| Woody debris (WD), including coarse woody debris (CWD) and fine woody debris (FWD), is an essential structural and functional component in forest ecosystems. CWD is considered to be the major part in forest woody debris and it is primarily composed of logs, snags, stumps and large branches, while FWD is mainly consisted of small twigs and is much less ecologically functional as compared to CWD. WD plays critical roles in maintaining the integrity of forest ecosystems and influences the biological and non-biological process within the forest ecosystem, as they not only provide habitats for organisms such as amphibians, arthropods, birds, small mammals, fungi and plants, but also serves as the carbon and nutrient pool. Furthermore, WD also has many ecological functions such as biodiversity maintenance, regeneration, water holding capacity and improves soil fertility.Based on the primary survey and data collection, setting typical plots according to forest age, elevation, aspect and other environmental elements to investigate the storage and composition of WD, diameter class distribution and the decomposition of the grade distribution; sampling some WD to measure the contents and storage of carbon and nutrient; ecological functions such as biodiversity maintenance, regeneration, water holding capacity and improve soil fertility were also analyzed. The result showed that:The results showed the total storage of woody debris in the Quercus aliena forests in the Qinling Mountains was45.91t/hm2. The mean storage of CWD (Coarse woody debris) was42.04t/hm2while the mean storage of FWD (Fine woody debris) was3.87t/hm2, so CWD was the main part of WD in the study area. The storage of CWD was mainly influenced by forest age, slope and forest density. Quercus alienavar. Acuteserrata, Toxicodendron vernicifluum, Pinus armandii and Pinus tabulaeformis were the main four species of CWD, which account for41.55%of the total storage of CWD; among snags, logs, large branches and stumps, logs accounted the biggest percentage which reached72.31%;72.41%of the whole storage of CWD was the diameter class between20and50cm while78.76%of the whole storage of CWD was belong to decay class I and â…¡. The total storage of carbon in WD was22.22t/hm2, in which the storage of CWD and FWD were20.26t/hm2and1.96t/hm2respectively account for91.18%and8.82%. The total storage of all the nutrients in woody debris was537.95kg/hm2. The total storage of N, P, K was496.21kg/hm2in CWD, in which N, K, P shared66.00%,30.57%and3.43%respectively. The total storage of N, P, K was41.74kg/hm2in FWD, in which N, K, P shared71.24%(29.74kg/hm2),25.11%(10.48kg/hm2) and3.64%(1.52kg/hm2)respectively.The Margalef richness index, Pielou evenness index, Shannon-wiener diversity index and Simpson dominance index of plant around CWD increased as the improving of decay class and the four indexes were higher than the control group in global aspect. The seedlings on logs approximately showed a normal distribution, there were more in the middle but less in the beginning and the end. The number of seedlings was more as the decay class higher. The mean number of seedlings on and around the logs was2.16per square meter, which is further more than the mean0.66per square meter in forest land.According to the level of decay class, the order of CWD natural capacity was:â…¢>â…£> â…¡>â…¤>â… while both saturation capacity and effective capacity were:â…¢>â…£>â…¤>â…¡>â… ï¼› the order of water storage ability of CWD was:â…¤>â…£>â…¢>â…¡>â… .High-rotting is obviously higher than low-rotting in the water storage ability of CWD.With the increase of decomposition level, the content of organic matter, total nitrogen and total phosphorus decreased as the soil layer deepen, the content of total potassium showed the opposite trend. In different soil layer, the content of every nutrient increased with the increased of decomposition. Besides, the content of each nutrient was higher than the control group, which showed CWD had an obvious effect on the content of soil nutrient also an important role to improve the soil quality. |
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