Beyond total carbon: conversion of amazon forest to pasture alters indicators of soil C cycling
Beyond total carbon: conversion of amazon forest to pasture alters indicators of soil C cycling
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DOI：
10.1007/s10533-020-00743-x
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发表时间：
2021-01-08
期刊：
影响因子：
4
通讯作者：
Rodrigues, Jorge L. Mazza
中科院分区：
文献类型：
--
作者：
Durrer, Ademir;Margenot, Andrew J.;Rodrigues, Jorge L. Mazza
在热带地区，土地利用变化（LUC）会影响土壤有机碳（SOC），但LUC对土壤质量和碳循环的长期影响尚不清楚。在这里，我们评估了土地利用变化如何影响土壤碳循环在亚马逊地区使用100年的观测时序跨越主要森林到牧场的转换和随后的次生林演替。我们发现，尽管在前25年内森林来源的SOC损失较大（> 85%），但转换后60年表土SOC浓度惊人地增加。SOC的分子组成的变化，确定与漫反射红外傅立叶变换（DRIFT）光谱，发生在串联的高锰酸盐可氧化碳（POXC）和β-葡萄糖苷酶活性（每单位SOC）的显着下降，解释为土壤碳循环减速后，牧草成为C输入到土壤的主要来源。次生林演替引起快速逆转的条件下观察到的原始森林β-葡萄糖苷酶活性，但不是SOC分子组成（DRIFT光谱），反映了土地利用变化对土壤碳循环的长期影响。我们的研究结果表明，在SOC的起源发生快速变化后，森林砍伐与遗产的影响，对某些指标的C循环（如酶活性），但不是其他（如分子组成）。这种方法提供了亚马逊流域土地利用变化的机械理解，并可用于帮助解释有关森林砍伐如何影响该地区SOC的相互矛盾的报告。
It is well established that land use change (LUC) can impact soil organic carbon (SOC) in tropical regions, but the long-term effects of LUC on soil quality and C cycling remain unclear. Here, we evaluated how LUC affects soil C cycling in the Amazon region using a 100-year observational chronosequence spanning primary forest-to-pasture conversion and subsequent secondary forest succession. We found a surprising increase in topsoil SOC concentrations 60 years following conversion, despite major losses (> 85%) of forest-derived SOC within the first 25 years. Shifts in molecular composition of SOC, identified with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, occurred in tandem with a significant decline in permanganate-oxidizable C (POXC) and beta-glucosidase activity (per unit SOC), interpreted as a deceleration of soil C cycling after pasture grasses became the dominant source of C inputs to soil. Secondary forest succession caused rapid reversal to conditions observed under primary forest for beta-glucosidase activity but not for SOC molecular composition (DRIFT spectroscopy), reflecting a long-lasting effect of LUC on soil C cycling. Our results show that rapid changes in the origin of SOC occur following deforestation with legacy effects on some indicators of C cycling (e.g. enzyme activity) but not others (e.g. molecular composition). This approach offers mechanistic understanding of LUC in the Amazon basin and can be used to help explain conflicting reports on how deforestation impacts SOC in the region.