Light and nutrient limitations for tree growth on young versus old soils in a Bornean tropical montane forest

Shin-Ichiro Aiba,Kanehiro Kitayama

doi:10.1007/s10265-020-01217-9

Shin-Ichiro Aiba, Kanehiro Kitayama

Open Access

https://doi.org/10.1007/s10265-020-01217-9

Copy DOI

Abstract

We examined forest and tree responses to decreasing nutrient availability with soil aging in a species-rich tropical montane rain forest on Mount Kinabalu, Borneo. Community composition and structure and tree growth rates were compared between two 1 ha plots on nutrient-rich young soil versus nutrient-deficient old soil. Myrtaceae and Fagaceae dominated both plots. With soil aging, the dominance of Lauraceae, stem density, basal area and aboveground biomass decreased, and the forest understory became brighter. Some dominant taxa on the old soil (Podocarpaceae and the genus Tristaniopsis in Myrtaceae) were virtually absent on the young soil; this was attributed to light limitation in the understory. Growth rates of understory trees were lower on the young soil, whereas those of canopy trees were lower on the old soil. This suggested that the growth of understory trees was limited by light on the young soil, whereas that of canopy trees was limited by nutrients on the old soil. Of the eight species that were abundant in both plots, the dominance of five species was considerably lower on the old soil, four of which also exhibited decreased maximum sizes and lower growth rates. The remaining three species showed similar dominance across plots without a decline in growth rates, although they exhibited decreased maximum sizes on the old soil. These analyses demonstrated divergent responses of species to the soil-age gradient. We suggest that the differential responses of species to decreasing nutrient availability with a concomitant increase in understory light levels explain floristic turnover with soil aging.

Highlights

Tropical rain forests are home to a high diversity of plants, which are associated with a rapid rate of spatial species turnover or ‘beta diversity’ (Condit et al 2002; Slik et al 2009)
Assuming that soil formation initiated after the uplift of Mount Kinabalu, which probably commenced approximately eight million years ago (Hall et al 2008), the age of the soil in the old-soil plot would be the order of millions of years old
By comparing the two plots, one can examine the effects of pedogenesis from young (< 34,300 years old) to old soils formed from essentially the same parent material

Summary

Introduction

Tropical rain forests are home to a high diversity of plants, which are associated with a rapid rate of spatial species turnover or ‘beta diversity’ (Condit et al 2002; Slik et al 2009). Soil nutrient conditions are an important cause of beta diversity among tropical rain forest stands under the same climatic conditions (John et al 2007; Potts et al 2002). When the first four factors are controlled, the soil properties change as a function of time since the onset of soil formation. Under such conditions, the availability of Stunted vegetation occurs on severely nutrient-impoverished soil at the late stage of pedogenesis (Kitayama et al 1997; Wardle et al 2004).

Methods

Results

Conclusion