Variation in leaf and soil δ15N in diverse tree species in a lowland dipterocarp rainforest, Malaysia

• Published in: Trees (Berlin, West) Vol. 30; no. 2; pp. 509 - 522
• Main Authors: Tanaka-Oda, Ayumi, Kenzo, Tanaka, Inoue, Yuta, Yano, Midori, Koba, Keisuke, Ichie, Tomoaki
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2016
• Subjects: Agriculture; Biomedical and Life Sciences; Forestry; Life Sciences; Original Paper; Plant Anatomy/Development; Plant Pathology; Plant Physiology; Plant Sciences; Nitrogen acquirement; Nitrogen stable isotope; Root symbiosis; Dipterocarpaceae; Tropical rainforest
• ISSN: 0931-1890; 1432-2285
• DOI: 10.1007/s00468-015-1298-9

Key message Large variations in leaf δ 15 N in Bornean tropical rainforest trees may indicate that various tropical species have species-specific strategy for nitrogen uptake under low soil nutrient conditions, including root symbiotic microorganisms such as ectomycorrhiza. Lowland tropical rainforests in Southeast Asia are characterized by high species diversity despite limited soil nutrient conditions. The plant nitrogen isotope ratio (δ 15 N) reflects plant uptake of soil nitrogen. We analyzed δ 15 N values and nitrogen content (N %) in leaves and roots of 108 woody species with different types of symbiotic microorganisms, of different life forms (emergent, canopy, sub-canopy, understory, and canopy gap species), and from different families in a Bornean lowland dipterocarp forest to gain more insight into the diversity of nitrogen uptake strategy in the rhizosphere. Leaf δ 15 N values in the species studied varied largely from −7.2 to 5.0 ‰, which is comparable to the values of known Asian trees including temperate, sub-tropical, and tropical mountain forests. Leaf δ 15 N also varied significantly among both life forms and families, though the phylogenetically independent contrast (PIC) relationships were not statistically significant among life form, family, and symbiotic types. Some families showed specific leaf δ 15 N values; Dipterocarpaceae, the dominant family in the canopy layer with symbiotic ectomycorrhiza in Southeast Asia, had small intraspecific variation and higher leaf δ 15 N values (0.03 ‰) compared with species exhibiting arbuscular mycorrhiza, whereas several families such as Burseraceae, Euphorbiaceae, and Myrtaceae showed large interspecific variation in leaf δ 15 N (e.g., from −7.2 to 5.0 ‰ in Euphorbiaceae). These variations suggest that tropical species may have family- or species-specific strategy, such as root symbiotic microorganisms, for nitrogen uptake under low-nutrient conditions in tropical rainforests in Southeast Asia.