Effects Of Vegetation Reconstruction On Soil Respiration In Degraded Red Soil

In this study, the effect of vegetation reconstruction on soil respiration have been studied in Hetian town, Changting country, Fujian province by infrared gas analyze method for measuring soil respiration. Two regeneration ecosystems viz. Pinus massoniana forest, Paspalum notatum grassland, and severely eroded land as a control ecosystem before reconstruction, the secondary forest which conserved best in local as the control ecosystem after reconstruction were involved in this study. The objective of this study is that: l)to examine the effect of vegetation reconstruction on diel dynamic trend and magnitude of soil respiration; 2) to examine the effect of vegetation reconstruction on seasonal dynamic trend and magnitude of soil respiration; 3)to study the relation between soil respiration and two most environment variable including soil temperature and soil water content; 4) to quantify annual flux of soil respiration in eroded land and these vegetation reconstruction lands; 5) to quantify the contribution of the component respiration for total soil respiration.Major conclusions were summarized as follows:1)Total soil respiration and mineral soil respiration appear an unimodal diel pattern in severely eroded land and Paspalum notatum grassland , with the maximum presents during 13:00～15:00. Adopting vegetation reconstruction of Paspalum notatum grassland have no significant effect on that of diel dynamic trend, while after adopting vegetation reconstruction of Pinus massoniana forest have some effect on that of diel dynamic trend which were nearly equal to the secondary forest. After adopting vegetation reconstruction, the diel dynamic magnitude of soil respiration were significantly decerse. Root respiration of Paspalum notatum grassland have a significant diel dynamic in spring and summer, while that of Pinus masoniana foreset in summer, autumn and winter. Respiration from litter layer appear an unimodal diel pattern in summer and autumn ,while others season have no obvious diel fluctuation.2)TotaI soil respiration and mineral soil respiration appear an unimodal seasonal pattern in severely eroded and these vegetation reconstruction, with the maximum presents between June and July and the minimum presents in winter. Root respiration of Paspalum notatum grassland, Pinus massoniana forest and the secondary forest appear an unimodal seasonal pattern , with the maximum present June, July and June respectively, and with the valley present May in Paspalum notatum grassland and Pinus massoniana forest. Seasonal dynamics of respiration from litter layer have a high-magnitude fluctuation in Pinus massoniana forest and the secondary forest, generally summer of that was higher than winter.3)To analyse relation between soil temperature and respiration, the result show that soil temperature can explain 50% 84% variation of total soil respiration and mineral soil respiration in severely eroded land and these vegetation reconstruction, but only explain 11% root respiration variation in Paspalum notatum grassland. The order of total soil respiration Q₁₀ value: Pinus massoniana forest(2.07)>secondary forest(1.95)>severely eroded land(1 .86)>Paspalum notatum grassland(1.75). Q₁₀ value of mineral soil respiration in severely eroded land,Paspalum notatum grassland , Pinus massoniana forest and the secondary forest were 1.86,2.01,1.84 and 1.61, respectively. The Q₁₀ value of root respiration was lower than it of soil mineral respiration in Paspalum notatum grassland. The Q₁₀ value of root respiration was slightly larger than that of respiration from soil mineral, but was significantly lower than from litter layer in Pinus massoniana forest. The Q₁₀ value of root respiration was significantly larger than that of respiration from litter layer and soil mineral in the secondary forest.4) We were studied seasonal dynamic of a ( basal respiration ) and Q₁₀ temperature sensitivity ) value in season scale. In the severely eroded land, a value in summer was significantly larger than the other season, while the other season was no significant difference; the order in Paspalum notatum grassland : autumn > spring > summer > winter; the order in Pinus massoniana forest: summer > autumn > spring > winter; the order in the secondary forest: autumn> summer>winter>spring. The maximum of Q₁₀ value appeared in autumn , while the minimum value appeared in spring in severely eroded land. The maximum of Q₁₀ value appeared in winter , while the minimum value appeared in autumn in Paspalum notatum grassland. The Q₁₀ value in winter and spring were larger than in summer and autumn in Pinus massoniana forest and the secondary forest.5) The relation between soil component respiration and soil water content were depict the poor , negative correlation even more except to depict the medium positive correlation in the secondary forest.6) Estimation of annual flux were adopting single variable model with integrating weather data for field observation stand. The annual heterotrophic respiration flux in Paspalum notatum grassland and Pinus massoniana forest were 3.50, 3.75 times higher respectively than that of the severely eroded land, which were achieved 72.16% , 76.14% of the secondary forest respectively. 7) The annual respiration flux from soil mineral were significantly higher than that from root in Paspalum notatum grassland. The annual respiration flux from soil mineral were significantly higher than root respiration in Pinus massoniana forest and the secondary forest, while that from litter layer was lowest. The contribution of heterotrophic respiration were significant difference in Paspalum notatum grassland and Pinus massoniana forest, which were 71.89% and 59.63%, respectively. Root respiration account for 28.11%, 40.37% and 34.50% respectively in Paspalum notatum grassland, Pinus massoniana forest and the secondary forest. The contribution of respiration from litter layer to total soil respiration was 13.56% in Pinus massoniana forest, which was similar to the secondary forest (13.15%).