating research or monitoring results, conducting conservation planning, and modeling impacts of future climate change. Using a combination of stochastic and empirical data, we identified impacts to playas and playa watersheds and quantified the extent and rate of these impacts relative to physical loss. Only 0.2% of playas had no wetland or watershed modification and we conservatively estimate that 17% of playas recently existing on the landscape no longer are represented by an apparent depression. With the inclusion of sediment volume estimates where ≥100% of the volume of original differentiated playa soil has been filled, 60% or 16,855 playas have been physically lost from the SGP despite a continued presence of a depression. Data also show that small playas are being lost more rapidly than larger ones; the average size (±SE) of extant playas has increased from 7.5 ± 0.47 to 8.5 ± 0.55 ha. The reduced ecological condition of 95.3% of playas remaining on the landscape exceeds historical predictions of a maximum 85% of playas ever being modified. Given the results of this study these changes can now be accounted for, resulting in more informed management and conservation of playas and bring awareness to the urgency of implementation of effective conservation measures for playas and the species that depend on this keystone ecosystem.
滨海湿地是北美大平原南部（SGP）的主要湿地系统，为西半球的候鸟提供了重要的中途停留栖息地。这些湿地共同构成了该地区的关键生态系统，支持着北美的生物多样性，并为本地动植物提供了栖息地，这些动植物是维持国际生物多样性以及其他本地和区域生态服务所必需的。该地区的大规模景观变化主要是由于农业人为影响造成的，这些变化威胁着滨海湿地的功能丧失和物理灭绝。这些影响在当前对现存功能滨海湿地数量的估计中没有考虑在内，导致研究或监测结果、进行保护规划和模拟未来气候变化影响的团体或机构得出有偏差的估计。我们使用随机和经验数据的组合，确定了对滨海湿地和滨海湿地流域的影响，并量化了这些影响相对于物理损失的程度和速度。只有 0.2%的滨海湿地没有湿地或流域的改变，我们保守估计，最近在景观上存在的 17%的滨海湿地不再以明显的洼地来表示。如果包括沉积物体积估计，其中≥100%的原始分化滨海土壤体积已被填满，则尽管洼地仍然存在，但 SGP 中仍有 60%或 16,855 个滨海湿地已经从物理上消失。数据还表明，较小的滨海湿地比较大的滨海湿地消失得更快；现存滨海湿地的平均大小（±SE）已从 7.5±0.47 公顷增加到 8.5±0.55 公顷。景观上剩余的 95.3%的滨海湿地的生态条件已经恶化，超过了历史上预测的 85%的滨海湿地曾经被改变的最大比例。考虑到这项研究的结果，现在可以考虑这些变化，从而更明智地管理和保护滨海湿地，并使人们意识到实施有效的滨海湿地保护措施的紧迫性以及依赖这个关键生态系统的物种的紧迫性。
