Effects Of Stand Characteristics And Climate On Carbon Storage And Its Distribution In Pinus Massoniana Forest

Forest carbon sequestration capacity is related to the ability to reduce atmospheric CO₂concentration and curb global warming trend.Pinus massoniana is the main indigenous afforestation tree in southern China and Pinus massoniana forest is the main forest type in the eastern subtropical region.It not only has economic value,protective efficiency and aesthetic function,but also plays a very important role in maintaining the carbon and oxygen balance of the ecosystem.However,the carbon storage and its distribution in Pinus massoniana forests under different stand characteristics and climate are still not clear.This study in Hubei,Jiangxi,Hunan,Guangxi,four different temperature and precipitation area of different density（high density、medium density and low density）,different forest ages（young forest、middle forest and mature forest）in the pine tree layer,undergrowth biomass,litter layer and soil organic carbon content determination on the basis of investigation and analysis.The effects of stand characteristics and climate factors on the carbon storage and distribution of Pinus massoniana forest were discussed in order to provide a basis for the management and carbon sink administration of Pinus massoniana forest.The main research results are as follows:（1）The mean total carbon storages of high,medium and low density Pinus massoniana stands is 162.13 t/hm²、120.89 t/hm²、144.97 t/hm²respectively,showing that the high density stand had the highest carbon storage and the medium density stand had the lowest carbon storage.Among them,the mean carbon storage of tree layer of high,medium and low density Pinus massoniana forest is 65.96 t/hm²、62.62t/hm²、57.75 t/hm².The mean carbon storage of shrub layer is 0.90 t/hm²、1.33 t/hm²、0.26 t/hm².The mean carbon storage of herb layer is 0.58 t/hm²、0.47 t/hm²、0.25t/hm².The mean carbon storage of litter layer is 3.62 t/hm²、2.43 t/hm²、2.52 t/hm².The mean carbon storage of soil layer is 91.07 t/hm²、54.04 t/hm²、84.19 t/hm².The variation range of carbon storage among Pinus massoniana forests with different densities in the same layer from largest to smallest is soil layer（37.03t/hm²）>tree layer（8.21 t/hm²）>litter layer（1.20t/hm²）>shrub layer（1.07t/hm²）>herb layer（0.33t/hm²）.（2）Of the total carbon storage in Pinus massoniana stands of different densities,only the total carbon storage in the middle density stands was significantly lower than that in other densities.The effect of density on total carbon storage is mainly reflected in the difference of soil carbon storage.Density had significant effects on carbon storage in shrub layer,herb layer and soil layer,but had no significant effects on carbon storage in tree layer and litter layer of Pinus massoniana forest.Density also had a significant effect on the carbon storage of Pinus massoniana leaves.The carbon storage of high density leaves is significantly higher than that of low density leaves,but density had no significant effect on the carbon storage of trunk、branches and roots of Pinus massoniana forest.The total carbon storage of medium density shrub layer and aboveground and underground part of shrub layer were significantly higher than those of other densities.The total carbon storage of high density shrub layer and aboveground and underground part of shrub layer were significantly higher than those of low density stand.The total carbon storage of aboveground and underground carbon storage of high density herbaceous layer were significantly higher than those of other density stands,medium density herbaceous layer and aboveground and underground carbon storage were significantly higher than those of low density stands.（3）The mean total carbon storages of mature,middle and young Pinus massoniana stands is 202.53 t/hm²、162.13 t/hm²、101.61t/hm²respectively,indicating that the total carbon storage increased with the increase of stand age.Among them,the mean carbon storage of tree layer in mature forest,middle stand and young stand is 118.31 t/hm²、65.96 t/hm²、31.36 t/hm².The mean carbon storage of shrub layer is0.55 t/hm²、0.90 t/hm²、0.52 t/hm².The mean carbon storage of herb layer is 0.43t/hm²、0.21 t/hm²、0.14 t/hm².The mean carbon storage of litter layer is 0.81 t/hm²、3.74 t/hm²、2.65 t/hm².The mean carbon storage of soil layer is 82.43 t/hm²、91.07t/hm²、66.69 t/hm².The variation range of carbon storage among Pinus massoniana forests with different ages in the same layer from largest to smallest is tree layer（86.95t/hm²）>soil layer（24.38 t/hm²）>litter layer（2.93 t/hm²）>shrub layer（0.47t/hm²）and>herb layer（0.29 t/hm²）.（4）The total carbon storage of Pinus massoniana stands at different ages is significantly different.The mature stand is significantly higher than that of other stand ages,and the middle stand is significantly higher than that of young stand ages.There were significant differences in carbon storage in tree layer,shrub layer,herb layer,litter layer and soil layer of Pinus massoniana forests of different ages.The total carbon storage of tree layer and trunk,branches,leaves and roots in mature forest were significantly higher than those in other stand ages,and the total carbon storage of tree layer and trunk,branches,leaves and roots in middle stand age were significantly higher than those in young stand age.The total carbon storage of aboveground and underground parts of shrub layer in middle stand age were significantly higher than those in other stand ages.The total carbon storage and aboveground part of herb layer in middle stand age were significantly higher than those in other stand ages.The carbon storage in litter layer of middle stand age was significantly higher than that of other stand ages.The carbon storage in litter layer of young stand age was significantly higher than that of mature stand.The total soil carbon storage and soil carbon storage in middle stand age were significantly higher than those in other stand ages.（5）The mean total carbon storage of Pinus massoniana forest in low,middle and high annual average temperature area is 161.34 t/hm²、262.55 t/hm²、238.76 t/hm²respectively,indicating that the total carbon storage of Pinus massoniana forest is the highest in the middle annual average temperature region and the lowest in the low annual average temperature region.Among them,the mean carbon storage of tree layer of Pinus massoniana forest in low,medium and high annual temperature area is75.87t/hm²、128.38 t/hm²、155.39 t/hm².The mean carbon storage of shrub layer is0.77 t/hm²、2.02 t/hm²、0.81 t/hm².The mean carbon storage of herb layer is 0.52t/hm²、0.50 t/hm²、0.50 t/hm².The mean carbon storage of litter layer is 2.14 t/hm²、4.44 t/hm²、1.71 t/hm².The mean carbon storage of soil layer is 82.04 t/hm²、127.21t/hm²、80.35 t/hm².The variation range of carbon storage among Pinus massoniana forests with different annual average temperature area in the same layer from largest to smallest is tree layer（79.52t/hm²）>soil layer（46.86 t/hm²）>litter layer（2.73 t/hm²）>shrub layer（1.25 t/hm²）>herb layer（0.02 t/hm²）.（6）The total carbon storages of Pinus massoniana forests in different temperature area is significantly different.The total carbon storage of Pinus massoniana forests in low annual average temperature region is significantly lower than that in middle and high annual average temperature region.Temperature had a significant effect on carbon storage in tree layer,shrub layer,litter layer and soil layer,but had no significant effect on carbon storage in herb layer of Pinus massoniana forest.The total carbon storage of tree layer in low annual average temperature region is significantly lower than that in other annual average temperature region.Temperature also has a significant effect on the carbon storage of the trunk,branches,leaves and roots of Pinus massoniana.Carbon storage of trunk in high annual average temperature region is significantly higher than that of other annual average temperature region,and carbon storage of branches and roots in middle annual average temperature region is significantly higher than that of other annual average temperature region.The carbon storage of branches and roots in the high annual average temperature region is significantly higher than that of the low annual average temperature region,the carbon storage of leaves in the high annual average temperature region is significantly higher than that of other annual average temperature area,and the carbon storage of leaves in the middle annual average temperature region is significantly higher than that of the low annual average temperature region.The total carbon storage in the shrub layer and the aboveground and underground parts of the shrub layer in the middle annual average temperature region were significantly higher than those in other annual average temperature region.The carbon storage of litter layer in the middle annual average temperature region is significantly higher than that in the other annual average temperature region.The total carbon storage in the soil layer and the lower soil layer in the middle and average annual temperature area were significantly higher than that in other average annual temperature areas.（7）The mean total carbon storage of Pinus massoniana forest in low,medium and high annual average precipitation area is 120.89 t/hm²、262.55 t/hm²、166.68 t/hm²respectively,indicating that the total carbon storage of Pinus massoniana forest is the highest in the middle annual average precipitation region and the lowest in the low annual average precipitation region.The mean carbon storage in tree layer of Pinus massoniana forest in low,medium and high annual precipitation area is 62.62t/hm²、128.38 t/hm²、93.56 t/hm²,and the mean carbon storage in shrub layer is 1.33 t/hm²、2.02 t/hm²、0.74 t/hm².The carbon storage of herbaceous layer is 0.47 t/hm²、0.50t/hm²、0.60 t/hm²,and that of litter layer is 2.43 t/hm²、4.44 t/hm²、4.37 t/hm².The average carbon storage of soil layer is 54.04 t/hm²、127.21t/hm²、67.41 t/hm².The variation range of carbon storage among Pinus massoniana forests with different annual average precipitation area in the same layer from largest to smallest is soil layer（73.17 t/hm²）>tree layer（65.76t/hm²）>litter layer（2.01 t/hm²）>shrub layer（1.28 t/hm²）>herb layer（0.13 t/hm²）.（8）The total carbon storages of Pinus massoniana forests in different annual average precipitation area was significantly different.The total carbon storage of Pinus massoniana forests in low annual precipitation region was significantly lower than that in medium and high annual average precipitation region,and the total carbon storage of Pinus massoniana forests in middle precipitation region was significantly higher than that in high annual average temperature region.There were significant differences in carbon storage in different levels and organs of Pinus massoniana forest in different annual precipitation area.The total carbon storage of tree layer in the low annual precipitation area was significantly lower than that in the middle and high annual precipitation area,and the total carbon storage of tree layer in the middle precipitation area was significantly higher than that in the high annual average temperature area.The carbon storage of branches and roots in middle age precipitation area was significantly higher than that in other precipitation treated Pinus massoniana forests.Carbon storage of branches and roots in high annual precipitation area was significantly higher than that in middle age precipitation area.The carbon storage of tree trunks in low annual precipitation area was significantly lower than that of other precipitation treatments,and the carbon storage of leaves in middle age precipitation area was significantly higher than that of other precipitation treatments.Shrub total carbon storage and aboveground part carbon storage in middle age precipitation area were significantly higher than those in other precipitation treated forests,while shrub total carbon storage and aboveground part carbon storage in low annual precipitation area were significantly higher than those in high precipitation area.The total carbon storage and underground carbon storage of herbage in high annual precipitation area were significantly higher than those of other precipitation treatments.The carbon storage in litter layer of low annual precipitation area was significantly lower than that of other precipitation treated Pinus massoniana forest.The total carbon storage in the soil layer and the soil carbon storage in the upper,middle and lower layers in the middle precipitation area were significantly higher than those in the Pinus massoniana forest treated with other precipitation.