TROPICS Vol. 16 (1) Issued January 31, 2007 Nutritional ecology of plants grown in a tropical peat swamp 1) 2) 3) 1) 1,4) Monrawee YANBUABAN , Tanit NUYIM , Takeshi MATSUBARA , Toshihiro WATANABE and Mitsuru OSAKI 1) Research Faculty of Agriculture, Hokkaido University, Sapporo, 060−8589, Japan 2) Princess Sirindhorn Peat Swamp Forest Research and Nature Study Center Narathiwat, 96120, Thailand 3) College of Cross-Cultural Communication and Business, Shukutoku University, Japan 4) Corresponding author ABSTRACT The relationships between plant and peatland (45, 264 ha), however 60% of the peatland soil in peat swamp forests in two different growth in Thailand is found in Narathiwat Province (Suzuki stages, primary and secondary, were examined and Niyomdham, 1992). Floristic composition of peat by analyzing nutritional characteristics (e.g. N, P, swamp forest is rich, consisting of 124 families and 470 K, Ca, Mg, Na, Fe, Mn, Zn, Cu, Mo, Al, B, and species of plants, of which 109 families and 437 species 15 Si concentrations) and natural abundances of N are flowering plants, and 15 families and 33 species of 15 13 13 (δ N) and C (δ C) of plant and soils. Fifty-two fern. Yoshioka et al. (2002) reported that most of the plant species from primary forests and thirty from To Daeng swamp area is a primary swamp forest. Peat secondary forests were randomly sampled. Plants swamp forests in Narathiwat Province are classified as in both forests belonged to the phylogenic groups four types: typical mixed swamp forest on thick peat Euasterids II, Euasterids I, Ericales, Eurosids II, layer, Macaranga-dominated swamp on thick peat layer, Eurosids I, Eudicots, and Magnoliids, which were Melaleuca-dominated forest on thin peat layer or sandy from a newly evolved order. The results showed that soils, and Fagraea-dominated forest on sandy soil with a Eurosids I plants in primary forests accumulated thin peat layer (Suzuki and Niyomdham, 1992). Primary higher P, K, Mg, Fe, and B than those in secondary forests are dominated by Syzygium pyrifolium, Ganua forests. motleyana, Campnossperma coriaceum, Macaranga Other minerals did not limit plant growth at pruinosa, Calophyllum teysmannii, Neesia malayana, either forest type. For Eurosids I plants nutrients Endiandra macrophylla, Syzygium obatum, Sterculia depended on soil K, Mg, and Fe, but for P and B bicolour, Stermonurus secumdiflorus, Syzygium muelleri, they relied on their own nutrient acquisition. This and Baccaurea bracteata (Bunyavajchewin, 1995). Former is similar to other plant phylogenies in both forests destructive anthropogenic use of the peatlands caused the whose nutrient contents reflected their own nutrient disappearance of peat swamp forest, leading to peat soil requirements rather than soil nutrients. Since the degradation and forest type changes or transformation to 15 leaf δ N of plants in both forests is lower than grassland ecosystem (Nagano et al. 1996). 15 soil δ N, N2−fixing microorganism activity may Peat soil is characterized as a nutrient-poor be high. It can be hypothesized that peat swamp ecosystem with very high acidity and loads of organic forests have developed symbiotic systems with N2− matter e.g. lignin (Safford and Maltby, 1998; Paavilaine fixing microorganisms, because of poor N nutrition. and Päivänen, 1995). To Daeng peat swamp is fed by rainfall and by river run-off from mountainous areas in Key words: peat soil, plant phylogeny, primary the west. Ueda et al. (2000) reported that this swamp forest, secondary forest water has low pH, nutrient levels and very low levels of anions and cations in the surface water, even lower than in the ground water. This kind of nutrient-limited INTRODUCTION soil retards plant growth. Therefore, plants growing on The largest areas of peatland in the world are located peat soil must develop some specific mechanisms, such in the Southeast Asian coastal areas along peninsula as organic acid exudation from roots, to accumulate Malaysia and Indonesian Java, Sumatra, and Borneo. nutrients (Osaki et al. 2003, 1998a, and 1998b, Tuah, Thailand is a country that contains a small area of tropical 2003). In general, plant species that grow and dominate 32 Monrawee YANBUABAN, Tanit NUYIM, Takeshi MATSUBARA, Toshihiro WATANABE and Mitsuru OSAKI in an ecosystem are affected by various environmental parameters, so differences in plant physiology, e.g. seed Soil sampling and analysis germination, relative growth rate, and competition with Soil samples were collected from several points at each other plant species, can also express the changes in the forest type at three depths (0−20, 20−40 and 40−60 environmental development of an ecosystem (Berendse, cm), air-dried and ground prior to chemical analysis. 1990). Soils were analyzed for N content using an MT−6 CHN 15 13 Recently, natural abundances of stable isotopes CORDER (YANAKO). The δ N and δ C were analysed plus N ( δ 15N) and C ( δ 13C) are being used widely in using an isotope mass spectrometer (EA1110-DELTA research on N and C assimilation cycling in organisms Advantage ConFloIII System). Two grams of soil were , and ecosystems (Robinson, 2001; O Lear y, 1981). shaken for 2 hrs, extracted with 1 N HCl and filtrated Measurements of whole plants are inadequate because through Whatman no 42 filtrate paper. Concentrations of , they don t address seasonal life stage differences and P, K, Ca, Mg, Na, Fe, Mn, Zn, Cu, Mo, Al, B, and Si in the are limited by time or sample size. Therefore, the extract were determined using ICPS-7000. relative abundance of isotopic assay, which integrates physiological processes over larger temporal and spatial Data analysis scales, is required (Nilsen and Orcutt, 1996). Nitrogen The general tendency of plant mineral element dynamics are fundamental in natural ecosystems and accumulation was explained and comparisons between essential for all plants. However, N cycling in plant and plant phylogenies were made. Phylogenetic classification soil is complex. This study, therefore, aims to highlight was categorized by referring to the orders and families of some aspects of N cycling and other physiological angiosperms and gymnosperms. This classification can mechanisms of plants growing in two growth stages of be accessed at http://biodiverisy.uno.edu.delta. Mineral peat swamp forest. concentration means were compared with a t-test using SPSS 10.0 MATERIALS AND METHODS Study site RESULTS This study was conducted in peat swamp forests of To Vegetation Daeng Peat Swamp Forest, Narathiwat Province Thailand. Fifty-two plant species in primary forests and thirty in This site comprises of primary and secondary forests. secondary forests were observed. These plants were Primary forest is at a climax stage and undisturbed, in classified into 7 phylogenic groups: Ericales, Euasterids contrast to secondary forest, which is dominated by native I, Euasterids II, Eudicots, Eurosids I, Eurosids II, and trees and those that grow quickly after deforestation by Magnoliids. humans or a natural disaster. Primary forest comprised of Ardisia lanceolata, Diospyros lanceifolia, Dispyros siamang, and Ganua Plant sampling, preparation, and analysis motleyana for Ericales, Ochreinauclea maingayi, Ixora Mature leaves were randomly sampled from primary and grandifolia, Tarenna wallichii, and Euodia roxburghiana secondary forests. Samples were oven-dried at 80 ˚C to for Euasterids I, Stemonurus secundiflorus for Euasterids constant weight, ground into a fine powder, and weighed II, Bhesa indica, Crudia caudata, Dialium patens, for subsequent chemical analysis. Archidendron clypearia, Parastemon urophyllus, Baccaurea bracteata, Blumeodendron kurzii, Macaranga griffithiana, Plant analysis Macaranga pruinosa, Garcinia bancana, Cartoxylum Samples were completely digested with a mixture of arborescens, Calophyllum teysmannii, Gynotroches H2SO4 and H2O2 following Mizuno and Minami (1980). axillaries, Elaeocarpus griffithii, and Elaeocarpus Leaf N was analysed using a CN analyser (SUMIGRAPH macrocerus for Eurosids I, Neesia malayana, Vatica NC-1000). Concentrations of P, K, Ca, Mg, Na, Fe, Mn, Zn, pauciflora, Stercalia bicolour, Eugenia grandis, Eugenia Cu, Mo, Al, B, and Si were determined using inductively tumida, Eugenia spicata, Eugenia caudate, Eugenia coupled plasma emission spectrometry (ICPS-7000, cerasiformis, Eugenia operculata, Eugenia kunstleri, 15 13 SHIMADZU). Leaf δ N and δ C were analysed using Campnosperma coriaceum, Melanochyla bracteata, an isotope mass spectrometer (EA1108-ConfloII-delta-S Sandoricum beccarianum , Aglaia rubiginosa, Chisocheton system). patens, Aglaia odoratissima, and Nephelium maingayi for 13 13 15 15 Nutritional ecologyofplantsgrown inatropical peatswamp Table 1. Nutrient concentrations and natural abundances of stable isotope C (δ C) and N (δ N) of some native plants in a primary peat swamp forest 13 15 Cladistic group Order Family Species δ C δ N C N P K Ca Mg Na Fe Al Cu Zn Mn Si B Mo −1 −1 ‰ ‰ g kg mg kg Ericales Ericales Ebenaceae Diospyros lanceifolia −34 3 363 14.4 0.5 9.6 8.4 2.2 153 45 26 4.8 46.8 2210 27.4 8 4 Ericales Ericales Ebenaceae Dispyros siamang −33 0 368 9.6 0.1 1.4 2.9 1.2 70 32 28 0.9 7.1 77.3 11.1 41.3 11.3 Ericales Ericales Myrsinaceae Ardisia lanceolata −32 0 313 11.2 0.3 27.2 12.8 3.3 191 37 25 5.6 12.7 14.2 19.6 0.0 12.9 Ericales Ericales Sapotaceae Ganua motleyana −34 0 333 11.5 0.1 8.0 2.1 0.6 121 54 11 3.6 21.6 11.8 25.5 0.3 11.5 Euasterids I Gentianales Rubiaceae Ochreinauclea maingayi −30 4 354 12.4 0.4 5.0 4.4 0.5 200 40 36 0.4 15.8