Patterns of both above-and belowground biomass and production were evaluated using published information from 200 individual data-sets. Data sets were comprised of the following types of information: organic matter storage in living and dead biomass (e.g. surface organic horizons and soil organic matter accumulations), aboveand belowground net primary production (NPP) and biomass, litter transfers, climatic data (i.e. precipitation and temperature), and nutrient storage (N, P, Ca, K) in above-and belowground biomass, soil organic matter and litter transfers. Forests were grouped by climate, foliage life-span, species and soil order. Several climatic and nutrient variables were regressed against fine root biomass or net primary production to determine what variables were most useful in predicting their dynamics. There were no significant or consistent patterns for above-and belowground biomass accumulation or NPP change across the different climatic forest types and by soil order. Similarly, there were no consistent patterns of soil organic matter (SOM) accumulation by climatic forest type but SOM varied significantly by soil order-the chemistry of the soil was more important in determining the amount of organic matter accumulation than climate. Soil orders which were high in aluminum, iron, and clay (e.g. Ultisols, Oxisols) had high total living and dead organic matter accumulations -especially in the cold temperate zone and in the tropics. Climatic variables and nutrient storage pools (i.e. in the forest floor) successfully predicted fine root NPP but not fine root biomass which was better predicted by nutrients in litterfall. The importance of grouping information by species based on their adaptive strategies for water and nutrient-use is suggested by the data. Some species groups did not appear to be sensitive to large changes in either climatic or nutrient variables while for others these variables explained a large proportion of the variation in fine root biomass and/or NPP.
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Summary 1We conducted a field experiment to test whether aggregated spatial distributions were related to soil variation in locally sympatric tree species in the rain forests of Sarawak, Malaysia. Dryobalanops aromatica , Shorea laxa , and Swintonia schwenkii are naturally aggregated on low-fertility humult ultisols, Dryobalanops lanceolata and Hopea dryobalanoides on moderate-fertility udult ultisols and Shorea balanocarpoides is found on both soil types. 2 Seedlings of all six species were grown in a nested-factorial experiment for 20 months in humult and udult soils in gaps and in the understorey to test for soil-specific differences in performance. Phosphorus addition was used to test for effects due to P-limitation. 3 Four species showed significantly higher growth on their natural soils, but one humultsoil species ( D. aromatica ) and the broadly distributed species were not significantly affected by soil type. 4 One udult-soil species, D. lanceolata , had both lower relative growth rate and lower mycorrhizal colonization on humult soil. However, humult soils also had lower levels of Ca, Mg, K, N and probably water availability. 5 The overall ranking of growth rates among species was similar on the two soils. Growth rates were strongly positively correlated with leaf area ratio and specific leaf area among species in both soils. With the exception of D. aromatica , species of the higher-nutrient soils had higher growth rates on both soils. 6 Although P addition led to elevated soil-P concentrations, elevated root-and leaf-tissue P concentrations on both soils, there was no significant growth enhancement and therefore no evidence that P availability limits the growth or constrains the distribution of any of the six species in the field. Differences in soil water availability between soils may be more important. 7 Our results suggest that habitat-mediated differences in seedling performance strongly influence the spatial distributions of tropical trees and are therefore likely to play a key role in structuring tropical rain forest communities.
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