Proxy soil temperature and moisture regimes (climate regimes) in southwestern U.S. drylands: 1980-1999 and 2000-2019

Spatially explicit and climate sensitive information on the responses of ecosystems to global change processes is required for strategic planning and prioritization of conservation and restoration. Indicators of ecological resilience and invasion resistance (R&R) are used increasingly to understand the influence of climate regimes on ecosystem responses to global change processes and determine effective management strategies. We developed proxy soil temperature and moisture regimes, or climate regimes, for southwestern U.S. drylands that accounted for precipitation seasonality and climate change at a scale of 1 kilometer (km). The climate variables that we used, mean annual temperature, precipitation, and monsoon index, allowed us to construct climate sensitive and ecologically meaningful climate regimes that mirrored the soil temperature and moisture regimes in the U.S. National Cooperative Soil Survey data and Ecological Site Descriptions that are widely used by managers in the western U.S. The climate regimes reflected the dominant ecological types and plant functional groups and allowed us to develop meaningful indicators of R&R. Particularly important was identification of a monsoon index value (0.30) to delineate areas with an ustic (summer moist) precipitation regime as indicated by the frequency of C4 vs. C3 grass species. This data publication provides climate regimes raster data (GeoTIFF format) that include four temperature regimes (cryic, frigid, mesic, and hypermesic), both ustic and xeric/aridic moisture regimes, and multiple moisture subclasses based on average precipitation zones (PZ). These climate regimes were used to develop two spatial data layers of the climate regimes for two consecutive time periods: 1980-1999, and 2000-2019.Previous indicators of ecological resilience and resistance to invasion (R&R) focused on the sagebrush biome and relied on soil temperature and moisture regimes mapped as part of the U.S. National Cooperative Soil Survey or climate and water availability indicators derived from ecohydrological process models. However, proxy soil temperature and moisture regimes (climate regimes), and their associated R&R indicators, based on atmospheric climate variables are likely preferable to those based on soil climate because (1) soil temperature and moisture regimes from the Soil Survey are static and challenges exist in evaluating climate change effects based on these indicators, (2) discontinuities exist in soil map units across state boundaries, and (3) many areas, notably some U.S. National Forests, do not yet have published soil surveys. The finer-scale climate regimes and multiclass R&R indicators that we developed allowed us to account for precipitation seasonality and thus to provide more accurate information on the likely responses to disturbances and climate suitability to the widespread invasive annual, cheatgrass (Bromus tectorum), across the southwest drylands. We expect the climate regimes and R&R indicators will provide valuable information for strategic planning and prioritization and will be useful to develop prioritization strategies for fire prevention and management, invasive species management, conservation of species habitat, and to evaluate restoration success.

These two spatial data layers represent climate regimes for two consecutive time periods: 1980-1999, and 2000-2019. The creation of two sets of climate regimes for different time periods allows comparison of climate-sensitive expected responses.For more information about these data, see Chambers et al. (in review).

为战略规划和优先考虑生态系统的保护和恢复，以及生态系统对全球变化过程的响应，亟需空间明确且对气候敏感的信息。生态韧性及入侵抗性（R&R）指标日益被用于理解气候制度对生态系统响应全球变化过程的影响，并确定有效的管理策略。我们针对美国西南干旱地区，基于1千米（km）的尺度，开发了代理土壤温度和湿度制度，或气候制度，该制度考虑了降水季节性和气候变化。我们所使用的气候变量，包括年平均温度、降水和季风指数，使我们能够构建出对气候敏感且具有生态意义的气候制度，这些制度与美国国家合作土壤调查数据以及西部美国广泛使用的生态站点描述中的土壤温度和湿度制度相呼应。气候制度反映了主导的生态类型和植物功能群，并使我们能够开发出有意义的R&R指标。特别是，通过识别季风指数值（0.30）来界定具有ustic（夏季湿润）降水制度的区域，该制度由C4与C3草本植物种类的频率所指示，这一点尤为重要。本数据出版物提供了气候制度栅格数据（GeoTIFF格式），包括四种温度制度（寒温带、冷温带、温带和超温带）、ustic和xeric/aridic湿度制度，以及基于平均降水区（PZ）的多个湿度亚类。这些气候制度被用于开发两个连续时间段的气候制度空间数据层：1980-1999年和2000-2019年。以往关于生态韧性和抗入侵性（R&R）的指标主要关注 sagebrush 生物群落，并依赖于作为美国国家合作土壤调查一部分的土壤温度和湿度制度，或来自生态水文学过程模型的气候和水可用性指标。然而，基于大气气候变量的代理土壤温度和湿度制度（气候制度）及其相关的R&R指标，可能比基于土壤气候的指标更可取，原因如下：（1）土壤调查中的土壤温度和湿度制度是静态的，且基于这些指标评估气候变化效应存在挑战；（2）土壤图单元在州界之间存在间断；（3）许多地区，尤其是美国国家森林的一些地区，尚未公布土壤调查。我们开发的更精细尺度的气候制度和多类R&R指标使我们能够考虑降水季节性，从而提供关于可能对干扰的响应和气候适宜性的更准确信息，尤其是在西南干旱地区广泛入侵的年度植物， cheatgrass（Bromus tectorum）。我们预计气候制度和R&R指标将为战略规划和优先考虑提供宝贵信息，并将有助于制定防火和入侵物种管理的优先策略，以及物种栖息地保护和恢复成功的评估。这两个空间数据层代表了两个连续时间段的气候制度：1980-1999年和2000-2019年。创建不同时间段的气候制度集，允许比较气候敏感的预期响应。更多关于这些数据的信息，请参阅Chambers等人（待发表）。