Saintilan N.,Office of Environment and Heritage |
Wilson N.C.,Forest Science Institute of Vietnam |
Rogers K.,University of Wollongong |
Rajkaran A.,Rhodes University |
Krauss K.W.,U.S. Geological Survey
Global Change Biology | Year: 2014
Mangroves are species of halophytic intertidal trees and shrubs derived from tropical genera and are likely delimited in latitudinal range by varying sensitivity to cold. There is now sufficient evidence that mangrove species have proliferated at or near their poleward limits on at least five continents over the past half century, at the expense of salt marsh. Avicennia is the most cold-tolerant genus worldwide, and is the subject of most of the observed changes. Avicennia germinans has extended in range along the USA Atlantic coast and expanded into salt marsh as a consequence of lower frost frequency and intensity in the southern USA. The genus has also expanded into salt marsh at its southern limit in Peru, and on the Pacific coast of Mexico. Mangroves of several species have expanded in extent and replaced salt marsh where protected within mangrove reserves in Guangdong Province, China. In south-eastern Australia, the expansion of Avicennia marina into salt marshes is now well documented, and Rhizophora stylosa has extended its range southward, while showing strong population growth within estuaries along its southern limits in northern New South Wales. Avicennia marina has extended its range southwards in South Africa. The changes are consistent with the poleward extension of temperature thresholds coincident with sea-level rise, although the specific mechanism of range extension might be complicated by limitations on dispersal or other factors. The shift from salt marsh to mangrove dominance on subtropical and temperate shorelines has important implications for ecological structure, function, and global change adaptation. © 2013 John Wiley & Sons Ltd.
Harbard J.L.,University of Tasmania |
Griffin A.R.,University of Tasmania |
Foster S.,University of Tasmania |
Brooker C.,University of Tasmania |
And 2 more authors.
Forestry | Year: 2012
Australian acacias are widely planted as exotics and in some cases as invasive. Impact may be reduced if sterile triploid planting stock can be developed. This article reports the first step in such a breeding programme, the production of a population of tetraploid lines for inter-breeding with diploids. Three methods of polyploid induction with colchicine were compared. A conversion rate of 8.9 per cent was obtained by applying 1.5 per cent colchicine to the shoot apical meristem of seedlings. A 7 per cent conversion rate was obtained by germination of scarified seed on filter paper saturated with 0.02 per cent colchicine for 16 h and this method is recommended on logistical and safety grounds. Poor results were obtained when scarified seed were submerged in aqueous solutions of colchicine. Flow cytometry is the preferred method for ploidy determination, sampling after vegetative phase change on a minimum of two opposing phyllodes per plant. Visual classification was inaccurate due to the confounding effects of growth-retarding properties of colchicine. Size and distribution of stomata can also be used but is more time consuming than flow cytometry. At 26 months, tetraploid plants had heavier, thicker, wider and more cupped shaped phyllodes than diploids and the bark: stem diameter ratio was greater.
Huong V.D.,University of Tasmania |
Nambiar E.K.S.,CSIRO |
Quang L.T.,Forest Science Institute of Vietnam |
Mendham D.S.,CSIRO |
Dung P.T.,Forest Science Institute of Vietnam
Southern Forests | Year: 2015
We studied the productivity of Acacia auriculiformis plantations in South Vietnam over three successive rotations covering 15 years. The focus of our study was on the effects of inter-rotation management on stand growth and soil properties. Contrastin g slash and litter management treatments were applied at the start of the sec ond rotation, and reapplied at the start of the third rotation with an additional phosphorus fertiliser treatment. There were improvements in the genetics of planting stock, weed control and stocking with each rotation. Average growth rates (mean annual increment) increased from 10.6 m3 ha−1 y−1 in the first rotation (age 7 years) to 28.3 m3 ha−1 y−1 in the second rotation (age 6 years) and to 33.9 m3 ha−1 y−1 at age 5 years in the third rotation. Removal of slash and litter after harvesting the first rotation removed 20.2 Mg ha−1 biomass, containing 169.6, 13.9, 76.3 and 25.1 kg ha−1 of nitrogen (N), phosphorus (P), potassium and calcium, respectively, from the site. Greater amounts were removed after the second rotation commensurate with higher amounts of biomass produced. Slash and litter removal reduced growth of the second rotation by 13% compared to their retention. Soil organic carbon (C) in the 0–10 cm soil layer increased from 16.7 g kg−1 at the end of the first rotation to 22.8 g kg−1 at the end of the second rotation with a corresponding increase in soil N from 1.2 g kg−1 to 1.7 g kg−1. Over the same time, soil organic C and N contents were 26% and 40% greater, respectively, in treatments with slash and litter retained compared to initial levels before treatment application. In the second rotation, extractable soil P declined and in the third rotation there was a response to added P. Overall results demonstrate that there is an opportunity to increase and sustain production of A. auriculiformis over at least three rotations by integrated management practices promoting better stocking, planting of genetically improved stock, organic matter and nutrient conservation, and judicious weed management. © 2015, Copyright © NISC (Pty) Ltd.
Kien N.D.,Forest Science Institute of Vietnam |
Harwood C.,International Center for Research in Agroforestry
Small-scale Forestry | Year: 2016
Households and wood processing businesses in the provinces of Son La, Dien Bien and Lai Chau in the Northwest of Vietnam were surveyed to determine patterns of local wood demand and supply, changes in species utilized over time, and whether timber from planted trees might substitute for species previously harvested from local natural forests. In each province, 5–6 sawmills and 4–6 villages representing 3 main ethnic groups were selected for investigation. Managers of selected sawmills and 3–4 randomly selected households in each village were interviewed using semi-structured questionnaires. There was high and uniform household demand for fuelwood in the surveyed villages, making fuelwood the dominant use, in terms of wood volume. Use of sawn timber for furniture, home repair and construction consumed less wood but required logs of acceptable species. Sawmills surveyed were small, with input capacity ranging from <15 to 500 m3 of logs per year, suggesting a total log requirement of about 30,000 m3/year for the 192 known wood processing businesses in the three provinces. Most sawmills still used wood from natural forests, sourced locally or imported from Laos. A trend of switching from prized timber species from natural forests, now effectively unavailable, to alternatives from natural and planted forests was reported by both sawmills and households. Some planted species grown on short-medium rotations appear able to substitute for local sawn timber requirements. © 2016 Steve Harrison, John Herbohn
Zuidema P.A.,University Utrecht |
Jongejans E.,Radboud University Nijmegen |
Chien P.D.,University Utrecht |
Chien P.D.,Forest Science Institute of Vietnam |
And 2 more authors.
Journal of Ecology | Year: 2010
Matrix models are popular tools for plant demographic studies, but their application to long-lived, slow-growing species is hampered by the fact that (i) model output is highly sensitive to category width and (ii) growth variation between individuals can only be partially accounted for. Integral Projection Models (IPMs) - an extension of matrix models - offer a solution to these problems. Here, we introduce a new method to parameterize IPMs for trees - the 'integration method'- which allows constructing IPMs for long-lived, slow-growing species. This approach is more suitable than the 'midpoint rule', which is customarily used. We built IPMs for six tree species from Vietnamese (sub)tropical forests. For four of these species, population growth rate (λ) was highly sensitive to the number of categories in the transition matrix. Population growth stabilized for IPMs with 100-1000 categories, corresponding to categories of 0.1-1 cm in trunk diameter. This preferred width is much narrower than the 10-cm-wide categories customarily used in tree models. The distribution of elasticity values over transition types (stasis, progression to next and further categories) is also highly sensitive to matrix dimension in IPMs. In addition, elasticity distribution is influenced by including or excluding growth variation. Age estimates obtained from IPMs were also highly sensitive to matrix dimension: an IPM with 1000 size categories yielded 2-4 times higher age estimates for large trees than one with 10 size categories. Observed ages obtained from tree ring analyses for four of the study species allowed validating these estimates. IPMs with 10 categories strongly underestimated age, while those with 1000 categories yielded slight age overestimates. Underestimating age in small matrices is caused by the occurrence of unrealistically fast pathways through the life cycle and is probably widespread among tree models with broad categories. Overestimating ages in IPMs with narrow categories may be due to temporally autocorrelated growth or errors in fitting growth curves. Synthesis. IPMs are highly suitable tools to analyse tree demography. We recommend that tree IPMs (and classical matrix models) apply narrow diameter categories (0.1-1 cm width) to obtain reliable model output. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.
Van Do T.,Kyoto University |
Van Do T.,Forest Science Institute of Vietnam |
Osawa A.,Kyoto University |
Thang N.T.,Forest Science Institute of Vietnam
Forest Ecology and Management | Year: 2010
The recovery process of fallow stands in the mountainous region of Northwestern Vietnam was studied, based on a chronosequence of 1-26-year-old secondary forests after intensive shifting cultivation. The number of species present in a 26-year-old secondary forest attained 49% of the 72 species present in an old-growth forest. Total stem density decreased gradually from 172,500 ha-1 in a 3-year-old forest to 24,600 ha-1 in the 26-year-old stand, but stem density of larger trees (diameter at breast height (D) ≥ 5 cm) increased from 60 ha-1 in a 7-year-old to 960 ha-1 in the 26-year-old forests, which was similar to that of an old-growth forest. Annual biomass increment of the 26-year-old stand was 4.2 Mg ha-1 year-1. A saturation curve was fitted to biomass accumulation in secondary forests. After an estimated time of 60 years, a secondary forest can achieve 80% of the biomass of old-growth forests (240 Mg ha-1). Species diversity expressed by Shannon Index shows that it takes 60 years for a secondary forest in fallow to achieve a plant species diversity similar to that of old-growth forests. © 2010 Elsevier B.V. All rights reserved.
Zuidema P.A.,University Utrecht |
Zuidema P.A.,Forest Science Institute of Vietnam |
Vlam M.,University Utrecht |
Chien P.D.,University Utrecht |
Chien P.D.,Forest Science Institute of Vietnam
Trees - Structure and Function | Year: 2011
Conservation of threatened tree species requires basic information on growth rates and ages. This information is lacking for many species, but can be obtained relatively easily from tree ring analysis. We studied four threatened Vietnamese species: three conifers from high-elevation forests (Calocedrus macrolepis, Dacrydium elatum and Pinuskwangtungensis) and one broad-leaved species from lowland forest (Annamocarya sinensis). We collected increment cores from remnant populations in protected areas and measured ring width. We built chronologies and found significant correlations with rainfall (all species) and temperature (two species), indicating that rings were formed annually. Diameter-age trajectories showed that species reached reproductive size at 60-80 years. Maximum observed ages were 128-229 years. Some species showed large variation in long-term growth rates among individuals, which was partially explained by strong persistence of growth differences. We also assessed whether growth rates changed over time. For certain size categories in some species, we found higher recent growth rates of juvenile trees compared to those in the distant past. This shift requires a cautious interpretation, but is consistent with a CO2 fertilization effect. For other size categories, we found contrasting results: extant large trees had higher growth rates as small juveniles compared to extant small trees. Such correlations, which we found for all species, suggest a 'juvenile selection effect': the preferential survival of fast-growing juveniles to the canopy. Information on ages, historical growth rates and juvenile selection effect is relevant for the planning of conservation actions. © 2010 The Author(s).
Kim N.T.,Forest Science Institute of Vietnam |
Matsumura J.,Kyushu University |
Oda K.,Kyushu University
Journal of Wood Science | Year: 2011
We investigated clonal and site variations in wood fiber length, microfibril angle, and specific gravity of seven natural hybrid clones of Acacia (Acacia mangium × Acacia auriculiformis) grown in northern and southern Vietnam. Fiber length did not differ between clones or between sites. The microfibril angle of the S2 layer did not significantly differ between clones but significantly differed between sites. Clone and site significantly affected specific gravity. The significant effects of genetic × environmental interactions on wood properties indicated the difference in the response of clones to different growing conditions. The trends of changes in fiber length, microfibril angle, and specific gravity from the vicinity of the pith to near the bark were similar for all clones at each site; however, variations in fiber length, microfibril angle, and specific gravity were more visible in northern Vietnam than in southern Vietnam, with a significant effect of genetic factors. This difference may be attributable to winter, which is experienced in northern Vietnam but not in southern Vietnam. For clone selection for plantation in the northern region, combining growth rate with wood properties was recommended. On the other hand, for plantation in the southern region, clone selection depends mainly on the growth rate, taking into consideration the specific gravity. © 2011 The Japan Wood Research Society.
Putzel L.,Center for International Forestry Research |
Dermawan A.,Center for International Forestry Research |
Moeliono M.,Center for International Forestry Research |
Trung L.Q.,Forest Science Institute of Vietnam
International Forestry Review | Year: 2012
Since 1992, the Vietnamese Government has implemented far reaching policies and programs to increase the country's tree cover by promoting plantation forestry. In addition to providing environmental services, these efforts are intended to alleviate rural poverty through sustainable forestry. Towards this goal, more than 4 million ha have been assigned to households and rural cooperatives through forestland reallocation or management contracts. Although the extent of primary forest has continued to decrease, overall tree cover has increased by 47% since 1990, largely due to the spread of tree plantations. Meanwhile, in the last decade, with Vietnam's economic liberalisation policies, the timber processing industry has shifted from State-owned enterprises to private companies. By 2008, the processing sector had expanded into a3 billion industry, one of Vietnam's top five export sectors and a major source of demand for logs and sawnwood. In 2010, an assessment in the industrial wood processing center of Binh Dinh province was conducted to gain insights on market opportunities for smallholder produced timber. The assessment revealed a number factors preventing local smallholders from fully capitalising on demand for wood from the processing industry. These included competition between the manufacturing sectors (e.g. furniture, woodchips and pulp industries), which creates an incentive for premature timber harvesting, and a lack of domestic supply of certified timber, resulting in Vietnam's furniture companies importing raw materials. To address the former, better segmentation of the wood production for the different sectors is recommended. The latter might be addressed through more aggressive efforts to certify household-scale timber plantations through simplified schemes such as the Forest Stewardship Council's Small and Low Intensity Managed Forests (SLIMF) certification, pending additional research to better understand the potential costs, benefits and risks of such a strategy.
Sang P.M.,Forest Science Institute of Vietnam |
Lamb D.,University of Queensland |
Bonner M.,University of Queensland |
Schmidt S.,University of Queensland
Plant and Soil | Year: 2013
Purpose: Much tropical land requires rehabilitation but the capacity of reforestation with plantations or naturally regenerating secondary forests for overcoming soil degradation remains unclear. We hypothesised that desirable effects, including improved soil fertility and carbon sequestration, are achieved to a greater extent in Acacia mangium plantations and secondary forests than in Eucalyptus urophylla plantations. Methods: We tested our hypothesis across soil and climate gradients in Vietnam with linear mixed-effect models and other, comparing A. mangium and E. urophylla plantations, secondary forests and pasture. Results: A. mangium plantations and secondary forests showed a positive correlation between biomass production and desirable soils properties including increased soil carbon, nitrogen and phosphorus, and reduced bulk density. All plantations, but not secondary forests, caused increases in soil acidity. Eight-year old A. mangium plantations contained most carbon in biomass+soil, and secondary forests and pastures had similar or higher soil carbon. E. urophylla plantations had the lowest soil carbon status, raising doubt about their sequestration capacity in current 6-8 year rotations. Conclusions: The study demonstrates that appropriate reforestation enhances soil fertility and promotes carbon sequestration on degraded tropical lands and that unmanaged secondary forests are effective at improving soil fertility and sequestering carbon at low cost. © 2012 Springer Science+Business Media B.V.