RECOVER MAP 3.1.3.2 Regional Diatribution of Soil Nutrients

Mapping soil quality (nutrients, carbon quality, process dynamics) has recently been undertaken as part of an effort to characterize baseline conditions for performance assessment of Everglades recovery activities. While large scale maps are useful for characterization of spatial pattern, several layers of uncertainty limit use as measures of performance and restoration progress. In particular, large scale maps (Greater Everglades) make specific assumptions about short range variability that are not well quantified. Nugget variance (variability in space over short separation distances) directly confounds use of baseline map products because future spatial sampling will not, in practicality, be at identical locations. If nugget variability is high, then significant uncertainty about ecosystem change arises from not knowing if observed differences arise from intrinsic ecosystem processes or from responses to human management. Our primary objective is to determine the extent to which spatial variability and sampling uncertainty confound ecological change detection. We will use hierarchically nested sampling of soils to establish nugget variability so that change through time can be assigned as observational uncertainty or management response. A related issue for mapping soil nutrients is greatly improving our understanding of the role of ecosystems in regulating nutrient conditions. Previous mapping efforts regarded space as the primary co-variate with soil nutrients, when there are numerous reasons to expect that ecological type and status are more important descriptors (with spatial autocorrelation playing a secondary, though still significant role). Our second objective is to partition variability in soil nutrient conditions in space and time, by ecosystem type, ecological status, and proximity to canals. We anticipate sampling of soils on a fine scale which traverse ecological transitions will help develop predictive models of the role of ecosystem type, geographic setting and, eventually, spatial structuring in regulating soil processes.土壤质量（涵盖养分、碳质属性、过程动态）的制图工作，近期作为大沼泽地（Everglades）修复活动绩效评估基线条件表征工作的一部分启动开展。尽管大尺度地图可有效表征空间格局，但多层级不确定性限制了其作为绩效与修复进展衡量指标的应用价值。具体而言，大沼泽地全域（Greater Everglades）的大尺度地图针对尚未被充分量化的短程空间变异性做出了特定假设。块金方差（Nugget variance，即短距离空间间隔下的空间变异性）直接制约基线地图产品的应用，因为实际开展的未来空间采样无法完全匹配原点位。若块金变异性较高，则生态系统变化的不确定性将显著提升，因为无法判定观测到的差异是源自生态系统固有过程，还是人类管理措施的响应结果。本研究的首要目标是明确空间变异性与采样不确定性在多大程度上干扰生态变化检测工作。我们将采用分层嵌套式土壤采样方法以确定块金变异性，从而将时间维度上的变化归因于观测不确定性或管理措施响应。 土壤养分制图领域的另一相关议题，是深化对生态系统在调控养分条件中所起作用的认知。过往的制图工作将空间视为土壤养分的首要协变量，但诸多理论与实践依据表明，生态类型与生态状态才是更关键的描述因子（空间自相关（spatial autocorrelation）虽仍发挥重要作用，但仅处于次要地位）。本研究的第二目标是，基于生态类型、生态状态以及与运河的距离，对土壤养分条件在时空维度上的变异性进行分解解析。我们预计，穿越生态过渡带的精细尺度土壤采样工作，将有助于构建预测模型，以解析生态类型、地理背景乃至空间结构在调控土壤过程中所发挥的作用。