Scheuermann Cynthia M, Nave Lucas E, Fahey Robert T, Nadelhoffer Knute J, Gough Christopher M
Department of Biology, Virginia Commonwealth University, Box 842012, 1000 West Cary St, Richmond, VA, 23284, USA.
Biological Station and Department of Ecology and Evolutionary Biology, University of Michigan, Pellston, MI, 49769, USA.
Oecologia. 2018 Oct;188(2):405-415. doi: 10.1007/s00442-018-4236-x. Epub 2018 Aug 4.
Canopy structure and tree species diversity, shaped by succession, disturbance, and community composition, are linked to numerous ecosystem functions, including net primary production (NPP). Understanding of how ecosystem structural metrics are interrelated and mechanistically link to NPP, however, is incomplete. We characterized leaf area index (LAI), Simpson's index of Diversity (D', a measure of species diversity), and canopy rugosity (R, a measure of canopy physical complexity) in 11 forest stands comprising two chronosequences varying in establishing disturbance, and in three late successional communities. We related LAI, D', and R to wood NPP (NPPw), and examined whether absorption of photosynthetically active radiation and light use-efficiency (LUE) link NPPw with ecosystem structure. We found that recovery of LAI and D' was delayed following more severe establishing disturbances, but that the development of R was strikingly conserved regardless of disturbance, converging on a common mean value in late-successional stands irrespective of differences in leaf area index and species diversity. LAI was significantly correlated with NPPw in each stage of ecosystem development, but NPPw was only correlated with R in early successional stages and with D' in late successional stages. Across all stands, NPPw was coupled with LAI and R, (but not D') through positive relationships with light absorption and LUE. We conclude by advocating for better integration of ecological disciplines investigating structure-function interactions, suggesting that improved understanding of such relationships will require ecologists to traverse disciplinary boundaries.
由演替、干扰和群落组成塑造的林冠结构和树种多样性与众多生态系统功能相关联，包括净初级生产力（NPP）。然而，对于生态系统结构指标如何相互关联以及与NPP建立机制联系的理解并不完整。我们对11个林分的叶面积指数（LAI）、辛普森多样性指数（D'，一种物种多样性度量）和林冠粗糙度（R，一种林冠物理复杂性度量）进行了表征，这些林分包括两个在建立干扰方面有所不同的时间序列以及三个晚期演替群落。我们将LAI、D'和R与木材NPP（NPPw）相关联，并研究光合有效辐射的吸收和光利用效率（LUE）是否将NPPw与生态系统结构联系起来。我们发现，在更严重的建立干扰之后，LAI和D'的恢复会延迟，但无论干扰如何，R的发展都显著保持稳定，在晚期演替林分中收敛于一个共同的平均值，而与叶面积指数和物种多样性的差异无关。在生态系统发展的每个阶段，LAI与NPPw都显著相关，但NPPw仅在早期演替阶段与R相关，在晚期演替阶段与D'相关。在所有林分中，NPPw通过与光吸收和LUE的正相关关系与LAI和R（而非D'）相耦合。我们通过倡导更好地整合研究结构 - 功能相互作用的生态学科来得出结论，表明对这种关系的更好理解将要求生态学家跨越学科界限。
