Bruland Gregory L, Richardson Curtis J
Duke University Wetland Center, Nicholas School of the Environment and Earth Sciences, Box 90333, Durham, NC 27708-0333, USA.
J Environ Qual. 2004 Mar-Apr;33(2):785-94. doi: 10.2134/jeq2004.7850.
Soils of riparian wetlands are highly effective at phosphorus (P) sorption. However, these soils exhibit extreme spatial variability across riparian zones. We used a spatially explicit sampling design in two riparian wetlands in North Carolina to better understand the relationships among P sorption, soil properties, and spatial variability. Our objectives were to quantify patterns of spatial variability of P sorption and related soil properties, and to determine which soil properties best explained the variability in P sorption after accounting for the effects of spatial autocorrelation. We measured bulk density, moisture, pH, soil organic matter (SOM), texture (percent clay, silt, and sand), oxalate-extractable aluminum (Al(ox)), iron (Fe(ox)), and the phosphorus sorption index (PSI). Due to differences in texture, Al(ox), and Fe(ox), the two sites had substantially different mean PSIs. At each site, we found considerable differences in the spatial variability of soil properties. For example, semivariance analysis and kriging illustrated that soil properties at Site 1 varied at smaller scales than those at Site 2. At both sites, after accounting for the effects of spatial autocorrelation and all other soil properties, we determined that Al(ox) had the highest Mantel correlation with PSI. We believe this geostatistic and Mantel approach is robust and could serve as a model for research on other biogeochemical processes such as denitrification.
河岸湿地的土壤对磷（P）具有高效的吸附能力。然而，这些土壤在河岸带表现出极大的空间变异性。我们在北卡罗来纳州的两个河岸湿地采用了空间明确的采样设计，以更好地理解磷吸附、土壤性质和空间变异性之间的关系。我们的目标是量化磷吸附和相关土壤性质的空间变异模式，并确定在考虑空间自相关影响后，哪些土壤性质能最好地解释磷吸附的变异性。我们测量了容重、湿度、pH值、土壤有机质（SOM）、质地（粘土、粉砂和砂的百分比）、草酸盐可提取铝（Al(ox)）、铁（Fe(ox)）以及磷吸附指数（PSI）。由于质地、Al(ox)和Fe(ox)的差异，两个研究地点的平均PSI存在显著不同。在每个地点，我们发现土壤性质的空间变异性存在相当大的差异。例如，半方差分析和克里金插值法表明，研究地点1的土壤性质在较小尺度上变化，而研究地点2的变化尺度较大。在两个地点，在考虑空间自相关和所有其他土壤性质的影响后，我们确定Al(ox)与PSI的Mantel相关性最高。我们认为这种地质统计学和Mantel方法是可靠的，并且可以作为研究其他生物地球化学过程（如反硝化作用）的模型。
