Plantation conversion of Eucalyptus promotes soil microbial necromass C accumulation

IF 3.7 2区 农林科学 Q1 ECOLOGY
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引用次数: 0

Abstract

Context

Stand conversion in subtropical regions has altered soil physicochemical properties and microbial communities, leading to changes in microbially mediated processes, such as microbial necromass C (MNC) formation and accumulation. However, previous studies on the effects of stand conversion on MNC are lacking, leading to gaps in our understanding regarding the influence of long-term stand conversion on MNC accumulation in different soil layers and the relative importance of soil properties for regulating MNC.

Aims

In this study, we used field surveys and soil analysis to assess the effects of converting a Eucalyptus forest into other planted forest (broadleaf mixed forest [BM] and Acacia mangium × Acacia auriculiformis forest [AM]) on soil properties, enzyme activity, microbial community composition, and MNC after conversion 20 years in Guangdong, South China.

Results

We found that the content of soil organic C (SOC) in the surface soil (0–10 cm after litter removal) increased by 64.9 % when Eucalyptus was converted to AM, whereas there was no significant difference in the subsurface soil (10–20 cm). β-1,4-glucosidase (BG) and β-1,4-N-acetaminophen glucosidase (NAG) activity increased significantly, while leucine aminopeptidase (LA) activity decreased significantly in the surface soil. In the subsurface soil, BG activity did not change significantly; nonetheless, acid phosphomonoesterase (AP) activity decreased. The fungal, bacterial, and gram-negative bacterial biomass did not significantly differ among the different forests in the surface soil, but the fungal, bacterial, gram-positive, and gram-negative bacterial biomass decreased significantly in the subsurface soil. The ratio of fungi to bacteria was highest in the BM, whereas the ratio of gram-positive to gram-negative bacteria was highest in the AM. Soil fungal and microbial necromass C and the ratio of fungal to bacterial necromass C increased significantly in the surface soil when Eucalyptus was converted to AM. The contribution of MNC and fungal necromass C to SOC content significantly increased by 22.20 % and 26.23 %, respectively, when Eucalyptus was converted to AM. The main controlling factors of MNC accumulation in the surface soil were pH and total N, whereas soil enzyme activity (BG related to C-acquisition) was the dominant determinant of MNC accumulation in the subsurface soil.

Conclusion

Our study provides evidence that converting Eucalyptus to AM may promote MNC accumulation in the surface soil by changing soil pH and TN content to affect soil enzyme activity and microbial community structure, and ultimately changed MNC accumulation. Therefore, developing effective forest management practices, such as reasonable stand conversion may help to enhance forest SOC accumulation by increasing MNC accumulation.
桉树的种植转化促进了土壤微生物坏质碳的积累
背景亚热带地区的林分转换改变了土壤理化性质和微生物群落,导致微生物介导的过程发生变化,如微生物坏死物质 C(MNC)的形成和积累。然而,以前缺乏有关林分转换对 MNC 影响的研究,导致我们对长期林分转换对不同土层中 MNC 积累的影响以及土壤特性对调节 MNC 的相对重要性的认识存在差距。目的 在本研究中,我们利用实地调查和土壤分析评估了在中国南方广东将桉树林改造成其他人工林(阔叶混交林 [BM] 和芒果相思树 × 金合欢林 [AM])20 年后对土壤性质、酶活性、微生物群落组成和 MNC 的影响。结果我们发现,当桉树转化为 AM 后,表层土壤(去除枯落物后 0-10 厘米)的土壤有机碳(SOC)含量增加了 64.9%,而表层下土壤(10-20 厘米)则无显著差异。表层土壤中,β-1,4-葡萄糖苷酶(BG)和β-1,4-N-乙酰氨基酚葡萄糖苷酶(NAG)活性显著增加,而亮氨酸氨肽酶(LA)活性显著降低。在地下土壤中,BG 活性没有明显变化;但酸性磷单酯酶(AP)活性有所下降。在表层土壤中,不同森林的真菌、细菌和革兰氏阴性菌生物量没有显著差异,但在表层下土壤中,真菌、细菌、革兰氏阳性菌和革兰氏阴性菌生物量显著下降。真菌与细菌的比例在 BM 中最高,而革兰氏阳性菌与革兰氏阴性菌的比例在 AM 中最高。当桉树转化为 AM 时,表层土壤中的土壤真菌和微生物坏死物质 C 以及真菌与细菌坏死物质 C 之比显著增加。桉树转化为 AM 后,MNC 和真菌坏死物质 C 对 SOC 含量的贡献率分别大幅增加了 22.20 % 和 26.23 %。表层土壤中 MNC 积累的主要控制因素是 pH 值和全氮,而土壤酶活性(与 C 获取有关的 BG)是表层下土壤中 MNC 积累的主要决定因素。因此,制定有效的森林管理措施,如合理的林分转换,可能有助于通过增加 MNC 积累来提高森林 SOC 积累。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
European Journal of Soil Biology
European Journal of Soil Biology 环境科学-生态学
CiteScore
6.90
自引率
0.00%
发文量
51
审稿时长
27 days
期刊介绍: The European Journal of Soil Biology covers all aspects of soil biology which deal with microbial and faunal ecology and activity in soils, as well as natural ecosystems or biomes connected to ecological interests: biodiversity, biological conservation, adaptation, impact of global changes on soil biodiversity and ecosystem functioning and effects and fate of pollutants as influenced by soil organisms. Different levels in ecosystem structure are taken into account: individuals, populations, communities and ecosystems themselves. At each level, different disciplinary approaches are welcomed: molecular biology, genetics, ecophysiology, ecology, biogeography and landscape ecology.
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