Effects Of Different Application Rates Of Biochar On The Soil Respiration Components In Moso Bamboo Forests

Moso bamboo?Phyllostachys pubescens?is one of the most important bamboo resources in South China.Recently,the planting area is over 3500 thousand hm2 in China and it is widely distributed in Zhejiang Province.In order to obtain high economic value,people commonly take the intensive management.However,the management pratices lead to the decrease of soil active carbon pool,soil enzyme and microbial activity.The application of biochar can improve soil quality.However,effects of the different application rate of biochar on soil respiration and the mechanism involved still remain unclear.In this study,a typically intensively managed Moso bamboo plantation was secleted to conduct the experiment.Through one year of positioning test,the effects of different application rates of biochar on soil temperature,soil moisture content,the soil labile C pool,soil respiration components and soil enzyme activity were investigated,the relationships between soil respiration components and soil environmental factors in Moso bamboo plantations were analyzed.The internal mechanism of the effect of different application rates of biochar on soil respiration components in Moso bamboo forest was revealed.The main results obtained from the present study were listed as follows:?1?In 0,5,15 t hm^-2 application rates of biochar,the soil respiration,heterotrophic and autotrophic respiration rate all reflects the seasonal variations characteristic.The highest rate of soil total respiration and autotrophic respiration is all in summer,the lowest in winter.The highest rate of heterotrophic respiration is in autum and the lowest in winter.Soil respiration,autotrophic respiration rate increased with the increasion of biochar quantity,but the soil heterotrophic respiration rate decreased.Compared with the control,the application 15 t hm^-2 rate of biochar significantly increased the annual cumulative CO2 emissions of soil respiration?P < 0.05?,while there is no significant effect in the application rate of 5 t hm^-2 biochar.Biochar significantly decreased the annual cumulative CO2 emission of soil heterotrophic respiration?P < 0.05?.There was no significant difference between the the application 5 and 15 hm^-2 rate of biochar.Biochar significantly increased the annual cumulative CO2 emission of soil autotrophic respiration successively?P < 0.05?.In 0,5,15 t hm^-2 application rates of biochar,the percentage of soil heterotrophic respiration was 63.87%,57.19,54.56%,autotrophic respiration was 36.13%,42.81%,45.44%,respectively.Obviously the percentage of heterotrophic respiration was higher than that of autotrophic respiration.?2?In the application rates of 0,5,15 t hm^-2 biochar,the contents of WSOC and MBC in Phyllostachys pubescens forest were significantly different,but both of them reflected the seasonal variations characteristic.The highest contents of WSOC appeared in July or August,the lowest in January or February.The highest contents of MBC appeared in November,the lowest in January or February.In 5,15 t hm^-2 application rates of biochar,the contents of WSOC increased 13.9% and 27.0%,MBC increased 12.4% and 15.1%,respectively.?3?Compared with the control,after one month of biochar treatments,soil urease activity significantly decreased?P < 0.05?,soil invertase activity had no obvious change.15 t hm^-2 boichar treatment significantly decreased soil ?-glucosidase and dehydrogenase activity?P < 0.05?,but the 5 t hm^-2 biochar treatment had no significant effec t on the two kinds of enzyme activity.After Twelve months of biochar treatments,15 t hm^-2 boichar treatment significantly decreased soil invertase,urease,?-glucosidase and dehydrogenase activity?P < 0.05?.5 t hm^-2 biochar treatment significantly decreased soil urease and ?-glucosidase activity?P < 0.05?,but had no significant effect on soil urease and dehydrogenase activity.?4?In 0,5,15 t hm^-2 application rates of biochar,there are significant correlation between soil respiration components and soil temperature in soil surface 5 cm?P < 0.05?,the soil respiration Q10 was 2.10,2.07,2.04,the heterotrophic respiration Q10 was 2.21,2.30,2.24,and the autotrophic respiration Q10 was 1.94,1.81,1.75.Compared with the control,biochar treatments had no significant effect on soil Q10.In different quantity of biochar treatment,the heterotrophic respiration was more sensitive than autotrophic respiration.There was no significant correlation between soil respiration components and soil moisture content.?5?In the control,soil respiration,heterotrophic respiration,autotrophic respiration rate were all significantly correlated with soil WSOC contents?P < 0.01?.In biochar treatments,there was no correlation between soil respiration components and soil WSOC contents.In the control,soil respiration components were all significantly correlated with soil MBC contents?P < 0.05?.There was also no correlation in biochar treatments.