Soil nutrients and beta diversity in the Bornean Dipterocarpaceae: evidence for niche partitioning by tropical rain forest trees
Article first published online: 25 NOV 2005
Journal of Ecology
Volume 94, Issue 1, pages 157–170, January 2006
How to Cite
PAOLI, G. D., CURRAN, L. M. and ZAK, D. R. (2006), Soil nutrients and beta diversity in the Bornean Dipterocarpaceae: evidence for niche partitioning by tropical rain forest trees. Journal of Ecology, 94: 157–170. doi: 10.1111/j.1365-2745.2005.01077.x
- Issue published online: 25 NOV 2005
- Article first published online: 25 NOV 2005
- Received 7 June 2005 revision accepted 13 September 2005 Handling Editor: David Burslem
- mass effects;
- 1The relative importance of niche- and dispersal-mediated processes in structuring diverse tropical plant communities remains poorly understood. Here, we link mesoscale beta diversity to soil variation throughout a lowland Bornean watershed underlain by alluvium, sedimentary and granite parent materials (c. 340 ha, 8–200 m a.s.l.). We test the hypothesis that species turnover across the habitat gradient reflects interspecific partitioning of soil resources.
- 2Floristic inventories (≥ 1 cm d.b.h.) of the Dipterocarpaceae, the dominant Bornean canopy tree family, were combined with extensive soil analyses in 30 (0.16 ha) plots. Six samples per plot were analysed for total C, N, P, K, Ca and Mg, exchangeable K, Ca and Mg, extractable P, texture, and pH.
- 3Extractable P, exchangeable K, and total C, N and P varied significantly among substrates and were highest on alluvium. Thirty-one dipterocarp species (n = 2634 individuals, five genera) were recorded. Dipterocarp density was similar across substrates, but richness and diversity were highest on nutrient-poor granite and lowest on nutrient-rich alluvium.
- 4Eighteen of 22 species were positively or negatively associated with parent material. In 8 of 16 abundant species, tree distribution (≥ 10 cm d.b.h.) was more strongly non-random than juveniles (1–10 cm d.b.h.), suggesting higher juvenile mortality in unsuitable habitats. The dominant species Dipterocarpus sublamellatus (> 50% of stems) was indifferent to substrate, but nine of 11 ‘subdominant’ species (> 8 individuals ha−1) were substrate specialists.
- 5Eighteen of 22 species were significantly associated with soil nutrients, especially P, Mg and Ca. Floristic variation was significantly correlated with edaphic and geographical distance for all stems ≥ 1 cm d.b.h. in Mantel analyses. However, juvenile variation (1–10 cm d.b.h.) was more strongly related to geographical distance than edaphic factors, while the converse held for established trees (≥ 10 cm d.b.h.), suggesting increased importance of niche processes with size class.
- 6Pervasive dipterocarp associations with soil factors suggest that niche partitioning structures dipterocarp tree communities. Yet, much floristic variation unrelated to soil was correlated with geographical distance between plots, suggesting that dispersal and niche processes jointly determine mesoscale beta diversity in the Bornean Dipterocarpaceae.