DOI: 10.1007/s10533-015-0120-5
Scopus记录号: 2-s2.0-84941878322
论文题名: Reducing conditions, reactive metals, and their interactions can explain spatial patterns of surface soil carbon in a humid tropical forest
作者: Hall S.J. ; Silver W.L.
刊名: Biogeochemistry
ISSN: 0168-2563
EISSN: 1573-515X
出版年: 2015
卷: 125, 期: 2 起始页码: 149
结束页码: 165
语种: 英语
英文关键词: Iron reduction
; Poorly-crystalline minerals
; Redox
; Root biomass
; Soil carbon
; Soil oxygen
Scopus关键词: anoxic conditions
; belowground biomass
; carbon sequestration
; concentration (composition)
; decomposition
; environmental factor
; fine root
; heavy metal
; humid environment
; litterfall
; metabolism
; microbial activity
; organic matter
; reduction
; soil carbon
; soil respiration
; spatial analysis
; tropical forest
; Luquillo Experimental Forest
; Puerto Rico
英文摘要: Humid tropical forests support large stocks of surface soil carbon (C) that exhibit high spatial variability over scales of meters to landscapes (km). Reactive minerals and organo-metal complexes are known to contribute to C accumulation in these ecosystems, although potential interactions with environmental factors such as oxygen (O2) availability have received much less attention. Reducing conditions can potentially contribute to C accumulation, yet anaerobic metabolic processes such as iron (Fe) reduction can also drive substantial C losses. We tested whether these factors could explain variation in soil C (0–10 and 10–20 cm depths) over multiple spatial scales in the Luquillo Experimental Forest, Puerto Rico, using reduced iron (Fe(II)) concentrations as an index of reducing conditions across sites differing in vegetation, topographic position, and/or climate. Fine root biomass and Fe(II) were the best overall correlates of site (n = 6) mean C concentrations and stocks from 0 to 20 cm depth (r = 0.99 and 0.98, respectively). Litterfall decreased as reducing conditions, total and dead fine root biomass, and soil C increased among sites, suggesting that decomposition rates rather than C inputs regulated soil C content at the landscape scale. Strong relationships between Fe(II) and dead fine root biomass suggest that reducing conditions suppressed particulate organic matter decomposition. The optimal mixed-effects regression model for individual soil samples (n = 149) showed that aluminum (Al) and Fe in citrate/ascorbate and oxalate extractions, Fe(II), fine root biomass, and interactions between Fe(II) and Al explained most of the variation in C concentrations (pseudo R2 = 0.82). The optimal model of C stocks was similar but did not include fine root biomass (pseudo R2 = 0.62). In these models, soil C concentrations and stocks increased with citrate/ascorbate-extractable Al and oxalate-extractable Fe. However, soil C decreased with citrate/ascorbate-extractable Fe, an index of Fe susceptible to anaerobic microbial reduction. At the site scale (n = 6), ratios of citrate/ascorbate to oxalate-extractable Fe consistently decreased across a landscape O2 gradient as C increased. We suggest that the impact of reducing conditions on organic matter decomposition and the presence of organo-metal complexes and C sorption by short-range order Fe and Al contribute to C accumulation, whereas the availability of an Fe pool to sustain anaerobic respiration in soil microsites partially attenuates soil C accumulation in these ecosystems. © 2015, Springer International Publishing Switzerland. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/83468
Appears in Collections: 气候减缓与适应 气候变化事实与影响
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作者单位: Department of Environmental Science, Policy, and Management, University of California-Berkeley, 130 Mulford Hall, UC Berkeley, Berkeley, CA, United States; Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA, United States
Recommended Citation:
Hall S.J.,Silver W.L.. Reducing conditions, reactive metals, and their interactions can explain spatial patterns of surface soil carbon in a humid tropical forest[J]. Biogeochemistry,2015-01-01,125(2)