摘要
很少证据显示南半球大陆高度风化、低磷、酸性土壤中氮(N)循环与北美和欧洲有很大的差别。来自南半球的证据表明:不同的土地利用方式中,氮损失的形态和时间模式有相似性;不同大陆林地地表/枯枝落叶层的碳氮比(C:N)对于全球尺度上一系列过程有强烈的预示性;根据北半球增施氮对"受磷制约"的生态系统影响的归纳很可能不适用于南半球生态系统,当地植物结构上和生理上对低磷土壤的适应使得磷制约概念变得可疑;大大地增加了氮的输入和周转的土地利用变化很可能是南半球生态系统的最大威胁;局部氮施入的增加很可能与北半球观测到的效果相似。
There is little evidence that nitrogen (N) cycling in the highly weathered,low-phosphorus (P), acidic soils found in Southern Hemisphere continents will differ greatly from that in North America and Europe.Evidence from the 'south' shows:the similarity in forms and temporal patterns in losses of N from different land uses;that the C:N ratios of the forest floor/ litter layer from different continents are strongly predictive of a range of processes on a global scale;that generalizations based on Northern Hemisphere experience of the impact of N additions to 'P-limited' ecosystems are likely to fail for southern ecosystems where anatomical and physiological adaptation of native plants to low-P soils makes questionable the concept of 'P-limitation';that the greatest threats in the 'south' are probably changes in land use that may greatly increase N inputs and turnover;that localized increases in N inputs produce similar effects to those seen in the 'north'.
