Composition,Carbon Storage And Decomposition Of CWD In Evergreen And Secondary Forest Of Lingshi M Ts

Coarse woody debris (CWD) typically includes the snags(D>2.5cm), the trunk lying on the ground has not yet to decomposed and been decomposed, large branches ,stumps and coarse root.Snags and logs were intermingled with each other, forest floor were fertile,different saprophytic and parasitic species were got eccellent growing conditions from CWD and forest floor.CWD are the important structural and functional elements in the forest, through its physical and biological effects,affects the relevant biology and non-biological processes inside and outside the system,and plays an important role in mantaining the integrity of forest ecosystems.(1) During the research , the elevation response of the composition , biomass and carbon storage of CWD in the moist evergreen secondary forest in Lingshi Mountains was studied. There were four kinds of composititon , such as snags, logs, stumbs and branches. There was no logs in the elevation of 187m because of the serious jamming.The results showed that the highest biomass of CWD in evergreen secondary forest in Lingshi Mountains was 104.10 t·hm-2, the lowest one was 7.41 t·hm-2. The lowest one the same as Wuyi Mountains,the highest one higher than Ailao Mountains and Dinghu Mountains, it was related with their regions, forest types, climats,etc.With the elevation changes,the biomass of CWD was rising,and reached a peak in 362m.It droped quickly until 442m,and droped slowly afer that.(2) In the past,when we estimated the global forest litter carbon storage ,we had not think about the CWD,so the biomass of carbon storage lower than it was.In our reacher,the biomass of carbon storage of CWD in Lingshi M ts was lower than the average biomass of the world,it was because that the warm and humid climate was conducive to the decomposition of CWD. With the elevation changes,the biomass of carbon storage of CWD was similar with the biomass of CWD. The elevation response of logs would signify different types of CWD.(3) The nylon bag method was adopted to observe the decomposition of CWD and litter-fall for one year. By studying apprehensively the process of differernt kinds of CWD and litter-fall decomposition and comparing quantitatively of them, the author quantitatived the mass changes and build the dynamic model to analyze the characteristics and to predict the half-life.The results showed that the decomposed peak of CWD and litter-fall is between 90^-152 d.The outcome shows that in five decompose level of CWD, the annual remains ratio is 47.90%,58.68%,33.47%,60.50% and 71.37%.As to the weightlessness rate of the five decompose level of CWD,the order isⅢ>Ⅰ>Ⅱ>Ⅳ>Ⅴ. The finish time of 95% decomposition of five level of CWD were 3.499a,4.637a,2.348a,6.774a,9.769a, the order isⅤ>Ⅳ>Ⅱ>Ⅰ>Ⅲ, the rate order of the decomposition isⅢ>Ⅰ>Ⅱ>Ⅳ>Ⅴ.It shows that ,from decompositionⅠtoⅡ,the rate of decomposition was dropped,from decompositionⅡtoⅢ,the rate of decomposition was rising quickly,fromⅢtoⅣ, the rate of decomposition was dropped quickly, fromⅣtoⅤ, the rate of decomposition was the slowest.Set up the same area of roughly ground , it shows that the rate of decomposition of differert diameters of CWD were 24.13%,20.17% and 28.10%. As to the weightlessness rate of the three diameters of CWD,the order is diameter 3> 1> 2. The finish time of 95% decomposition of three diameters of CWD were 11.662a,12.027a,7.412a, the order is diameter 2> 1> 3. In the full range of the diameters studied,the decay constants K from diameter 5cm to 20cm was similar,beyond 20cm, the decay constants K increased with the diameter increase. The study shows that,during the decomposition of CWD ,beyond diameter 20cm, it was the negative correlation between the diameter and the rate of decomposition .The result shows that ,the annual weightlessness rate of branches and leaves were 34.60%,45.12%,leaves>branches, The finish time of 95% of branches and leaves were 6.167a and 5.842a, the order is branches >leaves, the rate order of the decomposition is leaves>branches.(4) Studying on the rules of concentration,releasing amount and relasing rate of 6 major nutrient elements in the decomposing process of different kinds of CWD and litter-fall and comparing with the rules of them..The result shows that there are 592.409 g.kg^-1, 561.550 g.kg^-1, 509.273 g.kg^-1, 504.270 g.kg^-1, 477.146 g.kg^-1 6 major nutrient elements in early stage in five decompose level of CWD, but only 288.300 g.kg^-1, 275.015 g.kg^-1, 274.647 g.kg^-1, 268.075 g.kg^-1, 239.124 g.kg^-1, remained after a year ,with the losing rate 51.33%, 51.03%, 46.07%, 46.81%, 49.88%. As to the average concentration of the 6 major nutrient elements in five level of CWD, the order at early stage is : levelⅠ,Organic C> K > Ca> Mg> N> P; levelⅡ,Organic C > N > Ca > Mg> K> P; levelⅢ,Organic C > K > Ca > N> Mg> P;levelⅣ,Organic C > N> Ca > K> Mg > P; levelⅤ,Organic C > N> K> Ca > Mg> P.After a year, the order is: levelⅠ,Organic C> N> K> Ca> Mg > P; levelⅡ,Organic C > N> K>Ca > Mg> P; levelⅢ,Organic C> N> K > Ca > Mg > P;levelⅣ,Organic C > N> Ca> K> Mg> P; levelⅤ,Organic C > N> K> Ca> Mg> P. The result shows that there are 629.660 g.kg^-1,756.572 g.kg^-1,764.344 g.kg^-1 6 major nutrient elements in early stage in three diameters of CWD, but only 321.911 g.kg^-1,327.507 g.kg^-1,321.173 g.kg^-1 remained after a year ,with the losing rate 48.88 %, 56.71 %, 57.98%. As to the average concentration of the 6 major nutrient elements in three diameters of CWD, the order at early stage is : D1,Organic C> K> Ca> Mg > N > P; D2,Organic C > K> Mg > Ca> N>P; D3,Organic C > K > Mg >Ca> N> P.After a year, the order is: D1,Organic C> K > N > Ca> Mg> P; D2,Organic C > N> K>Ca > Mg> P;D3 ,Organic C> K> N> Ca> Mg> P.The result shows that there are 486.249g.kg^-1,555.382 g.kg^-1 6 major nutrient elements in early stage in the litter-fall, but only 228.743 g.kg^-1,279.485 g.kg^-1 remained after a year ,with the losing rate 52.96%, 49.68 %. As to the average concentration of the 6 major nutrient elements in the litter-fall, the order at early stage is : branches,Organic C> N > K> Ca> Mg >P; leaves ,Organic C > N >K > Ca > Mg> P.After a year, the order is: branches,Organic C> N> Ca>K > P> Mg; leaves,Organic C > N> Ca > K > P> Mg.