Effects Of Simulated Rainfall On Leaf Litter Decomposition In A Plantation Of Yunnan Pine In An Arid River Valley Of China

Nowadays, the change of precipitation pattern has received extensive attention of the world, the change of precipitation pattern, so as to change and continue to change the global structure and function of terrestrial ecosystems, seriously affects human health and survival. Also affect plant physiological and metabolic processes at the same time, change the chemical substances in the litter content, which changes in forest ecosystem nutrient elements release and the balance of the relationship between soil microbial absorption, and changing the chemical composition of litter itself indirectly, affect the litter decomposition. Arid River Valley is a special kind of ecological system, this kind of area rainfall, water factor is an important factor of restricting its ecosystem stability exist. Research shows that in extreme rainfall in arid regions and arid areas have overall increasing trend. Study area is typical of arid valley, according to Ya’an City Shimian change in recent decades rainfall, precipitation has increased significantly compared to the past. Therefore, arid forest ecosystem due to changes in precipitation patterns and subject to study the impact of predicted changes in forest ecosystems in arid area of great significance. Based on this, in the Arid River Valley of the district representative Yunnan pine(Pinus yunnanensis Franch.) for the study, by year-situ decomposition of litter bag experiment, the 10%increase in precipitation (Al),20%(A2),30%(A3) and natural precipitation (CK) on the arid valley area Yunnan pine plantation litter decomposition and nutrient release effects. The main results are as follows:(1)Under natural precipitation, cloud pine leaf litter decomposition of 95% required 7.923 a, increased precipitation in leaf litter decomposition to reduce the time required for 95% 2.444 a (Al),1.772 a (A2) and 1.309 a (A3), A1 decomposition rate significantly faster than A2, A3,and CK. This represents an increase of precipitation promotes decomposition of leaf litter, but excessive moisture (A2 and A3) will promote the production of such inhibition.(2)Add water to the residual rate of less than CK, and A1 and A2 processing residue C was significantly lower than CK. This represents an increase of precipitation promotes leaf litter decomposition C elements, but will slow down the release of excess water C elements.(3)A1 is lower than the processing rate of the N residual CK, but the difference was not significant, A2 and A3 treatment of the N residual rate was significantly higher than CK; P varies with the residual ratio N just the opposite. Where, N solid handle holding strength lowest A1, A3 highest; P solid handle A3 holding strength minimum and maximum A1. This indicates that the decomposition test 1a, excess moisture (A2 and A3) inhibited the release of Nelements, but to promote the release of P elements.(4)Significantly promoted by water leaf litter decomposition of lignin, and the higher the water, the more obvious role in promoting; while significantly inhibited cellulose decomposition, and the higher the water, the more obvious inhibition. This represents an increase of precipitation contributed to the release of lignin, but inhibits the release of cellulose.(5)Add water to make K residual rate was significantly lower than CK, which represents an increase of precipitation contributed to the release of leaf litter K elements; add water to the residual Ca and Mg were significantly higher than CK, suggesting that inhibition of the release of leaf litter increased precipitation of Ca and Mg elements.(6)Correlation analysis showed that the decomposition rate of CK and lignin/N and lignin concentration of the most relevant, A3 litter decomposition rate and C/N and N content most relevant. This indicates that under natural rainfall conditions Yunnan pine plantation litter decomposition rate is mainly affected by the lignin/N of influence; but with increased precipitation, leaf litter decomposition rate is mainly affected by the lignin/N may be gradually converted by C/N affected.