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Huntingdon, United Kingdom

Kaonga M.L.,A Rocha International | Bayliss-Smith T.P.,University of Cambridge
Agroforestry Systems | Year: 2010

This paper presents allometric functions for estimation of C stocks in aboveground tree biomass in 2-year-old improved fallows in eastern Zambia. A total of 222 individual trees representing 12 tree species were destructively harvested for C analysis by LECO CHN-1000 analyzer. Allometric models relating collar diameter (D10) and total tree height (H) to stem and total aboveground C stocks were developed using data from tree fallows. Logarithmically transformed power functions displayed a good ability to stabilize variance of aboveground C stocks and showed a good fit (84 < R2 < 99) with a bias of 0. 7-3. 6%. D10 alone and in combination with H explained most of the variability in total aboveground C stocks. Validation of the species-specific and generalized models with field data indicated that they accurately predicted aboveground tree C stocks. Generalized C estimation functions were also validated and described 73-97% of variability in aboveground C stocks with an average unsigned deviation of 1. 5-4. 9%. The C functions will serve as a vital tool for predicting and monitoring C pool sizes in long-term studies and agroforestry projects, especially where destructive sampling is not possible. © 2009 Springer Science+Business Media B.V. Source

Kaonga M.L.,A Rocha International | Mafongoya P.L.,University of Zimbabwe
Biogeochemistry | Year: 2013

This study evaluated the effects of tree species and sites on soil carbohydrates, litterfall, and litter chemistry in 2-, 4- and 10-year-old improved fallows at three sites in eastern Zambia. Between April 2002 and August 2003, litter was collected in 2-year-old tree fallows at Kalichero, Kalunga and Msekera for chemical analyses. Soil samples collected at 0-30 cm from all experiments were analysed for total soil organic carbon (SOC), but only those from 4- and 10-year-old fallows were analysed for carbohydrates. Soil arabinose- and mannose-C stocks, and carbohydrate-C percentages of SOC (7. 7-20. 6 %) significantly (P < 0. 05) differed across tree species in 10-year-old coppicing fallows at Msekera. Converting M + F to improved fallows resulted in a decline in monosaccharide-C, carbohydrate-C stocks and carbohydrate-C percentage of SOC. There were significant (P < 0. 05) variations in litterfall (0. 7-2. 3 t ha-1 year-1) and litter C contents (0. 3-1. 1 t ha-1 year-1) across 2-year-old coppicing tree fallows at Msekera. Litter production and C contents were significantly greater on sandy soils at Kalunga than on fine-textured soils at Msekera. Litter chemical contents (C, N, AUR and polyphenols) and ratios (C:N, P:N, AUR:N, and (AUR + P):N) for litter in fallows differed significantly (P < 0. 05) across species and sites. In this study, the role of litter in carbon cycling in improved fallows depended on tree species and site conditions. © 2012 Springer Science+Business Media B.V. Source

Hillers A.,Center for Conservation Science | Buchanan G.M.,Center for Conservation Science | Garteh J.C.,Society for the Conservation of Nature of Liberia | Tommy S.M.,Gola Rainforest National Park | And 2 more authors.
ORYX | Year: 2016

The contribution of protected areas to biodiversity conservation is well attested but many taxa in many regions remain dependent on the unprotected wider landscape. To develop conservation plans for large mammals such as the Endangered pygmy hippopotamus Choeropsis liberiensis of West Africa's Upper Guinea Forests it is critical to understand the importance of unprotected land. Despite being a conservation priority, little is known about the habitat associations of this species, or its distribution across its range. Through a combination of field surveys, species distribution models and community questionnaires we investigated the use of unprotected areas by the pygmy hippopotamus in the Sierra Leone–Liberia border region. We found signs of the species in 128 of 525 1-km2 cells surveyed. Our analysis suggested that the species is reasonably widespread in this region and is associated with major rivers. It occurred close to, but rarely within, large areas of intact forest, and 80.4% of pygmy hippopotamus signs were recorded outside protected areas. The expansion of the protected area network in this area is unrealistic in Sierra Leone and to some extent in Liberia, mainly because of anthropogenic pressure and the overlap of proposed protected areas with mining and logging concessions. Thus pygmy hippopotamus conservation activities in the region need to include programmes on community lands while maintaining a robust network of protected forests. Community-based conservation of the pygmy hippopotamus may prove valuable for other threatened and endemic species that are not confined to protected areas in this region. Copyright © Fauna & Flora International 2016 Source

A study was conducted at Msekera Regional Agricultural Research Station in eastern Zambia to (1) describe canopy branching properties of Acacia angustissima, Gliricidia sepium and Leucaena collinsii in short rotation forests, (2) test the existence of self similarity from repeated iteration of a structural unit in tree canopies, (3) examined intra-specific relationships between functional branching characteristics, and (4) determine whether allometric equations for relating aboveground tree biomass to fractal properties could accurately predict aboveground biomass. Measurements of basal diameter (D10) at 10cm aboveground and total height (H), and aboveground biomass of 27 trees were taken, but only nine trees representative of variability of the stand and the three species were processed for functional branching analyses (FBA) of the shoot systems. For each species, fractal properties of three trees, including fractal dimension (Dfract), bifurcation ratios (p) and proportionality ratios (q) of branching points were assessed. The slope of the linear regression of p on proximal diameter was not significantly different (P<0.01) from zero and hence the assumption that p is independent of scale, a pre-requisite for use of fractal branching rules to describe a fractal tree canopy, was fulfilled at branching orders with link diameters >1.5 cm. The proportionality ration q for branching patterns of all tree species was constant at all scales. The proportion of q values >0.9 (fq) was 0.8 for all species. Mean fractal dimension (Dfract) values (1. 5-1. 7) for all species showed that branching patterns had an increasing magnitude of intricacy. Since Dfract values were ≥1.5, branching patterns within species were self similar. Basal diameter (D10), proximal diameter and Dfract described most of variations in aboveground biomass, suggesting that allometric equations for relating aboveground tree biomass to fractal properties could accurately predict aboveground biomass. Thus, assessed Acacia, Gliricidia and Leucaena trees were fractals and their branching properties could be used to describe variability in size and aboveground biomass. © 2012 Northeast Forestry University and Springer-Verlag Berlin Heidelberg. Source

Kaonga M.L.,A Rocha International | Bayliss-Smith T.P.,University of Cambridge
Agroforestry Systems | Year: 2012

Agroforestry systems have the potential to contribute significantly to climate change mitigation and adaptation. However, data on tree and soil organic carbon (SOC) pools for most agroforestry systems are lacking because reliable methods for estimating ecosystem carbon (C) pools are scarce. This study quantified the effects of five Leucaena species (L. leucocephala, L. macrophylla, L. diversifolia, L. collinsii and L. pulverulenta) on vegetal and soil C stocks and on mean annual increment (MAI) in aboveground tree C stocks. Specifically, it tested the validity of the CO2FIX model using empirical data from 7 year-old woodlots at Msekera, Zambia, and assessed the impact of converting a degraded agricultural ecosystem to woodlots on C stocks. Measured above- and below-ground tree C stocks and MAI of aboveground biomass differed significantly among the Leucaena species. Measured stem and total aboveground tree C stocks in seven-year old woodlots ranged from 17.1 to 29.2 and from 24.5 to 55.9 Mg ha -1, respectively. Measured SOC stocks at 0-200 cm depth in Leucaena stands ranged from 106.9 (L. diversifolia) to 186.0 Mg ha -1 (L. leucocephala). Modeled stem and branch C stocks closely matched measured stocks, but the soil module of CO2FIX did not predict the soil C. The soil C data are inconclusive at this stage. We recommend that a fractionation and a soil aggregate hierarchy study backed by C dating is carried out to explain soil C dynamics in these soils. However, the model can be used only for estimating changes in aboveground tree C stocks in woodlots until soil C module is proven to predict SOC stocks. © 2011 Springer Science+Business Media B.V. Source

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