In Lower Casamance, <i>Pterocarpus erinaceus</i> occupies a very important place in agroforestry parks. It is often grown in association with the most important cash crop of the area, groundnut <i>(A...In Lower Casamance, <i>Pterocarpus erinaceus</i> occupies a very important place in agroforestry parks. It is often grown in association with the most important cash crop of the area, groundnut <i>(Arachis hypogea L.).</i> Thus, the objective of this study is to contribute to a better understanding of the interactions between trees and groundnut cultivation in agroforestry parks in Lower Casamance. To this end, in each of the two districts (Tenghory and Kataba 1) three <i>Pterocarpus erinaceus</i> trees were selected in three separate communes. For each <i>P. erinaceus</i> tree selected and following each of the four cardinal directions, three situations were defined: at R/2, at 1.5 R and at 2 R from the trunk, with R the radius of the crown. Thus, 12 yield squares were installed around each selected tree, for a total of 72 yield squares installed in the two districts. The parameters measured were the height of the peanut plants, the number of pods produced per plant, and the yield in flakes and pods. The results show that geographical orientation significantly influenced plant height (p = 0.004) but not the number of pods/plant (p = 0.6). As for the distance to the trunk of <i>Pterocarpus erinaceus</i>, it induced a significant variation in the number of pods/plant (p = 0.009) but did not induce a significant effect on the other parameters. Yields varied between 1.56 Tons M S /ha and 2.02 Tons M S /ha for the hay, and between 1.03 Tons M S /ha and 1.45 Tons M S/ha for the pods. The results of this study constitute a useful source of information for a better management of the productivity of the agroforestry parks of the department of Bignona.展开更多
An experiment was carried out at the Agroforestry and Environment Research Farm, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh, during April, 2014 to January 2015. The experiment was la...An experiment was carried out at the Agroforestry and Environment Research Farm, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh, during April, 2014 to January 2015. The experiment was laid out in two factors Randomized Complete Block Design (RCBD) with three replications. Among the two factors, one factor like A was two production systems: S1 = Mango + Turmeric and S2 = Turmeric (sole crop);another factor like B was three turmeric variety: V1 = BARI Holud-1, V2 = BARI Holud-2 and V3 = BARI Holud-3. So, the treatment combinations were: S1V1 = Mango + BARI Holud-1, S1V2 = Mango + BARI Holud-2, S1V3 = Mango + BARI Holud-3, S2V1 = sole cropping of BARI Holud-1, S2V2 = sole cropping of BARI Holud-2 and S2V3 = sole cropping of BARI Holud-3. The result of the experiment revealed that interaction effect of production systems and variety was found significant on plant height, number of leaf per plant, length of leaf blade, breadth of leaf blade, number of finger per rhizome, fresh and dry yield per hectare. The higher fresh yield of turmeric (34.75 t/ha) and dry yield (6.10 t/ha) was found from S1V1 treatment (Mango + BARI Holud-1). Whereas the lowest fresh yield (33.41 t/ha) and dry yield (4.93 t/ha) was found from S2V2 treatment (sole cropping of BARI Holud-2). However, the suitability of the cultivation of different turmeric variety under mango based agroforestry systems may be ranked as S1V1 > S2V1 > S1V3 > S2V3 > S1V2 > S2V2. Finally it may be concluded that, BARI Holud-1 would be the best variety to be grown under mango based agroforestry.展开更多
Like several Sahelian countries, Senegal is facing a strong degradation of woody and arable resources. This is due to the development of certain inappropriate agricultural practices. To mitigate this situation, the po...Like several Sahelian countries, Senegal is facing a strong degradation of woody and arable resources. This is due to the development of certain inappropriate agricultural practices. To mitigate this situation, the populations tend to preserve and maintain certain woody species of interest in the fields, thus constituting agroforestry parks. Thus, the objective of this study was to contribute to a better understanding of the characteristics of woody vegetation in agroforestry parks in the department of Bignona. To this end, a plot of 2500 m<sup>2</sup> (50 m × 50 m) was installed in the fields of each farmer selected in a sample of 99 farm managers distributed in the three communes (Djinaky, Kataba1 and Kafountine) of the Kataba1 district, for a total of 99 plots installed. A total of seventy-three (73) species divided into fifty-five (55) genera and twenty-eight (27) botanical families were inventoried. In the agroforestry parks of the Kataba 1 district, the density of woody vegetation is 56.12 individuals/ha, the cover rate is 27.9% and the basal area is 5.9 m<sup>2</sup>/ha. The vertical structure of the woody vegetation is characterized by a predominance of individuals between 2 and 4 m in height (48.07%). As for the horizontal structure, it is characterized by a predominance of individuals of diameter between 5 and 20 cm (39.19%). These results obtained will serve as a source of information for better management of these agroforestry parks by the populations.展开更多
The prevalence of insect pests was studied on rice BRI 1 （mukta） as understory crop grown in association with 11 years old selected tree species viz, Akashmoni. Jhau and Albida in the field laboratory of the Departm...The prevalence of insect pests was studied on rice BRI 1 （mukta） as understory crop grown in association with 11 years old selected tree species viz, Akashmoni. Jhau and Albida in the field laboratory of the Department of Agroforestry, Bangladesh Agricultural University （BAU）. Mymensingh during the period from July to December, 2003. Among the three species Albida and Jhau possessed the largest canopy and there light penetration rate were high. On the other hand. Akashmoni had the lowest canopy but it penetrated low amount of light. Albida-rice association showed the lowest infestation of major rice insects followed by Jhau-rice association, while Akashmoni-rice association showed the highest insect infestation. Light intensity in the control plot （absent of tree species） was maximum and it caused minimum severity of insects infestation as compared to other associations. From the result it appeared that light interception has the relationship with insect population in rice. Therefore, tree species having sparse canopy which allowed easy penetration of sunlight is suitable for tree-flee agroforestry system.展开更多
Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is curren...Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is currently undergoing continuous degradation due to climatic hazards and anthropogenic actions. As a result, it is essential to gather information for the sustainable and rational management of woody formations. It is with this in mind that this study aims to contribute to a better understanding of the state of woody vegetation in the different land-use types in Basse Casamance. To this end, stratified random sampling of woody vegetation was carried out in the different land-use types (fields, fallow land and forests) of the Coubalan commune. The sampling unit for fields and fallows was a 2500 m<sup>2</sup> plot, and for forests was a 900 m<sup>2</sup> plot. A total of 53 species, divided into 48 genera belonging to 22 families, were inventoried in the commune. Structural parameters were higher in the forest, with 1321.3 ± 635.8 individuals/ha, 13.09 ± 0.1 m<sup>2</sup> and 79.25% ± 21.08% respectively for observed density, basal area and cover rate. As for dendrometric parameters, they are higher in the fields, with 20.4 ± 13.6 cm and 7.4 ± 3.8 m respectively for trunk diameter and woody height. Fallow land is characterized by species with low dendrometric parameters. These results provide a useful database for rational management of the various land-use types in the commune of Coubalan.展开更多
Change detection of land-cover to recommend the future directions of land-use is indispensable for sustainable development and the proper utilization of land resources. In this research, unsupervised classification ma...Change detection of land-cover to recommend the future directions of land-use is indispensable for sustainable development and the proper utilization of land resources. In this research, unsupervised classification maps produced using images of Landsat 8 OLI from 2013 until 2021 (with a 4-year interval) reveal important land-cover changes, along with their drivers, in Kapasia, Bangladesh. Overall, a substantial increase in paddy (24.7% to 27.2%) and urban (3.5% to 10.1%) and a decrease in homestead (67.5% to 59.3%) and forest (4.2% to 3.4%) were observed within the time interval. To direct the land-use towards long-term biodiversity and sustainability of the region, it is important to implement types of agroforestry systems as the observed decrease in homestead and forest areas are alarming. Agroforestry practices will not only have a positive environmental impact but can help diversify food systems, increase economic return and optimize natural resource use.展开更多
Chemical fertilizers are a source of soil degradation. In order to mitigate soil degradation and to face the negative impacts of climate change, the use of organic fertilizers, accessible to small farmers can maintain...Chemical fertilizers are a source of soil degradation. In order to mitigate soil degradation and to face the negative impacts of climate change, the use of organic fertilizers, accessible to small farmers can maintain the productivity of cereals including rice. The objective of this experiment is to study the effect of organo-mineral fertilizers on soil chemical properties, growth and physiology parameters and yield of rice. For this purpose, a completely randomized block design with three replications was adopted. Different organic (Fertinova, Organova and Fertinova + Organova) and mineral (NPK + Urea) fertilizers were applied to cultivate the NERICA L19 variety of rice. The soil chemical properties (pH), germination rate, growth, yield and physiological (chlorophyll content) parameters were assessed. The results revealed a germination rate of the grains varying between 87.5 and 100%. Fertinova and Fertinova + Organova had the highest germination rates. Soil pH decreased significantly from initial (6.71 ± 0.01) to final (5.73 ± 0.04) with the development cycle of the rice. Organo-mineral fertilizers influenced significantly (p = 5.36e−09) soil chemical properties by increasing pH (4%) compared to Control. Analysis of variance on growth and yield parameters, yield and chlorophyll content revealed a significant difference (p < 0.05) between fertilizers. Growth and yield parameters and yield were significantly higher in NPK and Fertinova + Organova than in Fertinova, Organova and Control. For the biomass the NPK + Urea recorded significantly highest biomass (488.28 ± 60.83 g). Leaves chlorophyll content varied significantly according to the daytime and the status of leaf development. The higher chlorophyll content was recorded at noon (27.96 ± 0.32 SPAD value) and with young leaves (30.21 ± 0.35 SPAD value). NPK + Urea (29.36 ± 0.45 SPAD value) and Fertinova (27.78 ± 0.40 SPAD value) favored more chlorophyll content in the rice leaves. Rice performed better in NPK + Urea and Fertinova + Organova fertilizers.展开更多
The use of organic fertilizers is less expensive and advantageous for both the development of the plant and the sanitation of the environment. This is why this investigation aims to promote the ash from emptying of oi...The use of organic fertilizers is less expensive and advantageous for both the development of the plant and the sanitation of the environment. This is why this investigation aims to promote the ash from emptying of oil mill boilers as a source of organic fertilization in the production of palm bunches. To do this, different doses of oil mill boiler emptying ash were tested on oil palms in production. The results showed that the oil palms responded favorably regardless of the dose of oil mill boiler emptying ash. Thus, the comparison of the different doses Tv1 (1 kg), Tv2 (1.5 kg), Tv3 (2 kg), Tv4 (3 kg), Tv5 (4 kg), Tv6 (5 kg) and Tv7 (7 kg) showed that the high doses led to an increase in the weight of the bunches. Better still, the Tv6 treatment at a dose of 5 kg/tree proved to be optimal for good production of palm bunches with a gain of 73.9% compared to the treatment without oil mill boiler emptying ash (absolute control).展开更多
This study evaluated the molecular characterization of different ecotypes of B. aegyptiaca populations in the four sites: Koily alpha, Labgar, Ranérou and Ballou according to the environment with the aim of devel...This study evaluated the molecular characterization of different ecotypes of B. aegyptiaca populations in the four sites: Koily alpha, Labgar, Ranérou and Ballou according to the environment with the aim of developing protection strategies. We sampled leaves of B. aegyptiaca in each individual from each site to extract and amplify a fragment of mitochondrial DNA including cytochrome b and then carefully preserved. DNA extraction, polymerase chain amplification and sequencing of MT-CYB were performed in 64 individuals. Genetic diversity and structure of B. aegyptiaca were determined using the MEGA, DNasp and Arlequin software. The results showed a high haplotype diversity and low nucleotide diversity, indicating a population expansion linked to an important gene flow. Genetic distances between populations were positively correlated with geographic distance. The importance of having highlighted this genetic differentiation of the B. aegyptiaca species between these sites is to be able to understand the degree of genetic heterogeneity of each and correlate it with adaptability because genetic diversity influences the adaptation of the species.展开更多
The present study was undertaken to determine the effects of different levels of urea-N fertilizer in addition to ipil-ipil tree litter on yield of rice and insect prevalence. The field study was conducted at the Agro...The present study was undertaken to determine the effects of different levels of urea-N fertilizer in addition to ipil-ipil tree litter on yield of rice and insect prevalence. The field study was conducted at the Agroforestry Field Laboratory, Bangladesh Agricultural University, Mymensingh during July-December 2004. The treatments included 0, 90, 180, and 270 kg urea per hectare. All four treatments received five tons ipil-ipil tree litter per hectare. The experiment was laid out in a randomized complete block design （RCBD） with four replications. The results showed that the different treatments significantly influenced the yield and yield component viz. total tillers/hill, effective tillers/hill, filled grains and unfilled grains/panicle. The highest yield of 4.62 t·h^m-2 with an increase of 21.57% over the control was recorded in treatment 180 kg urea·h^m-2, which was statistically similar to treatment 90 kg urea·h^m-2. The prevalence of insects viz. green leafhopper, brown plant hopper, rice bugs, leaf folder and stem borers were mostly correlated with N-levels. The prevalence of insects in general gradu- ally increased with the increase of N. Therefore, this study suggests that the combined application of organic materials （tree litter of ipil-ipil） and N-fertilizer of 90 kg·h^m-2 may oroduce good yield while minimizine insect arevalence in the rice field.展开更多
Mapping rice cultivation is indispensable for monitoring food supply conditions in Bangladesh because of the economical importance of the crop for supporting ever increasing population in the country. In this paper, w...Mapping rice cultivation is indispensable for monitoring food supply conditions in Bangladesh because of the economical importance of the crop for supporting ever increasing population in the country. In this paper, we extract the rice paddy field using the MODIS satellite data for five districts of Pabna, Manikganj, Sherpur, Sylhet, and Gazipur, each of which is characterized with its own aspects in terms of rice cultivation. Land classification is implemented using the vegetation index information derived from the red (band 1) and near-infrared (band 2) bands of MODIS 8-day composite time series data for the two time periods of 2001-2003 and 2011-2013. Results of unsupervised classification indicate that the paddy area coverage increased about 4% and 1% in Gazipur and Sylhet, respectively. In Pabna, Manikganj, and Sherpur, on the other hand, paddy area decreased by 10%, 2% and 5%, respectively, whereas notable increase of 12%, 2% and 7% was found in homestead area coverage, which is becoming more and more important for better management of small-scale agroforestry. At the same time, in Sherpur and Sylhet, forest area increased by 1% and 2% over the same time period. As a validation of these results, the changes detected in Gazipur are compared with those previously derived from the analysis of Landsat data with higher spatial resolution of 30 m as compared with that of MODIS (250 m). Also, the seasonal rice cropping pattern is studied in these five districts for discriminating cultivated rice types. These changes suggest that as a whole, efforts are being made to increase the food production, though the influence of population pressure and economic growth is apparent in these regions.展开更多
Drought is the most common form of abiotic stress that reduces plant growth and productivity.It causes plant injuries through elevated production of reactive oxygen species(ROS).Potassium(K)is a vital plant nutrient t...Drought is the most common form of abiotic stress that reduces plant growth and productivity.It causes plant injuries through elevated production of reactive oxygen species(ROS).Potassium(K)is a vital plant nutrient that notably ameliorates the detrimental effect of drought stress in the plant.A pot experiment was conducted at the Laboratory of Plant Stress Responses,Faculty of Agriculture,Kagawa University,Japan,under controlled environment of green house to explore the role of K in mitigating drought severity in wheat(Triticum asevitum L.)seedlings.Three days after germination,seedlings were exposed to three water regimes viz.,100,50,and 20%field capacity(FC)for 21 days.Potassium was adjusted in Hoagland nutrient solution at 0,6 and 12 mM concentration and applied to pot instead of normal water.Results show that,water deficit stress notably reduced plant growth,biomass accumulation,leaf relative water content(RWC)along with reduced photosynthetic pigments.Increased amount of biochemical stress markers viz.,malondialdehyde(MDA),hydrogen peroxide(H_(2)O_(2)),methylglyoxal(MG),proline(Pro)as well as an impaired antioxidant defense system were observed in drought affected wheat plants.On the contrary,K supplementation resulted in improvement of biochemical and physiological parameters that worked behind in improving growth and development of the wheat plants.In addition,enzymes of ascorbateglutathione(AsA-GSH)cycle were also enhanced by supplemented K that accelerated the ROS detoxification process in plant.Although glyoxalse system did not performed well till MG was detoxified might following another short stepped pathways.Our results revealed that drought stressed plants showed better performances in terms of biochemical and physiological attributes,antioxidant defense and glyoxalase system,as well as ROS detoxification due to K supplementation with better performance at 12 mM K added in 50%FC growing condition.展开更多
Few studies have compared the variability of soil properties using different types of mulches in semi-arid forests.This study evaluated the changes in physico-chemical soil properties in a semi-arid forest of Central ...Few studies have compared the variability of soil properties using different types of mulches in semi-arid forests.This study evaluated the changes in physico-chemical soil properties in a semi-arid forest of Central Eastern Spain,where straw and pine wood chips were distributed as mulch three months after a wildfire.Soils were sampled under burned and unmulched and burned and mulched plots three and nine months after the treatments.The data was processed using Principal Component Analysis(PCA)and Analytical Hierarchical Cluster Analysis(AHCA).Mulching with straw or wood chips did not have any significant effects on the texture and chemical properties of burned sites few months after the treatment.In contrast,significant changes are expected over time in organic matter,nutrients and many ions.There were no significant differences in soil properties between the two mulches.These low changes were confirmed by PCA coupled with AHCA,which did not show a clear distinction among the three soil conditions.However,a noticeable and significant variability of many of these properties over time was evident.This study shows that mulching does not degrade of soil properties in the short-term after a wildfire and after post-fire treatments,and thus helps protect semi-arid forest ecosystems against the negative impacts of high-severity fires.展开更多
The objective of this study was to develop allometric models for estimating the biomass of Sclerocarya birrea (A.Rich) Hoscht and Boscia senegalensis (Pers.) Lam. ex Poir. The inventory of these ligneous was carried o...The objective of this study was to develop allometric models for estimating the biomass of Sclerocarya birrea (A.Rich) Hoscht and Boscia senegalensis (Pers.) Lam. ex Poir. The inventory of these ligneous was carried out at Widou Thiengoly (North of Senegal). The sample consists of 43 individuals of Boscia senegalensis and 15 individuals of Sclerocarya birrea. The selected individuals were dendrometrically characterized before being cut, compartmentalized (trunk, branches, and twigs) and weighed entirely. Simple regression tests were performed to examine the most explanatory dendrometric parameter (x) for biomass (y) according to two types of models: the linear model (y = ax + b) and the polynomial model of degrees 2 (y = ax<sup>2</sup> + bx + c). The criteria for selection and validity of the models are based firstly on the tests of normality, nullity, heterogeneity and autocorrelation of the residues. The results showed that the most explanatory dendrometric parameter of the biomass was the crown surface for Boscia senegalensis and the 1.30 m diameter for Sclerocarya birrea of all the tests performed, the second-order Polynomial model is the best predictor of above ground biomass for these two species. Thus, the allometric models established to predict the biomass of these two species are: y = 0.0023x<sup>2</sup> + 0.4851x - 0.0519 for Boscia senegalensis and y = 0.35x<sup>2</sup> + 10.35x - 12.90 for S. birrea;with very significant correlation coefficients (R<sup>2</sup>) of 0.85 and 0.94 respectively. These results can be used for a sequestered carbon assessment study and will play a role in monitoring the carbon market in Africa.展开更多
Biological methane oxidation is a crucial process in the global carbon cycle that reduces methane emissions from paddy fields and natural wetlands into the atmosphere.However,soil organic carbon accumulation associate...Biological methane oxidation is a crucial process in the global carbon cycle that reduces methane emissions from paddy fields and natural wetlands into the atmosphere.However,soil organic carbon accumulation associated with microbial methane oxidation is poorly understood.Therefore,to investigate methane-derived carbon incorporation into soil organic matter,paddy soils originated from different parent materials(Inceptisol,Entisol,and Alfisol) were collected after rice harvesting from four major rice-producing regions in Bangladesh.Following microcosm incubation with 5%(volume/volume)^(13) CH_(4),soil^(13) C-atom abundances significantly increased from background level of 1.08% to 1.88%–2.78%,leading to a net methane-derived accumulation of soil organic carbon ranging from 120 to 307 mg kg^(-1).Approximately 23.6%–60.0% of the methane consumed was converted to soil organic carbon during microbial methane oxidation.The phylogeny of^(13) C-labeled pmoA(enconding the alpha subunit of the particulate methane monooxygenase) and 16 S rRNA genes further revealed that canonical α(type II) and γ(type I) Proteobacteria were active methane oxidizers.Members within the Methylobacter-and Methylosarcina-affiliated type Ia lineages dominated active methane-oxidizing communities that were responsible for the majority of methane-derived carbon accumulation in all three paddy soils,while Methylocystis-affiliated type IIa lineage was the key contributor in one paddy soil of Inceptisol origin.These results suggest that methanotroph-mediated synthesis of biomass plays an important role in soil organic matter accumulation.This study thus supports the concept that methanotrophs not only consume the greenhouse gas methane but also serve as a key biotic factor in maintaining soil fertility.展开更多
Understanding the environmental factors that influence tree species composition is essential for successful management of biodiversity and sustainable use of community forest resources.This study aims to assess tree s...Understanding the environmental factors that influence tree species composition is essential for successful management of biodiversity and sustainable use of community forest resources.This study aims to assess tree species composition and distribution in the deciduous Ban Mae Chiang Rai Lum Community Forest in Northern Thailand and to analyze the influence of environmental factors on tree biodiversity in the forest.We conducted a stratified systematic sampling of the forest’s total area of 3925 ha,and twenty-five 0.16 ha survey plots were established in three different stands of the deciduous forests to estimate and characterize the difference in biological diversity among the stands.Canonical correspondence analysis(CCA)was used to investigate the environment factors affecting such differences in biodiversity of the stands.The results showed a high diversity of trees in the forest as 197 species,144 genera,and 62 plant families were recorded.The CCA ordination identified the environmental factors—the most important of which were elevation,distance to streams,soil moisture,organic matter,and distance to communities—that signifi-cantly influenced the diversity and distribution of tree species(p<0.05)in the community forest.Our findings indicate that the implementation of drought reduction measures such as building check dams,fire protection,and monitoring community forest-product usage would be recommended to further biodiversity conservation and the sustainable use of community forest resources.展开更多
<em>Momordica charantia</em> is a plant species widely used in food and traditional medicine. However, the germination techniques and the performances of <em>M. charantia</em> are poorly unders...<em>Momordica charantia</em> is a plant species widely used in food and traditional medicine. However, the germination techniques and the performances of <em>M. charantia</em> are poorly understood by the populations. This study aims to better understand the germination, growth and development characteristics, and yield of <em>M. charantia</em>. Three pretreatments of the seeds are used for the shortening of the pre-germination period: soaking the seeds in tap water for 24 hours (batch 2), in hot water at 80<span style="white-space:nowrap;">˚</span>C (batch 3), for 24 hours and in the boiling water at 100<span style="white-space:nowrap;">˚</span>C for 24 hours (batch 4). A control without soaking (batch 1) was also carried out. The seeds were sown in plastic boxes in the laboratory with sterile sand and directly in the nursery in polyethylene sleeves. The influence of the light factor (light and dark) and watering frequency (every day and every two days) on the growth and yield parameters was evaluated respectively in the laboratory and in the nursery. Germination, growth and yield parameters were determined. The results show that the light and frequency of watering factors have no influence (p > 0.05) on the rate and duration of seed germination unlike pretreatments. Thus, Batch1 and 2 exhibit significantly higher germination rates (70% ± 16%) than Lots 3 and 4 (21% ± 15%) in the laboratory and in the nursery. On the other hand in terms of germination time, batch 3 and 4 displayed shorter durations (14 days) than those batch1 and 2 (23 days). Growth parameters and yield (fruit and seeds) are strongly influenced by watering frequency, unlike pretreatments which only affect yield. Growth and yield parameters are significantly higher with daily watering than daily watering. Ultimately, this study showed that pretreatments have an influence on the duration and rate of germination as well as the frequency of watering on the performance of <em>M. charantia</em>.展开更多
We contrast a new continuous approach(CA)for estimating plot-level above-ground biomass(AGB)in forest inventories with the current approach of estimating AGB exclusively from the tree-level AGB predicted for each tree...We contrast a new continuous approach(CA)for estimating plot-level above-ground biomass(AGB)in forest inventories with the current approach of estimating AGB exclusively from the tree-level AGB predicted for each tree in a plot,henceforth called DA(discrete approach).With the CA,the AGB in a forest is modelled as a continuous surface and the AGB estimate for a fixed-area plot is computed as the integral of the AGB surface taken over the plot area.Hence with the CA,the portion of the biomass of in-plot trees that extends across the plot perimeter is ignored while the biomass from trees outside of the plot reaching inside the plot is added.We use a sampling simulation with data from a fully mapped two hectare area to illustrate that important differences in plot-level AGB estimates can emerge.Ideally CA-based estimates of mean AGB should be less variable than those derived from the DA.If realized,this difference translates to a higher precision from field sampling,or a lower required sample size.In our case study with a target precision of 5%(i.e.relative standard error of the estimated mean AGB),the CA required a 27.1%lower sample size for small plots of 100 m2 and a 10.4%lower sample size for larger plots of 1700 m2.We examined sampling induced errors only and did not yet consider model errors.We discuss practical issues in implementing the CA in field inventories and the potential in applications that model biomass with remote sensing data.The CA is a variation on a plot design for above-ground forest biomass;as such it can be applied in combination with any forest inventory sampling design.展开更多
The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer a...The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^(-2), 795.4 trees·hm^(-2) and 3.9 m2·hm-2, 5.8 m^2·hm^(-2), respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.展开更多
The original version of this article unfortunately contained three mistakes. （1） The spelling of the [A. Nishad＇] name was incorrect. The corrected spelling is given below.
文摘In Lower Casamance, <i>Pterocarpus erinaceus</i> occupies a very important place in agroforestry parks. It is often grown in association with the most important cash crop of the area, groundnut <i>(Arachis hypogea L.).</i> Thus, the objective of this study is to contribute to a better understanding of the interactions between trees and groundnut cultivation in agroforestry parks in Lower Casamance. To this end, in each of the two districts (Tenghory and Kataba 1) three <i>Pterocarpus erinaceus</i> trees were selected in three separate communes. For each <i>P. erinaceus</i> tree selected and following each of the four cardinal directions, three situations were defined: at R/2, at 1.5 R and at 2 R from the trunk, with R the radius of the crown. Thus, 12 yield squares were installed around each selected tree, for a total of 72 yield squares installed in the two districts. The parameters measured were the height of the peanut plants, the number of pods produced per plant, and the yield in flakes and pods. The results show that geographical orientation significantly influenced plant height (p = 0.004) but not the number of pods/plant (p = 0.6). As for the distance to the trunk of <i>Pterocarpus erinaceus</i>, it induced a significant variation in the number of pods/plant (p = 0.009) but did not induce a significant effect on the other parameters. Yields varied between 1.56 Tons M S /ha and 2.02 Tons M S /ha for the hay, and between 1.03 Tons M S /ha and 1.45 Tons M S/ha for the pods. The results of this study constitute a useful source of information for a better management of the productivity of the agroforestry parks of the department of Bignona.
文摘An experiment was carried out at the Agroforestry and Environment Research Farm, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh, during April, 2014 to January 2015. The experiment was laid out in two factors Randomized Complete Block Design (RCBD) with three replications. Among the two factors, one factor like A was two production systems: S1 = Mango + Turmeric and S2 = Turmeric (sole crop);another factor like B was three turmeric variety: V1 = BARI Holud-1, V2 = BARI Holud-2 and V3 = BARI Holud-3. So, the treatment combinations were: S1V1 = Mango + BARI Holud-1, S1V2 = Mango + BARI Holud-2, S1V3 = Mango + BARI Holud-3, S2V1 = sole cropping of BARI Holud-1, S2V2 = sole cropping of BARI Holud-2 and S2V3 = sole cropping of BARI Holud-3. The result of the experiment revealed that interaction effect of production systems and variety was found significant on plant height, number of leaf per plant, length of leaf blade, breadth of leaf blade, number of finger per rhizome, fresh and dry yield per hectare. The higher fresh yield of turmeric (34.75 t/ha) and dry yield (6.10 t/ha) was found from S1V1 treatment (Mango + BARI Holud-1). Whereas the lowest fresh yield (33.41 t/ha) and dry yield (4.93 t/ha) was found from S2V2 treatment (sole cropping of BARI Holud-2). However, the suitability of the cultivation of different turmeric variety under mango based agroforestry systems may be ranked as S1V1 > S2V1 > S1V3 > S2V3 > S1V2 > S2V2. Finally it may be concluded that, BARI Holud-1 would be the best variety to be grown under mango based agroforestry.
文摘Like several Sahelian countries, Senegal is facing a strong degradation of woody and arable resources. This is due to the development of certain inappropriate agricultural practices. To mitigate this situation, the populations tend to preserve and maintain certain woody species of interest in the fields, thus constituting agroforestry parks. Thus, the objective of this study was to contribute to a better understanding of the characteristics of woody vegetation in agroforestry parks in the department of Bignona. To this end, a plot of 2500 m<sup>2</sup> (50 m × 50 m) was installed in the fields of each farmer selected in a sample of 99 farm managers distributed in the three communes (Djinaky, Kataba1 and Kafountine) of the Kataba1 district, for a total of 99 plots installed. A total of seventy-three (73) species divided into fifty-five (55) genera and twenty-eight (27) botanical families were inventoried. In the agroforestry parks of the Kataba 1 district, the density of woody vegetation is 56.12 individuals/ha, the cover rate is 27.9% and the basal area is 5.9 m<sup>2</sup>/ha. The vertical structure of the woody vegetation is characterized by a predominance of individuals between 2 and 4 m in height (48.07%). As for the horizontal structure, it is characterized by a predominance of individuals of diameter between 5 and 20 cm (39.19%). These results obtained will serve as a source of information for better management of these agroforestry parks by the populations.
文摘The prevalence of insect pests was studied on rice BRI 1 （mukta） as understory crop grown in association with 11 years old selected tree species viz, Akashmoni. Jhau and Albida in the field laboratory of the Department of Agroforestry, Bangladesh Agricultural University （BAU）. Mymensingh during the period from July to December, 2003. Among the three species Albida and Jhau possessed the largest canopy and there light penetration rate were high. On the other hand. Akashmoni had the lowest canopy but it penetrated low amount of light. Albida-rice association showed the lowest infestation of major rice insects followed by Jhau-rice association, while Akashmoni-rice association showed the highest insect infestation. Light intensity in the control plot （absent of tree species） was maximum and it caused minimum severity of insects infestation as compared to other associations. From the result it appeared that light interception has the relationship with insect population in rice. Therefore, tree species having sparse canopy which allowed easy penetration of sunlight is suitable for tree-flee agroforestry system.
文摘Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is currently undergoing continuous degradation due to climatic hazards and anthropogenic actions. As a result, it is essential to gather information for the sustainable and rational management of woody formations. It is with this in mind that this study aims to contribute to a better understanding of the state of woody vegetation in the different land-use types in Basse Casamance. To this end, stratified random sampling of woody vegetation was carried out in the different land-use types (fields, fallow land and forests) of the Coubalan commune. The sampling unit for fields and fallows was a 2500 m<sup>2</sup> plot, and for forests was a 900 m<sup>2</sup> plot. A total of 53 species, divided into 48 genera belonging to 22 families, were inventoried in the commune. Structural parameters were higher in the forest, with 1321.3 ± 635.8 individuals/ha, 13.09 ± 0.1 m<sup>2</sup> and 79.25% ± 21.08% respectively for observed density, basal area and cover rate. As for dendrometric parameters, they are higher in the fields, with 20.4 ± 13.6 cm and 7.4 ± 3.8 m respectively for trunk diameter and woody height. Fallow land is characterized by species with low dendrometric parameters. These results provide a useful database for rational management of the various land-use types in the commune of Coubalan.
文摘Change detection of land-cover to recommend the future directions of land-use is indispensable for sustainable development and the proper utilization of land resources. In this research, unsupervised classification maps produced using images of Landsat 8 OLI from 2013 until 2021 (with a 4-year interval) reveal important land-cover changes, along with their drivers, in Kapasia, Bangladesh. Overall, a substantial increase in paddy (24.7% to 27.2%) and urban (3.5% to 10.1%) and a decrease in homestead (67.5% to 59.3%) and forest (4.2% to 3.4%) were observed within the time interval. To direct the land-use towards long-term biodiversity and sustainability of the region, it is important to implement types of agroforestry systems as the observed decrease in homestead and forest areas are alarming. Agroforestry practices will not only have a positive environmental impact but can help diversify food systems, increase economic return and optimize natural resource use.
文摘Chemical fertilizers are a source of soil degradation. In order to mitigate soil degradation and to face the negative impacts of climate change, the use of organic fertilizers, accessible to small farmers can maintain the productivity of cereals including rice. The objective of this experiment is to study the effect of organo-mineral fertilizers on soil chemical properties, growth and physiology parameters and yield of rice. For this purpose, a completely randomized block design with three replications was adopted. Different organic (Fertinova, Organova and Fertinova + Organova) and mineral (NPK + Urea) fertilizers were applied to cultivate the NERICA L19 variety of rice. The soil chemical properties (pH), germination rate, growth, yield and physiological (chlorophyll content) parameters were assessed. The results revealed a germination rate of the grains varying between 87.5 and 100%. Fertinova and Fertinova + Organova had the highest germination rates. Soil pH decreased significantly from initial (6.71 ± 0.01) to final (5.73 ± 0.04) with the development cycle of the rice. Organo-mineral fertilizers influenced significantly (p = 5.36e−09) soil chemical properties by increasing pH (4%) compared to Control. Analysis of variance on growth and yield parameters, yield and chlorophyll content revealed a significant difference (p < 0.05) between fertilizers. Growth and yield parameters and yield were significantly higher in NPK and Fertinova + Organova than in Fertinova, Organova and Control. For the biomass the NPK + Urea recorded significantly highest biomass (488.28 ± 60.83 g). Leaves chlorophyll content varied significantly according to the daytime and the status of leaf development. The higher chlorophyll content was recorded at noon (27.96 ± 0.32 SPAD value) and with young leaves (30.21 ± 0.35 SPAD value). NPK + Urea (29.36 ± 0.45 SPAD value) and Fertinova (27.78 ± 0.40 SPAD value) favored more chlorophyll content in the rice leaves. Rice performed better in NPK + Urea and Fertinova + Organova fertilizers.
文摘The use of organic fertilizers is less expensive and advantageous for both the development of the plant and the sanitation of the environment. This is why this investigation aims to promote the ash from emptying of oil mill boilers as a source of organic fertilization in the production of palm bunches. To do this, different doses of oil mill boiler emptying ash were tested on oil palms in production. The results showed that the oil palms responded favorably regardless of the dose of oil mill boiler emptying ash. Thus, the comparison of the different doses Tv1 (1 kg), Tv2 (1.5 kg), Tv3 (2 kg), Tv4 (3 kg), Tv5 (4 kg), Tv6 (5 kg) and Tv7 (7 kg) showed that the high doses led to an increase in the weight of the bunches. Better still, the Tv6 treatment at a dose of 5 kg/tree proved to be optimal for good production of palm bunches with a gain of 73.9% compared to the treatment without oil mill boiler emptying ash (absolute control).
文摘This study evaluated the molecular characterization of different ecotypes of B. aegyptiaca populations in the four sites: Koily alpha, Labgar, Ranérou and Ballou according to the environment with the aim of developing protection strategies. We sampled leaves of B. aegyptiaca in each individual from each site to extract and amplify a fragment of mitochondrial DNA including cytochrome b and then carefully preserved. DNA extraction, polymerase chain amplification and sequencing of MT-CYB were performed in 64 individuals. Genetic diversity and structure of B. aegyptiaca were determined using the MEGA, DNasp and Arlequin software. The results showed a high haplotype diversity and low nucleotide diversity, indicating a population expansion linked to an important gene flow. Genetic distances between populations were positively correlated with geographic distance. The importance of having highlighted this genetic differentiation of the B. aegyptiaca species between these sites is to be able to understand the degree of genetic heterogeneity of each and correlate it with adaptability because genetic diversity influences the adaptation of the species.
文摘The present study was undertaken to determine the effects of different levels of urea-N fertilizer in addition to ipil-ipil tree litter on yield of rice and insect prevalence. The field study was conducted at the Agroforestry Field Laboratory, Bangladesh Agricultural University, Mymensingh during July-December 2004. The treatments included 0, 90, 180, and 270 kg urea per hectare. All four treatments received five tons ipil-ipil tree litter per hectare. The experiment was laid out in a randomized complete block design （RCBD） with four replications. The results showed that the different treatments significantly influenced the yield and yield component viz. total tillers/hill, effective tillers/hill, filled grains and unfilled grains/panicle. The highest yield of 4.62 t·h^m-2 with an increase of 21.57% over the control was recorded in treatment 180 kg urea·h^m-2, which was statistically similar to treatment 90 kg urea·h^m-2. The prevalence of insects viz. green leafhopper, brown plant hopper, rice bugs, leaf folder and stem borers were mostly correlated with N-levels. The prevalence of insects in general gradu- ally increased with the increase of N. Therefore, this study suggests that the combined application of organic materials （tree litter of ipil-ipil） and N-fertilizer of 90 kg·h^m-2 may oroduce good yield while minimizine insect arevalence in the rice field.
文摘Mapping rice cultivation is indispensable for monitoring food supply conditions in Bangladesh because of the economical importance of the crop for supporting ever increasing population in the country. In this paper, we extract the rice paddy field using the MODIS satellite data for five districts of Pabna, Manikganj, Sherpur, Sylhet, and Gazipur, each of which is characterized with its own aspects in terms of rice cultivation. Land classification is implemented using the vegetation index information derived from the red (band 1) and near-infrared (band 2) bands of MODIS 8-day composite time series data for the two time periods of 2001-2003 and 2011-2013. Results of unsupervised classification indicate that the paddy area coverage increased about 4% and 1% in Gazipur and Sylhet, respectively. In Pabna, Manikganj, and Sherpur, on the other hand, paddy area decreased by 10%, 2% and 5%, respectively, whereas notable increase of 12%, 2% and 7% was found in homestead area coverage, which is becoming more and more important for better management of small-scale agroforestry. At the same time, in Sherpur and Sylhet, forest area increased by 1% and 2% over the same time period. As a validation of these results, the changes detected in Gazipur are compared with those previously derived from the analysis of Landsat data with higher spatial resolution of 30 m as compared with that of MODIS (250 m). Also, the seasonal rice cropping pattern is studied in these five districts for discriminating cultivated rice types. These changes suggest that as a whole, efforts are being made to increase the food production, though the influence of population pressure and economic growth is apparent in these regions.
文摘Drought is the most common form of abiotic stress that reduces plant growth and productivity.It causes plant injuries through elevated production of reactive oxygen species(ROS).Potassium(K)is a vital plant nutrient that notably ameliorates the detrimental effect of drought stress in the plant.A pot experiment was conducted at the Laboratory of Plant Stress Responses,Faculty of Agriculture,Kagawa University,Japan,under controlled environment of green house to explore the role of K in mitigating drought severity in wheat(Triticum asevitum L.)seedlings.Three days after germination,seedlings were exposed to three water regimes viz.,100,50,and 20%field capacity(FC)for 21 days.Potassium was adjusted in Hoagland nutrient solution at 0,6 and 12 mM concentration and applied to pot instead of normal water.Results show that,water deficit stress notably reduced plant growth,biomass accumulation,leaf relative water content(RWC)along with reduced photosynthetic pigments.Increased amount of biochemical stress markers viz.,malondialdehyde(MDA),hydrogen peroxide(H_(2)O_(2)),methylglyoxal(MG),proline(Pro)as well as an impaired antioxidant defense system were observed in drought affected wheat plants.On the contrary,K supplementation resulted in improvement of biochemical and physiological parameters that worked behind in improving growth and development of the wheat plants.In addition,enzymes of ascorbateglutathione(AsA-GSH)cycle were also enhanced by supplemented K that accelerated the ROS detoxification process in plant.Although glyoxalse system did not performed well till MG was detoxified might following another short stepped pathways.Our results revealed that drought stressed plants showed better performances in terms of biochemical and physiological attributes,antioxidant defense and glyoxalase system,as well as ROS detoxification due to K supplementation with better performance at 12 mM K added in 50%FC growing condition.
基金funded by the Spanish Research Agency(AEI)(project code PID2021-126946OB-I00)the financial support from the EPy RIS(SOE2/P5/E0811)project funded by the European Union through the SUDOE INTERREG Program。
文摘Few studies have compared the variability of soil properties using different types of mulches in semi-arid forests.This study evaluated the changes in physico-chemical soil properties in a semi-arid forest of Central Eastern Spain,where straw and pine wood chips were distributed as mulch three months after a wildfire.Soils were sampled under burned and unmulched and burned and mulched plots three and nine months after the treatments.The data was processed using Principal Component Analysis(PCA)and Analytical Hierarchical Cluster Analysis(AHCA).Mulching with straw or wood chips did not have any significant effects on the texture and chemical properties of burned sites few months after the treatment.In contrast,significant changes are expected over time in organic matter,nutrients and many ions.There were no significant differences in soil properties between the two mulches.These low changes were confirmed by PCA coupled with AHCA,which did not show a clear distinction among the three soil conditions.However,a noticeable and significant variability of many of these properties over time was evident.This study shows that mulching does not degrade of soil properties in the short-term after a wildfire and after post-fire treatments,and thus helps protect semi-arid forest ecosystems against the negative impacts of high-severity fires.
文摘The objective of this study was to develop allometric models for estimating the biomass of Sclerocarya birrea (A.Rich) Hoscht and Boscia senegalensis (Pers.) Lam. ex Poir. The inventory of these ligneous was carried out at Widou Thiengoly (North of Senegal). The sample consists of 43 individuals of Boscia senegalensis and 15 individuals of Sclerocarya birrea. The selected individuals were dendrometrically characterized before being cut, compartmentalized (trunk, branches, and twigs) and weighed entirely. Simple regression tests were performed to examine the most explanatory dendrometric parameter (x) for biomass (y) according to two types of models: the linear model (y = ax + b) and the polynomial model of degrees 2 (y = ax<sup>2</sup> + bx + c). The criteria for selection and validity of the models are based firstly on the tests of normality, nullity, heterogeneity and autocorrelation of the residues. The results showed that the most explanatory dendrometric parameter of the biomass was the crown surface for Boscia senegalensis and the 1.30 m diameter for Sclerocarya birrea of all the tests performed, the second-order Polynomial model is the best predictor of above ground biomass for these two species. Thus, the allometric models established to predict the biomass of these two species are: y = 0.0023x<sup>2</sup> + 0.4851x - 0.0519 for Boscia senegalensis and y = 0.35x<sup>2</sup> + 10.35x - 12.90 for S. birrea;with very significant correlation coefficients (R<sup>2</sup>) of 0.85 and 0.94 respectively. These results can be used for a sequestered carbon assessment study and will play a role in monitoring the carbon market in Africa.
基金financially supported by the National Natural Science Foundation of China (Nos. 91751204, 41630862, 41701302, 41530857, and 41877062)The first author, Ms. Nasrin Sultana, gratefully acknowledges the Organization for Women in Science for the Developing World (OWSD) Ph.D. Fellowship。
文摘Biological methane oxidation is a crucial process in the global carbon cycle that reduces methane emissions from paddy fields and natural wetlands into the atmosphere.However,soil organic carbon accumulation associated with microbial methane oxidation is poorly understood.Therefore,to investigate methane-derived carbon incorporation into soil organic matter,paddy soils originated from different parent materials(Inceptisol,Entisol,and Alfisol) were collected after rice harvesting from four major rice-producing regions in Bangladesh.Following microcosm incubation with 5%(volume/volume)^(13) CH_(4),soil^(13) C-atom abundances significantly increased from background level of 1.08% to 1.88%–2.78%,leading to a net methane-derived accumulation of soil organic carbon ranging from 120 to 307 mg kg^(-1).Approximately 23.6%–60.0% of the methane consumed was converted to soil organic carbon during microbial methane oxidation.The phylogeny of^(13) C-labeled pmoA(enconding the alpha subunit of the particulate methane monooxygenase) and 16 S rRNA genes further revealed that canonical α(type II) and γ(type I) Proteobacteria were active methane oxidizers.Members within the Methylobacter-and Methylosarcina-affiliated type Ia lineages dominated active methane-oxidizing communities that were responsible for the majority of methane-derived carbon accumulation in all three paddy soils,while Methylocystis-affiliated type IIa lineage was the key contributor in one paddy soil of Inceptisol origin.These results suggest that methanotroph-mediated synthesis of biomass plays an important role in soil organic matter accumulation.This study thus supports the concept that methanotrophs not only consume the greenhouse gas methane but also serve as a key biotic factor in maintaining soil fertility.
基金supported by the Southeast Asian Regional Center for Graduate Study and Research in Agriculture(SEARCA)-ASEAN Working Group on Social Forestry Strategic Response Fund(ASRF)under the ASEANSwiss Partnership on Social Forestry and Climate Change and by the R&D Program for Forest Science Technology(Project No.2018113C10-2020-BB01)provided by Korea Forest Service(Korea Forestry Promotion Institute).
文摘Understanding the environmental factors that influence tree species composition is essential for successful management of biodiversity and sustainable use of community forest resources.This study aims to assess tree species composition and distribution in the deciduous Ban Mae Chiang Rai Lum Community Forest in Northern Thailand and to analyze the influence of environmental factors on tree biodiversity in the forest.We conducted a stratified systematic sampling of the forest’s total area of 3925 ha,and twenty-five 0.16 ha survey plots were established in three different stands of the deciduous forests to estimate and characterize the difference in biological diversity among the stands.Canonical correspondence analysis(CCA)was used to investigate the environment factors affecting such differences in biodiversity of the stands.The results showed a high diversity of trees in the forest as 197 species,144 genera,and 62 plant families were recorded.The CCA ordination identified the environmental factors—the most important of which were elevation,distance to streams,soil moisture,organic matter,and distance to communities—that signifi-cantly influenced the diversity and distribution of tree species(p<0.05)in the community forest.Our findings indicate that the implementation of drought reduction measures such as building check dams,fire protection,and monitoring community forest-product usage would be recommended to further biodiversity conservation and the sustainable use of community forest resources.
文摘<em>Momordica charantia</em> is a plant species widely used in food and traditional medicine. However, the germination techniques and the performances of <em>M. charantia</em> are poorly understood by the populations. This study aims to better understand the germination, growth and development characteristics, and yield of <em>M. charantia</em>. Three pretreatments of the seeds are used for the shortening of the pre-germination period: soaking the seeds in tap water for 24 hours (batch 2), in hot water at 80<span style="white-space:nowrap;">˚</span>C (batch 3), for 24 hours and in the boiling water at 100<span style="white-space:nowrap;">˚</span>C for 24 hours (batch 4). A control without soaking (batch 1) was also carried out. The seeds were sown in plastic boxes in the laboratory with sterile sand and directly in the nursery in polyethylene sleeves. The influence of the light factor (light and dark) and watering frequency (every day and every two days) on the growth and yield parameters was evaluated respectively in the laboratory and in the nursery. Germination, growth and yield parameters were determined. The results show that the light and frequency of watering factors have no influence (p > 0.05) on the rate and duration of seed germination unlike pretreatments. Thus, Batch1 and 2 exhibit significantly higher germination rates (70% ± 16%) than Lots 3 and 4 (21% ± 15%) in the laboratory and in the nursery. On the other hand in terms of germination time, batch 3 and 4 displayed shorter durations (14 days) than those batch1 and 2 (23 days). Growth parameters and yield (fruit and seeds) are strongly influenced by watering frequency, unlike pretreatments which only affect yield. Growth and yield parameters are significantly higher with daily watering than daily watering. Ultimately, this study showed that pretreatments have an influence on the duration and rate of germination as well as the frequency of watering on the performance of <em>M. charantia</em>.
文摘We contrast a new continuous approach(CA)for estimating plot-level above-ground biomass(AGB)in forest inventories with the current approach of estimating AGB exclusively from the tree-level AGB predicted for each tree in a plot,henceforth called DA(discrete approach).With the CA,the AGB in a forest is modelled as a continuous surface and the AGB estimate for a fixed-area plot is computed as the integral of the AGB surface taken over the plot area.Hence with the CA,the portion of the biomass of in-plot trees that extends across the plot perimeter is ignored while the biomass from trees outside of the plot reaching inside the plot is added.We use a sampling simulation with data from a fully mapped two hectare area to illustrate that important differences in plot-level AGB estimates can emerge.Ideally CA-based estimates of mean AGB should be less variable than those derived from the DA.If realized,this difference translates to a higher precision from field sampling,or a lower required sample size.In our case study with a target precision of 5%(i.e.relative standard error of the estimated mean AGB),the CA required a 27.1%lower sample size for small plots of 100 m2 and a 10.4%lower sample size for larger plots of 1700 m2.We examined sampling induced errors only and did not yet consider model errors.We discuss practical issues in implementing the CA in field inventories and the potential in applications that model biomass with remote sensing data.The CA is a variation on a plot design for above-ground forest biomass;as such it can be applied in combination with any forest inventory sampling design.
文摘The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^(-2), 795.4 trees·hm^(-2) and 3.9 m2·hm-2, 5.8 m^2·hm^(-2), respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.
文摘The original version of this article unfortunately contained three mistakes. （1） The spelling of the [A. Nishad＇] name was incorrect. The corrected spelling is given below.
