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

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，森林砍伐和排水取得了巨大的进展。此外，厄尔尼诺和南方涛动(ENSO)干旱和大规模火灾在干旱条件下变得更大，正在加速泥炭地的破坏。这种破坏加剧了土壤有机质的分解，增加了碳以CO_2的形式释放到大气中。这一现象表明，热带泥炭地已经成为一个巨大的CO_2源，但相关的定量信息有限。因此，我们利用2002-2004年利用涡旋协方差技术测量的三年的CO_2通量，对印度尼西亚加里曼丹中部的一片热带泥炭沼泽林的CO_2平衡进行了评估。森林受到排水的干扰，因此地下水位(GL)降低。生态系统净CO_2产生量(NEP)的测量表明，Se…更多的逆风变化，在旱季早期略为正或几乎为零，在旱季后期或雨季早期为最负。这种季节性可归因于气候、树木物候和火灾的季节模式。在高光合光量子通量密度(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。GPP较小、RE较大是NEP负值最大的原因。较小的GPP与较高的水汽压差(VPD)、较小的LAI和较低的PPFD有关，因为火灾产生的烟雾。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 gcm^&lt；-2；y^&lt；-1。这些负的NEP值表明，热带泥炭沼泽林受排水干扰，起到了CO_2源的作用。这一源强度在2002年最高，这是ENSO的一年，主要是因为大火排放的浓烟造成的PPFD较低。较少

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