Affects Of Reduce Carbon Input To The Respiration In Four Kinds Forests Of Subtropics

The soil respiration, soil temperature and soil humidity have been observed in four subtropical forest types in botanical garden of hunan province from May 2009 to May 2010, and the relation between soil respirations have been researched. The soil respiration was measured with three treatments including the control, litter removal and root and litter removal, to determine the relationship between soil respiration and environmental factors. The results are as fellows:(1)There are some obvious month changes of soil respiration between three kinds of treatments in mixed of coniferous and broadleaf forest, whose character curve is similar single-perk type, with the soil respiration both showed rise and then decline. Generally, with temperature rising, soil respiration rise gradually, and after reaching the highest value, then declining gradually. The dynamic characteristic of soil respiration which is the other three types of vegetation ecosystems is similar with the mixed.The control soil respiration both showed rise and then decline in the month dynamic characteristics of the same treatment, whose character curve is similar single-perk type. Generally, with temperature rising, soil respiration rise gradually, and after reaching the highest value, then declining gradually.(2)In conifer and broadleaf mixed ecosystem, the seasonal variation of soil respiration in three treatments showed similar a single peak, with temperature rising, soil respiration rise gradually, and after reaching the highest value, then declining gradually. The soil respiration of control in autumn is lowest. The soil respiration of remove litter and remove root and litter reach the highest value in the summer and the lowest in the winter. No root and litter of Pinus massoniana reach the lowest in the autumn. The soil respiration of the other two forest ecosystems reaches the highest value in the summer and the lowest in the winter.The same way of different forest ecosystems soil respiration exist seasonal changes. The seasonal characteristics of control are that seasonal changes in spring and summer are the orders as fellow:Cinnamomum camphora>Camphor and pine mixed>Liquidambar> Pinus massoniana. The order of soil respiration in autumn is that:Cinnamomum camphora> Liquidambar> Camphor and pine mixed>Pinus massoniana. The order of soil respiration in autumn is that:Cinnamomum camphora> Camphor and pine mixed>Pinus massoniana>Liquidambar. The seasonal characteristics of the other two forest ecosystems are similar with control.(3)Interrelationships between the soil respiration of same forest ecosystem and temperature can be done by regression analysis, building regression equation between soil respiration and soil temperatures. Through analysis of the correlation know the correlation relations between soil respiration and soil temperatures. Correlation coefficient is 0.3574(p>0.05) between control of mixed stand soil respiration and soil temperatures. Correlation relation has no significant.0.6082 (**)(P<0.01) between no litter soil respiration and soil temperature. Correlation relation has significant.0.5069 (*) (P<0.05) between no litter and no root of soil respiration and soil temperatures. Correlation relation has significant. The other forest ecosystems have significant. Through related analysis of the same treatment can know that:soil respiration and soil temperature of the control which is in mixed stand and Pinus massoniana have no significant (p>0.05). Soil respiration and soil temperature of Cinnamomum camphora have significant (p<0.05). Soil respiration and soil temperature of liquidambar have very significant (P<0.01). Soil respiration and soil temperature of the other treatments has significant (p<0.05).(4)The Q10 value of control and no litter are the highest in the different forest ecosystems, and no root and no litter of Cinnamomum camphora is the highest. This show that soil respiration of broadleaf is more sensitive to temperature. The Q10 value of no root and no litter is the highest in the same forest ecosystems, except for liquidambar.(5) Soil respiration of no litter and no root was correlated with soil humidity in Cinnamomum camphora (p<0.05). Soil respiration of control was correlated with soil humidity in Cinnamomum camphora (p<0.01). Others have no interrelationship Relations. This shows that: soil temperature and humidity have an impact on soil respiration.