低强度林窗式疏伐对云杉人工纯林地表微气候和土壤养分的短期影响

选择高密度云杉人工纯林,模拟天然林窗形成方式,开展了低强度林窗式疏伐试验,监测了地表空气温、湿度和不同土壤层次的养分状况.结果表明:疏伐后第1年,生长季(5—9月)林窗内地表日均温升高而日均湿度降低,林窗内土壤腐殖层(O层)有机质(SOM)和铵态氮(NH4+-N)含量分别增加了19.62%和283.85%,硝态氮(NO3--N)和可溶性有机碳(DOC)含量分别减少77.86%和23.60%.而0～10cm土层SOM、全氮(TN)和NO3--N含量分别比对照增加45.77%、37.14%和75.11%;NH4+-N、DOC和全磷(TP)含量分别减少48.56%、33.33%和13.11%.上述结果说明,低强度林窗式疏伐迅速改善了高密度云杉人工纯林地表阴湿的环境,增强了O层土壤微生物活性与土壤矿化过程,促进了土壤养分释放与土壤肥力恢复.

Short term effects of low intensity thinning simulated by gap on ground microclimate and soil nutrients of pure spruce plantation

Taking a dense spruce pure plantation as test object and simulating the formation of natural forest gap, this paper studied the effects of low intensi
ty thinning by gap creation on the ground temperature, ground humidity, and nutrient contents in different soil layers of the plantation. In the first year of gap creation, the mean diurnal temperature in the gap across the growth season (May-September) increased, while the mean diurnal humidity decreased. The soil organic matter (SOM) and NH₄⁺-N contents in O-horizon (humus layer) increased by 19.62% and 283.85%, and the dissolved organic carbon (DOC) and NO₃^--N contents decreased by 77.86% and 23.60%, respectively. The SOM, total nitrogen (TN), and NO₃^--N contents in 0-10 cm soil layer increased by 45.77%, 37.14%, and 75.11%, and the  NH₄⁺-N, DOC, and total phosphorus (TP) contents decreased by 48.56%, 33.33%, and 13.11%, respectively. All the results suggested that low intensity thinning by gap creation could rapidly improve the ground microclimate of the plantation, and consequently, promote the soil microbial activity and mineralization processes in O-horizon, the release of soil nutrients, and the restoration of soil fertility.