Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas  

作　　者：Alan N.Costa Jeane R.Souza Karyne M.Alves Anderson Penna-Oliveira Geisciele Paula-Silva Ingrid S.Becker Kelly Marinho-Vieira Ana L.Bonfim Alessandra Bartimachi Ernane H.M.Vieira-Neto 

机构地区：[1]Instituto de Biologia,Universidade Federal de Uberlândia,Uberlândia 38405-320,MG,Brazil [2]Instituto de Biotecnologia,Universidade Federal de Goiás,Catalão 75704-000,GO,Brazil [3]Department of Wildlife Ecology and Conservation,University of Florida,Gainesville,FL 32611,USA

出　　处：《Journal of Plant Ecology》2020年第5期517-524,共8页植物生态学报（英文版）

基　　金：supported by the Brazilian National Research Council-CNPq(Long Term Ecological Projects-PELD,grant no.403733/2012-0 and 441225/2016-0).

摘　　要：Aims Litterfall at a global scale is affected by climate,edaphic features and vegetation structure,with litter production increasing from grasslands to forests following the rise in standing biomass.However,at landscape scales,the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent,structurally distinct communities are lacking.Here,we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado.Methods We evaluated the woody vegetation structure and composition in 48 sites,equally distributed across four physiognomies and monitored the monthly litter production from April 2014 to March 2015.Important Findings Results showed that the density,basal area,cylindrical volume and aboveground biomass of woody vegetation differ among physiognomies,increasing consistently from cerrado ralo,cerrado típico,cerrado denso and cerradão.Indeed,we found a strong and positive relationship between aboveground biomass and annual litter production,with litter yield increasing from 0.9 to 8.4 Mg ha^(−1)across different physiognomies,following the increment in vegetation structure.Monthly production was seasonal and similar among vegetation types,increasing during the dry season.Leaves comprised the dominant fraction(approx.85%)and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months.However,the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types,likely following the decrease of deciduous species abundance in the plant community.Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies,which co-occur across the Cerrado landscape,with potential implications for the overall functioning of this ecosystem.Moreover,these 全球尺度上的凋落物受气候,土壤特征和植被结构的影响,随着植被现存生物量的增加,从草地到森林的凋落物产量增加。然而,在景观尺度上,凋落物的产量与植被结构之间的相同关系却很少被研究,相邻的结构不同的群落之间凋落物格局的比较研究也比较缺乏。本研究使用一种标准化的方法来描述四种稀树草原地貌之间的结构差异,并分析了在巴西塞拉多保护区(Cerrado)中地貌与凋落物变化的关系。我们评估了平均分布在4个地貌的48个地点的木本植被结构和组成,并从2014年4月到2015年3月每月监测凋落物产量。研究结果表明,不同地貌的木本植被密度、断面积、柱状体积和地上生物量各不相同。地上生物量与年凋落物产量之间存在着很强的正相关关系,凋落物产量随植被结构的增加从0.9增加到8.4 Mg ha^(−1)。不同植被类型间的月产量具有季节性和相似性,旱季产量增加。叶组成显性部分(约85%)和凋落物的季节性主要是由于干旱月份落叶集中所致。然而,可能是随着植物群落中落叶物种丰度的减少,全年凋落物的时间格局显示出从开放植被类型到封闭植被类型的季节性逐渐减少。我们的研究结果表明,植被结构的变化可能会影响不同地貌凋落物的空间和时间分布格局,这些格局在整个塞拉多保护区景观中同时发生,可能对该生态系统的整体功能产生影响。此外,这些发现强调了使用标准化方法是正确比较不同环境中凋落物格局的必要条件。

关 键 词：CERRADO ecosystem functioning habitat heterogeneity Neotropical savannas nutrient cycling 

分 类 号：Q94[生物学—植物学]