We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, an...We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, and ecological importance values. For survey of types and estimation of density of tree species in the forest, we randomly distributed 97 circular sample plots (0.1 hectare (ha)). In each sample plot we identified all trees to the species level, recorded their frequencies and computed species diversity and importance value indices (IVI). A total of 13 tree species, which belong to 12 genera and nine families, were identified in the tree layer of the forest. Mean tree density in ANFR was 116 trees/ha, composed mainly of Boswellia papyrifera (Del.) Hochst. (48), followed by Combretum hartmannianu (19) and Lannea fruticosa (18). Fabaceae was the most common family followed by Combretaceae and Malvaceae. B. papyrifera Delile Hochst was the most abundant while Acacia seyal was the least abundant species. Species richness (R = 1.71), evenness (E = 0.69), dominance (0.24) indices and Simpson’s Index of Diversity (D' = 0.76) suggest a moderate diversity, moderate numbers of individuals in each species and a moderate community stability. The research provides empirical results on diversity and ecological importance value of species, signifies the urging need to safeguard threatened species and to prioritize them for conservation, as well as the need to promote management of abundant species to provide multiple forest ecosystem services.展开更多
In 2000 and 2001, 1-year-old seedlings of 7 economic tree species including chestnut, apricot, persimmon, peach, walnut, pear and apple were cultured in garden pots that had a diameter of 40 cm and were filled with cl...In 2000 and 2001, 1-year-old seedlings of 7 economic tree species including chestnut, apricot, persimmon, peach, walnut, pear and apple were cultured in garden pots that had a diameter of 40 cm and were filled with clean sand. The major components of exudates released from their roots were isolated and analysed by GC-MS. Totally 200 kinds of organic chemicals were isolated, of which 3 kinds i.e. naphthalene, dimethylbenzene and dibutyl phthalate were principally controlled pollutants according to 'Blacklist of Principal Environment Pollutants in China' and the standard of U.S. Environmental Protection Agency (EPA). The research result provided theoretical evidence for selecting low-pollution economic forest crops in the water source protection area in Miyun Reservoir.展开更多
With completion of the Populus genome sequencing project and the availability of many expressed sequence tags (ESTs) databases in forest trees, attention is now rapidly shifting towards the study of individual genet...With completion of the Populus genome sequencing project and the availability of many expressed sequence tags (ESTs) databases in forest trees, attention is now rapidly shifting towards the study of individual genetic variation in natural populations. The most abundant form of genetic variation in many eukaryotic species is represented by single nucleotide polymorphisms (SNPs), which can account for heritable inter-individual differences in complex phenotypes. Unlike humans, the linkage disequilibrium (LD) rapidly decays within candidate genes in forest trees. Thus, SNPs-based candidate gene association studies are considered to be a most effective approach to dissect the complex quantitative traits in forest trees. The present study demonstrates that LD mapping can be used to identify alleles associated with quantitative traits and suggests that this new approach could be particularly useful for performing breeding programs in forest trees. In this review, we will describe the fundamentals, patterns of SNPs distribution and frequency, summarize recent advances in SNPs discovery and LD and comment on the application of LD in the dissection of complex quantitative traits in forest tress. We also put forward the outlook for future SNPs-based association analysis of quantitative traits in forest trees.展开更多
This work was to generate landslide susceptibility maps for the Three Gorges Reservoir(TGR) area, China by using different machine learning models. Three advanced machine learning methods, namely, gradient boosting de...This work was to generate landslide susceptibility maps for the Three Gorges Reservoir(TGR) area, China by using different machine learning models. Three advanced machine learning methods, namely, gradient boosting decision tree(GBDT), random forest(RF) and information value(InV) models, were used, and the performances were assessed and compared. In total, 202 landslides were mapped by using a series of field surveys, aerial photographs, and reviews of historical and bibliographical data. Nine causative factors were then considered in landslide susceptibility map generation by using the GBDT, RF and InV models. All of the maps of the causative factors were resampled to a resolution of 28.5 m. Of the 486289 pixels in the area,28526 pixels were landslide pixels, and 457763 pixels were non-landslide pixels. Finally, landslide susceptibility maps were generated by using the three machine learning models, and their performances were assessed through receiver operating characteristic(ROC) curves, the sensitivity, specificity,overall accuracy(OA), and kappa coefficient(KAPPA). The results showed that the GBDT, RF and In V models in overall produced reasonable accurate landslide susceptibility maps. Among these three methods, the GBDT method outperforms the other two machine learning methods, which can provide strong technical support for producing landslide susceptibility maps in TGR.展开更多
Background: After their death, Scots pine trees can remain standing for decades and sometimes up to 200 years,forming long-lasting and ecologically important structures in boreal forest landscapes. Standing dead pine...Background: After their death, Scots pine trees can remain standing for decades and sometimes up to 200 years,forming long-lasting and ecologically important structures in boreal forest landscapes. Standing dead pines decay very slowly and with time develop into ‘kelo' trees, which are characterized by hard wood with silvery-colored appearance. These kelo trees represent an ecologically important, long lasting and visually striking element of the structure of natural pine-dominated forests in boreal Fennoscandia that is nowadays virtually absent from managed forest landscapes.Methods: We examined and mapped the amount, structural features, site characteristics and spatial distribution of dead standing pine trees over a ten hectare area in an unmanaged boreal forest landscape in the Kalevala National Park in Russian Viena Karelia.Results: The mean basal area of dead standing pine trees in the forested part of the landscape was 1.7 m^2·ha^-1 and the estimated volume 12.7 m^3·ha^-1. From the total number of standing dead pine trees 65% were kelo trees, with a basal area of 1.1 m^2·ha^-1 and volume of 8.0 m^3·ha^-1, the remainder consisting of standing dead pines along the continuum between a recently dead tree and a kelo tree. Overall, standing dead pines were distributed throughout the study area, but there was a tendency towards spatial clustering up to 〈100 m distances. Standing dead pines were most commonly situated on flat ground or in the mid slope in the local topography.In addition, standing dead pines contributed to substrate diversity also by commonly having charred wood and broken tops. Based on the presence of dead pine snags in different stage of transition from a recently dead pine to a kelo with silvery surface, it seems evident that the process of kelo recruitment was continuously in action in the studied landscape.Conclusions: Kelo trees are an omnipresent feature in natural pine-dominated forest landscapes with important contribution to forest structural and substrate diversity. Because of their longevity and extremely slow turnover dynamics and importance for biodiversity, protection of vulnerable kelo tree populations, and ensuring their continuous recruitment, should be of high priority in forest restoration and sustainable management.展开更多
Ectomycorrhizal fungi were investigated on five different forest tree species growing in pure stands on the south slope of the Taunus Mountains, which are situated at the northern end of the Rhine rift valley in Centr...Ectomycorrhizal fungi were investigated on five different forest tree species growing in pure stands on the south slope of the Taunus Mountains, which are situated at the northern end of the Rhine rift valley in Central Germany. Mycorrhizal fungi accompanying the genus Xerocomus were identified and their frequencies counted. Using ITS markers, 22 different fungal species were identified down to species level and 6 down to genus level. On European beech (Fagus sylvatica) 16 fungal species and 4 genera were identified and on Sessile oak (Quercus petraea) 16 ectomycorrhizal species and 2 genera were determined. On both deciduous trees we observed exclusively: Cortinarius subsertipes, Genea hispidula, Lactarius quietus, Tylopilus felleus and a Melanogaster genus. On Norway spruce (Picea abies) we identified 13 different mycorrhizal species and 3 different genera, on Silver fir (Abies alba) 12 species and 3 genera, and in association with European larch (Larix decidua) 11 species and 3 genera. On these conifers Cortinarius anomalus, Lactarius necator and a Piloderma genus occurred exclusively. Comparisons with published data of ectomycorrhizal diversity on the same five tree species, growing in different areas of Germany and Europe, led to the conclusion that there is relative site specificity for ectomycorrhizal communities. Upper soil compartments of the stands investigated in the Taunus Mountainssuffer from soil acidification (pH-H20 ~3.7 to ~4.8). However, a clear correlation between upper soil pH-values and fungal diversity was not observed. On the other hand, nitrate concentrations in upper soil compartments (~26 to ~91 kgNO3-/ha) were higher in older stands as compared to younger ones. Higher nitrate concentrations in upper soils correlated with lower numbers of mycorrhizal individuals.展开更多
Trees Outside Forests (TOF) is a reliable source of income for farmers in rural area but study regarding this has not been explored in depth yet. Therefore, this study was objectively conducted to assess the contribut...Trees Outside Forests (TOF) is a reliable source of income for farmers in rural area but study regarding this has not been explored in depth yet. Therefore, this study was objectively conducted to assess the contribution of income from TOF products in annual income of rural household. Dhangadimai Municipality of Siraha district, Nepal was selected as study site. Altogether, 300 household surveys and 20 Focus Group Discussions (FGD) were conducted to find the income sources and their contribution including TOF. The descriptive analysis and unitary method were applied to analyze the collected data. The off-farm income was US$ 1802.57 in total per household. Among it, the highest income was from remittance around US$ 762.34 (42.29%) and the lowest from government job around US$ 166.68 (9.25%). The farm based total annual income per household was US$ 685.94 on which, the highest income was US$ 220.28 (32.11%) from grains and the lowest income was US$ 0.04 from ploughing other farmers’ field. The total value of livestock of average household was US$ 805.99 and out of this, the highest value was of buffalo i.e. US$ 333.01. At the same time, annual income from TOF product was about US$ 853.31 in total per household. Out of this, the highest income was approximately US$ 521.90 (61.16%) from fruits followed by US$ 214.77 (25.17%) from selling of timber. The highest net income per household was US$ 448.66 respectively from selling timber by rich family while US$ 233.78 for medium family. In addition, the net income from selling fruit by rich, medium and poor family was US$ 427.82, 550.71, and 382.43 respectively. Specifically, the total contribution of income only from TOF product was US$ 853.3027 (20.57%). This research will be useful document to develop the economic policy related to TOFs in different agroforestry展开更多
Identifying tree locations is a basic step in the derivation of other tree parameters using remote sensing techniques, particularly when using airborne laser scanning. There are several techniques for identifying tree...Identifying tree locations is a basic step in the derivation of other tree parameters using remote sensing techniques, particularly when using airborne laser scanning. There are several techniques for identifying tree positions. In this paper, we present a raster-based method for determining tree position and delineating crown coverage. We collected data from nine research plots that supported different mixes of species. We applied a raster-based method to raster layers with six different spatial resolutions and used terrestrial measurement data as reference data. Tree identification at a spatial resolution of 1.5 m was demonstrated to be the most accurate, with an average identification ratio (IR) of 95% and average detection ratio of 68% being observed. At a higher spatial resolution of 0.5 m, IR was overestimated by more than 600%. At a lower spatial resolution of 3 m, IR was underestimated at less than 44% of terrestrial measurements. The inventory process was timed to enable evaluation of the time efficiency of automatic methods.展开更多
Height–diameter relationships are essential elements of forest assessment and modeling efforts.In this work,two linear and eighteen nonlinear height–diameter equations were evaluated to find a local model for Orient...Height–diameter relationships are essential elements of forest assessment and modeling efforts.In this work,two linear and eighteen nonlinear height–diameter equations were evaluated to find a local model for Oriental beech(Fagus orientalis Lipsky) in the Hyrcanian Forest in Iran.The predictive performance of these models was first assessed by different evaluation criteria: adjusted R^2(R^2_(adj)),root mean square error(RMSE),relative RMSE(%RMSE),bias,and relative bias(%bias) criteria.The best model was selected for use as the base mixed-effects model.Random parameters for test plots were estimated with different tree selection options.Results show that the Chapman–Richards model had better predictive ability in terms of adj R^2(0.81),RMSE(3.7 m),%RMSE(12.9),bias(0.8),%Bias(2.79) than the other models.Furthermore,the calibration response,based on a selection of four trees from the sample plots,resulted in a reduction percentage for bias and RMSE of about 1.6–2.7%.Our results indicate that the calibrated model produced the most accurate results.展开更多
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 descri...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.展开更多
This study was designed to use LiDAR data to research tree heights in montane forest blocks of Kenya. It uses a completely randomised block design to asses if differences exist in forest heights: 1) among montane fore...This study was designed to use LiDAR data to research tree heights in montane forest blocks of Kenya. It uses a completely randomised block design to asses if differences exist in forest heights: 1) among montane forest blocks, 2) among Agro ecological zones (AEZ) within each forest block and 3) between similar AEZ in different forest blocks. Forest height data from the Geoscience Laser Altimeter System (GLAS) on the Ice Cloud and Land Elevation Satellite (ICE-SAT) for the period 2003-2009 was used for 2146 circular plots, of 0.2 - 0.25 ha in size. Results indicate that, tree height is largely influenced by Agro ecological conditions and the wetter zones have taller trees in the upper, middle and lower highlands. In the upper highland zones of limited human activity, tree heights did not vary among forest blocks. Variations in height among forest blocks and within forest blocks were exaggerated in regions of active human intervention.展开更多
Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high pr...Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea p. cuspidate and Podocarpus falcatus). Thesubsp. collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall. Results: The results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region. Conclusions: Overall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great implications for further paleo-climatic reconstructions and in the restoration of degraded lands. Further knowledge on the growth characteristics of tree species from the region is required to improve the network of tree-ring data and quality of the chronology so as to successfully reconstruct historic environmental changes.展开更多
Background: Many tree species in tropical forests have distributions tracking local ridge-slope-valley topography. Previous work in a 50-ha plot in Korup National Park, Cameroon, demonstrated that 272 species, or 63%...Background: Many tree species in tropical forests have distributions tracking local ridge-slope-valley topography. Previous work in a 50-ha plot in Korup National Park, Cameroon, demonstrated that 272 species, or 63% of those tested, were significantly associated with topography. Methods: We used two censuses of 329,000 trees ≥1 cm dbh to examine demographic variation at this site that would account for those observed habitat preferences. We tested two predictions. First, within a given topographic habitat, species specializing on that habitat ('residents') should outperform species that are specialists of other habitats ('foreigners'). Second, across different topographic habitats, species should perform best in the habitat on which they specialize ('home') compared to other habitats ('away'). Species' performance was estimated using growth and mortality rates. Results: In hierarchical models with species identity as a random effect, we found no evidence of a demographic advantage to resident species. Indeed, growth rates were most often higher for foreign species. Similarly, comparisons of species on their home vs. away habitats revealed no sign of a performance advantage on the home habitat. Conclusions" We reject the hypothesis that species distributions along a ridge-valley catena at Korup are caused by species differences in trees _〉1 cm dbh. Since there must be a demographic cause for habitat specialization, we offer three alternatives. First, the demographic advantage specialists have at home occurs at the reproductive or seedling stage, in sizes smaller than we census in the forest plot. Second, species may have higher performance on their preferred habitat when density is low, but when population builds up, there are negative density-dependent feedbacks that reduce performance. Third, demographic filtering may be produced by extreme environmental conditions that we did not observe during the census interval.展开更多
Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging ...Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging to 46 family, 103 genera and 144 species were counted at ≥30 cm DBH (diameter at breast height) using 28 permanent belt transects with a size of 1 ha (10 m × 1000 m). Four different tree communities were identified. The primary forests was dominated by Shorea robusta (mean density 464.77 trees.ha^-1, 105 species) and Schima wallichii (336.25 trees.ha^-1, 82 species), while the secondary forests was dominated by Tectona grandis (333.88 trees.ha^-1, 105 species) and Hevea brasiliensis (299.67 trees.ha^-1, 82 species). Overall mean basal area in this study was 18.01m2.ha^-1; the maximum value was recorded in primary Shorea forest (26.21 m2.ha^-1). Mean density and diversity indices were differed significantly within four different communities. No significant differences were observed in number of species, genera, family and tree basal cover area. Significant relationships were found between the species richness and different tree population groups across the communities. Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumu- lation of native oligarchic small tree species. Seventeen species were recorded with 〈2 individuals of which Saraca asoka (Roxb.) de Wilde and Entada phaseoloides (L.) Men'. etc. extensively used in local ethnomedicinal formulations. The present S. robusta Gaertn dominated forest was recorded richer (105 species) than other reported studies. Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests. Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur. The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T. grandis L. dominated community.展开更多
Tree species composition and diversity were investigated in the riparian forest around Lake Barombi Kotto, Cameroon. This study aimed at determining</span><span style="font-family:""> </s...Tree species composition and diversity were investigated in the riparian forest around Lake Barombi Kotto, Cameroon. This study aimed at determining</span><span style="font-family:""> </span><span style="font-family:Verdana;">the tree species composition, population structure, and providing evidence of anthropogenic disturbances in the riparian forest of Lake Barombi Kotto. The objectives were to determine the tree species composition and diversity in the riparian forest around Lake Barombi Kotto, to elucidate the forest structure and to document the anthropogenic disturbances in this forest. Five plots were laid within which </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">tree enumeration and measurement of dbh were carried out.</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">Trees were identified using scientific identification keys in the Flora of W</span><span style="font-family:Verdana;">est Africa. Disturbance scores were given to each site by qualitatively assessing various disturbances. A total of 340 trees belonging to 70 plant species, 63 genera and 28 plant families were enumerated. Shannon-Wiener diversity varied across sites, with the highest value (H = 3.45) recorded in Tung and the lowest (H = 2.21) in Malenda. Population structure differed across sites,</span><span style="font-family:Verdana;"> the largest stand basal area of 43.78 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">/ha was recorded in Bondokombo while the smallest (2.15 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">/ha)</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">was recorded in the Sacred Island. </span><i><span style="font-family:Verdana;">Cecropia</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">peltata</span></i><span style="font-family:""><span style="font-family:Verdana;"> L., </span><i><span style="font-family:Verdana;">Pseudospondias</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">macrocarpa</span></i><i><span style="font-family:""> </span></i><span style="font-family:""><span style="font-family:Verdana;">Oliv. Pierre and </span><i><span style="font-family:Verdana;">Ceiba</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">pentandra</span></i><span style="font-family:Verdana;"> (L.) Gaertn had the largest basal areas across the different sites. Species rich families were Malvaceae (9 species), Fabaceae (9 species), Annonaceae</span><span style="font-family:""> </span><span style="font-family:Verdana;">(4 species), and Anacardiaceae (4). This study shows that, there is a high tree species diversity in the protected forest (Tung) but the other unprotected sites are highly disturbed by anthropogenic activities. There is need to develop and enhance existing management policies for this riparian forest, especially by replanting the cut trees and creating a protected riparian buffer to conserve its floristic diversity and ecological functions.展开更多
The levels of heavy metals that accumulated in stemwood of mature trees grown for 20 years in a plantation in an abandoned peat quarry in areas that were fertilized with different amounts of domestic sewage sludge(180...The levels of heavy metals that accumulated in stemwood of mature trees grown for 20 years in a plantation in an abandoned peat quarry in areas that were fertilized with different amounts of domestic sewage sludge(180,360,and720 Mg ha-1on a dry basis) were compared with trees grown in a reference nonfertilized area.Included in the study was a hybrid poplar(Populus tremula x Populus tremuloides) developed for use as an energy crop,three local tree species and one introduced tree species.The concentrations of Cd,Cr,Cu,Ni,Pb and Zn in the stemwood of the trees grown in the fertilized and nonfertilized fields were determined,and found to be significantly lower than their respective concentrations in the soil.Cd and Cr were found only in several wood samples at concentrations close to the limits of detection or qualification; therefore,they were not analyzed further.A correlation analysis suggested that 75%of the correlations between the concentrations of heavy metals in the stemwood and the concentrations in the soil were negative.The ability of trees to accumulate the metals from soil in most cases decreased for Cu and Ni; however,the correlations were not as clear for Pb and Zn.The followingsequence for the levels of heavy metals found in the stemwood of the analysed trees was Zn [ Pb [ Ni [ Cu [(Cr,Cd).The results of this study showed that the levels of heavy metals in the studied wood would not exceed the permitted limits of heavy metal pollution in the air and ash when used for energy production.展开更多
Interactions between water and carbon dynamics underlie drought-related tree mortality.While whole-tree water relations have been shown to play a key role in the response to and recovery from drought,the role of nonst...Interactions between water and carbon dynamics underlie drought-related tree mortality.While whole-tree water relations have been shown to play a key role in the response to and recovery from drought,the role of nonstructural carbohydrates(NSC) and how their storage and allocation changes surrounding drought events deserves further attention and is critical for understanding tree survival.Here,we quantified in situ NSC responses of temperate forest trees to the 2016 drought in the northeastern United States.Sugar and starch concentrations were measured in the stemwood of five tree species from 2014 to 2019,which allowed us to monitor NSCs in relation to climatic conditions before,during,and after the natural drought.We found that immediately following the drought,measured stemwood NSC concentrations decreased.However,NSC concentrations rebounded quickly within three years.Notably,trees allocated proportionally more to starch than to sugars following the 2016 drought.In winter 2017,starch comprised 45% of total stemwood stores,whereas starch made up only 1-2% in other years.Further,we modeled and assessed the climatic drivers of total NSC concentrations in the stem.Variation in total NSC concentrations was significantly predicted by the previous year’s temperature,precipitation,and standardized precipitation-evapotranspiration index(SPEI),with stemwood concentrations decreasing following hotter,drier periods and increasing following cooler,wetter periods.Overall,our work provides insight into the climatic drivers of NSC storage and highlights the important role that a tree’s carbon economy may play in its response and recovery to environmental stress.展开更多
We investigated the floristic composition, woody species diversity and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracks, Bangladesh. We recorded 25 fam...We investigated the floristic composition, woody species diversity and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracks, Bangladesh. We recorded 25 families, 37 genera, 40 species and 1771 woody individuals in a 0.09 ha plot. Euphorbiaceae and Moraceae were the most species- rich families, and Castanopsis, Ficus and Terminaliawere the most species-rich genera. Bursera serrata Wall. ex Colebr. was the dominant species in terms of highest importance value (13%). Trema orientalis (L.) B1 was typically a light demanding species as it appeared in the top can- opy with only one individual having the seventh highest IV, but had no regeneration. The expected maximum number of species (Smax) was 140, indicating that many species may invade the forest as the Sm~ is greater than the recorded total number of species. The nature of the disappear- ance and appearance of species in the present forest reflects instability of floristic composition. The values of Shannon's index H' and Pielou's index J' (evenness) were 3.36 bit and 0.63, respectively. These values show moderately high species diversity as compared to other subtropical forests in the tropics. In addition, a sample area of 200 m2 in this forest would be sufficient for measuring the diversity indices H" and ,/', whereas the trend of J'may indicate the rate of equality of individuals among the different species decreased with increasing area. The distribu- tion pattern for the total stand was completely random. However, the dominant species showed aggregate distribution for small areas, but random distribution for large areas. The spatial association between species showed that the strongest positive interspecific association occurred between Streblus asper Lour. and Castanea indica Roxh. (09 = 0.51). As a whole, most species were weakly associated with each other, of which 58% species associations were completely negative. The result of cluster analysis showed that species pairs were spatially independent at all or most small clusters; stands of species from all clusters are mosa- ics of complete habitat and pioneer habitat. All patches in this forest community have similar habitat and regeneration niches, which could be a phenomenon for a young growth forest. Thus, the existence of habitat and regeneration niches may be an important factor in the maintenance of diversity in this forest.展开更多
The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.How...The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.However,for some species,the numbers of surviving transplants has declined.Hence,it is necessary to develop properly adapted and resilient genotypes that can eff ectively support the programs of forest restoration.In this context we evaluated the eff ects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species(Pycnanthus angolensis,Terminalia superba,Mansonia altissima and Pterygota macrocarpa).We analyzed these parameters for seeds of three provenances(Daloa,Akoupéand Daoukro)of four species and for thirty plants aged 6 months per provenance.Time to begin germination and time to reach maximum germination were similar among species,and were not infl uenced by either treatment or provenance.Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates,irrespective of species or provenance.The one exception was P.angolensis,for which no germination was recorded.Within species,some provenances produced higher germination percentages than did others.No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied signifi cantly between provenances.Plant growth and morphological variability also depended greatly on provenance.Genetic factors might be implicated,therefore provenance trials should be undertaken and evaluated.Furthermore,molecular analysis should be undertaken to confi rm the implications of genetic factors and allow for genetic selection.展开更多
Forest health is currently assessed in Europe (ICP Forests monitoring program). Crown defoliation and dieback, tree mortality, and pathogenic damage are the main aspects considered in tree health assessment. The wor...Forest health is currently assessed in Europe (ICP Forests monitoring program). Crown defoliation and dieback, tree mortality, and pathogenic damage are the main aspects considered in tree health assessment. The worsening of environmental conditions (i.e., increase of temperature and drought events) may cause large-spatial scale tree mortality and forest decline. However, the role of stand features, including tree species assemblage and diversity as factors that modify environmental impacts, is poorly considered. The present contribution reanalyses the historical dataset of crown conditions in Italian forests from ] 997 to 2014 to identify ecological and structural factors that influence tree crown defoliation, highlighting in a special manner the role of tree diversity. The effects of tree diversity were explored using the entire data set through multivariate cluster analyses and on individual trees, analysing the influence of the neighbouring tree diversity and identity at the local (neighbour) level. Preliminary results suggest that each tree species shows a specific behaviour in relation to crown defoliation, and the distribution of crown defoliation across Italian forests reflects the distribution of the main forest types and their ecological equilibrium with the environment. The potentiality and the problems connected to the possible extension of this analysis at a more general level (European and North American) were discussed.展开更多
文摘We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, and ecological importance values. For survey of types and estimation of density of tree species in the forest, we randomly distributed 97 circular sample plots (0.1 hectare (ha)). In each sample plot we identified all trees to the species level, recorded their frequencies and computed species diversity and importance value indices (IVI). A total of 13 tree species, which belong to 12 genera and nine families, were identified in the tree layer of the forest. Mean tree density in ANFR was 116 trees/ha, composed mainly of Boswellia papyrifera (Del.) Hochst. (48), followed by Combretum hartmannianu (19) and Lannea fruticosa (18). Fabaceae was the most common family followed by Combretaceae and Malvaceae. B. papyrifera Delile Hochst was the most abundant while Acacia seyal was the least abundant species. Species richness (R = 1.71), evenness (E = 0.69), dominance (0.24) indices and Simpson’s Index of Diversity (D' = 0.76) suggest a moderate diversity, moderate numbers of individuals in each species and a moderate community stability. The research provides empirical results on diversity and ecological importance value of species, signifies the urging need to safeguard threatened species and to prioritize them for conservation, as well as the need to promote management of abundant species to provide multiple forest ecosystem services.
基金The study was supported by Natural Science Foundation of Beijing to Wang Yuzhu (No. 6992013).
文摘In 2000 and 2001, 1-year-old seedlings of 7 economic tree species including chestnut, apricot, persimmon, peach, walnut, pear and apple were cultured in garden pots that had a diameter of 40 cm and were filled with clean sand. The major components of exudates released from their roots were isolated and analysed by GC-MS. Totally 200 kinds of organic chemicals were isolated, of which 3 kinds i.e. naphthalene, dimethylbenzene and dibutyl phthalate were principally controlled pollutants according to 'Blacklist of Principal Environment Pollutants in China' and the standard of U.S. Environmental Protection Agency (EPA). The research result provided theoretical evidence for selecting low-pollution economic forest crops in the water source protection area in Miyun Reservoir.
文摘With completion of the Populus genome sequencing project and the availability of many expressed sequence tags (ESTs) databases in forest trees, attention is now rapidly shifting towards the study of individual genetic variation in natural populations. The most abundant form of genetic variation in many eukaryotic species is represented by single nucleotide polymorphisms (SNPs), which can account for heritable inter-individual differences in complex phenotypes. Unlike humans, the linkage disequilibrium (LD) rapidly decays within candidate genes in forest trees. Thus, SNPs-based candidate gene association studies are considered to be a most effective approach to dissect the complex quantitative traits in forest trees. The present study demonstrates that LD mapping can be used to identify alleles associated with quantitative traits and suggests that this new approach could be particularly useful for performing breeding programs in forest trees. In this review, we will describe the fundamentals, patterns of SNPs distribution and frequency, summarize recent advances in SNPs discovery and LD and comment on the application of LD in the dissection of complex quantitative traits in forest tress. We also put forward the outlook for future SNPs-based association analysis of quantitative traits in forest trees.
基金This work was supported in part by the National Natural Science Foundation of China(61601418,41602362,61871259)in part by the Opening Foundation of Hunan Engineering and Research Center of Natural Resource Investigation and Monitoring(2020-5)+1 种基金in part by the Qilian Mountain National Park Research Center(Qinghai)(grant number:GKQ2019-01)in part by the Geomatics Technology and Application Key Laboratory of Qinghai Province,Grant No.QHDX-2019-01.
文摘This work was to generate landslide susceptibility maps for the Three Gorges Reservoir(TGR) area, China by using different machine learning models. Three advanced machine learning methods, namely, gradient boosting decision tree(GBDT), random forest(RF) and information value(InV) models, were used, and the performances were assessed and compared. In total, 202 landslides were mapped by using a series of field surveys, aerial photographs, and reviews of historical and bibliographical data. Nine causative factors were then considered in landslide susceptibility map generation by using the GBDT, RF and InV models. All of the maps of the causative factors were resampled to a resolution of 28.5 m. Of the 486289 pixels in the area,28526 pixels were landslide pixels, and 457763 pixels were non-landslide pixels. Finally, landslide susceptibility maps were generated by using the three machine learning models, and their performances were assessed through receiver operating characteristic(ROC) curves, the sensitivity, specificity,overall accuracy(OA), and kappa coefficient(KAPPA). The results showed that the GBDT, RF and In V models in overall produced reasonable accurate landslide susceptibility maps. Among these three methods, the GBDT method outperforms the other two machine learning methods, which can provide strong technical support for producing landslide susceptibility maps in TGR.
基金the EBOR-project funded by the Academy of Finland (proj.no.276255)
文摘Background: After their death, Scots pine trees can remain standing for decades and sometimes up to 200 years,forming long-lasting and ecologically important structures in boreal forest landscapes. Standing dead pines decay very slowly and with time develop into ‘kelo' trees, which are characterized by hard wood with silvery-colored appearance. These kelo trees represent an ecologically important, long lasting and visually striking element of the structure of natural pine-dominated forests in boreal Fennoscandia that is nowadays virtually absent from managed forest landscapes.Methods: We examined and mapped the amount, structural features, site characteristics and spatial distribution of dead standing pine trees over a ten hectare area in an unmanaged boreal forest landscape in the Kalevala National Park in Russian Viena Karelia.Results: The mean basal area of dead standing pine trees in the forested part of the landscape was 1.7 m^2·ha^-1 and the estimated volume 12.7 m^3·ha^-1. From the total number of standing dead pine trees 65% were kelo trees, with a basal area of 1.1 m^2·ha^-1 and volume of 8.0 m^3·ha^-1, the remainder consisting of standing dead pines along the continuum between a recently dead tree and a kelo tree. Overall, standing dead pines were distributed throughout the study area, but there was a tendency towards spatial clustering up to 〈100 m distances. Standing dead pines were most commonly situated on flat ground or in the mid slope in the local topography.In addition, standing dead pines contributed to substrate diversity also by commonly having charred wood and broken tops. Based on the presence of dead pine snags in different stage of transition from a recently dead pine to a kelo with silvery surface, it seems evident that the process of kelo recruitment was continuously in action in the studied landscape.Conclusions: Kelo trees are an omnipresent feature in natural pine-dominated forest landscapes with important contribution to forest structural and substrate diversity. Because of their longevity and extremely slow turnover dynamics and importance for biodiversity, protection of vulnerable kelo tree populations, and ensuring their continuous recruitment, should be of high priority in forest restoration and sustainable management.
文摘Ectomycorrhizal fungi were investigated on five different forest tree species growing in pure stands on the south slope of the Taunus Mountains, which are situated at the northern end of the Rhine rift valley in Central Germany. Mycorrhizal fungi accompanying the genus Xerocomus were identified and their frequencies counted. Using ITS markers, 22 different fungal species were identified down to species level and 6 down to genus level. On European beech (Fagus sylvatica) 16 fungal species and 4 genera were identified and on Sessile oak (Quercus petraea) 16 ectomycorrhizal species and 2 genera were determined. On both deciduous trees we observed exclusively: Cortinarius subsertipes, Genea hispidula, Lactarius quietus, Tylopilus felleus and a Melanogaster genus. On Norway spruce (Picea abies) we identified 13 different mycorrhizal species and 3 different genera, on Silver fir (Abies alba) 12 species and 3 genera, and in association with European larch (Larix decidua) 11 species and 3 genera. On these conifers Cortinarius anomalus, Lactarius necator and a Piloderma genus occurred exclusively. Comparisons with published data of ectomycorrhizal diversity on the same five tree species, growing in different areas of Germany and Europe, led to the conclusion that there is relative site specificity for ectomycorrhizal communities. Upper soil compartments of the stands investigated in the Taunus Mountainssuffer from soil acidification (pH-H20 ~3.7 to ~4.8). However, a clear correlation between upper soil pH-values and fungal diversity was not observed. On the other hand, nitrate concentrations in upper soil compartments (~26 to ~91 kgNO3-/ha) were higher in older stands as compared to younger ones. Higher nitrate concentrations in upper soils correlated with lower numbers of mycorrhizal individuals.
文摘Trees Outside Forests (TOF) is a reliable source of income for farmers in rural area but study regarding this has not been explored in depth yet. Therefore, this study was objectively conducted to assess the contribution of income from TOF products in annual income of rural household. Dhangadimai Municipality of Siraha district, Nepal was selected as study site. Altogether, 300 household surveys and 20 Focus Group Discussions (FGD) were conducted to find the income sources and their contribution including TOF. The descriptive analysis and unitary method were applied to analyze the collected data. The off-farm income was US$ 1802.57 in total per household. Among it, the highest income was from remittance around US$ 762.34 (42.29%) and the lowest from government job around US$ 166.68 (9.25%). The farm based total annual income per household was US$ 685.94 on which, the highest income was US$ 220.28 (32.11%) from grains and the lowest income was US$ 0.04 from ploughing other farmers’ field. The total value of livestock of average household was US$ 805.99 and out of this, the highest value was of buffalo i.e. US$ 333.01. At the same time, annual income from TOF product was about US$ 853.31 in total per household. Out of this, the highest income was approximately US$ 521.90 (61.16%) from fruits followed by US$ 214.77 (25.17%) from selling of timber. The highest net income per household was US$ 448.66 respectively from selling timber by rich family while US$ 233.78 for medium family. In addition, the net income from selling fruit by rich, medium and poor family was US$ 427.82, 550.71, and 382.43 respectively. Specifically, the total contribution of income only from TOF product was US$ 853.3027 (20.57%). This research will be useful document to develop the economic policy related to TOFs in different agroforestry
基金supported by the Scientific Grant Agency of the Ministry of Education,Science,Research and Sport of the Slovak Republicthe Slovak Academy of Sciences under Project No.1/0953/13:‘‘Geographic information on forest and forest landscape:creation and utilization of particularity’’
文摘Identifying tree locations is a basic step in the derivation of other tree parameters using remote sensing techniques, particularly when using airborne laser scanning. There are several techniques for identifying tree positions. In this paper, we present a raster-based method for determining tree position and delineating crown coverage. We collected data from nine research plots that supported different mixes of species. We applied a raster-based method to raster layers with six different spatial resolutions and used terrestrial measurement data as reference data. Tree identification at a spatial resolution of 1.5 m was demonstrated to be the most accurate, with an average identification ratio (IR) of 95% and average detection ratio of 68% being observed. At a higher spatial resolution of 0.5 m, IR was overestimated by more than 600%. At a lower spatial resolution of 3 m, IR was underestimated at less than 44% of terrestrial measurements. The inventory process was timed to enable evaluation of the time efficiency of automatic methods.
基金This research received no specific grant from any funding agency in the public,commercial,or not-for-profit sectors
文摘Height–diameter relationships are essential elements of forest assessment and modeling efforts.In this work,two linear and eighteen nonlinear height–diameter equations were evaluated to find a local model for Oriental beech(Fagus orientalis Lipsky) in the Hyrcanian Forest in Iran.The predictive performance of these models was first assessed by different evaluation criteria: adjusted R^2(R^2_(adj)),root mean square error(RMSE),relative RMSE(%RMSE),bias,and relative bias(%bias) criteria.The best model was selected for use as the base mixed-effects model.Random parameters for test plots were estimated with different tree selection options.Results show that the Chapman–Richards model had better predictive ability in terms of adj R^2(0.81),RMSE(3.7 m),%RMSE(12.9),bias(0.8),%Bias(2.79) than the other models.Furthermore,the calibration response,based on a selection of four trees from the sample plots,resulted in a reduction percentage for bias and RMSE of about 1.6–2.7%.Our results indicate that the calibrated model produced the most accurate results.
文摘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.
文摘This study was designed to use LiDAR data to research tree heights in montane forest blocks of Kenya. It uses a completely randomised block design to asses if differences exist in forest heights: 1) among montane forest blocks, 2) among Agro ecological zones (AEZ) within each forest block and 3) between similar AEZ in different forest blocks. Forest height data from the Geoscience Laser Altimeter System (GLAS) on the Ice Cloud and Land Elevation Satellite (ICE-SAT) for the period 2003-2009 was used for 2146 circular plots, of 0.2 - 0.25 ha in size. Results indicate that, tree height is largely influenced by Agro ecological conditions and the wetter zones have taller trees in the upper, middle and lower highlands. In the upper highland zones of limited human activity, tree heights did not vary among forest blocks. Variations in height among forest blocks and within forest blocks were exaggerated in regions of active human intervention.
基金financial supports for this study were obtained from the Pan African University(PAU)African Union(AU)Addis Ababa,Ethiopia as part of its PhD scholarship scheme
文摘Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea p. cuspidate and Podocarpus falcatus). Thesubsp. collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall. Results: The results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region. Conclusions: Overall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great implications for further paleo-climatic reconstructions and in the restoration of degraded lands. Further knowledge on the growth characteristics of tree species from the region is required to improve the network of tree-ring data and quality of the chronology so as to successfully reconstruct historic environmental changes.
基金the National Institutes of Health award U01 TW03004 under the NIH-NSF-USDA funded International Cooperative Biodiversity Groups programfinancial support from the U.S. Agency for International Development’s Central Africa Regional Program for the Environment and the Smithsonian Tropical Research Institute+3 种基金Financial support for the 2008 recensus was provided by the Frank Levinson Family Foundationsupported by U.S. National Science Foundation award DEB-9806828provided by the Bioresources Development and Conservation Programme-Cameroonthe WWF Korup Project
文摘Background: Many tree species in tropical forests have distributions tracking local ridge-slope-valley topography. Previous work in a 50-ha plot in Korup National Park, Cameroon, demonstrated that 272 species, or 63% of those tested, were significantly associated with topography. Methods: We used two censuses of 329,000 trees ≥1 cm dbh to examine demographic variation at this site that would account for those observed habitat preferences. We tested two predictions. First, within a given topographic habitat, species specializing on that habitat ('residents') should outperform species that are specialists of other habitats ('foreigners'). Second, across different topographic habitats, species should perform best in the habitat on which they specialize ('home') compared to other habitats ('away'). Species' performance was estimated using growth and mortality rates. Results: In hierarchical models with species identity as a random effect, we found no evidence of a demographic advantage to resident species. Indeed, growth rates were most often higher for foreign species. Similarly, comparisons of species on their home vs. away habitats revealed no sign of a performance advantage on the home habitat. Conclusions" We reject the hypothesis that species distributions along a ridge-valley catena at Korup are caused by species differences in trees _〉1 cm dbh. Since there must be a demographic cause for habitat specialization, we offer three alternatives. First, the demographic advantage specialists have at home occurs at the reproductive or seedling stage, in sizes smaller than we census in the forest plot. Second, species may have higher performance on their preferred habitat when density is low, but when population builds up, there are negative density-dependent feedbacks that reduce performance. Third, demographic filtering may be produced by extreme environmental conditions that we did not observe during the census interval.
基金supported by DBT Network Project (BT/PR7928/NDB/52/9/2006)Department of Biotechnology(DBT),Govt. of India
文摘Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging to 46 family, 103 genera and 144 species were counted at ≥30 cm DBH (diameter at breast height) using 28 permanent belt transects with a size of 1 ha (10 m × 1000 m). Four different tree communities were identified. The primary forests was dominated by Shorea robusta (mean density 464.77 trees.ha^-1, 105 species) and Schima wallichii (336.25 trees.ha^-1, 82 species), while the secondary forests was dominated by Tectona grandis (333.88 trees.ha^-1, 105 species) and Hevea brasiliensis (299.67 trees.ha^-1, 82 species). Overall mean basal area in this study was 18.01m2.ha^-1; the maximum value was recorded in primary Shorea forest (26.21 m2.ha^-1). Mean density and diversity indices were differed significantly within four different communities. No significant differences were observed in number of species, genera, family and tree basal cover area. Significant relationships were found between the species richness and different tree population groups across the communities. Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumu- lation of native oligarchic small tree species. Seventeen species were recorded with 〈2 individuals of which Saraca asoka (Roxb.) de Wilde and Entada phaseoloides (L.) Men'. etc. extensively used in local ethnomedicinal formulations. The present S. robusta Gaertn dominated forest was recorded richer (105 species) than other reported studies. Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests. Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur. The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T. grandis L. dominated community.
文摘Tree species composition and diversity were investigated in the riparian forest around Lake Barombi Kotto, Cameroon. This study aimed at determining</span><span style="font-family:""> </span><span style="font-family:Verdana;">the tree species composition, population structure, and providing evidence of anthropogenic disturbances in the riparian forest of Lake Barombi Kotto. The objectives were to determine the tree species composition and diversity in the riparian forest around Lake Barombi Kotto, to elucidate the forest structure and to document the anthropogenic disturbances in this forest. Five plots were laid within which </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">tree enumeration and measurement of dbh were carried out.</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">Trees were identified using scientific identification keys in the Flora of W</span><span style="font-family:Verdana;">est Africa. Disturbance scores were given to each site by qualitatively assessing various disturbances. A total of 340 trees belonging to 70 plant species, 63 genera and 28 plant families were enumerated. Shannon-Wiener diversity varied across sites, with the highest value (H = 3.45) recorded in Tung and the lowest (H = 2.21) in Malenda. Population structure differed across sites,</span><span style="font-family:Verdana;"> the largest stand basal area of 43.78 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">/ha was recorded in Bondokombo while the smallest (2.15 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">/ha)</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">was recorded in the Sacred Island. </span><i><span style="font-family:Verdana;">Cecropia</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">peltata</span></i><span style="font-family:""><span style="font-family:Verdana;"> L., </span><i><span style="font-family:Verdana;">Pseudospondias</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">macrocarpa</span></i><i><span style="font-family:""> </span></i><span style="font-family:""><span style="font-family:Verdana;">Oliv. Pierre and </span><i><span style="font-family:Verdana;">Ceiba</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">pentandra</span></i><span style="font-family:Verdana;"> (L.) Gaertn had the largest basal areas across the different sites. Species rich families were Malvaceae (9 species), Fabaceae (9 species), Annonaceae</span><span style="font-family:""> </span><span style="font-family:Verdana;">(4 species), and Anacardiaceae (4). This study shows that, there is a high tree species diversity in the protected forest (Tung) but the other unprotected sites are highly disturbed by anthropogenic activities. There is need to develop and enhance existing management policies for this riparian forest, especially by replanting the cut trees and creating a protected riparian buffer to conserve its floristic diversity and ecological functions.
文摘The levels of heavy metals that accumulated in stemwood of mature trees grown for 20 years in a plantation in an abandoned peat quarry in areas that were fertilized with different amounts of domestic sewage sludge(180,360,and720 Mg ha-1on a dry basis) were compared with trees grown in a reference nonfertilized area.Included in the study was a hybrid poplar(Populus tremula x Populus tremuloides) developed for use as an energy crop,three local tree species and one introduced tree species.The concentrations of Cd,Cr,Cu,Ni,Pb and Zn in the stemwood of the trees grown in the fertilized and nonfertilized fields were determined,and found to be significantly lower than their respective concentrations in the soil.Cd and Cr were found only in several wood samples at concentrations close to the limits of detection or qualification; therefore,they were not analyzed further.A correlation analysis suggested that 75%of the correlations between the concentrations of heavy metals in the stemwood and the concentrations in the soil were negative.The ability of trees to accumulate the metals from soil in most cases decreased for Cu and Ni; however,the correlations were not as clear for Pb and Zn.The followingsequence for the levels of heavy metals found in the stemwood of the analysed trees was Zn [ Pb [ Ni [ Cu [(Cr,Cd).The results of this study showed that the levels of heavy metals in the studied wood would not exceed the permitted limits of heavy metal pollution in the air and ash when used for energy production.
基金the National Science Foundation’s Graduate Research Fellowship (Grant Nos.DGE-1144152 and DGE-1745303)the Garden Club of New Jersey。
文摘Interactions between water and carbon dynamics underlie drought-related tree mortality.While whole-tree water relations have been shown to play a key role in the response to and recovery from drought,the role of nonstructural carbohydrates(NSC) and how their storage and allocation changes surrounding drought events deserves further attention and is critical for understanding tree survival.Here,we quantified in situ NSC responses of temperate forest trees to the 2016 drought in the northeastern United States.Sugar and starch concentrations were measured in the stemwood of five tree species from 2014 to 2019,which allowed us to monitor NSCs in relation to climatic conditions before,during,and after the natural drought.We found that immediately following the drought,measured stemwood NSC concentrations decreased.However,NSC concentrations rebounded quickly within three years.Notably,trees allocated proportionally more to starch than to sugars following the 2016 drought.In winter 2017,starch comprised 45% of total stemwood stores,whereas starch made up only 1-2% in other years.Further,we modeled and assessed the climatic drivers of total NSC concentrations in the stem.Variation in total NSC concentrations was significantly predicted by the previous year’s temperature,precipitation,and standardized precipitation-evapotranspiration index(SPEI),with stemwood concentrations decreasing following hotter,drier periods and increasing following cooler,wetter periods.Overall,our work provides insight into the climatic drivers of NSC storage and highlights the important role that a tree’s carbon economy may play in its response and recovery to environmental stress.
文摘We investigated the floristic composition, woody species diversity and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracks, Bangladesh. We recorded 25 families, 37 genera, 40 species and 1771 woody individuals in a 0.09 ha plot. Euphorbiaceae and Moraceae were the most species- rich families, and Castanopsis, Ficus and Terminaliawere the most species-rich genera. Bursera serrata Wall. ex Colebr. was the dominant species in terms of highest importance value (13%). Trema orientalis (L.) B1 was typically a light demanding species as it appeared in the top can- opy with only one individual having the seventh highest IV, but had no regeneration. The expected maximum number of species (Smax) was 140, indicating that many species may invade the forest as the Sm~ is greater than the recorded total number of species. The nature of the disappear- ance and appearance of species in the present forest reflects instability of floristic composition. The values of Shannon's index H' and Pielou's index J' (evenness) were 3.36 bit and 0.63, respectively. These values show moderately high species diversity as compared to other subtropical forests in the tropics. In addition, a sample area of 200 m2 in this forest would be sufficient for measuring the diversity indices H" and ,/', whereas the trend of J'may indicate the rate of equality of individuals among the different species decreased with increasing area. The distribu- tion pattern for the total stand was completely random. However, the dominant species showed aggregate distribution for small areas, but random distribution for large areas. The spatial association between species showed that the strongest positive interspecific association occurred between Streblus asper Lour. and Castanea indica Roxh. (09 = 0.51). As a whole, most species were weakly associated with each other, of which 58% species associations were completely negative. The result of cluster analysis showed that species pairs were spatially independent at all or most small clusters; stands of species from all clusters are mosa- ics of complete habitat and pioneer habitat. All patches in this forest community have similar habitat and regeneration niches, which could be a phenomenon for a young growth forest. Thus, the existence of habitat and regeneration niches may be an important factor in the maintenance of diversity in this forest.
文摘The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.However,for some species,the numbers of surviving transplants has declined.Hence,it is necessary to develop properly adapted and resilient genotypes that can eff ectively support the programs of forest restoration.In this context we evaluated the eff ects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species(Pycnanthus angolensis,Terminalia superba,Mansonia altissima and Pterygota macrocarpa).We analyzed these parameters for seeds of three provenances(Daloa,Akoupéand Daoukro)of four species and for thirty plants aged 6 months per provenance.Time to begin germination and time to reach maximum germination were similar among species,and were not infl uenced by either treatment or provenance.Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates,irrespective of species or provenance.The one exception was P.angolensis,for which no germination was recorded.Within species,some provenances produced higher germination percentages than did others.No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied signifi cantly between provenances.Plant growth and morphological variability also depended greatly on provenance.Genetic factors might be implicated,therefore provenance trials should be undertaken and evaluated.Furthermore,molecular analysis should be undertaken to confi rm the implications of genetic factors and allow for genetic selection.
基金funded and carried out within SMART4Action LIFE+project“Sustainable Monitoring and Reporting to Inform Forest and Environmental Awareness and Protection”LIFE13 ENV/IT/000813
文摘Forest health is currently assessed in Europe (ICP Forests monitoring program). Crown defoliation and dieback, tree mortality, and pathogenic damage are the main aspects considered in tree health assessment. The worsening of environmental conditions (i.e., increase of temperature and drought events) may cause large-spatial scale tree mortality and forest decline. However, the role of stand features, including tree species assemblage and diversity as factors that modify environmental impacts, is poorly considered. The present contribution reanalyses the historical dataset of crown conditions in Italian forests from ] 997 to 2014 to identify ecological and structural factors that influence tree crown defoliation, highlighting in a special manner the role of tree diversity. The effects of tree diversity were explored using the entire data set through multivariate cluster analyses and on individual trees, analysing the influence of the neighbouring tree diversity and identity at the local (neighbour) level. Preliminary results suggest that each tree species shows a specific behaviour in relation to crown defoliation, and the distribution of crown defoliation across Italian forests reflects the distribution of the main forest types and their ecological equilibrium with the environment. The potentiality and the problems connected to the possible extension of this analysis at a more general level (European and North American) were discussed.