不同人为干扰措施对天然次生灌丛土壤肥力及蓄水能力的影响

亚热带常绿阔叶林遭反复干扰后退化形成的天然次生灌丛在未管护模式下难以恢复为乔木林。在浙江省临安市选择典型天然次生灌丛,以强度人为干扰为对照、分别进行保护性干扰和适度人为干扰,探讨灌丛土壤蓄水能力和肥力质量的响应。4年试验结果表明:与强度人为干扰相比,保护性干扰和适度人为干扰后的土壤总贮水量、吸持贮水量和滞留贮水量分别提高了12.41%、5.33%、17.37%和29.13%、33.23%和26.24%;最大持水量、毛管持水量和最小持水量分别提高了23.35%、9.51%、17.55%和48.63%、56.08和71.05%;与强度人为干扰相比,保护性干扰和适度人为干扰的综合肥力分别提高了1.9%和38.5%,其中保护性干扰的水解氮、有机碳和有机质含量提高了12.11%、38.91%和38.94%,适度人为干扰的水解氮、有效磷、有机碳和有机质含量提高了61.97%、90.57%、130%和130.04%,保护性干扰和适度人为干扰的土壤综合评价指数分别提高了15.43%和58.94%。研究表明,与保护性干扰相比,适度人为干扰在土壤的蓄水保水、肥力和固碳增汇等方面更能达到预期的目标。在有条件经营的情况下,可以选择适度人为干扰措施对天然次生灌丛进行管理从而达到加快土壤恢复的目的。

Effects of different human disturbances on soil water conversation and fertility of natural secondary shrub

It is difficult for the natural secondary shrub originated from subtropical evergreen broad-leaved forest by repetitive disturbance to recover to the arbor forest without protective measures. To explore the response of soil water storage capacity and fertility quality of shrub to different disturbance, moderate human disturbance and protective human disturbance(PHD) were taken in typical natural secondary shrub with high human disturbance as control during the period 2012-2015 in Lin''an, Zhejiang Province, China. No protective measures were taken in high human disturbance stands, but artificial interference activities such as wood chopping and herb gathering occurred occasionally. As for the protective interference, no one was permitted entry. Target trees in the natural secondary thickets were selected and tended in moderate human disturbance stands. The integrated soil fertility was determined by Nemero index, and correlation methods were used to estimate the comprehensive evaluation index of soil. Compared with the control, the soil total storage, retention storage and short term storage in protective disturbance and moderate disturbance plots increased by 12.41%, 5.33%,17.37% and by 29.13%,33.23%, 26.24%, respectively. Compared with control, soil maximum water-holding capacity, capillary water holding capacity, and minimum water-holding capacity in protective disturbance and moderate disturbance plots increased by 23.35%, 9.51%, and 17.55% by 48.63%, 56.08%, 71.05%, respectively. Comprehensive soil fertility of protective disturbance and moderate disturbance plots increased by 15.43% and 58.94% respectively when compared with control. Available nitrogen, organic carbon and soil organic matter of protective disturbance plots increased by 12.11%, 38.91% and 38.94%. Moreover, available nitrogen, available phosphorus, organic carbon and soil organic matter of moderate disturbance plots increased by 61.97%, 90.57%, 130% and 130.04%. The integrated soil quality index of protective disturbance and moderate disturbance plots increased by 15.43% and 58.94%, respectively. Bivariate correlation analysis indicated that there were strong positively correlation between the comprehensive soil fertility, soil water storage and soil organic carbon. The results showed that protective disturbance treatment decreased soil density, increased the total soil porosity, total water storage, available nitrogen and organic matter, which could be attributed to the faster growth rate of the trees and increasing amount of litterfall owing to the prohibiti on of firewood chopping and collection. Moderate disturbance not only banned firewood chopping and collection, but also selected and tended the target trees, releasing their competition. It accelerated the closure and biomass of the secondary shrub and enhanced the capability of vegetation interception on precipitation, thus, lessening precipitation on soil erosion. Tending biomass was kept inside leading an increase amount of litter. Compared to the high disturbance and protective disturbance, moderate disturbance decreased soil density, increased soil capillary, noncapillary, total porosity, total water storage, available nitrogen and organic matter. Protective disturbance and moderate disturbance reversed the retrogressive succession of the secondary shrub, accelerated the trees growth and improved the stand structure, resulting in improved soil nutrient cycling, increased soil organic matter and integrated fertility, forming a better status of tree growth and soil recovery, which promoted each other. In conclusion, MDH is better than PDH in leading the secondary shrub community to achieve the desired goal of soil water storage and water conservation, fertility and carbon sequestration. Thus, in the presence of favorable operating conditions, moderate human disturbance could be selected to accelerate the soil restoration of shrub.