Vegetation-environment relationships in the forests of Chitral district Hindukush range of Pakistan

We investigated the composition of plant communities to quantify their relationships with environmental parameters in the Chitral Hindukush range of Pakistan. We sampled tree vegetation using the Point Centered Quarter （PCQ） method while understory vegetation was sampled in 1.5-m circular quadrats. Cedrus deodara is the national symbol of Pakistan and was dominant in the sampled communities. Because environmental variables determine vegetation types, we analyzed and evaluated edaphic and topographic factors. DCA-Ordination showed the major gradient as an amalgam of elevation （p〈0.05） and slope （p〈0.01） as the topographic factors correlated with species distribution. Soil variables were the factors of environmental significance along DCA axes. However, among these factors, Mg2＋ , K ＋ and N2＋ contributed not more than 0.054% 0.20% and 0.073%, respectively, to variation along the first ordination axis. We conclude that the principal reason for weak or no correlation with many edaphic variables was the anthropogenic disturbance of vegetation. The understory vegetation was composed of perennial herbs in most communities and was most dense under the tree canopy. The understory vegetation strongly regulates tree seedling growth and regeneration patterns. We recommend further study of the understory vegetation using permanent plots to aid development of forest regeneration strategies.

Phytosociology, structure and dynamics of Pinus roxburghii associations from Northern Pakistan

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-term cultural practices in order to enhance wood production in lesser Himalaya and Hindukush ranges of Pakistan.

Future of Abies pindrow in Swat district,northern Pakistan

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, pre-dicted a considerable change in the future distribution ofAbies pindrow （Royle ex D.Don） Royle. AUC （area under the curve）values of 0.972 and 0.983 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.

Diversity analysis of chickpea (<i>Cicer arietinum</i>L.) germplasm and its implications for conservation and crop breeding

The exploration of genetically variable accessions is the key source of germplasm conservation and potential breeding material for the future. The more diverse group of cultivars provides an ample opportunity to breeders for releasing new and superior varieties, considering their quality traits for direct commercial utilization. In this study, we assessed the genetic diversity of Cicer arietinum 70 accessions from Pakistan and USA using morphological traits, seed protein and molecular markers. Based on four morphological traits, the average coefficient of variation was calculated as 56.8% with significant correlation among yield traits. The analysis revealed that the accessions 1898, 2819, 3022, 3037, 3040, 3043, 3054, 3059 and 3063 were best in performance with a total of 12% environmental error. The cluster analysis based on protein data revealed 50% genetic diversity among accessions. The clustering pattern did not show any grouping that could be attributed to either the geographic distribution or the field performance. For molecular characterization of germplasm 5 PCR based RAPD primers, OPA4, OPA9, OPG13, UBC181 and UBC733b used were found to be polymorphic with 37% genetic diversity among local and exotic accessions. Whereas, 3 SSR primers viz., CaSTMS2, Ca- STMS15 and CaSTMS21 scored the genetic variability up to 55% by cluster analysis through UPGMA percent disagreement. The primers, TA72 and TA130 were linked with yield related traits, indicated highest dissimilarity index value (0.69) and notable variation in the identified promising lines. The Morphometric, Biochemical and Molecular markers reported here, are helpful to assess the extent of genetic diversity among Chickpea accessions and can be used to identify the unreported cultivars with desirable quantitative traits for improving Chickpea yield in Pakistan. Based on the study, the accessions 3043 and 3054 have been recommended to the breeders for their future use in multiplication and screening against various diseases.

Vegetation-environment relationship in Pinus wallichiana forests of the Swat Hindukush range of Pakistan

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.

Composition,Structure and Regeneration Dynamics of Olea ferruginea Royle Forests from Hindukush Range of Pakistan

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.

Distribution pattern and ecological determinants of an invasive plant Parthenium hysterophorus L., in Malakand division of Pakistan

After habitat loss,drastic effects of biological invasion caused by alien invasive species to the native biodiversity have been acknowledged worldwide by the agriculturists,ecologists,and governments as it is more overwhelming than pollution,harvest and disease combined.One such example of biological invasion is P.hysterophorus which is considered to be one of the topmost noxious weeds threatening ecosystems diversity in the world,particularly in Pakistan due to its invasive success and generalist nature.Yet no studies have explored the pattern and determinants of plant biodiversity in the Parthenium dominated landscapes.Here we explored the current distribution pattern of this species with relation to environmental variables in the Malakand division of northern Pakistan.Twenty-three sites dominated by P.hysterophorus were identified through a participatory mapping process combined with traditional ecological knowledge and quantitative inventories were made.In total,we found 62 plant species in 55 genera and 32 families,predominately from Asteraceae,Poaceae,and Solanaceae.Ward’s agglomerative clustering procedure showed three well-differentiated,and ecologically meaningful but overlapping vegetation communities.P.hysterophorus was found to be the leading species with an average Importance value ranging from 33.28%to 65.59%.Based on our criteria,surprisingly we found significantly less to be fully(30%)or partially invaded(21%)than the less invaded(47%)plots,indicating the gradual invasive success of the species across the landscape.Canonical Correspondence Analysis(CCA-ordination)has explained 36.9%of the cumulative variance by the first three axes and identified elevation(r=-0.526),slope(r=0.438)and percent sand(r=-0.474)to be the major environmental factors affecting the distribution of P.hysterophorus and associated vegetation.These results suggested that elevation and percent sand negatively affect Parthenium distribution whereas slope has a positive relationship thereby promoting its populations in the region.The generalist nature of this invasive species is likely to have an overall adverse negative effect on the ecosystem functioning and cannot be ignored.Therefore,quick actions should be taken for the management of this noxious weed to avoid economic consequences and potential threats to fragile ecosystems such as that in Malakand division.

Nitriding of Aluminium Alloy in Nitrogen and Nitrogen-Helium Mixture Using 100 Hz-Pulsed DC Glow Discharge

Nitriding of aluminium alloy （AlFel.sZn0.8） in nitrogen and nitrogen-helium mixture was carried out by using 100 Hz-pulsed DC glow discharge. Samples are treated for different durations, namely 4 h, 8 h and 12 h, in nitrogen plasma as well as in a mixture of nitrogen- helium plasma for the same processing duration of 4 h. All nitriding treatments are carried out at an input power of 100 W, filling pressure of 1 mbar and substrates temperature of 250~C. X-ray diffraction （XRD） results show an expansion in lattice spacing and consequently shift of diffraction peaks towards lower angle with the addition of helium in nitrogen plasma. Surface morphology of the treated sample is investigated by scanning electron microscopy （SEM） and energy dispersive X-ray analysis （EDX）. Vickers micro-hardness testing results show increases in surface hardness with processing duration as well as with the addition of helium in nitrogen plasmas. This increase of surface hardness may be attributed to the diffusion of nitrogen content in the surface layer generating internal stresses. It is observed that the addition of helium positively affects the nitriding of samples.

Design and Fabrication of a High Voltage Lightning Impulse Generator

This paper reports 10 kV to 100 kV high voltage impulse generator. Generation of variable outputs impulse generator can be designed by combination of flyback transformer and Marx generator which can produce different high voltages. It is a portable device for field. The experimental final results have been taken by using spark gap measurements and voltage divider technique. This high voltage lightning impulse generator produces standard T1/T2 waveshape impulses. The testing of protection devices such as SPD (surge protection device) is extremely important to find out whether these devices can operate in standard conditions or not. That’s why the high voltage lightning impulse generator is developed for such testing. Similarly, our research work consists of modeling and practical design of a 100 kV impulse generator.