ABSTRACT

Necromass is crucial to understanding both carbon and nutrient cycling throughout the forest. In this study, we assessed the carbon stock and spatial distribution of necromass components in an Atlantic rainforest, southern Brazil, one hotspot of biodiversity. Necromass comprised: standing dead trees and stumps (SWN), large-sized woody necromass (LWN), medium-sized woody necromass (MWN), and litter (LTR). Specific sample designs assessed each component, while the Payandeh index indicated spatial distribution. Mean wood densities of LWN ranged from 0.24 to 0.46 g.cm⁻³, and mean carbon fraction ranged from 0.42 to 0.44 gC.g⁻¹ d.m. depending on decay class. The total necromass carbon stock was 12.83 MgC.ha⁻¹. SWN, LWN, MWN, and LTR carbon stores were 3.15, 4.24, 1.50, and 3.53 MgC.ha⁻¹, respectively. LWN and MWN showed a reverse J-curve skewed carbon stock distribution and clumped spatial pattern. LTR presented asymmetric distribution and a random spatial pattern. Coarse and heavy necromass is clumped near dead trees, while the wind scatters fine necromass throughout the forest. This study provides useful information to the understanding of the carbon cycle in Atlantic rainforests and may be helpful to improve the Brazilian Inventory of Anthropogenic Emissions and Removals of Greenhouse Gases and the Global Forest Resource Assessment.

摘要

Necromass对于了解整个森林的碳和养分循环至关重要。在这项研究中，我们评估了巴西南部大西洋雨林中死灵生物成分的碳储量和空间分布，这是生物多样性的一个热点。Necromass包括：立枯树木和树桩（SWN），大型木质necromass（LWN），中型木本necromass（MWN）和垃圾（LTR）。具体的样本设计评估了每个组成部分，而 Payandeh 指数表示空间分布。LWN 的平均木材密度范围为 0.24 至 0.46 g.cm ^-3，平均碳含量范围为 0.42 至 0.44 gC.g ^-1dm 取决于衰减等级。总死灵碳储量为12.83 MgC.ha ^-1。SWN、LWN、MWN和LTR碳库分别为 3.15、4.24、1.50 和 3.53 MgC.ha ^-1。LWN和MWN显示出反向 J 曲线偏斜的碳储量分布和聚集的空间格局。轻轨呈现不对称分布和随机空间格局。粗糙而沉重的死灵聚集在枯树附近，而风将细小的死灵散布在整个森林中。这项研究为了解大西洋热带雨林的碳循环提供了有用的信息，可能有助于改进巴西人为排放和温室气体清除清单和全球森林资源评估。