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| 1 | Phytosociology, structure and dynamics of Pinus roxburghii associations from Northern Pakistan显示文摘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(Nonmetric 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 <0.01) and slope(r2 = 0.391, p <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 juvenile and total density and basal area of the subordinate tree species were low. The low density of trees in the smallest diameter size-class suggested 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 multimodal pattern with some regeneration gaps. Browsing, heavy logging and other anthropogenic activities were the overriding factors responsible for the poor recruitment of P. roxburghii. We concluded from the age structure 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-term cultural practices in order to enhance wood production in lesser Himalaya and Hindukush ranges of Pakistan. | Nasrullah Khan Kishwar Ali Shahid Shaukat | 2014 | Journal of Forestry Research2014，25，3： | 5 |
| 2 | Future of Abies pindrow in Swat district,northern Pakistan显示文摘Swat district is a biodiversity hub of Pakistan.The plant species,especially trees,in the Swat District are exposed to extinction threat from global climate change.Maximum entropy(MaxEnt)modelling of species distribution,using HADCM3 A2a global climate change scenario,predicted a considerable change in the future distribution of Abies pindrow(Royle ex D.Don)Royle.AUC(area under the curve)values of 0.972 and0.983 were significant for the present and future distribution models of the species,respectively.It is clear that bioclimatic variables such as the mean temperature of the warmest quarter(bio_10)and the annual temperature range(bio_7)contribute significantly to the model and thus affect the predicted distribution and density of the species.The future model predicts that by the year 2080 population density will have decreased significantly.The highest density of the species is recorded in the eastern and western borders of the Valley in the areas of Sulatanr and Mankial.The changes in density and distribution of the species can have considerable impact,not only on the tree species itself,but on the associated subflora as well. | Kishwar Ali Habib Ahmad Nasrullah Khan Stephen Jury | 2014 | Journal of Forestry Research2014，25，1： | 4 |
| 3 | Vegetation-environment relationship in Pinus wallichiana forests of the Swat Hindukush range of Pakistan显示文摘Understanding the influence of environmental variables on the spatial distribution of ecological communities is essential to predict the response of vegetation to various environmental drivers.Ecological theory suggests that multiple environmental factors shape local species assemblages and should influence the various components of community structure and composition in different ways.This study aimed to classify Pinus wallichiana dominated forests in the Swat Hindukush range mountains to understand the relative influence of multiple environmental filters on its composition and structure.These forests represent the most typical of the species distribution in northern Pakistan and were not subjected to any phytosociological study.For this purpose,thirty forest stands,spanning a wide range of physical habitats were sampled using 10910 m plots and the importance value index was calculated.The floristic and environmental data were subjected to Ward’s agglomerative cluster analysis for objective classification and ordinated with NMS ordination for pattern description and testing the vegetation–environmental relationships.Three floristically and ecologically distinct communities were recognized along the topographic gradient(elevation,r=0.377;slope,r=0.5548)coupled with soil physical(clay,r=0.2782;silt,r=0.3225)and chemical properties(pH,r=0.4975;lime,r=3982).An elevation gradient of 100 m separated the low(Pinus wallichiana–Quercus dilatata community)and middle elevations forest stands(P.wallichiana pure population)from the highland population type(Pinus wallichiana–Cedrus deodara community).The floristics and structure of these forest types respond directly or indirectly to topographic and soil variables which were evidenced from the floristic composition,species richness,and community physiognomy.These characteristics of the communities changed from heterogenous,dense stands to sparsely dispersed conifers,broadleaved-evergreen,and deciduous vegetation types along the environmental gradients.We concluded that several factors explained the spatial pattern.Thus,we predict that elevation coupled with soil physical and chemical properties could be considered if the ultimate goal is the restoration and conservation of these forests.We also recommend broad-scale phytosociological study on P.wallichiana forests including multiple sampling from diverse locations to define the floristic diversity and to better understand its ecological requirements. | Inayat Ur Rahman Nasrullah Khan Kishwar Ali Siraj Ahmad | 2020 | Journal of Forestry Research2020，31，1： | 0 |
| 4 | Composition,Structure and Regeneration Dynamics of Olea ferruginea Royle Forests from Hindukush Range of Pakistan显示文摘The abundance of Olea ferruginea in Malakand Division has been significantly reduced across its distribution range due to anthropogenic pressure in the recent past. A number of initiatives were taken for grafting this species to obtain better seeds for oil production, without the basic information on their ecology and management. To address this knowledge gap, we quantified the composition, structure and regeneration dynamics of Olea ferruginea forests in Malakand Division, Hindukush range of Pakistan. In the present study, five communities dominated by Olea ferruginea were identified using Ward's agglomerative cluster analysis.Total tree density ranged from 153-2602 plants/ha, and basal area from 19.55 to 2353 m2 ha-1 with Olea having a relative density of 51% to 87% and basal area of 48% to 93%, respectively. The density of juveniles of the dominant and subordinate tree species were generally low which reflect their narrow distribution in the study area. Size-class distributions of O. ferruginea disclosed a bell-shaped pattern, indicating that forests were heavily exploited by local inhabitants in previous periods and recently by armed forces owing to security risks in the study area. The age(mean max. 300±34 years) and annual increment(3.2±1.2 years/cm) indicates that the species is long lived and generally slow growing among the different broad leaved species studied so far. However, the oldest trees can be found by the exploration of large diameter trees in the area. In addition, we found a stable linear relationship between the age and diameter(r2 = 0.779), indicating that diameter is a good predictor of age for this broad leaved species. In view of its relatively slow growth, longevity and positive ring-width characteristics O. ferruginea seems to be a suitable choice for dendroecological and dendrochronological studies in lesser Himalayan and Hindukush ranges of Pakistan. The results obtained from this study may help in understanding the composition, structure and regeneration dynamics of other subtropical broad leaved species. | NASRULLAH Khan FAYAZ Ali KISHWAR Ali SHAHID Shaukat | 2015 | Journal of Mountain Science2015，12，3： | 0 |
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