Influence of slope position and aspect on the vegetation attributes and treewater relations in forests of the central Himalayas

While the need for understanding the effects of topographical factors on forest structure and function is well recognized,comprehensive studies are scarce.This study evaluates the effect of slope aspect and slope position on water relations and forest attributes across six forest types occurring between 400 m and 2600 m altitude in the Central Himalaya(27°-38°N).We found that predawn tree water potential and soil water potential were generally higher on moist north slope aspect(-0.78±0.05 MPa and-3.34±0.18 MPa,respectively)than dry south slope aspect(-0.82±0.18 MPa and-3.77±0.18 MPa,respectively).Across six different forests,these values were higher at hill base(-0.71±0.06 MPa and-2.77±0.19 MPa,tree predawn water potential and soil water potential,respectively)than other topographical positions.The favorable effect of north aspect and hill base was also observed in maintaining soil water and tree water potential during the dry season.Vegetation attributes,such as species richness,unique species and plant density were also generally higher on north slope and hill base than southern aspect and lowest at hill top.Across forest types,the hill base provided shelter to 46 unique species,compared to 16-18 at the other positions,thus emphasizing its importance as refugia for species to survive climate change induced perturbations.The favorable conditions of hill base position not only contribute to increase in alpha diversity,but also to extended species distributional range.

Waterbirds in the Wetlands of Casiguran, Aurora, Philippines

The wetlands of Casiguran, Aurora, Philippines are primarily the source of livelihood for most of the coastal communities of the area. However, this also serves as a feeding ground for many of the migratory and resident waterbirds. There are waterbird species occurring in the area that need protection but only a few studies of these species exist. This study was conducted from February to March 2019 to census and identify the water birds present in the study site, determine the conservation status and index of abundance of identified waterbirds, and describe their habitat association. Based on the result, 18 waterbird species in five families were present in the area. Family Ardeidae had six representative species, Family Charadriidae had five representative species, Family Scolopacidae had five representative species while only one species represents the Family Anatidae and Family Rallidae. Two waterbird species observed (Anas luzonica and Egretta eulophotes) were listed by the International Union for Conservation of Nature (IUCN) as vulnerable and another species (Numerius madagascariensis) was listed as endangered. In terms of abundance, Intermediate Egret (Egretta intermedia) was revealed as the most abundant (94.68%) among waterbirds. Different waterbird species prefer specific habitats. Some usually frequent freshwater and saltwater habitats, including mangroves, open sea, and watercourses inside forests while some were observed in mudflats, and rice fields during the survey.

Old-growth mixed dipterocarp forests show variable losses and gains in aboveground biomass and standing carbon over forty years

Background:No studies have documented long-term trends in aboveground biomass(AGB)for mixed-dipterocarp forests(MDF),the dominant rain forest type in tropical wet equatorial Asia.In our study,we sought to document such trends over forty years across three sites representing lowland to lower montane elevations.Methods:To do this,we established fifty 100 m×25 m plots in 1978 across three sites sampled along an elevation gradient,identified as mature old-growth forest.We measured trees for diameter at breast height that we identified to species and tagged.We took wood samples to calculate species wood-specific gravity.We re-measured plots in 1998 and again in 2018.Results:We show standing AGB for all sites combined to be 517.52 Mg·ha^(-1)in 1978,but this declined by 17%over 40 years to 430.11 Mg·ha^(-1).No differences exist among sites in AGB primarily because of considerable within site variation;but interactions of time with site show declines across sites were not uniform,one remained about the same.Relatively few species represented a high proportion of the AGB with the top five species comprising between 34%and 65%,depending upon site and year sampled.One species,Mesua nagassarium,represented a disproportionately large amount of AGB and decline over time,particularly at the low elevation site.Conclusions:Our results are directly relevant to estimating AGB and standing carbon sequestered in MDF.Our study is the first to demonstrate varying but overall,declining trends in amounts of AGB among forests making predictions of biomass and standing carbon in MDF difficult over wide regions.

Analysis of existing agroforestry practices in Madhupur Sal forest: an assessment based on ecological and economic perspectives

A study was conducted in Madhupur sal forest of Tangail, Bangladesh to identify the suitable agroforestry practices of the area. Considering the ecological aspects of different agroforestry practices 10 sample plots （10 m× 10 m） from each land uses were taken, including natural forest to get a comparative scenario. The study showed that among the different agroforestry practices, Margalef and Shannon- Weiner index values are the maximum for pineapple agroforestry and lower for banana agroforestry, and Evenness index value is the maximum for lemon agroforestry. Determination of tree biomass in different land uses revealed that it is highest （3 078.6 kg/100 m^2） in natural forest followed by pineapple agroforestry, lemon agroforestry and banana agroforestry. Soil pH, moisture content, organic matter, organic carbon, phosphorus and total nitrogen showed statistically significant variation while bulk density, particle density, sulphur and potassium did not show any statistically significant variation among the land uses. Soil fertility status showed that pineapple agroforestry is more fertile than rest of other land uses. The Net Present Value （NPV） indicated that banana agroforestry is financially more profitable than other two systems, while the Benefit- Cost ratio （BCR） is higher in pineapple agroforestry （4.21 in participatory agroforestry and 3.35 in privately managed land）. Even though banana agroforestry gives higher NPV, capital required for this practice is much higher. The findings suggest that pineapple agroforestry has a tendency towards becoming ecologically and economically more sound than other two practices as it has better ecological attributes and required comparatively low investment.

Essential oil content and composition of Indian sandalwood (Santalum album) in Sri Lanka

Santalum album （Indian Sandalwood） is found in the mountainous regions of the intermediate zone of Sri Lanka. Few studies have been conducted on sandalwood ecology in this region, and ours is the first recorded study of essential oil content and chemical composition of heartwood. We harvested two trees with State permission and took cross-sections for analysis. We demonstrated a difference in the heartwood formation and oil yield of the trees. The composition of the oil was found to be consistent between trees and along the trunk of the tree. Main aromatic compounds were santalols and other compounds are recorded in lesser quantities. Results of this study comply with the other published work on sandalwood elsewhere. This initial study on S. album in Sri Lanka provided promising results for the future of sandalwood agroforestry.

A journey towards shared governance: status and prospects for collaborative management in the protected areas of Bangladesh

Establishment of Protected Areas （PAs）, in the face of rapid deforestation, forest degradation and climate change has been one of the key efforts in conservation of biodiversity worldwide in recent times. While Bangladesh has gained a degree of prominence in the world for its successful social forestry programs, the concept of collaborative pro- tected area management is rather new in the country, initiated in 2004 by the Bangladesh Forest Department in five PAs with financial assistance from USAID. Based on empirical evidence from three of the pilot PAs, we examined the achievements and associated challenges and prospects for co-management. Our fieldwork revealed a number of challenges faced by co-management institutions： （1） institutions were dominated by the elite group, overshadowing the voice of the community people; （2） mutual trust and collective performance are key to good governance but had not taken root in the PAs; （3） encroachment onto forest land and subsequent conversion to agriculture remained a serious problem that discouraged forest-dependent people from participating actively in co-management initiatives; （4） legal provisions （including acts, rules and policies） were not clearly and adequately disseminated and understood at the community level; （5） there remained a degree of ambiguity regarding the roles and responsibilities of forest department （FD） and co-management committees （CMC） in field operations, and this was not enhancing transparency and accountability of the overall initiative; （6） the long-term sustainability of co-management institutions was another major concern, as the local intuitional structure was still in a nascent stage, and provisioning of resources （either internally or externally） remained somewhat uncertain. We offer recommendations for improve- ment.

Status and ethno-medicinal usage of invasive plants in traditional health care practices: a case study from northeastern Bangladesh

Species diversity and ethno-medicinal usage of 39 species of invasive plants were explored in and around two protected areas, Khadimnagar National Park （KNP） and Rema-Kalenga Wildlife Sanctu- ary （RKWS）, of northeastern Bangladesh,. Status of invasive plants were investigated in 60 sample plots with 5 different habitat types, including forest, roadside, homestead, fallow land and others （ponds, canals, water logged areas, agricultural land, etc.）. Data about the usage of invasive plants in traditional health care were collected through interviewing 110 households. Among the five habitat types, fallow land （28 species）.possessed the highest number of species, followed by roadside （25 species）, forest （23 species）, homestead （22 species） and others （13 species）. Based on the survey, invasive plants of study areas were also categorized into five degrees of invasiveness e.g., naturalized, introduced, possibly invasive, moderately invasive and highly invasive. Additionally, there is the linear trend between degrees of invasivaness and use percentage of invasive plants. Total 39 species of invasive plants belonging to 29 families were recorded, which are generally used to treat 37 diseases, ranging from simple headache to highly complicated eye and heart diseases. The majority of the species used by the local inhabitants were herbs （16 species）, followed by some shrubs （11 species）, climbers （5 species）, trees （5 species） and grasses （2 species）. The use percentage of aboveground plant parts were higher （70.58%） than that of underground plant parts （16.18%）.

Spatial pattern of tree diversity and evenness across forest types in Majella National Park,Italy

Background： Estimation of tree diversity at broader scale is important for conservation planning. Tree diversity should be measured and understood in terms of diversity and evenness, two integral components to describe the structure of a biological community. Variation of the tree diversity and evenness with elevation, topographic relief, aspect, terrain shape, slope, soil nutrient, solar radiation etc. are well documented. Methods： Present study explores the variation of tree diversity （measured as Shannon diversity and evenness indices） of Majella National Park, italy with five available forest types namely evergreen oak woods, deciduous oak woods, blacWaleppo pine stands, hop-hornbeam forest and beech forest, using satellite, environmental and field data. Results： Hop-hornbeam forest was found to be most diverse and even while evergreen Oak woods was the lowest diverse and even. Diversity and evenness of forest types were concurrent to each other i.e. forest type which was more diverse was also more even. As a broad pattern, majority portion of the study area belonged to medium diversity and high evenness class. Conclusions： Satellite images and other GIS data proved useful tools in monitoring variation of tree diversity and evenness across various forest types. Present study findings may have implications in prioritizing conservation zones of high tree diversity at Majella.

Analysis of forest cover change at Khadimnagar National Park, Sylhet,Bangladesh, using Landsat TM and GIS data

We mapped the forest cover of Khadimnagar National Park （KNP） of Sylhet Forest Division and estimated forest change over a period of 22 years （1988-2010） using Landsat TM images and other GIS data. Supervised classification and Normalized Difference Vegetation Index （NDVI） image classification approaches were applied to the images to produce three cover classes, viz. dense forest, medium dense forest, and bare land. The change map was produced by differencing classified imageries of 1988 and 2010 as before image and after image, respectively, in ERDAS IMAGINE. Error matrix and kappa statistics were used to assess the accuracy of the produced maps. Overall map accuracies resulting from supervised classification of 1988 and 2010 imageries were 84.6% （Kappa 0.75） and 87.5% （Kappa 0.80）, respec- tively. Forest cover statistics resulting from supervised classification showed that dense forest and bare land declined from 526 ha （67%） to 417 ha （59%） and 105 ha （13%） to 8 ha （1%）, respectively, whereas medium dense forest increased from 155 ha （20%） to 317 ha （40%）. Forest cover change statistics derived from NDVI classification showed that dense forest declined from 525 ha （67%） to 421 ha （54%） while medium dense forest increased from 253 ha （32%） to 356 ha （45%）. Both supervised and NDVI classification approaches showed similar trends of forest change, i.e. decrease of dense forest and increase of medium dense forest, which indicates dense forest has been converted to medium dense forest. Area of bare land was unchanged. Illicit felling, encroachment, and settlement near forests caused the dense forest decline while short and long rotation plantations raised in various years caused the increase in area of medium dense forest. Protective measures should be undertaken to check further degradation of forest at KNP.

Assessment of natural regeneration status and diversity of tree species in the biodiversity conservation areas of Northeastern Bangladesh

A study was conducted at two-biodivcrsity conservation areas of Northeastern Bangladesh （a part of Sylhet Forest Division） to assess the species composition, diversity and density of natural regeneration of tree species both indigenous and exotic species. Data were collected by stratified random quadrate method during January 2010 to July 2010. Totally 200 circular plots of 2 m〉〈2 m in size had 5 different habitat types of plants namely; forest, roadside, homestead （surrounding forest dwellers house）, fallow land and others （canals, streams and tea gardens side）, which included a total of 55 regenerating species belonging to 28 families. Meliaceae is the dominant family and shows the highest family importance value （26.3）, having six species, followed by Moraeeae （24.24）. Among the five habitat types, forest （43 species） possess the highes number of species, followed by roadside （23 species）. Total 15 exotic species among 9 families and 40 indigenous species with 24 families were recorded. For exotic species, Tectona grandis possess the highest relative density （11.7%） and relative frequency （10.5%）; Senna siamea had highest relative abundance （7.83%）. In case of indigenous species, Chickrassia tabularis possess the highest relative density （4.23%） and relative frequency （4%）; Dipterocarpus turbinatus bad the highest relative abundance （3.92%）. Tectona grandis （29.66） and Chickrassia tabularis （10.8） had the highest IVI for exotic and indigenous species respectively. Different diversity indic＇es such as Shanon-Winner diversity index,＇ species diversity index, species richness index, species evenness index, Simpson index and species dominance index, etc. were applied to quantify definite diversity. The regeneration of species associated with low levelsof disturbance was in the exotic Species. Study suggests that proper protection from human disturbances and scientific management of natural regeneration of two-study forests may lead a rich biodiversity site in the country.

Assessing the effects of long-term recreational activities on landscape changes in Abant Natural Park,Turkey

Natural, protected areas offer many possibili- ties for recreation in rural areas such as camping, one of the most popular activities. The system established for pro- tected areas in Turkey aims to provide a foundation for conserving areas for recreation. One such area, Abant Natural Park, is convenient for visits from Turkey＇s two most populated metropolitan areas, Istanbul and Ankara. It also attracts tourists from other regions and countries. The aim of the present study was to evaluate the vegetation loss and land cover changes due to picnic/camping, transhu- mance, and construction over 40 years （1966-2004） in the park using data on visitor numbers, vegetation patches, corridors and connectivity. For evaluating landscape vari- ables, remote sensing data and aerial photos were used. When aerial photos were imported into the ERDAS Imagine program, ground control points identified, and individual images orthorectified, land degradation was not found in the use of camping areas. Moreover, manmade areas （road, car park and hotel） observably increased, thus decreasing the forest lands. The findings show that the land use types that have had the greatest ecological impact are transhumance and construction of hotels, which also require infrastructure development. The intensity of the ecological effects mandates precautions to lessen the impacts and the need for continuing assessment to ensure sustainable use of the area.

Seasonal variations in species diversity, dry matter and net primary productivity of herb layer of Quercus leucotrichophora-Pinus roxburghii mixed forest in Kumaun Himalaya, India

Plant biomass, species diversity and net primary productivity are presented for herb layer of banj oak （Quercus leucotrichophora A. Camus）-chir pine （Pinus roxburghii Sarg.） mixed forest in Kumaun, central Himalaya, India. The species diversity declined from a maximum （3.56） in September to a minimum （2.11） in December. The monthly live shoots biomass exhibited a single peak growth pattern with highest live shoot biomass of 185 g·m^-2 in August. The seasonal pattem showed that the maximum above-ground production （131 g·m^-2） occurred during the rainy season and the minimum （1 g·m^-2） during winter season. The be- low-ground production was maximum during winter season （84 g·m^2） and minimum during summer season （34 g＇m＇2）. The annual net shoot production was 171 g·^2m^-1 and total below-ground production was 165 g·m^2. Of the total input 61% was channeled to above-ground parts and 39% to below-ground parts. Transfer of live shoots to dead shoots compartments and that of dead shoots to litter compartments was 61% and 66%, respectively. The total dry matter disappearance was 61% of the total input within annual cycle. The herb layer showed a net accumulation of organic matter, indicating the seral nature of the community.

Comparative Study of Cooling under Shades of Some Forestry Tree Species with Respect to Ambient Temperatures

Trees create microclimate under their crowns in comparison to the outside ambient atmospheric temperature. Sun is the pivotal source of radiant energy reaching the earth atmosphere of which heat is more important than light. The radiant energy reaches the ground without any barricade whereas the tree crown impedes it in reaching the earth’s surface. During the day, when insolation impinges on tree crown, a portion of it is reflected back to the space, other portion is absorbed by the canopy increasing the temperature of leaves and the remaining part reaches the ground penetrating through the crown. Thus, a significant coolness is experienced under the shade of trees in comparison to open sunshine, with qualitative variations. The cooling produced by trees under their shades varies with species to species due to variation in several anatomical, structural and physiological attributes of the species. Climate is changing more rapidly prominently due to human activities especially indiscriminate felling of trees and it is feared that it will create problems on availability of energy, water and food security. Economic value takes over ecological benefits in selection of species in plantation programmes and this might have been due to the lack of scientific data about varying effectiveness of ecological services bestowed by different species. In the present study, an endeavor has been made to understand as to how a tree is integrated to the effects on atmosphere and responses to changing conditions with respect to differential cooling produced by five selected forestry tree species belonging to different categories. Analysis of data has come out with gradation of the sample species in respect to their cooling effect in the atmosphere in terms of yearly, quarterly, monthly and diurnal basis.

Analysis of the changes in forest ecosystem functions,structure and composition in the Black Sea region of Turkey

We used geographical information system to analyze changes in forest ecosystem functions, structure and composition in a typical department of forest management area consisting of four forest management planning units in Turkey. To assess these effects over a 25 year period we compiled data from three forest management plans that were made in 1986, 2001 and 2011. Temporal changes in forest ecosystem functions were estimated based on the three pillars of forest sustainability： economics, ecology and socio-culture. We assessed a few indicators such as land-use and forest cover, forest types,tree species, development stage, stand age classes, crown closure, growing stock and its increment, and timber biomass. The results of the case study suggested a shift in forest values away from economic values toward ecological and socio-cultural values over last two planning periods. Forest ecosystem structure improved, due mainly to increasing forest area, decreasing non-forest areas（especially in settlement and agricultural areas）, forestation on forest openings, rehabilitation of degraded forests, conversion of even-aged forests to uneven-aged forests and conversion of coppice forests to high forests with greater growing stock increments. There were also favorable changes in forest management planning approaches.

Gender Roles in the Utilization and Challenges in the Management of Mangrove Forests in Casiguran, Aurora, Philippines

Mangrove utilization and management were observed done by men and women depending on their needs and priorities in Casiguran, Aurora. This study, therefore, tried to investigate the gender roles in the utilization and management of mangrove forests, the existing mangrove management practices and their challenges, and the relationship between gender and mangrove resources management. A mixed-method approach was used and data were obtained through triangulation. Respondents were obtained through snowball sampling and interviewed using a structured questionnaire with a few open-ended questions. Results revealed that the majority of the respondents were women (60.7%) and residents of Brgy. Esteves (52.5%) live within or near the mangrove forest. Mostly married (59%) who were providing food and income for the family. They utilized mangrove woods (58.20%) with an average quantity of less than 10 board feet (34.4%) for cooking (40.2%). Roots were utilized in minimal amounts (2.50%) for mythical, medicine, and cork purposes. Mollusks (93.44%), commonly bivalves (93.4%), were primarily gleaned by women for food consumption (93.4%) and as a source of income (93. 61%). On the other hand, catching of crabs (57.4%) for consumption (56.6%) and as a source of income (14.8%) and catching of fish (31.1%) for consumption (27.9%) were done by men. Both genders were involved in mangrove management practices, although only 65% of them had actual involvement in mangrove planting, 19% in mangrove nursery development and maintenance, and 16% in mangrove plantation maintenance. Challenges in management include low survival rate of planted mangroves (33%), lack of maintenance activity (20%), and lack of funds for mobilization (20%). A chi-square test of independence revealed that both men and women have no significant difference in their involvement in nursery establishment and maintenance, mangrove planting, and plantation management.

Sea Cucumber Fishery in Aurora, Philippines

This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through snowball sampling, in each identified sea cucumber fishery area in six coastal municipalities (Baler, Dipaculao, Dinalungan, Casiguran, Dilasag and Dingalan) were interviewed using a structured interview schedule and focused group discussions (FGD). Results revealed that gathering sea cucumbers were accomplished by handpicking, skin diving or compressor diving. A total of 15 commercial species were regularly gathered. Out of this, three species are of very high economic value (≥Php 4000/kg) (Holothuria nobilis, Holothuria scabra, and Actinopyga lecanora). The average number of kilograms harvested per hour per trip ranges from 0.21 (Holothuria fuscopunctata) to 2.71 (Holothuria scabra), while the average size of commonly gathered sea cucumber varies among species with Holothuria lecanora showed an average length (29.26 cm) greater than recorded 24 cm. Processing mainly involves washing, slicing, boiling, drying and packing. Processed sea cucumbers or trepan were sold to middlemen or direct buyers who usually offered higher prices (36.36% up to 69.20%) than the former. Problems encountered by sea cucumber gatherers and traders include a decline in total catch, a shift in area of collection from intertidal zones to deeper waters, an increase in the number of hours spent in finding and gathering sea cucumbers, the use of compressors in gathering, the decline of larger species and gathering of smaller sizes in huge amount, the absence of conservation program for sea cucumber, and the lenient implementation of government policies with regards to coastal resources management.

Use of two fungal species to induce agarwood resin formation in Gyrinops walla

Gyrinops walla Gaertn. is the only species growing in Sri Lanka that belongs to the agarwood family,Thymelaeaceae. Although agarwood resin induction and extraction from Aquilaria species of the same family have been practised for many decades in Southeast Asian region,the ability of producing agarwood resins in G. walla was discovered recently. Since previous studies were on agarwood resins formed due to natural causes, the present study was conducted to identify the potential fungal species that are capable of artificially inducing agarwood resin formation in G. walla. Since this is the first ever study conducted on artificial inducement of agarwood resin formation in G.walla, Aspergillus niger and Fusarium solani were selected owing to their high abundance in the naturally formed agarwood resinous tissues collected from 25 G. walla trees.Both fungal species were separately grown in yeast extract glucose agar and used to inoculate healthy G. walla trees under aseptic conditions. Three holes were made for each tree and 2 g of fungal culture including the medium were placed in each hole. Tissue discoloration, characteristic aroma, resin content and resin constituents were checked at10 cm intervals above and below the inoculation points for a period of 1 year. Results revealed that tissue discoloration and resin content were higher in the trees inoculated with A. niger. Other than at 10 cm above and below the inoculation points, samples collected at all locations had significantly higher resin contents when inoculated with A. niger compared to F. solani. Sixteen agarwood resin constituents, which were also recorded in Aquilaria species, were identified from the discolored tissues using GC–MS analysis. Jinkohol, agarospirol and 2(2-phenyl)chromone derivatives were found in all discolored tissues collected at 10-cm intervals of the trees inoculated with both fungi. b-Seline, c-eudesmol and valerenal were found in nine of 10 sample points on the stem. c-Elemene was recorded only in one sample. The characteristic aroma during burning was stronger for dark-colored tissues than the light-colored ones. The present study confirmed the potential use of certain fungal species to induce agarwood resin in G. walla and that A. niger is more effective than F.solani.

Assaying the allelopathic effects of Eucalyptus camaldulensis in a nursery bed incorporated with leaf litter

Allelopathic effects of Eucalyptus camaldulensis Dehnh. were confirmed in Petri dish and pot experiments in our previous studies. However, the degree to which such effects under controlled experiments exist in more complex ecological settings remains to be tested. Thus, the present study was carried out by incorporating different proportions of ground litter of E. camaldulensis in soil. The growth of three agricultural crops: falen(Vigna unguiculata(L.) Walp.), chickpea(Cicer arietinum L.), and arhor(Cajanus cajan(L.) Millsp.), and two tree species, kala koroi(Albizia procera(Roxb.) Benth.) and ipil ipil(Leucaena leucocephala(Lam.) de Wit) were tested. There were inhibitory effects of leaf litter on germination, shoot and root growth, leaf number, and collar diameter as well as a reduction of nodulation by legume crops(25–80%reduction). The extent of the effects was dependent on the proportion of leaf litter, the species and the type of traits. In contrast to shoot growth, the effect on root growth was more severe. No effect on germination was found with the agriculture crops while the two tree species showed reduced germination. The effect was greater in the presence of higher proportions of leaf litter mixed in soil while in some cases lower proportions stimulated growth. Not all species were suppressed; A. procera, C. cajan, V. unguiculata showed compatible growth while C. arietinum and L.leucocephala were found incompatible. This study provides evidence that E. camaldulensis has allelopathic potential under field conditions and a careful selection of associated crops in agroforestry systems is highly recommended.

Patterns of tree buttressing at Lawachara National Park, Bangladesh

We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. showed maximum （87%） buttress formation, whereas Alstonia scholaris （L.） R. Br. did not show any buttress. Buttresses were recorded in 20%-40% of trees of six species and 40%-60% of trees in three species. Mean length and height of buttress varied among the species and ranged from 0.37-4.37 m and 0.71-2.13 m, respectively. Buttress height, mean buttress length, total buttress length, and total length plus length of secondaries increased with DBH （diameter at breast height） and tree height. Buttress number did not increase with DBH or tree height. Under-storey and mid-canopy trees produced less developed buttresses than did emergent trees （p〈0.01）. Wood density showed moderate effects on buttress characters （p〈0.05）, while the slope of the land did not. Canopy category was a primary regulating factor for tree buttressing, suggesting that buttresses are mechanical adaptations of trees to counter physical stresses.

Uses of Invasive Alien Plant Species in Rema-Kalenga Wildlife Sanctuary of Bangladesh

An exploratory survey was conducted on the uses and role of invasive alien species(IAS) to local livelihoods in the Rema-Kalenga Wildlife Sanctuary in the northeastern hilly region of Bangladesh.Vegetation was sampled in 50 quadrates,each 10 m×10 m,and 25 line transects,each 50 m×20 m,through a combination of random and systematic sampling.Group discussions were also arranged with fifty local inhabitants(17 % of the total inhabitants) to learn the various uses of IAS.A total of 17 alien plant species belonging to 10 different families,of which Leguminosae constitutes the highest number(5 species),include tree(53%) followed by herb(12%),shrub(12%) and others(weed,climber and palm).The majority of the identified species were found to be used for fuel,followed by timber production,medicinal or curative uses,fodder,and many others.In addition to providing various forest products,alien tree species planted in forest plantation help provide many vital ecosystem services such as soil amelioration through nitrogen fixation.It is true that the alien species have some negative impacts on local ecosystems,and not all of them are harmful.Therefore,a national programme must be initiated to distinguish the harmful from the harmless species and to identify the uses and impacts of the former and latter.