We investigated the phytosociology, structure and dynamics of Pinus roxburghii in 40 stands in northern areas of Pakistan by using cluster analysis （Ward’s agglomerative clustering） and ordination （Non-metric Mult...We investigated the phytosociology, structure and dynamics of Pinus roxburghii in 40 stands in northern areas of Pakistan by using cluster analysis （Ward’s agglomerative clustering） and ordination （Non-metric Multidimensional Scaling）. Cluster analysis revealed three major groups associated with specific environmental characteristics： （1） P. roxburghii （2） Pinus-Quercus baloot and （3） Pinus-Olea ferruginea community types. NMS-ordination showed the major gradient as an amalgam of elevation （r2=0.441, p＆lt;0.01） and slope （r2=0.391, p＆lt;0.05） as the two topographic factors correlated with species distribution. The first ordination axis also showed positive correlation with soil variables like pH and electrical conductivity, suggesting that soil chemistry was related to topographic characteristics and probably acted as a secondary gradient. We also examined size class distributions, age structures and growth rates of the three communities in order to describe community development and dynamics. Total tree density was 14700 plants/ha, with P. roxburghii having a relative density of 82%to 100%. Density of juve-nile and total density and basal area of the subordinate tree species were low. The low density of trees in the smallest diameter size-class sug-gested that the recruitment of small P. roxburghii plants into the adult population may be lower than the required replacement rate for the stands. Pooled size-class distributions for the species showed a multimo-dal pattern with some regeneration gaps. Browsing, heavy logging and＆amp;nbsp;other anthropogenic activities were the overriding factors responsible for the poor recruitment of P. roxburghii. We concluded from the age struc-ture that the forests were characterized by the dominance of young trees. Growth rate analysis revealed that P. roxburghii was the fastest growing species among the conifers species in Pakistan. In view of its relatively fast growth and longevity, P. roxburghii seems to be a suitable choice for short-t展开更多
The 170 samples obtained from ligneous investigation in Barkoissi,Galangashi and Oti-Keran protected areas（northern Togo） were subjected to floristic processing and several multivariate analyses in order to study pl...The 170 samples obtained from ligneous investigation in Barkoissi,Galangashi and Oti-Keran protected areas（northern Togo） were subjected to floristic processing and several multivariate analyses in order to study plant diversity,life form and chorological type distribution and to classify and identify the main plant communities with their demographic structure.First,the overall life form and phytogeographical type frequencies were calculated to analyze and show the distribution of the 68 plants species in this area.Then plant communities were determined by using the hierarchical clustering with wards method.The plant communities found were identified by the technique of indicator value（IndVal）.For each grouping diversity index such as specific richness,Shannon index and Pielou＇s evenness was set out.The canonical correspondence analysis（CCA） was also used to relate the impact of environment factors and the distribution of samples.Finally the variance analysis（ANOVA） associated to post-hoc test was used to compare the similarity between the groupings.From these 170 samples,12 plant communities were discriminated,three for the reserve of Barkoissi,three for the reserve of Galangashi and six for the reserve of Oti-Keran.The samples were well distributed in the factorial plan form by axe 1 and 3 of CCA.The plant communities were distributed along the moisture gradient in the ordination.The Sudano-Zambesian species followed by Sudanian species were the phytogeographical types most found in these areas.The microphanerophytes were the most represented life form.The structural parameters such as diameter and height means,the basal area and the densities determined and submitted to post-hoc test show some important similarity between some groups found.In overall,the vegetation condition of the three protected areas is somehow disturbed while most of the plant communities are stable.These preliminary ecological data obtained are essential and fundamental for the management and protection for these ecosyst展开更多
Wildfires have environmental,economic,and social impacts,and can shape the landscape and benefit ecosystems such as the Cerrado.This study evaluated the diversity,similarity,and floristic and structural differences of...Wildfires have environmental,economic,and social impacts,and can shape the landscape and benefit ecosystems such as the Cerrado.This study evaluated the diversity,similarity,and floristic and structural differences of woody savanna and forest formations of the Cerrado,when affected and not affected by fire.Twenty-eight 25-400m2 plots were randomly allocated and divided into Burnt Cerrado and Unburnt Cerrado,Burnt Forest,and Unburnt Forest,and divided into three levels of inclusion according to diameter class(smaller than 2 cm,2-5 cm and larger than5 cm).Species were identified,DBH and height measured,and phyto sociological parameters such as volume,diversity,and floristic similarity evaluated.Burnt Cerrado had lower diversity,density,and dominance at all inclusion levels compared to the Unburnt Cerrado,and showed similarities between treatments at the inclusion levels.Burnt Forest had smaller differences in diversity,density,and dominance than Unburnt Forest.Forest formation was similar at level 1 of inclusion and in the total area.However,it was dissimilar at lower levels.The lower density and diversity of species at the lowest levels of inclusion was associated with mortality from fire.展开更多
Background： The ＇Khasi hill sal＇ forest ecosystem in Meghalaya, India represents the easternmost limit of sal distribution. We tested if tree diversity and compositional heterogeneity of this ecosystem was higher t...Background： The ＇Khasi hill sal＇ forest ecosystem in Meghalaya, India represents the easternmost limit of sal distribution. We tested if tree diversity and compositional heterogeneity of this ecosystem was higher than other sal-dominated forests due to moister environment. Methods： Vegetation was sampled in 11 transects of 10 m width and up to 500 m length covering 5.2 ha area. All stems ≥10 cm girth at breast height were enumerated. Results： We found a pattern of mixed dominance of Shored robusta （sal） and Schima wollichii and co-dominance of Pinus kesiyo and Careya arborea. The Shannon＇s diversity index （H＇） was 3.395 nats. This value is remarkably high and competitive to that of moist sal forests of eastern Himalayan foothills and sal-dominated forests of Tripura. A high value of H＇ was manifested by： a） high species richness （S = 123）, b） good equitability （70.6%）, c） ＇fair＇ resource apportionment, and d） abundance of rare species （84% species with less than one per cent of total individuals, 67% species with two or less individuals ha-1 and 59% species with one or less individuals ha-1）. The compositional heterogeneity was ＇fair＇ （Whittaker＇sβw = 3.15）. The presence of Fagaceae with six species commanding 4.3% of importance value （IVl） and of a pine （P. kesiya） in sal forest was remarkable. As many as 58 species showed ＇low density （〈 10 individuals ha-1）, uniform dispersion＇, five species achieved ＇higher density （〉 10 individuals ha-l）, uniform dispersion＇ and six of the top 10 species were ＇clumped＇. The forest showed an exponential demographic curve illustrating ＇good＇ regeneration of an expanding community. Vertical stratification was simple with a poor canopy and fair subcanopy, which together with low basal area （15.65 m2 . ha-1 for individuals ≥ 10 cm gbh） indicated logging of mature sal trees in the past. Conclusions： The ＇Khasi hill sal＇ forest ecosystem is richer in alpha and beta diversi展开更多
The Atlantic Forest is among the 35 hotspots on the planet, and yet few floristic or structural studies have been conducted on mature forest fragments of that biome in Brazil. In view of this knowledge gap and of the ...The Atlantic Forest is among the 35 hotspots on the planet, and yet few floristic or structural studies have been conducted on mature forest fragments of that biome in Brazil. In view of this knowledge gap and of the need to further comprehend the importance of conserving mature forests, we surveyed the arboreal component of three little-altered forest remnants from the S?o Paulo metropolitan region (SPMR), southeastern Brazil, and compared our data with the one from other phytosociological studies performed in the region. Mature forests showed a different floristic composition from one of young forests. Overall, the former has a higher number and percentage of threatened and endemic species than the latter, and also a higher exclusivity of occurrence of threatened species. In areas up to twice as smaller, mature forests have 1.5 to 4.3 times more endemic species to the Atlantic Forest and up to 9 times more species threatened with extinction than young forests. These facts, along with the scarcity of remnants of mature forests, led us to consider such forests as hotspots within the Atlantic Forest hotspot in the SPMR, as well as to categorize them as of high relevance for conservation.展开更多
The productivity of traditional agrisilviculture system （agricultural crops ＋ trees） was investigated in the northern and south- ern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the ...The productivity of traditional agrisilviculture system （agricultural crops ＋ trees） was investigated in the northern and south- ern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004-2006. A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system. The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system. The results show that the annual produc- tivity of all tree species was 3 775 kg.ha-1.a^-1 in northern aspect （site-N） and 3 10! kg.ha^-1.a^-1 in southern aspect （site-S）. G. optiva had the highest productivity in both site-N and site-S among the tree species, followed by M. azedarach, Quercus leucotrichophora and C. australis. The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area. The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system. The sole agricultural crop productivity （without trees） in northern aspect was also higher than that in southern aspect. An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect. The overall productivity in traditional agrisilviculture system （crop ＋ tree） was 24% （in northern aspect） and 21% （in southern aspect） higher than that in sole cropping system.展开更多
Fagonia cretica L. is an important component of Mediterranean dry grasslands and a rare and isolated species of Italian flora. In this study, an assessment is presented on the distribution, habitat, and conservation s...Fagonia cretica L. is an important component of Mediterranean dry grasslands and a rare and isolated species of Italian flora. In this study, an assessment is presented on the distribution, habitat, and conservation status of F. cretica in Italy. The results of field investigation and herbarium analysis show that this species grows in a small area within the southern Calabria region characterized by a warmest and driest Mediterranean climate on the Italian peninsula. F. cretica is a semi-desert plant species growing in Italy in only one peripheral and isolated population at the northern limit of its distribution. Plant community analysis, using the phytosociological method, shows that F. cretica grows in wintergreen perennial dry grasslands dominated by Lygeum {partum and Hyparrhenia hirta. F. crelica plant communities are located in thermo-xeric habits such as south-, southeast- and east-facing slopes on clays and sandy clays in southern Calabria. The population of F. cretica is fragmented in six neighbouring localities, with two of which belonging to a Site of Community Importance （SC1）. The conservation status of F. cretica population is not very good, and is defined as ＂Critically Endangered＂ in accordance with IUCN criteria. There are many threats affecting the F. crelica population in ltaly, primarily the changes in land uses due to urban expansion and reforestation with exotic plants. The southern end of the Italian peninsula hosts other plants from thermo-xeric habits that do not adapt to the current local climate. This territory can be considered as a microrefugia for plants currently distributed in the arid territory of the southern Mediterranean. These results contribute to the discussion of some conservation measures, and the possibility of establishing a micro-reserve. For all these reasons, we propose to include F. cretica in the lists of protected plant species at regional （Calabria） and country （Italy） scales in Italy.展开更多
Idna, Hebron area, Palestine was subject to phytosociological study through the period from March to May 2013;this area has a characteristic dry, arid, semi-arid and very little of sub-humid and locates between Medite...Idna, Hebron area, Palestine was subject to phytosociological study through the period from March to May 2013;this area has a characteristic dry, arid, semi-arid and very little of sub-humid and locates between Mediterranean, Negev and Sinai regions. We took 237 samples of different species plants from Idna village;the absence of phytosociological studies on the area led us to run a statistical treatment on the 237 woody plant inventories. Moreover, the inventories were made following Braun-Blanquet 1979;we transformed the Braun-Blanquet species abundance-dominance values into those of Van der Maarel 1979. In the statistical treatment we obtained two large groups in the cluster: group (A), representing forests, copses and high shrublands influenced by climate (climatophilous);and group (B), representing Tamarix copses which are influenced by edaphohygrophilic. Working a great interest for Palestine. Due to the lack of phytosociological studies in this country. For the first time gets to sample and characterize the phytosociological methodology woody plant communities. The objective of this study is to obtain bioclimatic indicators to trigger sustainable agricultural development. We propose eight association plant communities such as ASL1 = association of woody plants (association one)—Pistacio palaestinae-Quercetum lokii;ASL2—Capparido sinaicae-Ceratonietum siliquae;ASL3—Cerasus microcarpae-Quercetum ithaburensis;ASL4—Pyro siriacae-Abietetum cilicicae;ASL5—Abio ciliciae-Ceratonietum siliquae;ASL6—Periploco aphylli-Pinetum halepensis;ASL7—Cytisopsis pseudocytiso-Tamaricetum tetragynae;ASL8—Crataego sinaicae-Tamaricetum jordanii.展开更多
Understanding the ecological dynamics of weed populations in no-tillage systems is important to establish strategies for integrated weed control capable of increasing agroecosystem sustainability. This study sought to...Understanding the ecological dynamics of weed populations in no-tillage systems is important to establish strategies for integrated weed control capable of increasing agroecosystem sustainability. This study sought to evaluate the effect of succession systems on the seed bank in a no-tillage system. The effects of fifteen succession systems, composed of seven grasses, seven Leguminosae, and a fallow condition, were evaluated on the seed bank at two soil depths (0 to 10 and 10 to 20 cm). The species found in the seed bank were quantified and identified by species and family. The precision of sampling, density, dominance, the indices of diversity of Simpson and Shannon-Weiner;index of sustainability;analysis of groupings of dissimilarities;and the value of importance of each species were calculated. High weed diversity was observed;29 species were counted, including members of 12 different families. The highest expression of weeds was observed at soil depths of 0 to 10 cm. The Simpson and Shannon-Weiner coefficients indicated high diversity in both systems of succession. The index of sustainability did not indicate significant alterations in the different systems of succession. The coefficients of confenetic correlation were 0.74% and 0.82% for the 0 - 10 and the 10 - 20 cm soil depths respectively. It is concluded that there is a high diversity of weeds in the agroecosystems of Amazonia, and different cover crops promote modifications in the community and expression of the weeds’ seed bank.展开更多
The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004?2...The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004?2006.A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system.The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system.The results show that the annual productivity of all tree species was 3 775 kg·ha-1·a-1 in northern aspect(site-N) and 3 101 kg·ha-1·a-1 in southern aspect(site-S).G.optiva had the highest productivity in both site-N and site-S among the tree species, followed by M.azedarach, Quercus leucotrichophora and C.australis.The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area.The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system.The sole agricultural crop productivity(without trees) in northern aspect was also higher than that in southern aspect.An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect.The overall productivity in traditional agrisilviculture system(crop + tree) was 24%(in northern aspect) and 21%(in southern aspect) higher than that in sole cropping system.展开更多
We aimed with this study to evaluate the potential of oilseed crops planted following soybean, in terms of their ability to inhibit the occurrence of weed species under Brazilian Savannah cropping systems. The long-te...We aimed with this study to evaluate the potential of oilseed crops planted following soybean, in terms of their ability to inhibit the occurrence of weed species under Brazilian Savannah cropping systems. The long-term experiment was installed in 2010 at Dourados, MS, Brazil, and in completely randomized blocks design with five replications with 12 × 24 m plot size. For three consecutive years (2010/11, 2011/12 and 2012/13), soybeans were planted in all the area by October/November being harvested in February/March, when previously marked plots were planted in April with: (1) radish (Raphanus sativus);(2) rapeseed (Brassica napus);(3) crambe (Crambe abyssinica);(4) winter fallow-no plantation after soybeans. In all years the same crop was repeated at the same plots, with no crop rotation. Phytosociological characterization of weed species was carried out in winter (after oilseeds harvest), pre-planting and post-emergence of soybean for the three years. Relative abundance, frequency and dominance, as well as the importance value for each species, was obtained. Areas were also intra-characterized by the coefficients of Simpson, Shannon-Weiner and Shannon-Weiner’s Evenness Proportion, and areas were compared for species dissimilarity with Jaccard’s presence-only coefficient, by multivariate cluster analysis. Oilseed crops definitely contribute for sustainable weed management as a cultural tool. The most important oilseed crop weeds in the Savannah-like region of Brazil were Amaranthus hybridus, Richardia brasiliensis, Lepidium virginicum, Leonotis nepetifolia and Hybanthus parviflorus. After three years of repetitive crop succession, some weeds were selected, and rotation in Winter is advised at least every two or three years.展开更多
The aim of this research was to answer the question of whether the floristic- phytosociological characteristics of the forest communities described in the mid-twentieth century in the Zielonka Experimental Forest (Pol...The aim of this research was to answer the question of whether the floristic- phytosociological characteristics of the forest communities described in the mid-twentieth century in the Zielonka Experimental Forest (Poland) have changed, and if so, what were the reasons for these changes and what were their environmental and economic consequences. The basis of the research was a comparison of plant community descriptions drawn up in 1957-1961 to descriptions of the states of those communities in 2010-2017. The study showed a significant decrease in the number of plant species. The reasons for the disappearance of some plant communities are seen in the natural or artificial changes of pine in sandy habitats, which evolved towards richer communities. The disappearance of xero-thermophile oak woods had two main causes: a natural cause, which was a consequence of regeneration towards oak-hornbeam woods after the anthropogenic phenomena responsible for their management, and anthropogenic disturbance related to the planting of Fagus sylvatica trees or Prunus serotina. The second case is described more broadly and considers both the positive and negative roles of changing the floristic compositions of forest ecosystems.展开更多
This study describes the tree community structure of three moist lowland Atlantic Forest fragments in Rio de Janeiro State, southeastern Brazil. Two fragments were disturbed and an undisturbed one was used as referenc...This study describes the tree community structure of three moist lowland Atlantic Forest fragments in Rio de Janeiro State, southeastern Brazil. Two fragments were disturbed and an undisturbed one was used as reference. Our hypothesis was that disturbed fragments show distinct structural patterns in comparison with undisturbed stands due to past disturbance practices and forest fragmentation. Four 100 ×5 m sampling plots were demarcated in each fragment and all live and dead trees with DBH C 5 cm were located, measured and identified. The results supported our hypothesis, due to the high values found for standing dead trees, an increase of dominance of a few pioneer species, lower values of large trees and species richness in disturbed fragments in comparison with the undisturbed one. The advanced fragmentation process in the Southern Brazilian lowland areas and the high species richness in undisturbed areas highlight these forest fragments as priority areas for conservation and management.展开更多
For the first time in this paper the forests of Betula platyphylla in Daxing’an Mountains are Subdivided by phytosociological methods. Three community types of B. platyphylla forest have been differentiated, e.g., Rh...For the first time in this paper the forests of Betula platyphylla in Daxing’an Mountains are Subdivided by phytosociological methods. Three community types of B. platyphylla forest have been differentiated, e.g., Rhododendron dahuricum-Betula platyphylla Corylus, Corylus heterophylla-Betula platyphylla community and Arternisia stolonifera-Betula platyphylla community. The distributed elevation, stand height, differential species, major composition species of tree layer, shrub layer and herb layer for each community were detail展开更多
This paper presents a floristic and vegetation study of the territories of the Idna-Hebron of Palestine, corresponding to one area with three different names as Abu Salman Forest Reserve, Khallet Osman mountains, and ...This paper presents a floristic and vegetation study of the territories of the Idna-Hebron of Palestine, corresponding to one area with three different names as Abu Salman Forest Reserve, Khallet Osman mountains, and Hamra Aslimi. These sites are very important at a local level of the flora with a high endemic rate. The floristic analysis revealed the existence of 48 species, of which 10 (20.83%) are endemic endemic. Seventeen plots of vegetation distributed in one area dominated and have been analyzed in this study. Methodology, the phytosociological approach is based on the Braun-Blanquet method. The results revealed three different kinds of forests, one dominated by the endemic Pino halepensis-Quercetum lookii, which is peculiar to the inframediterranean dry-thermomediterranean environments, with the terra rossa and brown rendzinas territory. The second type of forest is dominated by the Pistacio palaestinae-Ceratonietum silique, which is growing in the dry-subhumid ombrotype and the terra rossa and brown rendzinas territory. The third group of the forest of Khallet Osman and Hamra Aslimi dominated by Quercus lookii-Tamaricetum palestineae. Finally, in this study there are three associations and tow alliances are proposed as new Syntaxa based on statistical and phytosociological analyses in the study area.展开更多
The present work is devoted to the study of broad physiological and ecological characteris- tics of anthropophytic species on the high step- pe lands of the Tlemcen region. The bioclimatic analysis confirms the develo...The present work is devoted to the study of broad physiological and ecological characteris- tics of anthropophytic species on the high step- pe lands of the Tlemcen region. The bioclimatic analysis confirms the development of drought in this region with a dominance of spiny and/or toxic asylvatic: plant species of shrub and her- baceous size species. We used correspondence factor analysis (CFA) of the various factors causing degradation to better understand the complexity of this ecosystem, whose floristic composition was complemented by means of soil measurements (spectrum green/ecological spectrum). This analysis allowed us to identify five groups of anthropophytic species with in this highly degraded matorral. We show that this ecosystem is already showing symptoms of de-gradation, and propose a preservation policy for protecting ensuring the survival of native species under threat from human activities.展开更多
The lowland rainforests of Meghalaya, India represent the westernmost limit of the rainforests north of the Tropic of Cancer. These forests, on the Shillong plateau, are akin to Whitmore's ‘tropical lowland everg...The lowland rainforests of Meghalaya, India represent the westernmost limit of the rainforests north of the Tropic of Cancer. These forests, on the Shillong plateau, are akin to Whitmore's ‘tropical lowland evergreen rainforest' formation and exhibit striking similarities and conspicuous differences with the equatorial rainforests in Asia-Pacific as well as tropical seasonal rainforests in southwestern China near the Tropic of Cancer. We found these common attributes of the rainforests in Meghalaya: familial composition with predominance of Euphorbiaceae, Lauraceae, Meliaceae, Moraceae, Myrsiticaceae,Myrtaceae and Rubiaceae; deciduousness in evergreen physiognomy; dominance of mega-and mesophanerophytic life-forms; abundance of species with low frequency of occurrence(rare and aggregated species); low proportional abundance of the abundant species; and truncated lognormal abundance distribution. The levels of stand density and stand basal area were comparable with seasonal rainforests in southwestern China, but were lower than equatorial rainforests. Tropical Asian species predominated flora, commanding 95% of the abundance. The differences include overall low stature(height) of the forest, inconspicuous stratification in canopy, fewer species and individuals of liana, thicker understory,higher proportion of rare species, absence of locally endemic species and relatively greater dominance of Fagaceae and Theaceae. The richness of species per hectare(S) was considerably lower at higher latitudes in Meghalaya than in equatorial rainforests, but was comparable with seasonal rainforests. Shannon's diversity index(H’=4.40 nats for ≥10 cm gbh and 4.25 nats for ≥30 cm gbh) was lower on higher latitudes in Meghalaya in comparison to species-rich equatorial rainforests, but it was the highest among all lowland rainforests near the Tropic of Cancer.展开更多
文摘We investigated the phytosociology, structure and dynamics of Pinus roxburghii in 40 stands in northern areas of Pakistan by using cluster analysis （Ward’s agglomerative clustering） and ordination （Non-metric Multidimensional Scaling）. Cluster analysis revealed three major groups associated with specific environmental characteristics： （1） P. roxburghii （2） Pinus-Quercus baloot and （3） Pinus-Olea ferruginea community types. NMS-ordination showed the major gradient as an amalgam of elevation （r2=0.441, p＆lt;0.01） and slope （r2=0.391, p＆lt;0.05） as the two topographic factors correlated with species distribution. The first ordination axis also showed positive correlation with soil variables like pH and electrical conductivity, suggesting that soil chemistry was related to topographic characteristics and probably acted as a secondary gradient. We also examined size class distributions, age structures and growth rates of the three communities in order to describe community development and dynamics. Total tree density was 14700 plants/ha, with P. roxburghii having a relative density of 82%to 100%. Density of juve-nile and total density and basal area of the subordinate tree species were low. The low density of trees in the smallest diameter size-class sug-gested that the recruitment of small P. roxburghii plants into the adult population may be lower than the required replacement rate for the stands. Pooled size-class distributions for the species showed a multimo-dal pattern with some regeneration gaps. Browsing, heavy logging and＆amp;nbsp;other anthropogenic activities were the overriding factors responsible for the poor recruitment of P. roxburghii. We concluded from the age struc-ture that the forests were characterized by the dominance of young trees. Growth rate analysis revealed that P. roxburghii was the fastest growing species among the conifers species in Pakistan. In view of its relatively fast growth and longevity, P. roxburghii seems to be a suitable choice for short-t
基金supported by Chinese and Togolese governments under the direction of the Beijing Forest-ry University and Université de Lomé
文摘The 170 samples obtained from ligneous investigation in Barkoissi,Galangashi and Oti-Keran protected areas（northern Togo） were subjected to floristic processing and several multivariate analyses in order to study plant diversity,life form and chorological type distribution and to classify and identify the main plant communities with their demographic structure.First,the overall life form and phytogeographical type frequencies were calculated to analyze and show the distribution of the 68 plants species in this area.Then plant communities were determined by using the hierarchical clustering with wards method.The plant communities found were identified by the technique of indicator value（IndVal）.For each grouping diversity index such as specific richness,Shannon index and Pielou＇s evenness was set out.The canonical correspondence analysis（CCA） was also used to relate the impact of environment factors and the distribution of samples.Finally the variance analysis（ANOVA） associated to post-hoc test was used to compare the similarity between the groupings.From these 170 samples,12 plant communities were discriminated,three for the reserve of Barkoissi,three for the reserve of Galangashi and six for the reserve of Oti-Keran.The samples were well distributed in the factorial plan form by axe 1 and 3 of CCA.The plant communities were distributed along the moisture gradient in the ordination.The Sudano-Zambesian species followed by Sudanian species were the phytogeographical types most found in these areas.The microphanerophytes were the most represented life form.The structural parameters such as diameter and height means,the basal area and the densities determined and submitted to post-hoc test show some important similarity between some groups found.In overall,the vegetation condition of the three protected areas is somehow disturbed while most of the plant communities are stable.These preliminary ecological data obtained are essential and fundamental for the management and protection for these ecosyst
基金Fundacao Grupo Boticário de ProtecaoàNatureza,CAPES,FAPEMIG and CNPQ。
文摘Wildfires have environmental,economic,and social impacts,and can shape the landscape and benefit ecosystems such as the Cerrado.This study evaluated the diversity,similarity,and floristic and structural differences of woody savanna and forest formations of the Cerrado,when affected and not affected by fire.Twenty-eight 25-400m2 plots were randomly allocated and divided into Burnt Cerrado and Unburnt Cerrado,Burnt Forest,and Unburnt Forest,and divided into three levels of inclusion according to diameter class(smaller than 2 cm,2-5 cm and larger than5 cm).Species were identified,DBH and height measured,and phyto sociological parameters such as volume,diversity,and floristic similarity evaluated.Burnt Cerrado had lower diversity,density,and dominance at all inclusion levels compared to the Unburnt Cerrado,and showed similarities between treatments at the inclusion levels.Burnt Forest had smaller differences in diversity,density,and dominance than Unburnt Forest.Forest formation was similar at level 1 of inclusion and in the total area.However,it was dissimilar at lower levels.The lower density and diversity of species at the lowest levels of inclusion was associated with mortality from fire.
基金Department of Biotechnology (DBT), Government of India, New Delhi provided principal funding for this work through a project grant to US (grant number BT/PR7928/NDB/52/9/2006)
文摘Background： The ＇Khasi hill sal＇ forest ecosystem in Meghalaya, India represents the easternmost limit of sal distribution. We tested if tree diversity and compositional heterogeneity of this ecosystem was higher than other sal-dominated forests due to moister environment. Methods： Vegetation was sampled in 11 transects of 10 m width and up to 500 m length covering 5.2 ha area. All stems ≥10 cm girth at breast height were enumerated. Results： We found a pattern of mixed dominance of Shored robusta （sal） and Schima wollichii and co-dominance of Pinus kesiyo and Careya arborea. The Shannon＇s diversity index （H＇） was 3.395 nats. This value is remarkably high and competitive to that of moist sal forests of eastern Himalayan foothills and sal-dominated forests of Tripura. A high value of H＇ was manifested by： a） high species richness （S = 123）, b） good equitability （70.6%）, c） ＇fair＇ resource apportionment, and d） abundance of rare species （84% species with less than one per cent of total individuals, 67% species with two or less individuals ha-1 and 59% species with one or less individuals ha-1）. The compositional heterogeneity was ＇fair＇ （Whittaker＇sβw = 3.15）. The presence of Fagaceae with six species commanding 4.3% of importance value （IVl） and of a pine （P. kesiya） in sal forest was remarkable. As many as 58 species showed ＇low density （〈 10 individuals ha-1）, uniform dispersion＇, five species achieved ＇higher density （〉 10 individuals ha-l）, uniform dispersion＇ and six of the top 10 species were ＇clumped＇. The forest showed an exponential demographic curve illustrating ＇good＇ regeneration of an expanding community. Vertical stratification was simple with a poor canopy and fair subcanopy, which together with low basal area （15.65 m2 . ha-1 for individuals ≥ 10 cm gbh） indicated logging of mature sal trees in the past. Conclusions： The ＇Khasi hill sal＇ forest ecosystem is richer in alpha and beta diversi
文摘The Atlantic Forest is among the 35 hotspots on the planet, and yet few floristic or structural studies have been conducted on mature forest fragments of that biome in Brazil. In view of this knowledge gap and of the need to further comprehend the importance of conserving mature forests, we surveyed the arboreal component of three little-altered forest remnants from the S?o Paulo metropolitan region (SPMR), southeastern Brazil, and compared our data with the one from other phytosociological studies performed in the region. Mature forests showed a different floristic composition from one of young forests. Overall, the former has a higher number and percentage of threatened and endemic species than the latter, and also a higher exclusivity of occurrence of threatened species. In areas up to twice as smaller, mature forests have 1.5 to 4.3 times more endemic species to the Atlantic Forest and up to 9 times more species threatened with extinction than young forests. These facts, along with the scarcity of remnants of mature forests, led us to consider such forests as hotspots within the Atlantic Forest hotspot in the SPMR, as well as to categorize them as of high relevance for conservation.
文摘The productivity of traditional agrisilviculture system （agricultural crops ＋ trees） was investigated in the northern and south- ern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004-2006. A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system. The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system. The results show that the annual produc- tivity of all tree species was 3 775 kg.ha-1.a^-1 in northern aspect （site-N） and 3 10! kg.ha^-1.a^-1 in southern aspect （site-S）. G. optiva had the highest productivity in both site-N and site-S among the tree species, followed by M. azedarach, Quercus leucotrichophora and C. australis. The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area. The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system. The sole agricultural crop productivity （without trees） in northern aspect was also higher than that in southern aspect. An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect. The overall productivity in traditional agrisilviculture system （crop ＋ tree） was 24% （in northern aspect） and 21% （in southern aspect） higher than that in sole cropping system.
文摘Fagonia cretica L. is an important component of Mediterranean dry grasslands and a rare and isolated species of Italian flora. In this study, an assessment is presented on the distribution, habitat, and conservation status of F. cretica in Italy. The results of field investigation and herbarium analysis show that this species grows in a small area within the southern Calabria region characterized by a warmest and driest Mediterranean climate on the Italian peninsula. F. cretica is a semi-desert plant species growing in Italy in only one peripheral and isolated population at the northern limit of its distribution. Plant community analysis, using the phytosociological method, shows that F. cretica grows in wintergreen perennial dry grasslands dominated by Lygeum {partum and Hyparrhenia hirta. F. crelica plant communities are located in thermo-xeric habits such as south-, southeast- and east-facing slopes on clays and sandy clays in southern Calabria. The population of F. cretica is fragmented in six neighbouring localities, with two of which belonging to a Site of Community Importance （SC1）. The conservation status of F. cretica population is not very good, and is defined as ＂Critically Endangered＂ in accordance with IUCN criteria. There are many threats affecting the F. crelica population in ltaly, primarily the changes in land uses due to urban expansion and reforestation with exotic plants. The southern end of the Italian peninsula hosts other plants from thermo-xeric habits that do not adapt to the current local climate. This territory can be considered as a microrefugia for plants currently distributed in the arid territory of the southern Mediterranean. These results contribute to the discussion of some conservation measures, and the possibility of establishing a micro-reserve. For all these reasons, we propose to include F. cretica in the lists of protected plant species at regional （Calabria） and country （Italy） scales in Italy.
文摘Idna, Hebron area, Palestine was subject to phytosociological study through the period from March to May 2013;this area has a characteristic dry, arid, semi-arid and very little of sub-humid and locates between Mediterranean, Negev and Sinai regions. We took 237 samples of different species plants from Idna village;the absence of phytosociological studies on the area led us to run a statistical treatment on the 237 woody plant inventories. Moreover, the inventories were made following Braun-Blanquet 1979;we transformed the Braun-Blanquet species abundance-dominance values into those of Van der Maarel 1979. In the statistical treatment we obtained two large groups in the cluster: group (A), representing forests, copses and high shrublands influenced by climate (climatophilous);and group (B), representing Tamarix copses which are influenced by edaphohygrophilic. Working a great interest for Palestine. Due to the lack of phytosociological studies in this country. For the first time gets to sample and characterize the phytosociological methodology woody plant communities. The objective of this study is to obtain bioclimatic indicators to trigger sustainable agricultural development. We propose eight association plant communities such as ASL1 = association of woody plants (association one)—Pistacio palaestinae-Quercetum lokii;ASL2—Capparido sinaicae-Ceratonietum siliquae;ASL3—Cerasus microcarpae-Quercetum ithaburensis;ASL4—Pyro siriacae-Abietetum cilicicae;ASL5—Abio ciliciae-Ceratonietum siliquae;ASL6—Periploco aphylli-Pinetum halepensis;ASL7—Cytisopsis pseudocytiso-Tamaricetum tetragynae;ASL8—Crataego sinaicae-Tamaricetum jordanii.
文摘Understanding the ecological dynamics of weed populations in no-tillage systems is important to establish strategies for integrated weed control capable of increasing agroecosystem sustainability. This study sought to evaluate the effect of succession systems on the seed bank in a no-tillage system. The effects of fifteen succession systems, composed of seven grasses, seven Leguminosae, and a fallow condition, were evaluated on the seed bank at two soil depths (0 to 10 and 10 to 20 cm). The species found in the seed bank were quantified and identified by species and family. The precision of sampling, density, dominance, the indices of diversity of Simpson and Shannon-Weiner;index of sustainability;analysis of groupings of dissimilarities;and the value of importance of each species were calculated. High weed diversity was observed;29 species were counted, including members of 12 different families. The highest expression of weeds was observed at soil depths of 0 to 10 cm. The Simpson and Shannon-Weiner coefficients indicated high diversity in both systems of succession. The index of sustainability did not indicate significant alterations in the different systems of succession. The coefficients of confenetic correlation were 0.74% and 0.82% for the 0 - 10 and the 10 - 20 cm soil depths respectively. It is concluded that there is a high diversity of weeds in the agroecosystems of Amazonia, and different cover crops promote modifications in the community and expression of the weeds’ seed bank.
文摘The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004?2006.A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system.The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system.The results show that the annual productivity of all tree species was 3 775 kg·ha-1·a-1 in northern aspect(site-N) and 3 101 kg·ha-1·a-1 in southern aspect(site-S).G.optiva had the highest productivity in both site-N and site-S among the tree species, followed by M.azedarach, Quercus leucotrichophora and C.australis.The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area.The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system.The sole agricultural crop productivity(without trees) in northern aspect was also higher than that in southern aspect.An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect.The overall productivity in traditional agrisilviculture system(crop + tree) was 24%(in northern aspect) and 21%(in southern aspect) higher than that in sole cropping system.
文摘We aimed with this study to evaluate the potential of oilseed crops planted following soybean, in terms of their ability to inhibit the occurrence of weed species under Brazilian Savannah cropping systems. The long-term experiment was installed in 2010 at Dourados, MS, Brazil, and in completely randomized blocks design with five replications with 12 × 24 m plot size. For three consecutive years (2010/11, 2011/12 and 2012/13), soybeans were planted in all the area by October/November being harvested in February/March, when previously marked plots were planted in April with: (1) radish (Raphanus sativus);(2) rapeseed (Brassica napus);(3) crambe (Crambe abyssinica);(4) winter fallow-no plantation after soybeans. In all years the same crop was repeated at the same plots, with no crop rotation. Phytosociological characterization of weed species was carried out in winter (after oilseeds harvest), pre-planting and post-emergence of soybean for the three years. Relative abundance, frequency and dominance, as well as the importance value for each species, was obtained. Areas were also intra-characterized by the coefficients of Simpson, Shannon-Weiner and Shannon-Weiner’s Evenness Proportion, and areas were compared for species dissimilarity with Jaccard’s presence-only coefficient, by multivariate cluster analysis. Oilseed crops definitely contribute for sustainable weed management as a cultural tool. The most important oilseed crop weeds in the Savannah-like region of Brazil were Amaranthus hybridus, Richardia brasiliensis, Lepidium virginicum, Leonotis nepetifolia and Hybanthus parviflorus. After three years of repetitive crop succession, some weeds were selected, and rotation in Winter is advised at least every two or three years.
文摘The aim of this research was to answer the question of whether the floristic- phytosociological characteristics of the forest communities described in the mid-twentieth century in the Zielonka Experimental Forest (Poland) have changed, and if so, what were the reasons for these changes and what were their environmental and economic consequences. The basis of the research was a comparison of plant community descriptions drawn up in 1957-1961 to descriptions of the states of those communities in 2010-2017. The study showed a significant decrease in the number of plant species. The reasons for the disappearance of some plant communities are seen in the natural or artificial changes of pine in sandy habitats, which evolved towards richer communities. The disappearance of xero-thermophile oak woods had two main causes: a natural cause, which was a consequence of regeneration towards oak-hornbeam woods after the anthropogenic phenomena responsible for their management, and anthropogenic disturbance related to the planting of Fagus sylvatica trees or Prunus serotina. The second case is described more broadly and considers both the positive and negative roles of changing the floristic compositions of forest ecosystems.
基金supported financially by the Brazilian Ministry of Environment(MMA/FNMA)
文摘This study describes the tree community structure of three moist lowland Atlantic Forest fragments in Rio de Janeiro State, southeastern Brazil. Two fragments were disturbed and an undisturbed one was used as reference. Our hypothesis was that disturbed fragments show distinct structural patterns in comparison with undisturbed stands due to past disturbance practices and forest fragmentation. Four 100 ×5 m sampling plots were demarcated in each fragment and all live and dead trees with DBH C 5 cm were located, measured and identified. The results supported our hypothesis, due to the high values found for standing dead trees, an increase of dominance of a few pioneer species, lower values of large trees and species richness in disturbed fragments in comparison with the undisturbed one. The advanced fragmentation process in the Southern Brazilian lowland areas and the high species richness in undisturbed areas highlight these forest fragments as priority areas for conservation and management.
文摘For the first time in this paper the forests of Betula platyphylla in Daxing’an Mountains are Subdivided by phytosociological methods. Three community types of B. platyphylla forest have been differentiated, e.g., Rhododendron dahuricum-Betula platyphylla Corylus, Corylus heterophylla-Betula platyphylla community and Arternisia stolonifera-Betula platyphylla community. The distributed elevation, stand height, differential species, major composition species of tree layer, shrub layer and herb layer for each community were detail
文摘This paper presents a floristic and vegetation study of the territories of the Idna-Hebron of Palestine, corresponding to one area with three different names as Abu Salman Forest Reserve, Khallet Osman mountains, and Hamra Aslimi. These sites are very important at a local level of the flora with a high endemic rate. The floristic analysis revealed the existence of 48 species, of which 10 (20.83%) are endemic endemic. Seventeen plots of vegetation distributed in one area dominated and have been analyzed in this study. Methodology, the phytosociological approach is based on the Braun-Blanquet method. The results revealed three different kinds of forests, one dominated by the endemic Pino halepensis-Quercetum lookii, which is peculiar to the inframediterranean dry-thermomediterranean environments, with the terra rossa and brown rendzinas territory. The second type of forest is dominated by the Pistacio palaestinae-Ceratonietum silique, which is growing in the dry-subhumid ombrotype and the terra rossa and brown rendzinas territory. The third group of the forest of Khallet Osman and Hamra Aslimi dominated by Quercus lookii-Tamaricetum palestineae. Finally, in this study there are three associations and tow alliances are proposed as new Syntaxa based on statistical and phytosociological analyses in the study area.
文摘The present work is devoted to the study of broad physiological and ecological characteris- tics of anthropophytic species on the high step- pe lands of the Tlemcen region. The bioclimatic analysis confirms the development of drought in this region with a dominance of spiny and/or toxic asylvatic: plant species of shrub and her- baceous size species. We used correspondence factor analysis (CFA) of the various factors causing degradation to better understand the complexity of this ecosystem, whose floristic composition was complemented by means of soil measurements (spectrum green/ecological spectrum). This analysis allowed us to identify five groups of anthropophytic species with in this highly degraded matorral. We show that this ecosystem is already showing symptoms of de-gradation, and propose a preservation policy for protecting ensuring the survival of native species under threat from human activities.
基金The Department of Biotechnology,New Delhi provided principal funding through a grant to US(BT/PR7928/NDB/52/9/2006)
文摘The lowland rainforests of Meghalaya, India represent the westernmost limit of the rainforests north of the Tropic of Cancer. These forests, on the Shillong plateau, are akin to Whitmore's ‘tropical lowland evergreen rainforest' formation and exhibit striking similarities and conspicuous differences with the equatorial rainforests in Asia-Pacific as well as tropical seasonal rainforests in southwestern China near the Tropic of Cancer. We found these common attributes of the rainforests in Meghalaya: familial composition with predominance of Euphorbiaceae, Lauraceae, Meliaceae, Moraceae, Myrsiticaceae,Myrtaceae and Rubiaceae; deciduousness in evergreen physiognomy; dominance of mega-and mesophanerophytic life-forms; abundance of species with low frequency of occurrence(rare and aggregated species); low proportional abundance of the abundant species; and truncated lognormal abundance distribution. The levels of stand density and stand basal area were comparable with seasonal rainforests in southwestern China, but were lower than equatorial rainforests. Tropical Asian species predominated flora, commanding 95% of the abundance. The differences include overall low stature(height) of the forest, inconspicuous stratification in canopy, fewer species and individuals of liana, thicker understory,higher proportion of rare species, absence of locally endemic species and relatively greater dominance of Fagaceae and Theaceae. The richness of species per hectare(S) was considerably lower at higher latitudes in Meghalaya than in equatorial rainforests, but was comparable with seasonal rainforests. Shannon's diversity index(H’=4.40 nats for ≥10 cm gbh and 4.25 nats for ≥30 cm gbh) was lower on higher latitudes in Meghalaya in comparison to species-rich equatorial rainforests, but it was the highest among all lowland rainforests near the Tropic of Cancer.
