Response of Soil Nematode Community to Phosphorous Amendment in a Subalpine Spruce Plantation

An appropriate management practice is indispensable to the restoration of ecological functioning, particularly in ecologically vulnerable regions. The short-term effects of phosphorous (P) amendment on community structure and function of soil micro-food webs in a subalpine spruce (Picea asperata) plantation are examined. Experimental plots are established and treatments are performed with P addition at two levels: Low P (LP) input of 5gm(-2) per year and high P (HP) input 30gm(-2) per year as NaH2PO4 center dot 2H(2)O, and in control plots (CK) without external P input. The abundance, diversity, functional indices, community composition, and metabolic footprints of soil nematodes in the experimental plots are monitored for two consecutive growing seasons during 2013-2014 following P addition. A high variation of abundance of nematodes is observed especially in HP treatment, with reduction in abundance of omnivores and predators. Similarly, maturity index of free-living nematodes, plant parasitic index, enrichment index, structure index, and predator footprint are significantly reduced. However, basal index and channel index of soil nematodes are apparently increased in both years. Moreover, P addition considerably shifts soil nematode community composition, which correlates to soil pH, total P content, available P content, and molar C/P and N/P in soils. In summary, the results indicate that the impacts of P addition on soil nematode community in spruce plantation are mediated by changes in soil pH, P status, and C/N/P ecological stoichiometry.