Analysis On The Effects Of Different Cutting Methods To Salix On Soil Respiration

On a global scale,arid and semi-arid regions cover about two-fifth of the land area.It is not only an important part of the terrestrial ecosystem,but also one of the ecological type frailest areas.As a pioneer specie in Mu Us Desert,Salix is known as its windbreak and sand fixation,but the effect on carbon cycle of atmospheric is always overlooked.As the largest carbon pool in the terrestrial ecosystem,soil plays an important role in the global carbon cycle.However,soil respiration is one of the main methods to soil carbon input into the atmosphere.This article intends to study the effect of different cutting methods to Salix on land use system in arid and semi-arid regions,especial to the soil respiration.Consequently,we could explore an optimal way of eco-efficiency for different cutting method of Salix.In this paper,we took the artificial Salix pasmmophia protection forest in Mu Us Desert as research project and measured the soil respiration,soil temperature and soil moisture under clear-cut and thinning-cut system.The paper has studied and discussed the effects of different cutting methods to the land use system.The correlativities between soil temperature,soil water content and soil respiration rate were analyzed by SPSS.The single factor models of soil respiration,which were fitted by soil respiration rate and temperature or moisture,were constructed in both plots.The double factor models of soil respiration rate were also constructed by soil respiration rate,temperature and moisture in both sites.The results showed that:(1)The soil respiration rate has a typical diurnal variation,which is characterized by a single peak curve,its peak value appears at about 12 to 14 o 'clock.The soil respiration rate is highly consistent with the diurnal variation of soil temperature.The soil respiration rate is the highest in summer,and the lowest in winter.The diurnal variation of soil respiration rate has a large variation range in spring and summer,and has a small variation range in autumn and winter.(2)Clear cutting and thinning had significant(p<0.05)effects on soil temperature in different soil depths in October.Compared with the control group,clear cutting significantly(p<0.05)increases underground 5cm,10cm and 15cm soil temperature in July.The soil moisture(0-5cm?5-10cm?10-15cm)content of the samples with different cutting methods generally show a decreasing trend with the change of season,and the soil moisture content showed different degrees of decline after clear cutting and thinning.The diurnal variation of clear cutting soil respiration rate is greater than that of thinning and control plots.The soil respiration rate of clear cutting plots is greater than that of thinning and control plots in July,and the difference is significant(p>0.05)in July,which is not observed(p>0.05)in the other seasons.(3)There is a significant(p<0.001)positive correlation between soil respiration rate and surface temperature and underground 5cm,10cm,and 15cm soil temperature,the correlation between soil respiration rate and soil moisture content is weak.(4)The three kinds of soil respiration rate and soil temperature,underground 5cm,10cm,15cm soil temperature have a significant(p<0.001)exponential relationship.The Q10 range of the clear cutting plots is 1.8-2.7;the thinning plots is 2.0-3.0;the control plots is 1.9-2.9.Under different felling methods,soil respiration temperature sensitivity coefficient has a little difference.The soil respiration rate and unary two function model of soil 5-10cm soil moisture content can better explain the change of soil respiration,soil water content is less than about 15%,the soil respiration rate and soil moisture are positively correlated,while more than 15%,they show a negative correlation.(5)In all plots,compared with the single factor model,multiple regression model has improved explanation ability of soil respiration change in different degrees.The underground 5cm,10cm,15cm soil temperature and humidity can explain the changes of clear cutting plots of soil respiration rate 93%,94.2%,92.2%;the changes of thinning plots of soil respiration rate 94%,94.1%,93.4%;the changes of the control plots of soil respiration rate 92.9%,82.8%,89.1%which indicate that both temperature and humidity have a comprehensive effect on soil respiration.(6)Taken together,thinning-cut not only meets the need of Salix about its sprout regeneration,but also minimises the negative impact of cutting on the environment.Therefore,from the perspective of eco-efficiency about the land use system,thinning is the best cutting method for the Salix in Mu Us Desert.