东祁连山小叶金露梅+杯腺柳灌丛草地植被和土壤对其自然恢复演替的响应

Soil and vegetation successional responses in natural restoration of mixed Potentilla parvifolia-Salix cupularis shrubland in the Eastern Qilian Mountains

科学评价灌丛草地自然恢复演替特征,以期为灌丛草地的生态修复和可持续利用提供理论依据。采用"空间代替时间"的方法,研究了东祁连山小叶金露梅+杯腺柳灌丛植被碳储量和土壤理化性质对自然恢复演替的响应。结果表明,随着小叶金露梅+杯腺柳灌丛恢复演替期的延长(约20年),灌丛群落碳储量增加1.2~3.8倍;丛间土壤呼吸速率增大1.1~2.0倍,丛内保持不变;丛间和丛内土壤含水量减小1.0~1.5倍,容重增大1.0~2.0倍;丛间和丛内土壤有机质、速效氮和速效磷含量均呈先增后减的单峰曲线,其含量先增加2.0%~48.7%,后减少4.4%~32.0%,全磷和全钾含量增加3.0%~76.0%,其他养分含量变化各异。随着灌丛草地植被的恢复演替,草地碳储量增加,但土壤理化性质受负面影响。故建议积极探寻实现草地生态系统高效、平衡和持续发展的途径,使灌木和草本植物协调共生、和谐生长,稳定生态系统平衡,提高草牧业生产能力和增加农牧民经济收入。

This research aimed to scientifically evaluate the characteristics of natural succession and provide a theoretical basis for planning ecological restoration and sustainable utilization of shrub meadow. Differences in carbon storage and soil nutrient status were measured for a‘time series’ of sites at different successional stages in mixed Potentilla parvifolia-Salix cupularis shrub meadow in the Eastern Qilian Mountains. For a prolonged natural restorative succession of about 20 years,it was found that the carbon storage of shrub communities increased by 1. 1 to 3. 8 times and the respiration rate of soil between shrubs increased by 1. 1 to 2. 0 times,while soil respiration under shrubs remained unchanged. The soil water content of the 0-30 cm soil layer under shrubs of shrub decreased by up to one third and the soil bulk density under shrubs increased in the 0-30 cm soil depth. Soil organic matter levels in the 0-30 cm soil layer displayed a single-peak curve with an initial increase of 2. 0% to 48. 7% and then a decrease of 4. 4% to 32. 0% in soil organic matter,available nitrogen and available phosphorus,while levels of total phosphorus and total potassium increased by 3. 0% to 76. 0%. No consistent pattern over time was detected for levels of other soil nutrients. To summarize,the carbon storage increased,but the physical and chemical properties of soil were negatively affected over the course of restorative succession of shrub meadow vegetation. Therefore,it is suggested that for sustainable and balanced development of grassland ecosystems there will be a need for proactive exploration of ways to achieve efficiency,so that the shrubs and herbs can develop positive plant community interaction and grow harmoniously. In this way the goal of stabilizing and balancing the ecosystem could be achieved and the production capacity of grass and the economic income of farmers and herdsmen increased.