Impacts of changed litter inputs on soil CO_2 efflux in three forest types in central south China

Climate change is expected to cause the alteration of litter production in forests, which may result in substantial changes in soil CO2 effiux （FCO2） process as litter represents a major pathway of carbon from vegetation to the soils. In this study, we conducted an aboveground litter manipulation experiment to examine the influence of litter addition and exclusion on soil FCO2 in Camphor tree, Masson pine, and mixed Camphor tree and Masson pine forests in central south China. Litter input manipulation included three treatments： nonqitter input （litter exclusion）, double litter input （litter addition）, and natural litter input （control）. On average, litter exclusion significantly reduced soil FCO2 rate by approximately 39%, 24% and 22% in Camphor tree forests, the Mixed forests, and Masson pine forests, respectively. On a yearly basis, double litter addition significantly increased soil CO2 by 12% in the Mixed forests （P=0.02） but not in both Camphor tree and Masson pine forests （P〉0.05）, when compared with their corre- sponding control treatments. However, litter addition increased soil FCO2 rates in the months of June-August in Camphor tree and Masson pine forests, coinciding with high soil temperature of summer conditions. Litter exclusion reduced soil FCO2 more than litter addition increased it in the study sites. Responses of soil respiration to litter input treatments varied with forest types. Litter input treatments did not alter the seasonal patterns of soil temperature and soil water content. Our results indicated that changes in aboveground litter as a result of global climate change and/or forest management have a great potential to alter soil respiration and soil carbon balance in forest ecosystems.

Considerable impacts of litter inputs on soil nematode community composition in a young Acacia crassicapa plantation

Aboveground litter inputs and root exudates provide basal resources for soil communities,however,their relative contributions to soil food web are still not well understood.Here,we conducted a field manipulative experiment to differentiate the effects of litter inputs and living root on nematode community composition of surface and subsoils in a young Acacia crassicapa plantation in southern China.Our results showed that both litter addition and root presence significantly enhanced soil nematode abundance by 17.3%and 35.3%,respectively.Litter addition altered nematode trophic group composition,decreased fungivore to bacterivore ratio,and enhanced maturity index and structure index,which led to a bacterial-based energy channel and a more complex food web structure.However,root presence had a limited impact on the nematode community composition and ecological indices.Despite nematodes surface assembly,soil depth did not affect nematode trophic group composition or ecological index.Our findings highlight the importance of litter inputs in shaping soil nematode community structure and regulating soil energy channel.