Takyu Masaaki, Aiba Shin-Ichiro, Kitayama Kanehiro
Japanese Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi, P.O. Box 16, 305-8687 Ibaraki, Japan.
Oecologia. 2003 Feb;134(3):397-404. doi: 10.1007/s00442-002-1115-1. Epub 2002 Dec 19.
We have examined how the structure and function of a forest ecosystem change with topography (lower-slope versus ridge) and how the changes are modified by nutrient availability depending on geological substrate (Quaternary and Tertiary sedimentary rocks and ultrabasic rock) in the tropical montane rain forests of Mt. Kinabalu (Borneo) where climate is humid and aseasonal. Reflecting the difference in site age and parent rock, the pool size of soluble-P and inorganic-N in topsoil decreased from Quaternary sedimentary >Tertiary sedimentary >ultrabasic rock on the lower-slope, and they decreased from the lower-slope to the ridge on all substrates. Forest structural attributes [stature, above-ground biomass, and leaf area index (LAI)] decreased in the order of Quaternary sedimentary >Tertiary sedimentary >ultrabasic rock in association with soil nutrients on the lower-slopes, and decreased upslope consistently on each of the three substrates. Functional attributes [above-ground net primary productivity (ANPP) and decomposition rate] demonstrated similar patterns to structure. ANPP significantly correlated with LAI among the six sites, while net assimilation rate (ANPP divided by LAI assuming an even productivity between above vs below-ground system) was nearly constant. Therefore, ANPP could be explained primarily by LAI. Topographical change in LAI could be explained by leaf mass per area (LMA) combined with stand-level leaf biomass. LMA increased upslope on all substrates in association with the decrease in individual leaf area. Stand-level leaf biomass decreased upslope on all substrates but the Tertiary sedimentary rock. Our study demonstrated that topography and geological substrates interactively affected forest structure and processes. The effect of topography on forest structure and processes was greater on nutrient-rich substrates than on poor substrates, and the effect of geological substrate was greater on lower-slopes than on ridges.
我们研究了森林生态系统的结构和功能如何随地形（下坡与山脊）变化，以及在气候湿润且无明显季节变化的婆罗洲基纳巴卢山热带山地雨林中，这些变化如何因地质基质（第四纪和第三纪沉积岩以及超基性岩）导致的养分有效性差异而受到影响。反映出立地年龄和母岩的差异，下坡土壤表层中可溶性磷和无机氮的库大小从第四纪沉积岩>第三纪沉积岩>超基性岩依次降低，且在所有基质上均从下坡向山脊递减。森林结构属性[树高、地上生物量和叶面积指数（LAI）]在下坡与土壤养分相关联，按第四纪沉积岩>第三纪沉积岩>超基性岩的顺序递减，并且在三种基质的每一种上均沿上坡方向持续降低。功能属性[地上净初级生产力（ANPP）和分解速率]呈现出与结构相似的模式。在六个研究地点中，ANPP与LAI显著相关，而净同化率（假设地上与地下系统生产力均匀，ANPP除以LAI）几乎恒定。因此，ANPP主要可由LAI来解释。LAI的地形变化可由单位面积叶质量（LMA）结合林分水平叶生物量来解释。在所有基质上，LMA均随上坡方向增加，与单叶面积减小相关。除第三纪沉积岩外，在所有基质上林分水平叶生物量均随上坡方向降低。我们的研究表明，地形和地质基质交互影响森林结构和过程。地形对森林结构和过程的影响在养分丰富的基质上比在贫瘠基质上更大，而地质基质的影响在下坡比在山脊更大。
