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大熊猫是我国特有珍稀物种,是中国生物多样性保护的旗舰物种[1]。近年来受全球气候变化和人类活动影响,加之地震灾害等导致大熊猫国家公园内栖息地破碎化严重、生态廊道断裂,大量栖息地破坏,物种多样性受威胁和丧失速度加剧[2-4]。栖息地退化既是造成大熊猫生境破碎化的主要原因,也是造成大熊猫种群隔离的重要因素之一[5]。因此,研究大熊猫退化栖息地恢复技术,加快受损生态系统修复,促进破碎化栖息地斑块间的有机融合,实现大熊猫国家公园内栖息地整体保护,是目前大熊猫国家公园建设的重点任务。
岷山山系是野生大熊猫重要的分布区,是现存野生大熊猫栖息地面积最大和野生大熊猫种群数量最多的山系[6]。该区分布着大量的灌丛,多为区域森林采伐后次生发育而成的植被类型,生态系统稳定性差、抗干扰能力低、生产力和生物量低、生态服务功能较弱。该类植被多分布在各类原始植被之间,以连通廊道形式存在,经常作为大熊猫交流活动的通道,然而由于灌木生长致密,大熊猫主食箭竹几乎没有分布空间,这大大限制了大熊猫活动和迁徙交流。目前为止,对于岷山山系大熊猫栖息地灌丛还缺乏研究。
因此,本研究立足于大熊猫国家公园重点建设廊道——平武县黄土梁廊道,以康定柳灌丛为研究对象,对其进行带状皆伐,并在皆伐带进行了植被改造,分析了1年后保留带和皆伐带的土壤养分和微生物碳氮特征,以期为大熊猫国家公园退化栖息地建设提供理论与实践支持。
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从图1可以看出,与柳灌丛保留带相比,皆伐带土壤总有机质(TOC)在表层土中有所下降,而在亚表层中显著升高;全磷(TP)相反,在表层土中急剧升高了4.14倍,而在亚表层中降低了2.69倍。皆伐改造后全氮(TN)在表层土和亚表层分别提高了14.54%和29.50%;而全钾(TK)相反,在两个土层均显著下降。
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从图2可以看出,与柳灌丛保留带相比,皆伐带土壤铵态氮(AN)在表层土中无显著变化,在亚表层中升高了69.46%;硝态氮(NN)显著升高,在表层土和亚表层分别增加了10.86%和23.36%。皆伐改造后有效磷(AP)在表层土中提高了51.97%,在亚表层中降低了65.50%;而速效钾(AK)相反,在表层土中略有下降,在亚表层中升高了47.54%。
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从图3可以看出,与柳灌丛保留带相比,皆伐带土壤微生物氮(MBN)和土壤微生物氮熵(qMBN)显著升高,在表层土和亚表层中MBN分别升高51.31%和87.14%;qMBN分别升高43.12%和81.90%。皆伐改造后微生物碳(MBC)和微生物碳熵(qMBC)在表层土分别提高了39.32%和38.96%,而在亚表层中分别降低了57.82%和68.66%。
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从图4可以看出,与柳灌丛保留带相比,皆伐带土壤碳氮比(C/N)显著下降,在表层土和亚表层分别下降了30.52%和5.25%;皆伐改造后碳磷比(C/P)和氮磷比(N/P)在表层土中均显著下降,而在亚表层中却显著升高。土壤微生物碳氮比(MBC/MBN)皆伐带的两个土层和保留带的表土层无显著性差异,在保留带的亚表层土中很高,为另外3个土层的16.14~24.92倍。
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从表1可以看出,NN、AN与TN呈两两正相关,NN、AN与TOC呈正相关。MBN与TN、NN、AN、AK呈正相关,而与TK、AP、MBC、MBC/MBN呈负相关。AP、MBC、MBC/MBN呈两两正相关,与TOC、TN、NN、AN、AK均呈负相关。
参数 TN TP TK NN AN AP AK MBC MBN MBC/MBN TOC 0.545 −0.583* −0.011 0.579* 0.822** −0.929** 0.882** −0.910** 0.43 −0.819** TN −0.023 −0.686* 0.984** 0.912** −0.739** 0.676* −0.835** 0.987** −0.905** TP 0.117 −0.039 −0.383 0.608* −0.135 0.404 0.094 0.344 TK −0.645* −0.531 0.358 0.03 0.346 −0.716** 0.502 NN 0.912** −0.743** 0.707* −0.850** 0.971** −0.906** AN −0.948** 0.798** −0.976** 0.843** −0.987** AP −0.793** 0.966** −0.633* 0.933** AK −0.890** 0.601* −0.817** MBC −0.747** 0.969** MBN −0.843** Table 1. Correlation analysis of soil nutrients and microbial indicators in Salix shrub
Rapid Effects of Strip Clear-cutting on Soil Nutrients of Giant Panda Corridor Shrubs in the Minshan Mountains
doi: 10.12172/202107080001
- Received Date: 2021-07-08
- Available Online: 2022-03-09
- Publish Date: 2022-04-26
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Key words:
- Strip clear-cutting /
- Giant panda corridor /
- Shrub /
- Soil nutrient /
- Soil microorganism
Abstract: The Salix paraplesia shrubs in the giant panda corridor of the Minshan Mountains were chosen as the research object, and continuous strip clear-cutting and vegetation reconstruction were carried out. The characteristics of soil nutrients and microbial carbon and nitrogen contents in the clear-cutting zone and reserved zone of the shrubs were analyzed after 1 year. The results showed that the soil nutrient conditions and soil microbial conditions of the S. paraplesia shrubs were effectively improved after the clear-cutting reform. Compared with the reserved zone, the total nitrogen in the topsoil and subsoil of the clear-cutting zone increased by 14.54% and 29.50%, nitrate nitrogen increased by 10.86% and 23.36%, microbial nitrogen increased by 51.31% and 87.14%, microbial nitrogen entropy increased by 43.12% and 81.90%, microbial carbon and microbial carbon entropy in the topsoil increased by 39.32% and 38.96%, and ammonium nitrogen in the subsoil increased by 69.46%. After clear cutting, the C/N ratio decreased significantly, the microbial activity increased, the decomposition of organic matter accelerated, the total organic carbon of topsoil decreased, and the soluble nutrients may migrate and deplete to the lower layer. Measures can be taken to improve the surface vegetation and compensate for the consumption of soil organic matter.