Landscape-scale changes in forest canopy structure across a partially logged tropical peat swamp

[摘要] Forest canopy structure is strongly influenced by environmental factors anddisturbance, and in turn influences key ecosystem processes includingproductivity, evapotranspiration and habitat availability. In tropicalforests increasingly modified by human activities, the interplay betweenenvironmental factors and disturbance legacies on forest canopy structureacross landscapes is practically unexplored. We used airborne laser scanning(ALS) data to measure the canopy of old-growth and selectively logged peatswamp forest across a peat dome in Central Kalimantan, Indonesia, andquantified how canopy structure metrics varied with peat depth and underlogging. Several million canopy gaps in different height cross-sections ofthe canopy were measured in 100 plots of 1 km² spanning the peat dome,allowing us to describe canopy structure with seven metrics. Old-growthforest became shorter and had simpler vertical canopy profiles on deeperpeat, consistent with previous work linking deep peat to stunted treegrowth. Gap size frequency distributions (GSFDs) indicated fewer and smallercanopy gaps on the deeper peat (i.e. the scaling exponent of Paretofunctions increased from 1.76 to 3.76 with peat depth). Areas subjected toconcessionary logging until 2000, and illegal logging since then, had thesame canopy top height as old-growth forest, indicating the persistence ofsome large trees, but mean canopy height was significantly reduced. Withlogging, the total area of canopy gaps increased and the GSFD scalingexponent was reduced. Logging effects were most evident on the deepest peat,where nutrient depletion and waterlogged conditions restrain tree growth andrecovery. A tight relationship exists between canopy structure and peatdepth gradient within the old-growth tropical peat swamp forest. This relationshipbreaks down after selective logging, with canopy structural recovery, asobserved by ALS, modulated by environmental conditions. These findingsimprove our understanding of tropical peat swamp ecology and provideimportant insights for managers aiming to restore degraded forests.

[学科分类] 地球化学与岩石