Nutritional characteristics in leaves of plants native to tropical peat swamps and heath forests of Central Kalimantan, Indonesia

Abstract

Thirteen mineral element concentrations in leaf samples of 478 native plants growing in peat swamps and heath forests of Central Kalimantan were detemined. Chemical properties of surface soils in the study sites were also determined. In all sampling sites the mean concentrations of essential macro-elements were variable than that of micro-elements. The chemical properties of surface soils necessitate that the peat podzolic soils are nutrient-limited. However, some native plants growing on these soils show a preference to accumulate excessive concentrations of particular micro-elements, such as Na, Mn, Al, and Si, in their leaves. The results of this study confirm that the concentrations of elements in plant leaves appear to be indicative of site variation and are the result of environmental adaptation. AI, Si, and Na were the principal elements determining the nutritional characteristics of the native plant leaves. However, only AI has clear inter-element relationships for each plant group. Therefore, the relationships between AI-Na and Al-Si in leaves reveal important strategies of plant adaptation to the nutrient-poor ecosystems of peat swamps and heath forests. Native plants belonging to the Eurosid I evolutionary group had very high AI concentrations in their leaves, both in Lahei and Kalampangan peat swamp forests. Combre/ocarpus rotunda/us (Anisophylleaceae family) was predominant in the study sites and, could be regarded as an AI accumulating species (leaf AI concentration within the range of 2,000 - 10,000 mg kg-I). AI-accumulating species likely restrict the accumulation of other mineral elements in their leaves, whereas non AI-accumulating species tend to accumulate other mineral elements in their leaves. Although the mechanism for this eco-physiological adaptation remains unclear, it is suspected that AI-accumulating species (c.f. C. rotunda/us) have developed efficient strategies enabling them to utilize low amounts of essential elements in order to be able to grow in a nutrient-limited environment. Information gathered about AI-accumulation by certain wild plants will useful in selecting appropriate species to rehabilitate damaged peat swamp and heath forests.