| Global change is not only changing the ecological structure and function of the global biosphere, but has begun to affect the survival and health of human beings. So the global carbon sink & source problem becomes a research hotspot. Forest ecosystem plays a decisive role in the global carbon cycle and coarse woody debris (CWD) is an important part of material cycle and energy flow in forest ecosystem. Artificial forest ecosystem is an important part of forest ecosystem, which has become increasingly prominent in the mitigation of global climate change. So the artificial forest ecosystem of coarse woody debris caused more and more attention to forestry workers. With the expansion of the global forest area, and the stability of artificial forest ecosystem and restoration ability is poor, artificial forest degradation phenomenon more and more serious. Artificial forest coarse woody debris has the ecological effects of improving forest soil fertility, maintaining biodiversity and conserving soil and water, which can effectively alleviate the problem of artificial forest degradation. Artificial forest coarse woody debris study can enrich the database of CWD research of forest ecological system, and provide the basis for the ecological functions of coarse woody debris in a comprehensive understanding of the human. Stump is an important component of CWD in artificial forest ecosystem, so the research of storage and decomposition characteristics of artificial forest stump is needed. At present, China’s researches on organic matter in the forest ecological system mainly focus on studies of decomposition of litter and fine root decomposition, whereas studies of storage and decomposition characteristics during stump decomposition are quite rare, especially for the main artificial forest plantation tree species of Masson pine stump in southern China.Considering China’s research status of artificial forest coarse woody debris, in this experiment, an artificial Masson pine forest in southeast of Sichuan Province is selected as the research sample by using space-for-time method. Standing forests created next year after cutting during 1999 to 2012 and in 2013 are selected. Slope aspects and positions of the selected forests are approximately the same. The Masson Pine stumps collected were cut down after 9-10 years old. Choose the stump wood (SW),barks (B), stump root (SR) and roots with different diameters (0mm<R1≤10mm,10mm<R2≤25mm,25mm< R3≤100mm, R4>100mm) as study objects. Results shows as follows.Masson pine stumps decomposition in the process of different parts of the density and decomposition rate are different. Aboveground stump wood (SW), bark (B) and underground part of stump root (SR) decomposition the overall trend of the change of medium density is gradually reduced, and stable gradually, but the process of decomposition, showed a trend of gradual reduce the bark of trees, and the stump wood and the density of root at the beginning of the decomposition were greater than the bark, and four years before the decomposition density reduction; At the same time, along with the increasing length of decomposition, stump wood, bark, stump root decomposition rate with the increase of the decomposition time first increases then decreases, and gradually converge, stump the decomposition rate of the whole is greater than the bark and stump root;Stump wood(SW), and bark (B) and stump root (SR) to the plantation ecosystem for about 30.18 t/hm2, and still changes appear to be increased in the process of decomposition, quickly reduce, then gradually reduce the trend, and the capacity of each part of root stump root>stump wood> bark, and is the stump root capacity significantly greater than stump wood and bark of capacity, this shows the stump root contribution to the stump capacity is big, it is the change of the change on the stump of capacity. Also found that the moisture content, respectively, with no significant correlation between stump root, the decomposition rate of bark, and the significant correlation with the decomposition rate of stump root;Stump of underground part about can give plantation ecosystem type of 11.93 t/hm2 CWD, than stump wood, bark and stump root contribution to the plantation ecosystem CWD capacity is small. In 14 years in the process of decomposition, the root overall capacity increased first, quickly reduce, then slowly decreased, but the roots of different diameter grade, the change rule is slightly different. The change trend of R1, R2 is slowly reduced, through the single factor analysis of variance, R1 diameter level changes significantly (p<0.05), and R2 diameter level change was not significant (p>0.05). R3 and R4 reserves from the root diameter level change trend and the overall capacity of root change trend is consistent, is first increases, reduce rapidly, then gradually reduced, the change of R3 significantly (p<0.01), but the change of R4 was not significant (p>0.05);Along with the increasing length of decomposition, different diameter class root density change trend of decrease, and gradually stabilized. At the beginning of the root decomposition, the density of the R4 diameter class is a period in a rapidly decreases, and the density of R1, R2 and R3 size grade was lower, but is slowly reduced. After 14 years of decomposition, R4 diameter level root density and continue to reduce the trend, R1, R2 and R3 size grade of the density of root in decomposition change tends to be stable,4,5,6 years later. At the same time, the root of different diameter grade in 14 years in the process of decomposition of decomposition rate increased with the increase of decomposition time reduce after increases first, and gradually converge. R4 diameter level root decomposition rate of the whole is greater than the decomposition rate of R1, R2 and R3. Early stumps decomposition, R1, R2 and R3 diameter class is the root of a special slow decomposition lag phase, middle decomposition rate started to increase from 2 years ago, in 6 years,8 years,7 years increased to a maximum of the breakdown in the process of decomposition rate, then they gradually reduced respectively, and the decomposition rate and stable. R4 at the beginning of the decomposition, there is no obvious lag phase, but the decomposition rate increased rapidly, the decomposition of 2 years to reach the maximum value of 0.43, after a phase decomposition rate reduce rapidly,0.12, down from 5 years after the decomposition rate is slow, and gradually stabilized.In summary, stump storage, decomposition density and decomposition rate of an artificial masson pine forest show a clear change law in the process of decomposition in 14 years. These data and laws will have guiding significance for systematically know changes rules of stump wood (SW), bark (B), stump root (SR) and different diameter root (R) during the decomposition. At the same time, it may also have a certain reference to the management and control of Masson Pine Plantation. |
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