International Journal of Forestry Research
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Open Access journal
ISSN (Print) 1687-9368 - ISSN (Online) 1687-9376
Published by Hindawi [333 journals]
- Conventional and Indigenous Biodiversity Conservation Approach: A
Comparative Study of Jachie Sacred Grove and Nkrabea Forest Reserve
Abstract: Conventional managed forests and sacred groves are seldom assessed to determine their effectiveness in biodiversity conservation strategies. This study investigated tree and insect diversity in Jachie sacred grove (JSG) and Nkrabea forest reserve (NFR) in Ashanti region, Ghana. The study area constituted eight plots of 50 × 50 m along two 300 m long transects. Insects were sampled in eight pitfall traps, diagonally between the transects. Out of 150 individuals, 13 species in NFR and 15 species from JSG were registered. Celtis mildbraedii was the most dominant species in NFR = 43.18% and JSG = 23.58%. Mean DBH showed a significant relationship with basal area in NFR and JSG. Tree diversity and richness were higher in JSG ( = 1.43–2.3 ± 0.10; = 1.8–3.69 ± 0.30) compared to NFR ( = 0.86–1.56 ± 0.09; = 1.1–2.3 ± 0.57). However, insect diversity was higher in NFR ( = 1.34 ± 0.10) than in JSG ( = 0.5 ± 0.005). Camponotus furvus and Pachycondyla tarsata were most abundant in JSG and NFR, respectively. These findings will help conservationists work closely with traditional authorities in protecting sacred groves as key biodiversity hotspots.
PubDate: Thu, 30 Mar 2017 08:26:31 +000
- Tree Species Diversity and Composition of Miombo Woodlands in
South-Central Angola: A Chronosequence of Forest Recovery after Shifting
Abstract: The study was carried out in the Cusseque area of the Municipality of Chitembo in south-central Angola. Our objectives were to assess the floristic diversity, the species composition, and stand structure of Miombo woodlands during regeneration after shifting cultivation. A total of 40 plots of 1000 m2 were surveyed and analyzed, corresponding to mature forests/woodlands and three fallow types of different age. The analyses were based on plot inventories of all trees with DBH ≥ 5 cm. A total of 51 woody species, 38 genera, and 19 families were recorded. The dominant family was Fabaceae, with subfamily Caesalpinioideae being very abundant. Shannon Diversity and Evenness were highest in mature forests and young fallows, while the mature forest stands showed the highest species richness. A Principal Coordinates Analysis (PCoA) showed many species shared between the intermediate fallow types, but only few species were shared with young fallows. Mature forests formed a clearly distinct group. This study shows potential pathways of forest recovery in terms of faster regeneration after agricultural abandonment and, thus, the results presented here can be used in future conservation and management plans in order to reduce the pressure on mature forests.
PubDate: Wed, 01 Mar 2017 08:31:38 +000
- Detecting the Early Genetic Effects of Habitat Degradation in Small Size
Remnant Populations of Machilus thunbergii Sieb. et Zucc. (Lauraceae)
Abstract: Habitat degradation caused by human activities has reduced the sizes of many plant populations worldwide, generally with negative genetic impacts. However, detecting such impacts in tree species is not easy because trees have long life spans. Machilus thunbergii Sieb. et Zucc. (Lauraceae) is a dominant tree species of broad-leaved evergreen forests distributed primarily along the Japanese coast. Inland habitats for this species have become degraded by human activities. To investigate the effects of habitat degradation on genetic structure, we compared the genetic diversities of mature and juvenile trees of five M. thunbergii populations around Lake Biwa in Japan. Allelic diversity was influenced by past lineage admixture events, but the effects of forest size were not clear. On the other hand, the inbreeding coefficient of the juvenile stage was higher in small populations, whereas large populations maintained panmictic breeding. Also, the extent of genetic differentiation was greater in juveniles than in mature trees. We detected the early genetic effects of habitat degradation in small, isolated M. thunbergii populations, indicating that habitat degradation increases inbreeding and genetic differentiation between populations.
PubDate: Thu, 02 Feb 2017 00:00:00 +000
- Tree Species Richness, Diversity, and Vegetation Index for Federal Capital
Territory, Abuja, Nigeria
Abstract: This study was conducted to investigate the tree species richness and diversity of urban and periurban areas of the Federal Capital Territory (FCT), Abuja, Nigeria, and produce Normalized Difference Vegetation Index (NDVI) for the territory. Data were collected from urban (Abuja city) and periurban (Lugbe) areas of the FCT using both semistructured questionnaire and inventory of tree species within green areas. In the study location, all trees with diameter at breast height (dbh) ≥ 10 cm were identified; their dbh was measured and frequency was taken. The NDVI was calculated in ArcGIS 10.3 environment using standard formula. A cumulative total of twenty-nine (29) families were encountered within the FCT, with 27 occurring in Abuja city (urban centre) and 12 in Lugbe (periurban centre) of the FCT. The results of Shannon-Wiener diversity index for the two centres are 3.56 and 2.24 while Shannon’s maximum diversity index is 6.54 (Abuja city) and 5.36 (Lugbe) for the urban (Abuja city) and periurban (Lugbe) areas of the Federal Capital Territory (FCT). The result of tree species evenness (Shannon’s equitability () index) in urban and periurban centres was 0.54 and 0.42, respectively. The study provided baseline information on urban and periurban forests in the FCT of Nigeria, which can be used for the development of tree species database of the territory.
PubDate: Tue, 31 Jan 2017 00:00:00 +000
- Comparison of -Square, Point Centered Quarter, and -Tree Sampling Methods
in Pittosporum undulatum Invaded Woodlands
Abstract: Tree density is an important parameter affecting ecosystems functions and management decisions, while tree distribution patterns affect sampling design. Pittosporum undulatum stands in the Azores are being targeted with a biomass valorization program, for which efficient tree density estimators are required. We compared -Square sampling, Point Centered Quarter Method (PCQM), and -tree sampling with benchmark quadrat (QD) sampling in six 900 m2 plots established at P. undulatum stands in São Miguel Island. A total of 15 estimators were tested using a data resampling approach. The estimated density range (344–5056 trees/ha) was found to agree with previous studies using PCQM only. Although with a tendency to underestimate tree density (in comparison with QD), overall, -Square sampling appeared to be the most accurate and precise method, followed by PCQM. Tree distribution pattern was found to be slightly aggregated in 4 of the 6 stands. Considering (1) the low level of bias and high precision, (2) the consistency among three estimators, (3) the possibility of use with aggregated patterns, and (4) the possibility of obtaining a larger number of independent tree parameter estimates, we recommend the use of -Square sampling in P. undulatum stands within the framework of a biomass valorization program.
PubDate: Wed, 11 Jan 2017 06:57:48 +000
- Bark Thickness Equations for Mixed-Conifer Forest Type in Klamath and
Sierra Nevada Mountains of California
Abstract: We studied bark thickness in the mixed-conifer forest type throughout California. Sampling included eight conifer species and covered latitude and elevation gradients. The thickness of tree bark at 1.37 m correlated with diameter at breast height (DBH) and varied among species. Trees exhibiting more rapid growth had slightly thinner bark for a given DBH. Variability in bark thickness obscured differences between sample locations. Model predictions for 50 cm DBH trees of each species indicated that bark thickness was ranked Calocedrus decurrens > Pinus jeffreyi > Pinus lambertiana > Abies concolor > Pseudotsuga menziesii > Abies magnifica > Pinus monticola > Pinus contorta. We failed to find reasonable agreement between our bark thickness data and existing bark thickness regressions used in models predicting fire-induced mortality in the mixed-conifer forest type in California. The fire effects software systems generally underpredicted bark thickness for most species, which could lead to an overprediction in fire-caused tree mortality in California. A model for conifers in Oregon predicted that bark was 49% thinner in Abies concolor and 37% thicker in Pseudotsuga menziesii than our samples from across California, suggesting that more data are needed to validate and refine bark thickness equations within existing fire effects models.
PubDate: Sun, 04 Dec 2016 06:46:10 +000
- Developmental Trends of Black Spruce Fibre Attributes in Maturing
Abstract: This study assessed the temporal developmental patterns of commercially relevant fibre attributes (tracheid length and diameters, wall thickness, specific surface area, wood density, microfibril angle, fibre coarseness, and modulus of elasticity) and their interrelationships within maturing black spruce (Picea mariana (Mill.) B.S.P.) plantations. A size-based stratified random sample procedure within 5 semimature plantations located in the Canadian Boreal Forest Region was used to select 50 trees from which radial cross-sectional xylem sequences at breast-height (1.3 m) were cut and analyzed. Statistically, the graphical and linear correlation analyses indicated that the attributes exhibited significant () relationships among themselves and with morphological tree characteristics. Relative variation of each annually measured attribute declined with increasing size class (basal area quintile). The transitional shifts in temporal correlation patterns occurring at the time of approximate crown closure where suggestive of intrinsic differences in juvenile and mature wood formation processes. The temporal cumulative development patterns of all 8 of the annually measured attributes varied systematically with tree size and exhibited the most rapid rates of change before the trees reached a cambial age of 20 years. At approximately 50 years after establishment, plantation mean attribute values were not dissimilar from those reported for more mature natural-origin stands.
PubDate: Tue, 08 Nov 2016 12:35:15 +000
- Economic Contribution to Local Livelihoods and Households Dependency on
Dry Land Forest Products in Hammer District, Southeastern Ethiopia
Abstract: The study was conducted in Hammer district, Southern Ethiopia, to provide empirical evidence on economic contribution to local livelihoods and households dependency on dry forest products. One agropastoral and two pastoral kebeles were purposively selected, and data was collected through household survey, group discussions, market assessments, and field observation. A total of 164 households, selected based on a random sampling procedure, were interviewed using structured questionnaire. The study found that income from forest products contributes 21.4% of the total annual household income. The major dry forest products include honey, fuel wood, gum and resin, and crafts and construction materials, contributing 49%, 39%, 6%, and 6% of the forest income, respectively. Households of the pastoral site earned more forest income and were relatively more dependent on forest products income than those in the agropastoral study site. Significant variation was also found among income groups: households with higher total annual income obtain more forest income than those with lower income, but they are relatively less dependent on forest products than the lower counterpart. Besides, various socioeconomic and contextual factors were found to influence forest income and dependency. The findings of the study provide valuable information up on which important implications for dry land forest development and management strategies can be drawn.
PubDate: Wed, 26 Oct 2016 09:18:05 +000
- Carbon Stocks in the Small Estuarine Mangroves of Geza and Mtimbwani,
Abstract: Mangrove forests offer important ecosystem services, including their high capacity for carbon sequestration and stocking. However, they face rapid degradation and loss of ecological resilience particularly at local scales due to human pressure. We conducted inventory of mangrove forests to characterise forest stand structure and estimate carbon stocks in the small estuarine mangroves of Geza and Mtimbwani in Tanga, Tanzania. Forest structure, above-ground carbon (AGC), and below-ground carbon (BGC) were characterised. Soil carbon was estimated to 1 m depth using loss on ignition procedure. Six common mangrove species were identified dominated by Avicennia marina (Forsk.) Vierh. and Rhizophora mucronata Lamarck. Forest stand density and basal area were 1740 stems ha−1 and 17.2 m2 ha−1 for Geza and 2334 stems ha−1 and 30.3 m2 ha−1 for Mtimbwani. Total ecosystem carbon stocks were 414.6 Mg C ha−1 for Geza and 684.9 Mg C ha−1 for Mtimbwani. Soil carbon contributed over 65% of these stocks, decreasing with depth. Mid zones of the mangrove stands had highest carbon stocks. These data demonstrate that studied mangroves are potential for carbon projects and provide the baseline for monitoring, reporting, and verification (MRV) to support the projects.
PubDate: Wed, 28 Sep 2016 14:20:40 +000
- Livelihoods and Welfare Impacts of Forest Comanagement
Abstract: Comanagement programmes are gaining popularity among governments as one way of improving rural livelihoods. However, evidence of their effects on the livelihoods and welfare remains unclear. We used the sustainable livelihoods framework and stated preference techniques to assess the livelihoods and welfare impacts of forest comanagement on 213 households in Zomba and Ntchisi districts. The results show that approximately 63% of respondents perceive that, overall, comanagement has had no impact on their livelihoods. However, the programme is enhancing financial capital by introducing externally subsidised income generating activities and human and social capital among some community members through training programmes. A majority of households (80%) are willing to pay annual membership fees to participate in the programme (mean = 812 Malawi Kwacha), because of perceived potential future benefits. Education, gender of the household head, a positive perception of current livelihoods benefits, and a position on the committee increase household willingness to pay membership fees. However, the positive willingness to pay despite the negative perception of overall livelihoods impacts may also demonstrate the weaknesses of relying on stated preference surveys alone in estimating welfare effects.
PubDate: Mon, 26 Sep 2016 16:41:04 +000
- Analysis of the Distribution of Forest Management Areas by the Forest
Environmental Tax in Ishikawa Prefecture, Japan
Abstract: Forest management approaches vary according to the needs of individual municipalities with unique geographic conditions and local social contexts. Accordingly, there are two types of subsidies: a unified national subsidy and a prefecture-level subsidy, mainly from forest environmental taxes. The latter is a local tax. Our focus is on examining forest management using these two types of taxes (i.e., central and prefecture-level) and their correlations with social and natural environmental factors. In this paper, we examine the spatial distribution of management areas using subsidies from the central government, the Forestry Agency of Japan, and prefectural forest environmental taxes in Ishikawa. In concrete terms, the spatial correlations of the management areas under two tax schemes are compared with the natural hazard areas (as a natural environmental factor) and areas with high aging rates (as a social factor). The results are tested to see whether the correlations of areas with the two factors are significant, to examine whether the taxes are used for areas with natural and social needs. From the result, positive correlations are identified between the distribution of management areas and natural hazard areas and between the distribution of management areas and areas with high aging rates.
PubDate: Thu, 22 Sep 2016 12:50:15 +000
- Modelling Analysis of Forestry Input-Output Elasticity in China
Abstract: Based on an extended economic model and space econometrics, this essay analyzed the spatial distributions and interdependent relationships of the production of forestry in China; also the input-output elasticity of forestry production were calculated. Results figure out there exists significant spatial correlation in forestry production in China. Spatial distribution is mainly manifested as spatial agglomeration. The output elasticity of labor force is equal to 0.6649, and that of capital is equal to 0.8412. The contribution of land is significantly negative. Labor and capital are the main determinants for the province-level forestry production in China. Thus, research on the province-level forestry production should not ignore the spatial effect. The policy-making process should take into consideration the effects between provinces on the production of forestry. This study provides some scientific technical support for forestry production.
PubDate: Sun, 18 Sep 2016 08:48:43 +000
- Economic Valuation of Nontimber Forest Products under the Changing Climate
in Kilombero District, Tanzania
Abstract: Sustainable collection of Nontimber Forest Products (NTFPs) for trade is an appropriate measure to increase people’s adaptive capacity against adverse effects of climate change. However, information on the economic value for NTFPs for subsistence use and trade under the changing climate is inadequate, particularly in households around Iyondo Forest Reserve (IFR), in Kilombero District, Tanzania. The study identified and quantified NTFPs used for subsistence and trade, estimated its economic value, and examined factors influencing supply of NTFPs at household level. Data were collected through Focus Group Discussions, key informant interviews, questionnaire survey of 208 sample households, and spot market analysis to randomly selected NTFPs collectors, sellers, and buyers. The study identified 12 NTFPs used for subsistence and trade, which was evaluated in terms of the mean annual value per household. The mean annual value of the identified NTFPs ranged from TZS 4700 to 886 600. The estimated economic value of the studied NTFPs was TZS 51.4 billion (USD 36 million). The supply of NTFPs at household level was influenced by distance to the forest, change in forest management regime, seasonality, and change in rainfall pattern. NTFPs around IFR have high economic value which portrays the potential of developing them to enhance households’ adaptive capacity against climate change adverse effects.
PubDate: Wed, 31 Aug 2016 16:26:30 +000
- Tree Species Diversity, Richness, and Similarity in Intact and Degraded
Forest in the Tropical Rainforest of the Congo Basin: Case of the Forest
of Likouala in the Republic of Congo
Abstract: Trees species diversity, richness, and similarity were studied in fifteen plots of the tropical rainforests in the northeast of the Republic of Congo, based on trees inventories conducted on fifteen 0.25 ha plots installed along different types of forests developed on terra firma, seasonally flooded, and on flooded terra. In all of the plots installed, all trees with diameter at breast height, DBH ≥ 5 cm, were measured. The Shannon diversity index, species richness, equitability, and species dominance were computed to see the variation in tree community among plots but also between primary forest and secondary forest. A total of 1611 trees representing 114 species and 35 families were recorded from a total area of 3.75 ha. Euphorbiaceae was the dominant family in the forest with 12 species, followed by Fabaceae-Mimosoideae (10 species) and Phyllanthaceae (6 species) and Guttiferae (6 species). The biodiversity did not vary greatly from plot to plot on the whole of the study area (3.75 ha). The low value of Shannon index was obtained in plot 11 () whereas the highest value was obtained in plot 12 (). The values of this index vary from 0.23 to 0.95 in plots P11 and P15, respectively. Results obtained revealed high biodiversity of trees of the forest of Impfondo-Dongou. The information on tree species structure and function can provide baseline information for conservation of the biodiversity of the tropical forest in this area.
PubDate: Mon, 08 Aug 2016 09:33:46 +000
- Synchrony in Leafing, Flowering, and Fruiting Phenology of Senegalia
senegal within Lake Baringo Woodland, Kenya: Implication for Conservation
and Tree Improvement
Abstract: Leafing, flowering, and fruiting patterns of Senegalia senegal were studied over a period of 24 months from January 2014 to December 2015. The phenological events of the species are bimodal and follow the rainfall patterns. The leafing phase starts during the onset of rains and lasts for 18 weeks. New leaves continued to appear on the new shoots while old leaves persisted to the leaf fall period. Flowering event takes 12 weeks and is concentrated in the months of high relative humidity (April and October) with one-month peak flowering period. Fruiting phase starts at the peak of the rainy seasons (May and November) and peaks in June and December. This phase lasted for 14 weeks. The fruits mature towards the end of the rainy season (January/February and July/August). The fruits open for dispersal mainly in February/March and September during the peak dry season. High synchrony index (SI) was found in leafing (SI: 0.87), flowering (SI: 0.75), and fruiting (SI: 0.85) events among the populations. Temperature, precipitation, and soil moisture content were significantly correlated with the phenological events. Significant variations in floral morphology and fruits traits were also evident. Seed collections should be undertaken in the months of January/February and July/August.
PubDate: Tue, 10 May 2016 08:01:21 +000
- Role of Forest Resources to Local Livelihoods: The Case of East Mau Forest
Abstract: Forests in Kenya are threatened by unsustainable uses and conversion to alternative land uses. In spite of the consequences of forest degradation and biodiversity loss and reliance of communities on forests livelihoods, there is little empirical data on the role of forest resources in livelihoods of the local communities. Socioeconomic, demographic, and forest use data were obtained by interviewing 367 households. Forest product market survey was undertaken to determine prices of various forest products for valuation of forest use. Forest income was significant to households contributing 33% of total household income. Fuel wood contributed 50%, food (27%), construction material (18%), and fodder, and thatching material 5% to household forest income. Absolute forest income and relative forest income (%) were not significantly different across study locations and between ethnic groups. However, absolute forest income and relative forest income (%) were significantly different among wealth classes. Poor households were more dependent on forests resources. However, in absolute terms, the rich households derived higher forest income. These results provide valuable information on the role of forest resources to livelihoods and could be applied in developing forest conservation policies for enhanced ecosystem services and livelihoods.
PubDate: Wed, 16 Mar 2016 14:13:00 +000
- Biomass and Soil Carbon Stocks in Wet Montane Forest, Monteverde Region,
Abstract: We measured carbon stocks at two forest reserves in the cloud forest region of Monteverde, comparing cleared land, experimental secondary forest plots, and mature forest at each location to assess the effectiveness of reforestation in sequestering biomass and soil carbon. The biomass carbon stock measured in the mature forest at the Monteverde Institute is similar to other measurements of mature tropical montane forest biomass carbon in Costa Rica. Local historical records and the distribution of large trees suggest a mature forest age of greater than 80 years. The forest at La Calandria lacks historical documentation, and dendrochronological dating is not applicable. However, based on the differences in tree size, above-ground biomass carbon, and soil carbon between the Monteverde Institute and La Calandria sites, we estimate an age difference of at least 30 years of the mature forests. Experimental secondary forest plots at both sites have accumulated biomass at lower than expected rates, suggesting local limiting factors, such as nutrient limitation. We find that soil carbon content is primarily a function of time and that altitudinal differences between the study sites do not play a role.
PubDate: Mon, 29 Feb 2016 09:48:50 +000
- Allometric Models for Estimating Tree Volume and Aboveground Biomass in
Lowland Forests of Tanzania
Abstract: Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sample of 60 trees which were destructively harvested from both dry and wet lowland forests of Dindili in Morogoro Region (30 trees) and Rondo in Lindi Region (30 trees), respectively, this study developed site specific and general models for estimating total tree volume and aboveground biomass. Specifically the study developed (i) height-diameter (ht-dbh) models for trees found in the two sites, (ii) total, merchantable, and branches volume models, and (iii) total and sectional aboveground biomass models of trees found in the two study sites. The findings show that site specific ht-dbh model appears to be suitable in estimating tree height since the tree allometry was found to differ significantly between studied forests. The developed general volume models yielded unbiased mean prediction error and hence can adequately be applied to estimate tree volume in dry and wet lowland forests in Tanzania. General aboveground biomass model appears to yield biased estimates; hence, it is not suitable when accurate results are required. In this case, site specific biomass allometric models are recommended. Biomass allometric models which include basic wood density are highly recommended for improved estimates accuracy when such information is available.
PubDate: Thu, 14 Jan 2016 07:29:28 +000
- Effect of Disturbance Regimes on Spatial Patterns of Tree Species in Three
Sites in a Tropical Evergreen Forest in Vietnam
Abstract: The effects of disturbance regimes on the spatial patterns of the five most abundant species were investigated in three sites in a tropical forest at Xuan Nha Nature Reserve, Vietnam. Three permanent one-ha plots were established in undisturbed forest (UDF), lightly disturbed forest (LDF), and highly disturbed forest (HDF). All trees ≥5 cm DBH were measured in twenty-five 20 m × 20 m subplots. A total of 57 tree species belonging to 26 families were identified in the three forest types. The UDF had the highest basal area (30 m2 ha−1), followed by the LDF (17 m2 ha−1) and the HDF (13.0 m2 ha−1). The UDF also had the highest tree density (751 individuals ha−1) while the HDF held the lowest (478 individuals ha−1). Across all species, there were 417 “juveniles,” 267 “subadults,” and 67 “adults” in the UDF, while 274 “juveniles,” 230 “subadults,” and 36 “adults” were recorded in the LDF. 238 “juveniles,” 227 “subadults,” and 13 “adults” were obtained in the HDF. The univariate and bivariate data with pair- and mark-correlation functions of intra- and interspecific interactions of the five most abundant species changed in the three forest types. Most species indicated clumping or regular distributions at small scale, but a high ratio of negative interspecific small-scale associations was recorded in both the LDF and HDF sites. These were, however, rare in the UDF.
PubDate: Mon, 11 Jan 2016 08:05:11 +000
- Agricultural and Forest Land Use Potential for REDD+ among Smallholder
Land Users in Rural Ghana
Abstract: Reducing emissions from deforestation and forest degradation with other benefits (REDD+) mechanism is supposed to address the reversal of forest-based land degradation, conservation of existing carbon stocks, and enhancement of carbon sequestration. The Bosomtwe District is predominantly agrarian with potentials for climate change mitigation through REDD+ mechanism among smallholder farmers. The limited knowledge and practices of this strategy among farmers are limiting potentials of mitigating climate change. This paper assesses the REDD+ potentials among smallholder farmers in the district. Using a triangulation of quantitative and qualitative design, 152 farmer-respondents were purposively sampled and interviewed, using snowballing method from 12 communities. Quantitative data gathered were subjected to the tools of contingency and frequencies analysis, embedded in the Statistical Package for Social Sciences (SPSS) v.16. The qualitative data were analyzed thematically. Results indicate that respondents have knowledge of REDD+ but not the intended benefit sharing regimes that can accrue to the smallholder farmers. Farmers’ willingness to practice REDD+ will be based on the motivation and incentive potentials of the strategies. The Forestry Services Division should promote the practice of REDD+ among smallholder farmers through education, to whip and sustain interest in the strategy.
PubDate: Wed, 06 Jan 2016 09:46:11 +000
- An Evaluation of the Use of Simulated Annealing to Optimize Thinning Rates
for Single Even-Aged Stands
Abstract: We evaluated the potential of simulated annealing as a reliable method for optimizing thinning rates for single even-aged stands. Four types of yield models were used as benchmark models to examine the algorithm’s versatility. Thinning rate, which was constrained to 0–50% every 5 years at stand ages of 10–45 years, was optimized to maximize the net present value for one fixed rotation term (50 years). The best parameters for the simulated annealing were chosen from 113 patterns, using the mean of the net present value from 39 runs to ensure the best performance. We compared the solutions with those from coarse full enumeration to evaluate the method’s reliability and with 39 runs of random search to evaluate its efficiency. In contrast to random search, the best run of simulated annealing for each of the four yield models resulted in a better solution than coarse full enumeration. However, variations in the objective function for two yield models obtained with simulated annealing were significantly larger than those of random search. In conclusion, simulated annealing with optimized parameters is more efficient for optimizing thinning rates than random search. However, it is necessary to execute multiple runs to obtain reliable solutions.
PubDate: Mon, 30 Nov 2015 11:15:19 +000
- A Hidden Pitfall for REDD: Analysis of Power Relation in Participatory
Forest Management on Whether It Is an Obstacle or a Reliever on REDD
Abstract: Power relation among stakeholders is a key concept in collaborative approaches. This study aims to examine the reality of the acclaimed power sharing in Participatory Forest Management (PFM) and implication of existing power relation to the national REDD+ programme in Tanzania. The study involved a review of PFM policy and legal supporting documents; meta-analysis of previous studies done at two sites known to have succeeded in PFM; and empirical study at Kolo-Hills forests. Methods used include the meta-analysis of existing literature; Household Questionnaire Survey; Focused Group Discussion; and key person unstructured interviews. Results revealed that a large part of the PFM processes involved power struggle instead of power sharing. REDD+ pilot was perceived to have succeeded in improving PFM only in villages where the majority of the community about 70% experienced higher levels of inclusiveness and power balance with other PFM stakeholders in PFM processes. Power imbalance and power struggle were also noted in the REDD+ project adoption processes. Thus power relations exercised under PFM fall under potential obstacle rather than a reliever to the REDD+ programme. The study recommends reviewing of PFM legal frameworks to strengthen community empowerment for effectiveness of REDD+ on PFM platform.
PubDate: Tue, 10 Nov 2015 14:14:39 +000
- Phenotypic Variation in Fruit Morphology among Provenances of Sclerocarya
birrea (A. Rich.) Hochst.
Abstract: Sclerocarya birrea (A. Rich.) Hochst. is a multipurpose fruit tree which is very useful in providing food security and meeting nutritional and economic needs. This study was conducted to assess eighteen provenances of Sclerocarya birrea planted in Mangochi, Malawi. The trial was assessed for fruit traits at fifteen years of age. There were significant () variations among the provenances in number of fruits, fruit weight, pulp weight, seed weight, fruit length, and diameter. Magunde provenance from Mozambique had the highest mean number of fruits, 2196 ± 200. Mangochi and Moamba provenances from Malawi and Mozambique were the most outstanding in the other parameters measured attaining the mean fruit weight of 20.89 ± 0.25 g and 25.67 ± 0.67 g, pulp weight of 25.70 ± 0.08 g and 21.55 ± 0.83 g, seed weight of 4.81 ± 0.35 g and 4.12 ± 0.18 g, fruit length of 2.61 ± 0.14 cm and 2.33 ± 0.07 cm, and fruit diameter of 2.33 ± 0.15 cm and 1.97 ± 0.08 cm, respectively. There was no significant () correlation between number of fruits and the other fruit traits. However, there were significant () and strong positive relationships between fruit weight and pulp weight () and fruit length and diameter (). This suggests that fruit weight can be used indirectly for selection of pulp. Further studies should investigate fruit taste quality of products from the fruits.
PubDate: Thu, 15 Oct 2015 14:07:10 +000
- Effect of Spacing Regimes on Growth, Yield, and Wood Properties of Tectona
grandis at Longuza Forest Plantation, Tanzania
Abstract: This study examined the effects of planting spacing on growth, yield, and wood properties of teak planted at square spacing regimes of 2 m, 3 m, and 4 m at Longuza Forest Plantation, Tanzania. To achieve this, tree, stand, and wood properties were studied at age of 14 years. Results showed that diameter at breast height and total height increased with increasing spacing. Mean annual increment increased significantly with increasing spacing while spacing did not have significant effect on total volume production and basal area. Basic density is also not affected by spacing while heartwood proportion increases as planting spacing increases. All studied wood properties (modulus of rupture, modulus of elasticity, compression strength tangential to grain, and shear tangential to the grain) except cleavage tangential to grain were not significantly affected by increasing spacing. It is recommended to use the spacing of 3 × 3 m, but if thinning can be done before onset of competition at 5 years, the currently used spacing of 2.5 × 2.5 m can still be used. However, the use of a spacing of 4 × 4 m can give at least 50% heartwood at shorter rotation age of 30 years.
PubDate: Thu, 13 Aug 2015 11:21:07 +000
- Structural Characterization of Prosopis africana Populations (Guill.,
Perrott., and Rich.) Taub in Benin
Abstract: The structural characterization of Prosopis africana of Benin was studied on the basis of forest inventory conducted in three different vegetation types (savannah, fallow, and field) and three climate zones. The data collected in 139 plots of 1000 m2 each related to the diameter at breast (1.3 m above ground), total height, identification, and measurement of DBH related P. africana species height. Tree-ring parameters such as Blackman and Green indices, basal area, average diameter, height of Lorey, and density were calculated and interpreted. Dendrometric settings of vegetation type and climate zone (Guinea, Sudan-Guinea, and Sudan) were compared through analysis of variance (ANOVA). There is a significant difference in dendrometric settings according to the type of vegetation and climate zone. Basal area, density, and average diameter are, respectively, 4.47 m2/ha, 34.95 stems/ha, and 37.02 cm in the fields; 3.01 m2/ha, 34.74 stems/ha, and 33.66 cm in fallows; 3.31 m2/ha, 52.39 stems/ha, and 29.61 cm in the savannahs. The diameter distribution and height observed at the theoretical Weibull distribution show that the diameter and height of the populations of the species are present in all positively skewed distributions or asymmetric left, a characteristic of single-species stands with predominance of young individuals or small diameters or heights.
PubDate: Wed, 29 Jul 2015 07:40:49 +000
- Evaluation of Forest Fire Danger Indexes for Eucalypt Plantations in
Abstract: A Forest Fire Danger Index is a valuable tool in forest fire prevention and firefight because it grades fire occurrence possibility on a daily basis. Six Fire Danger Indexes were tested for accuracy based on forest fire occurrence in eucalyptus plantations of the north coast of Bahia, Brazil. They are Angstron, Nesterov, Telicyn Logarithmic Index, Monte Alegre, Rodríguez and Moretti, and Modified Monte Alegre. The results were analyzed using two parameters of the Heidke Skill Score test: Skill Score index and Percentage of Success. The Telicyn Logarithmic Index proved to be the most accurate for the study area.
PubDate: Thu, 02 Jul 2015 12:28:04 +000
- Height Growth of Korean Pine Seedlings Planted under Strip-Cut Larch
Plantations in Northeast China
Abstract: To develop two-storied forest management of larch plantations in Northeast China, this study examined the height growth of Korean pine (Pinus koraiensis Sieb. et Zucc.) seedlings planted under strip-cut larch canopies. We measured the height growth of the underplanted seedlings 4 years after planting. The larch canopies were of varying stand age (12, 17, and 37 years) and strip-cut width (4.5, 6.0, and 7.5 m). We measured the seedling height growth in an open site (i.e., a site with no canopy). Underplanted seedlings had a smaller height growth (12.1–20.1 cm year−1) than the seedlings planted in the open site (23.7 cm year−1). The seedlings underplanted in the wider strip-cuts tended to have greater height growth than the seedlings underplanted in the narrowest strip-cuts. A generalized linear mixed model analysis predicted the greatest seedling height growth in the open site. A 36–47% reduction in annual height growth was predicted for the narrowest strip-cuts (4.5 m) versus the open site, while a 13–36% reduction in annual height growth was predicted for the wider strip-cuts (6.0–7.5 m) versus the open site. To maintain adequate height growth, forest managers are recommended to create wider strip-cuts (i.e., ≥6.0 m) for the purpose of underplanting Korean pine seedlings in larch plantations.
PubDate: Wed, 01 Jul 2015 09:46:20 +000
- Selective Herbicides for Cultivation of Eucalyptus urograndis Clones
Abstract: Competition control is essential for successful eucalyptus plantation establishment, yet few selective herbicides have been identified. Five herbicides, flumioxazin, imazamox, imazapic, oxyfluorfen, and sulfometuron methyl, were evaluated for selective weed control in the establishment of genetically modified frost tolerant Eucalyptus urograndis clones. Herbicides were applied at two or three rates, either before or after weed emergence, and compared to a nontreated control and to near-complete weed control obtained with glyphosate directed sprays. Applications prior to weed emergence were most effective for weed control and, with the exception of imazapic, all resulted in enhanced eucalyptus growth relative to the nontreated control. Among postemergent treatments, only imazamox enhanced stem volume. Among selective herbicide treatments, preemergent 2240 g ha−1 oxyfluorfen produced the best growth response, resulting in stem volume index that was 860% greater than the nontreated control, although only 15% of the volume index obtained with near-complete weed control. Imazapic was the most phytotoxic of all herbicides, resulting in 40% mortality when applied preemergent. Survival was 100% for all other herbicide treatments. This research found the previously nontested herbicides imazamox and imazapic to be effective for selective weed control and refined application rate and timing of five herbicides for use in clonal plantations.
PubDate: Wed, 13 May 2015 08:13:53 +000
- Biomass Modelling of Androstachys johnsonii Prain: A Comparison of Three
Methods to Enforce Additivity
Abstract: Three methods of enforcing additivity of tree component biomass estimates into total tree biomass estimates for Androstachys johnsonii Prain were studied and compared, namely, the conventional (CON) method (a method that consists of using the same independent variables for all tree component models, and for total tree model, and the same weights to enforce additivity), seemingly unrelated regression (SUR) with parameter restriction, and nonlinear seemingly unrelated regression (NSUR) with parameter restriction. The CON method was found to be statistically superior to any other method of enforcing additivity, yielding excellent fit statistics and unbiased biomass estimates. The NSUR method ranked second best but was found to be biased. The SUR method was found to be the worst; it exhibited large bias and had a poor fit for the biomass. Therefore, we recommend that only the CON and NSUR methods should be used for further estimates, provided that their limitations are considered, that is, exclusion of contemporaneous correlations for the CON method and consideration of the significant bias of the NSUR method.
PubDate: Wed, 29 Apr 2015 06:53:11 +000
- A Structure Analysis for Ecological Management of Moist Tropical Forests
Abstract: Human interventions alter stand structure, species composition, and regeneration capacity of the forest. There is no enough information on how different management systems affect the forest structure. The main objective of this study was to analyze the differences on stand structure and species composition caused by different logging intensities. The study was conducted in a lowland evergreen moist forest of 22 000 ha in Cameroon. The forest was subdivided into three forest types with different human impacts: 2-Logged, 1-Logged, and Unlogged. The diameter corresponding to mean basal area of stems of 2-Logged (31.8 cm, ) was almost equal to that of Unlogged (30.1 cm, ). 1-Logged had a lower diameter of 27.7 cm, . In the three forest types, the diameter distribution followed the inverse J-shaped curve frequently observed in natural forests. The stand basal area increased from 29.4 m2/ha in 2-Logged, to 32 m2/ha in 1-Logged, and to 35.3 m2/ha in Unlogged. These results indicated that logging affected natural regeneration in 2-Logged. Above 60 cm dbh, the logging effect was not visible. On 103 tree species found in the sample forest, only nine were classified as harvestable commercial species.
PubDate: Sun, 22 Mar 2015 13:07:55 +000