Whitfeld T.J.S.,Brown University |
Lasky J.R.,Columbia University |
Damas K.,PNG Forest Research Institute |
Sosanika G.,The New Guinea Binatang Research Center |
And 3 more authors.
Biotropica | Year: 2014
Much of the world's tropical forests have been affected by anthropogenic disturbance. These forests are important biodiversity reservoirs whose diversity, structure and function must be characterized across the successional sequence. We examined changes in structure and diversity along a successional gradient in the lowlands of New Guinea. To do this, we measured and identified all stems ≥5 cm diameter in 19 0.25 ha plots ranging in age from 3 to >50 yr since disturbance. We also measured plant functional traits related to establishment, performance, and competitive ability. In addition, we examined change in forest structure, composition, species diversity, and functional diversity through succession. By using rarefaction to estimate functional diversity, we compared changes in functional diversity while controlling for associated differences in stem and species density. Basal area and species density increased with stand age while stem density was highest in intermediate secondary forests. Species composition differed strongly between mature and secondary forests. As forests increased in basal area, community-weighted mean wood density and foliar carbon increased, whereas specific leaf area and proportion of stems with exudate decreased. Foliar nitrogen peaked in medium-aged forests. Functional diversity was highest in mature forests, even after accounting for differences in stem and species diversity. Our study represents one of the first attempts to document successional changes in New Guinea's lowland forest. We found robust evidence that as succession proceeds, communities occupy a greater range of functional trait space even after controlling for stem and species density. High functional diversity is important for ecological resiliency in the face of global change. © 2014 The Association for Tropical Biology and Conservation.
Nuberg I.K.,University of Adelaide |
Gunn B.,CSIRO |
Tavune M.,PNG Forest Research Institute |
Sumareke A.,PNG Forest Research Institute |
Kravchuk O.,University of Adelaide
Biomass and Bioenergy | Year: 2015
A 2 year short-rotation coppicing (SRC) fuelwood production system was evaluated, at 2 tree densities (3333 and 6666 trees ha-1) for the Western Highlands Province (WHP) and National Capital District (NCD) of Papua New Guinea. Of the 10 species tested, the best production of firewood was from Eucalyptus grandis and Eucalyptus robusta in WHP and Eucalyptus tereticornis in the NCD, with values of 2.97m3, 2.55m3, and 0.92m3 for a 500m2 woodlot respectively at the denser spacing. E.grandis and E.robusta produced best tree form in WHP while Eucalyptuspellita produced best form in NCD. Best coppice performance was observed in E. robusta in WHP and E. tereticornis in NCD. The burning characteristics of SRC firewood and charcoal were also assessed, as well as how SRC firewood will appeal to consumers. In the highlands SRC firewood and charcoal yield higher estimated returns to labour (USD20.00 and USD11.16 person-1day-1) compared with main alternative crops of sweet potato and coffee (USD9.77 and USD6.98 person-1day-1 respectively). SRC pole production has a low return to labour (USD7.44 person-1day-1) but could complement SRC production as part of a thinning regime. The main limitation in promulgating SRC systems could be market acceptance and finding a small-business model that integrates well with the indigenous non-market economy. The poor growth rates around the NCD due to limiting biophysical conditions make a 2 year rotation cycle unfeasible. © 2015 Elsevier Ltd.
Slik J.W.F.,University of Brunei Darussalam |
Arroyo-Rodriguez V.,National Autonomous University of Mexico |
Aiba S.-I.,Kagoshima University |
Alvarez-Loayza P.,Duke University |
And 173 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015
The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa. © 2015, National Academy of Sciences. All rights reserved.