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Effects of large-scale environmental disturbances through land-use change and fires on the CO2 balance of tropical peat swamp forest

土地利用变化和火灾造成的大规模环境干扰对热带泥炭沼泽森林二氧化碳平衡的影响

基本信息

批准号：
15255001
负责人：
HIRANO Takashi
金额：
$ 22.88万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Tropical peatlands, which coexist with swamp forests, have accumulated vast amounts of carbon as soil organic matter. Since the 1970s, however, deforestation and drainage have progressed on an enormous scale. In addition, El Nino and Southern Oscillation (ENSO) drought and large-scale fires, which grow larger under the drought condition, are accelerating peatland devastation. That devastation enhances decomposition of soil organic matter and increases the carbon release to the atmosphere as CO_2. This phenomenon suggests that tropical peatlands have already become a large CO_2 source, but related quantitative information is limited. Therefore, we evaluated the CO_2 balance of a tropical peat swamp forest in Central Kalimantan, Indonesia, using three years of CO_2 fluxes measured using the eddy covariance technique from 2002 through 2004. The forest was disturbed by drainage; consequently, groundwater level (GL) was reduced. The net ecosystem CO_2 production (NEP) measurements showed se … More asonal variation, which was slightly positive or almost zero in the early dry season, and most-negative late in the dry season or early the rainy season. This seasonality is attributable to the seasonal pattern of climate, tree phenology and fires. Slightly positive NEP resulted from smaller ecosystem respiration (RE) and larger gross primary production (GPP) under conditions of high photosynthetic photon flux density (PPFD) and large leaf area index (LAI). The most-negative NEP resulted from smaller GPP and larger RE. The smaller GPP was related to high vapor pressure deficit (VPD), small LAI and low PPFD because of smoke from fires. The larger RE was related to low GL. Annual NEP values were estimated respectively as-602,-382 and-313 gC m^<-2> y^<-1> for 2002, 2003 and 2004. These negative NEP values show that the tropical peat swamp forest, disturbed by drainage, functioned as a CO_2 source. That source intensity was highest in 2002, an ENSO year, mainly because of low PPFD caused by dense smoke emitted from large fires. Less

与沼泽森林共存的热带泥炭地积累了大量的碳作为土壤有机质。然而，自 20 世纪 70 年代以来，森林砍伐和排水已经大规模发展。此外，厄尔尼诺现象和南方涛动（ENSO）干旱以及在干旱条件下愈演愈烈的大规模火灾，正在加速泥炭地的破坏。这种破坏增强了土壤有机质的分解，并增加了以CO_2 形式释放到大气中的碳。这一现象表明热带泥炭地已经成为一个巨大的CO_2来源，但相关的定量信息有限。因此，我们利用涡流协方差技术测量的2002年至2004年三年的CO_2通量，评估了印度尼西亚中加里曼丹热带泥炭沼泽森林的CO_2平衡。因此，地下水位（GL）降低了。生态系统净 CO_2 产量 (NEP) 测量结果显示出一些非季节性变化，在旱季初期略有正值或几乎为零，而在旱季末或雨季初期则最为负值。这种季节性归因于气候、树木物候和火灾的季节性模式。在高光合光子通量密度（PPFD）和大叶面积指数（LAI）的条件下，较小的生态系统呼吸（RE）和较大的总初级生产力（GPP）导致NEP略为正。最负面的 NEP 是由较小的 GPP 和较大的 RE 造成的。较小的 GPP 与高蒸气压赤字 (VPD)、小 LAI 和低 PPFD（由于火灾产生的烟雾）有关。 RE 越大，GL 越低。 2002年、2003年和2004年的年NEP值分别估计为-602、-382和-313 gC m^<-2> y^<-1>。这些负NEP值表明热带泥炭沼泽森林在排水干扰下充当了CO_2源。该源强度在 2002 年（ENSO 年）最高，主要是因为大火排放的浓烟导致 PPFD 较低。较少的