Degradation-driven changes in fine root carbon stocks, productivity, mortality, and decomposition rates in a palm swamp peat forest of the Peruvian Amazon

IF 3.9 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Carbon Balance and Management Pub Date : 2021-10-29 DOI:10.1186/s13021-021-00197-0

Nelda Dezzeo, Julio Grandez-Rios, Christopher Martius, Kristell Hergoualc’h

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Abstract

Background

Amazon palm swamp peatlands are major carbon (C) sinks and reservoirs. In Peru, this ecosystem is widely threatened owing to the recurrent practice of cutting Mauritia flexuosa palms for fruit harvesting. Such degradation could significantly damage peat deposits by altering C fluxes through fine root productivity, mortality, and decomposition rates which contribute to and regulate peat accumulation. Along a same peat formation, we studied an undegraded site (Intact), a moderately degraded site (mDeg) and a heavily degraded site (hDeg) over 11 months. Fine root C stocks and fluxes were monthly sampled by sequential coring. Concomitantly, fine root decomposition was investigated using litter bags. In the experimental design, fine root stocks and dynamics were assessed separately according to vegetation type (M. flexuosa palm and other tree species) and M. flexuosa age class. Furthermore, results obtained from individual palms and trees were site-scaled by using forest composition and structure.

Results

At the scale of individuals, fine root C biomass in M. flexuosa adults was higher at the mDeg site than at the Intact and hDeg sites, while in trees it was lowest at the hDeg site. Site-scale fine root biomass (Mg C ha⁻¹) was higher at the mDeg site (0.58 ± 0.05) than at the Intact (0.48 ± 0.05) and hDeg sites (0.32 ± 0.03). Site-scale annual fine root mortality rate was not significantly different between sites (3.4 ± 1.3, 2.0 ± 0.8, 1.5 ± 0.7 Mg C ha⁻¹ yr⁻¹ at the Intact, mDeg, and hDeg sites) while productivity (same unit) was lower at the hDeg site (1.5 ± 0.8) than at the Intact site (3.7 ± 1.2), the mDeg site being intermediate (2.3 ± 0.9). Decomposition was slow with 63.5−74.4% of mass remaining after 300 days and it was similar among sites and vegetation types.

Conclusions

The significant lower fine root C stock and annual productivity rate at the hDeg site than at the Intact site suggests a potential for strong degradation to disrupt peat accretion. These results stress the need for a sustainable management of these forests to maintain their C sink function.

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秘鲁亚马逊河流域棕榈沼泽泥炭森林退化导致的细根碳储量、生产力、死亡率和分解率变化。

背景：亚马逊棕榈沼泽泥炭地是主要的碳汇和碳库。在秘鲁，由于经常砍伐 Mauritia flexuosa 棕榈树以收获果实，这一生态系统受到广泛威胁。这种退化会严重破坏泥炭沉积，通过细根生产力、死亡率和分解率改变碳通量，从而促进和调节泥炭的积累。在同一泥炭层中，我们对未退化地点（Intact）、中度退化地点（mDeg）和严重退化地点（hDeg）进行了为期 11 个月的研究。通过连续取样，每月对细根的碳储量和通量进行取样。同时，使用垃圾袋调查细根的分解情况。在实验设计中，根据植被类型（柔毛棕榈和其他树种）和柔毛棕榈树龄等级分别评估了细根储量和动态。此外，根据森林的组成和结构，对单个棕榈树和树木的结果进行了现场缩放：结果：在个体尺度上，mDeg地点的M. flexuosa成虫细根C生物量高于Intact和hDeg地点，而在hDeg地点，树木的细根C生物量最低。mDeg地点的细根生物量（毫克碳公顷-1）（0.58 ± 0.05）高于Intact地点（0.48 ± 0.05）和hDeg地点（0.32 ± 0.03）。不同地点的年细根死亡率没有明显差异（完好、mDeg 和 hDeg 地点分别为 3.4 ± 1.3、2.0 ± 0.8、1.5 ± 0.7 Mg C ha-1 yr-1），而 hDeg 地点的生产力（同一单位）（1.5 ± 0.8）低于完好地点（3.7 ± 1.2），mDeg 地点居中（2.3 ± 0.9）。分解速度缓慢，300 天后剩余质量为 63.5-74.4%，不同地点和植被类型的分解速度相似：hDeg地点的细根碳储量和年生产率明显低于Intact地点，这表明强烈的退化可能会破坏泥炭的增生。这些结果强调了对这些森林进行可持续管理以保持其碳汇功能的必要性。

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来源期刊

Carbon Balance and Management Environmental Science-Management, Monitoring, Policy and Law

CiteScore

7.60

自引率

0.00%

发文量

审稿时长

14 weeks

期刊介绍： Carbon Balance and Management is an open access, peer-reviewed online journal that encompasses all aspects of research aimed at developing a comprehensive policy relevant to the understanding of the global carbon cycle. The global carbon cycle involves important couplings between climate, atmospheric CO2 and the terrestrial and oceanic biospheres. The current transformation of the carbon cycle due to changes in climate and atmospheric composition is widely recognized as potentially dangerous for the biosphere and for the well-being of humankind, and therefore monitoring, understanding and predicting the evolution of the carbon cycle in the context of the whole biosphere (both terrestrial and marine) is a challenge to the scientific community. This demands interdisciplinary research and new approaches for studying geographical and temporal distributions of carbon pools and fluxes, control and feedback mechanisms of the carbon-climate system, points of intervention and windows of opportunity for managing the carbon-climate-human system. Carbon Balance and Management is a medium for researchers in the field to convey the results of their research across disciplinary boundaries. Through this dissemination of research, the journal aims to support the work of the Intergovernmental Panel for Climate Change (IPCC) and to provide governmental and non-governmental organizations with instantaneous access to continually emerging knowledge, including paradigm shifts and consensual views.