Effects of soil compaction by a forestry machine and slash dispersal on soil N mineralization in Cryptomeria japonica plantations under high precipitation
Effects of soil compaction by a forestry machine and slash dispersal on soil N mineralization in Cryptomeria japonica plantations under high precipitation
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DOI：
10.1007/s11056-019-09768-z
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发表时间：
2020-01
期刊：
影响因子：
2.2
通讯作者：
S. Ugawa;Y. Inagaki;Fukuzawa Karibu;R. Tateno
中科院分区：
文献类型：
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作者：
S. Ugawa;Y. Inagaki;Fukuzawa Karibu;R. Tateno
使用重型林业机械进行皆伐和整地会造成土壤压实，从而降低森林生产力。在降水量高的森林中，由于表层土壤的侵蚀和沉积，这一过程变得复杂。在这里，我们调查了如何土壤压实和采伐迹地分散压实土壤影响土壤氮（N）矿化在日本南部的高降雨量地区与侵蚀性火山土。对3种柳杉人工林在皆伐整地后9-10个月，在有无分散迹地的条件下，测定了作业道路车辙内外土壤的理化性质。结果表明，压实土壤的氮素矿化速率，尤其是硝化速率较低，但土壤压实后采伐迹地的分散提高了土壤氮素矿化和硝化速率。土壤压实也导致了低的土壤透水性和高体积土壤含水量，并与侵蚀和沉积的表层土壤，土壤沉积，包括有机质，被观察到分散的斜线。压实土壤的C、N含量较低，而分散采伐迹地的C、N含量有所提高。主成分分析表明，在第一主成分上，土壤紧实度与土壤C、N含量密切相关，而在第二主成分上，土壤C/N比与其他因子分离。此外，PC 1和PC 2的得分与土壤氮矿化有关。这些结果表明，在高降水条件下，林业机械对土壤的压实对土壤氮素矿化有负面影响，但在压实土壤上进行采伐迹地分散是维持土壤氮素矿化的有效途径。土壤C/N比值可能与受影响土壤中的N矿化有关，但还应考虑通过含有这些元素的表层土壤的移动，土壤压实度与土壤C和N浓度之间的负相关关系，以充分了解高降水条件下森林土壤N矿化的变化。
The use of heavy forestry machines for clear-cutting and site preparation causes soil compaction, which can decrease forest productivity. This process becomes complicated in forests with high levels of precipitation due to the erosion and deposition of surface soil. Here, we investigated how soil compaction and slash dispersal on compacted soil affect soil nitrogen (N) mineralization in a high precipitation area with erodible volcanic soil in southern Japan. The physical and chemical properties of the soil were measured inside and outside the ruts of work roads in the presence and absence of dispersed slash in threeCryptomeria japonicaplantations 9–10 months after clear-cutting and site preparation. We found that the soil N mineralization rate, particularly the soil nitrification rate, was lower in compacted soil, but the dispersal of slash after soil compaction enhanced the soil N mineralization and nitrification rates. Soil compaction also led to a low soil water permeability and high volumetric soil water content and was associated with the erosion and deposition of surface soil, with soil deposition including organic matter, being observed under dispersed slash. Additionally, the soil carbon (C) and N concentrations were lower in compacted soil but improved under dispersed slash. Principal component analysis showed that soil compaction and the soil C and N concentrations were closely related to each other on the first principal component (PC1), while the soil C/N ratio was separated from other factors on PC2. Furthermore, the scores of both PC1 and PC2 were related to soil N mineralization. These results suggest that soil compaction by forestry machines has a negative impact on soil N mineralization under high precipitation, but slash dispersal on the compacted soil is an effective approach for maintaining the soil N mineralization. The soil C/N ratio is likely related with N mineralization in the impacted soils, but the negative relationship between soil compaction and soil C and N concentrations through the movement of surface soil containing these elements should also be considered to fully understand the changes in soil N mineralization that occurs in forests under high precipitation.