Mid Altitude Research Articles

Wake vortex safety assessment during cruise using a regional medium-short -range turbofan aircraft as an example

Regional turbofan aircraft, which are used for medium-short distances, have a heightened risk of high-altitude Wake Vortices(VV) because of their tail-mounted engines and high horizontal tail configurations. For some regional medium-short-range turbofan aircraft, this threat is higher than that for conventionally designed aircraft. To analyze the flight safety of turbofan aircraft during cruise, this study developed a model to assess wake vortex encounters based on evolutionary high-altitude wake flow patterns. First, the high-altitude wake vortex aircraft dissipation patterns were analyzed by combining Quick Access Recorder (QAR) flight data with the wake vortex evolution model. Then, to consider the uniqueness of the medium-short-range turbofan aircraft, the severity of the wake vortex encounters was simulated using an induced roll moment coefficient. The proposed high-altitude wake vortex encounter model was able to identify and assess the high-altitude wake vortex changes, the bearing moments at different altitudes, and the atmospheric pressure conditions. Using the latest wake separation standards from the International Civil Aviation Organization(ICAO), acceptable safety wake intervals for follower aircraft in different scenarios were determined for the safety assessment. The results indicate that compared to mid and low altitudes, the high-altitude aircraft wake vortex dissipation rate is faster, the ultimate bearing moment is weaker, and the roll moment coefficient is higher, which confirm that there is elevated wake vortex encounter severity for regional turbofan aircraft. As safety is found to deteriorate when encountering wake vortices at altitudes higher than 8 km, new medium-short-range turbofan regional aircraft require higher safety margins than the latest wake separation standards.

Expanding the habitat quality assessment of rivers in Greece using an updated River Habitat Survey toolbox

Although most of the EU members have adopted methods for assessing the hydromorphological quality of lotic ecosystems in line with the Water Framework Directive, until now, Greece lacked an integrated approach. In this article, we present the results of the first nationwide assessment of habitat quality for rivers in Greece, using the River Habitat Survey (RHS) alongside a typology of Greek rivers. The RHS toolbox software has been updated with data from the Greek monitoring program which allowed for type-specific assessments using the Habitat Quality Assessment (HQA) score. The HQA scores from 366 monitoring sites were analyzed to identify spatial patterns and significant variations. Sites were classified in five HQA classes based on the position of their HQA score relative to sites of similar types. We also investigated whether Ecological Quality Ratios (EQRs) for three biological quality elements (benthic diatoms, benthic macroinvertebrates and fish) differed significantly among HQA classes. Correlations showed that sites at mid and high altitude catchments with natural land cover had better HQA scores than lowland sites with agricultural land cover. In addition, large urbanized districts (e.g. Attica), and central Greece displayed lower habitat quality than Epirus and Western Macedonia. Our findings revealed that EQR values varied significantly among the HQA classes, with these differences being more prominent for small and medium lowland streams. This study shows that this approach can identify sites that are prone to habitat degradation and require further management, whilst providing a consistent framework for exploring the relationships between biota and hydromorphological conditions.

Evaluating released Maize hybrids parents for yield producibility and nicking time in mid altitude of western and north western Ethiopia

Evaluating released Maize hybrids parents for yield producibility and nicking time in mid altitude of western and north western Ethiopia

Prospecting for fine scale establishment of exotic stem borer pupal parasitoid (Xanthopimpla stemmator Thunberg) in Kenya

Lepidopteran stem borers are an important constraint to cereal production in Sub- Saharan Africa. The exotic Chilo partellus (Swinhoe) is one of the most economically important stem borer pest causing extensive losses on cereal crops in Kenya. This pest has also displaced indigenous species of stem borers while expanding its range in warm, mid and high altitude areas. In order to exert control on various developmental stages of this pest, both Cotesia flavipes Cameron (larval endoparasitoid) and Xanthopimpla stemmator Thunberg (pupal endoparasitoid) were imported and released in 2002 in the Eastern region of Kenya. This study was conducted to assess the establishment status, spread and impact of X. stemmator on C. partellus following its release in Kenya. Stem borer sampling was done on farms where the biocontrol agents had been released and on transects radiating outwards from them every 15km to assess spread. A total of 100 maize plants were inspected for stem borer infestation and destructive sampling done on 10 maize stems per farm to collect immature stem borer stages. Emerging parasitoids and adult moths were identified, counted and recorded. Results of this study showed that C. partellus was the most dominant stem borer species (constituted 71.2%) followed by Sesemia calamistis and Busseola fusca (26.0 and 2.8% respectively). A decrease in overall stem borer infestation (22.47±7.42%) with no significant difference across distances from parasitoid release points (F=0.4; df=3, 51; p>0.05) was also recorded. Seven parasitoid species were recovered, the most abundant being C. flavipes and this coupled with a significant increase in parasitism (25.27±3.27%) (V=1213, p˂0.05) from pre-release levels. The parasitoid of interest, X. stemmator was not recovered. This suggests a failure to establish though there is need to sample alternative hosts before this is declared. Key words: Classical biological control, lepidoptera, pupal parasitoid, post release survey, Xanthopimpla stemmator, Eastern Kenya

Combining ability and genetic distance analysis of mid altitude sub-humid agroecology adapted maize inbred lines for high grain yield

Understanding the combining ability effects, heterosis, and genetic relationships between parental lines would be helpful in the maize breeding program to develop high-yielding and genetically stable maize varieties for various contrasting environments. Hence, the objective of this study was to estimate combining ability effects, heterosis, genetic distance (GD) and associations for grain yield and other agronomic traits. Forty-five F1 diallel crosses, four commercial checks, and ten inbred lines were evaluated at Bako and Jima Agricultural Research Centers, Ethiopia. Significant differences were observed among environments, genotypes and genotype by environment interaction for grain yield and almost all studied agronomic traits. Combining ability analysis showed both additive and non-additive gene effects significantly controlled grain yield and all other studied traits. The preponderance of general combining ability (GCA) effects indicates the importance of additive gene action inheriting most agronomic traits. Lines L2, L7, and L9 were the best combiners for grain yield, whereas lines L3 and L4 had desirable GCA values to improve days to flowering and plant height. Among the top ten crosses, L6 × L9, L6 × L7 and L4 × L9 were good specific combiners and had 18.8 %, 17.2 % and 16.2 % grain yield advantage over the best check, BH546. These hybrids also had high mid and better-parent heterosis compared with other crosses. The associations of GD with mean of F1 and SCA effects were positive and highly significant for grain yield and some other traits. In contrast, correlations of GD with mid and better parent heterosis were non-significant for grain yield and most other traits. The results of this study are particularly useful for breeders who envisage combining conventional and molecular methods.

Assessing the Use of Butachlor 5G in High and Mid Altitude Rice Growing Areas in Bhutan: A Case Study

Rice is a vital cereal crop in Bhutan, cultivated widely for domestic consumption. Rice production is gradually decreasing due to diverse reasons including labour shortages and insufficient irrigation water. With the shortage of farm labour, weed management is challenging and Bhutanese farmers have long relied on Butachlor 5G for weed control. However, prolonged use of a single herbicide can lead to herbicide resistance in weeds. This study aimed to determine the extent of use of the weedicide and to assess the development of Butachlor resistance in paddy weeds through farmers’ perceptions. The study, conducted in four western rice-growing areas, surveyed 190 farmers using semi-structured questionnaires. The findings revealed that Butachlor has been extensively used for over three decades, with most farmers applying it more than the recommended dosage. Despite this, 86.85% of respondents reported a decrease in Butachlor's effectiveness over the years. More than half of the respondent (50.53%) believed that weeds had developed resistance to Butachlor, a concern that correlated with the increased dosage used. The findings suggest a diminishing efficacy of Butachlor, potentially attributed to the development of herbicide resistance. Of significance, the study identifies Potamogeton distinctus as the most prevalent weed, followed by Schoenoplectiella juncoides and Pontederia vaginalis in the surveyed areas.

Research on the Characteristics of Raindrop Spectrum and Its Water Vapour Transport Sources in the Southwest Vortex: A Case Study of 15–16 July 2021

This study investigated the convective weather features, precipitation microphysical characteristics, and water vapour transport characteristics associated with a southwest vortex precipitation event that occurred on the eastern edge of the Qinghai–Tibet Plateau, coinciding with a southwest vortex event, from 15 to 16 July 2021, using conventional observations of raindrop spectra, ERA5 reanalysis data, CMORPH precipitation data, and the HYSPLIT_v4 backward trajectory model. The findings aim to provide theoretical insights for improving the forecasting and numerical simulations of southwest vortex precipitation events. The findings revealed that the precipitation event induced by the southwestern vortex at Emeishan Station on 15–16 July 2021 was characterised by high rainfall intensity and significant precipitation accumulation. The raindrop spectrum exhibited a broad distribution with a notable bimodal structure. Both the Sichuan Basin and the Tibetan Plateau were dominated by the South Asian high pressure at higher altitudes, while a pronounced low-pressure system developed at mid and low altitudes within the basin, establishing a meteorological context marked by upper-level divergence and lower-level convergence. Throughout the event, notable vertical uplift velocities were recorded across the Sichuan Basin and Tibetan Plateau, along with distinct positive vorticity zones in the lower and middle strata of the Sichuan Basin, indicating that the atmosphere was in a state of thermal instability. The majority of moisture was in the mid and lower troposphere with evident convergence movements, which played a crucial role in the southwest vortex’s development. WRF numerical simulations of the Emeishan precipitation event more accurately modelled the weather conditions for this precipitation but tended to overestimate the level of precipitation. It was observed that the region around Emei Mountain primarily received moisture influx from the southern Bay of Bengal and the South China Sea, with moisture transport chiefly originating from the Sichuan Basin and in a south-westward trajectory.

Accelerated anti-oxidant enzymes and phytochemical potential of Taxus wallichiana (Himalayan yew) under moist temperate forest of Himalayan, Pakistan

Abstract Taxus wallichiana (Himalayan yew) antioxidant potential enhances the release of secondary metabolites and enzymes under stress; over the last few decades owing to changes in climatic regimes, such species are under constant threat in the moist temperate Himalayan forests. The present study aims to evaluate the effect of change in land-use pattern on the antioxidant and phytochemical potential of T. wallichiana (Himalayan yew) in the moist temperate Himalayan Forest of Galiyat-Khyber-Pakhtunkhwa-Pakistan. Three leaf samples from each location of T.W were collected from high (Ayubiya, 2,970 m.a.s.l.) undisturbed, disturbed mid (Baragali, Dongagali, Kuldana, Chegagali, 2,617, 2,375, 2,455, 2,804 m.a.s.l.) and low (Murree, 2,000 m.a.s.l.) altitudes of moist temperate forest of Galiayt-Himalayan-Khyber-Pakhtunkhwa-Pakistan, DPPH assay, total flavonoids and phenolic content, total protein and proline content, catalase, superoxide dismutase and peroxidase activities were analysed. The antioxidant activity (DPPH) response was more pronounced in low and mid altitude disturbed sites than the undisturbed site at high altitudes. Antioxidant enzymes and osmolyte content further supported the stress tolerance capacity of T. wallichiana to scavenge the ROS produced under oxidative stress conditions. In conclusion, Taxus wallichiana inhabiting in these sites could withstand long durations of drought, salinity, frost, high temperatures, and pathogenic attacks by activating the antioxidant enzymes.

Comparative in vitro evaluation of five Commelina forage species on ruminal fermentation and methanogenesis

In vitro gas measurement study was known to be a helpful tool for investigating the nutritional quality of feed for ruminant animals. This research was conducted to explore the ruminal fermentation and methane emission potential, and their variability pattern with changing seasons and altitudes for Commelina species, using in vitro test. Samples of the species were collected from different altitudes and seasons and used for the in vitro degradability study. Five species (C.africana, C. albescence, C. benghalensis, C. imberbis and C. diffusa), two altitudes (low and mid), and two seasons (wet and dry) were arranged in a 5 × 2 x 2 factorial manner in a completely randomized design, with three repeats of each treatment. In vitro gas and methane production as well as methane to total gas ratio were all meaningfully (P < 0.001) affected by season and altitude with the highest values observed in wet season and mid altitudes. At 24 h incubation, 44.76 and 37.82 ml/200 mg DM of total gas production was noted for wet and dry seasons respectively, while 39.77 and 47.38 ml/200 mg DM was recorded for low and mid altitudes respectively. Average gas production from immediately fermentable fractions (a) for wet season (4.21 ml) was reasonably (P < 0.001) higher than those for dry season (2.16 ml). Midlands (5.04 ml) had higher (P < 0.001) ‘a’ value than lowlands (2.77 ml). Both methane production and methane to total gas ratio exhibited a tangible decrease (P < 0.001) from wet season to dry season. 4.88 ml/200 mg DM and 6.52 ml/200 mg DM methane records were recorded for lowlands and midlands respectively. It appears that Commelina species contain nutrients that degrade in vitro, highlighting their potential supplement value for animals. The promising gas production potential added to its low methanogenic coefficient relative to the other species makes C. diffusa to the preferred supplement for poor-quality roughages followed by C. benghalensis and C. imberbis and the rest species being least preferred. But further nutrient analysis, minerals, secondary metabolites and the like, was required. And, in vivo trials must be conducted to strengthen the implications of this study.

BIOCLIM Modeling for Predicting Suitable Habitat for Endangered Tree Tapiscia sinensis (Tapisciaceae) in China

Climate change jeopardizes species survival, particularly for endangered species. This risk extends to the endangered Chinese endemic tree Tapiscia sinensis. The factors underpinning T. sinensis’s habitat distribution are poorly understood, and its potential response to future climate scenarios remains unclear. With six shortlisted climate factors and 117 occurrence records, we modeled T. sinensis’s potential distribution across China using the BIOCLIM model. We applied principal component analysis to examine the primary climate factors restricting its geographical range. The findings indicate that T. sinensis’ range is principally located in China’s middle subtropical climatic zone at low–mid altitudes. The principal component analysis identified two critical factors representing temperature and precipitation. Temperature was the most critical factor limiting T. sinensis distribution, especially the effect of temperature seasonality and isothermality. The habitat suitability model generated by BIOCLIM under current climate conditions demonstrated strong concordance between the predicted suitable areas and the present actual distribution range. These results verify that the model can reliably identify habitats conducive to T. sinensis growth and survival. However, under a hypothetical future climate scenario of doubled atmospheric CO2 concentrations for 2100, the model indicates a precipitous reduction and fragmentation in the areas with excellent suitability conditions. This predicted decline highlights the considerable threats posed by climate change to the long-term survival of this endangered species in China. Our habitat modeling yields critical insights that inform the development of science-based strategies and best practices to improve conservation management plans for research, protection, nursery cultivation, and sustainable planting in China. Habitat suitability knowledge could aid introduction and cultivation efforts for T. sinensis globally in places with analogous climates.

Double dare: Climate change and volcanic activity threatens local populations of Meta menardi (Araneae, Tetragnathidae) in Sicily

Meta menardi (Latreille, 1804) and M. bourneti Simon, 1922 (Araneae: Tetragnathidae) are ubiquitous inhabitants of the twilight zone of most hypogean sites across Europe. The two species are broadly distributed in Italy, including Sicily, where they show a remarkable segregation along the altitudinal gradient of Mount Etna. Thanks to our recent sampling activities in this area, we create a georeferenced dataset allowing the application of Species Distribution Modelling aiming at evaluating the current and the future habitat in light of the impacts caused by climate change on the local populations. We predicted a relatively wide suitable area for M bourneti, ranging from the sea level up to 1100 m a.sl., whereas for M. menardi the suitable area encompasses a narrow mid altitude strip, extending halfway between the areas suitable for M. bourneti, and the highly unsuitable volcanic uplands, heavily disturbed by the volcanic activity. The averaged future predictions for 2070 under RCP 8.5 scenario, show that M. bourneti will expand its range upwards, in areas that are now suitable for M. menardi. In turn, predictions for M. menardi indicate an extreme reduction of the current strip of suitable habitat, likely determining its local extinction. Our findings are further corroborated by the analysis of the bioclimatic niche of the two species assessed via multidimensional Hutchinsonian hypervolume, being much smaller in M. menardi compared to of M. bourneti. In light of our results, it seems likely that having wider climatic preference, M. bourneti will substitute M. menardi in most of its current range in Sicily. Future interventions aiming at the conservation of M. menardi on Mount Etna are strongly advised.

Evaluation of different apple planting systems in high, mid, and low altitudes of Kashmir Valley

Evaluation of different apple planting systems in high, mid, and low altitudes of Kashmir Valley

Race distribution pattern of Magnaporthe oryzae causing rice blast in mid and high altitudes of North-Western Himalayan region of India

Race distribution pattern of Magnaporthe oryzae causing rice blast in mid and high altitudes of North-Western Himalayan region of India

Genotype by environment interaction and yield stability of hybrid maize varieties evaluated in three locations of mid altitudes of Rwanda (lay summary)

Genotype by environment interaction and yield stability of hybrid maize varieties evaluated in three locations of mid altitudes of Rwanda (lay summary)

Study on Productive and Morpholgical traits of Goat Kids in different Ecozones of Rolpa district

Goat is a domesticated small ruminant, reared by small farmers across the country primarily for meat production. Productivity of goat is often low, which could be related to several genetic and non-genetic factors. A field study was carried out to characterize, evaluate and estimate the effect of non-genetic factors on the hill goat kids during December, 2015 to August 2016 in different eco-zones of Rolpa district, mid-west Nepal. Altogether150 goat kids were selected for this study. Morphological attributes productive performances based on field monitoring and measurements within different altitudes of Rolpa were collected. Least square analysis was performed using Harvey (1990) computer software package, and means were compared using DMRT. The mean body weight of goat kids at birth, pre-weaning, weaning at 5 months’ age were 2.62, 6.34, 10.15 and 13.87 kg respectively. Birth weight of kids significantly differed with respect to altitude(P&lt;0.01). Coat colour (P&lt;0.05) of does and parity (P&lt;0.001) of dams. Similarly, kidding rates of does significantly differed (P&lt;0.05) with respect to colour and altitude. Body weight of the kid at weaning were significantly (P&lt;0.05)correlated to body length, heart girth and wither height. Thus, the results of this study suggest that the performance of low altitude goat flocks was better than mid and high altitude goat flocks in Rolpa district in terms of production and reproduction traits. The selection of the best performing kids for higher weight gain could be done on the basis of both birth and weaning weights. This result could be attributed to superior genotype along with better management practices adopted by the farmers in Rolpa district.

Study of Reproductive Traits of Does in Different Altitudes of Rolpa District

Goat is a domesticated small ruminant, primarily reared by small farmers for meat production, across the country. Productivity of goat is often low, which could be related to several genetic and non-genetic factors. A field study was carried out to characterize, evaluate and estimate the effect of non-genetic factors on the reproductive performance of hill goats during December, 2015 to August 2016 in different eco-zones at Rolpa district of mid-western Nepal. Altogether 482 dams of different age groups were identified for this study. Reproductive performance were collected based on field monitoring and measurements within different altitudes of Rolpa district. Least square analysis was performed using Harvey (1990) computer software package, and means were compared using DMRT. Results revealed that the mean age of first heat in does (299 days), age at first kidding (493 days), gestation length (150 days), kidding interval (251 days), postpartum estrus (91 days), and kidding rates were (1.54 per doe), respectively. Altitude significantly influenced (P&lt;0.001) along with parity (P&lt;0.05) with respect to age of first heat in does. Significance difference of of kidding interval (P&lt;0.05) was significantly influenced within different altitude of goat farming. Similarly, colour and altitude also significantly differed (P&lt;0.05) with respect to kidding rates of does Thus the results of this study suggest that the performance of low altitude goat flocks was better than mid and high altitude goat flocks in Rolpa district in terms of production and reproduction traits. This result could be attributed to superior genotype along with better management practices followed by the farmers in Rolpa district.

Species-Site Suitability Matching Study of Introduced Bamboos in Ethiopia

In view of broadening the genetic base of bamboo resources and looking for alternative bamboo species that can grow in mid altitude areas where indigenous species are not growing in Ethiopia, different introduced bamboo species were tested for their adaptability and growth performance in different areas across the country. Data on ecological and climatic conditions of testing sites and corresponding growth in terms of diameter, height and density of the species were assessed; growth in Ethiopia was compared with growth of the species in their place of origin, i.e. South, Southeast and Tropical Asia. Accordingly, Dendrocalamus asper, Dendrocalamus hamiltonii, Bambusa vulgaris and Dendrocalamus giganteus were found to have similar diameter and height growth while Dendrocalamus membranaceus showed lower values in Ethiopia when compared to growth in its origin. The species-site matching effort of the species within Ethiopia in this regard, is conducted based on similarity in altitude and climatic conditions (rainfall, temperature) of experimental sites to other sites across the country. All the species, except B. bambos, perform well in Oromia, Amhara, SNNP and Tigray regions. All species, except D. gigantues. B. balcoa and B.bambos performed well in Benishangul-Gumuz region. Research on adaptability study needs to be extended in other regions of Ethiopia.

Stability and Performance Evaluation of Advanced Bread Wheat (Triticum aestivum L.) Genotypes in Low to Mid Altitude Areas of Ethiopia

Twenty three advanced bread wheat genotypes have been evaluated against two released bread wheat varieties in 2018−19 and 2019−20 in nine diverse environments of Ethiopia. The experiment was laid out using alpha lattice design with three replications. Ten stability models were employed in order to assess stability and performance of 23 advanced bread wheat genotypes. Combined analysis of variance for grain yield has revealed that the environments, the genotypes and GEI effects were significantly different (p&lt;0.001). In the present study, Environments, GEI and Genotypic effects accounted for 88.6%, 8.3% and 3.1% of the total grain yield variation, respectively. Twelve bread wheat genotypes, ETBW 9136, ETBW 9139, ETBW 9065, ETBW 9080, ETBW 9172, ETBW 9396, ETBW 9452, ETBW 9641, ETBW 9642, ETBW 9646, ETBW 9647 and ETBW 9648 produced grain yield that raged from 5.4 to 5.8 t ha-1, indicating their superior yielding potential. ETBW 9136, ETBW 9139, ETBW 9172, ETBW 9396, ETBW 9452, ETBW 9641, ETBW 9642 and ETBW 9646 were the most stable bread wheat genotypes as confirmed by five to ten stability models. However, ETBW 9452, ETBW 9641, ETBW 9642, ETBW 9646, ETBW 9647 and ETBW 9648 were susceptible to either stem rust or yellow rust or both. Providentially, ETBW 9136, ETBW 9139, ETBW 9172 and ETBW 9396 were superior yielding, stable, resistant and moderately resistant to wheat rusts. Thus, these four genotypes were the most promising advanced bread wheat genotypes to be verified and released in low to mid altitude areas of Ethiopia.

Assessment of commelina species feed use in Konso Zone, Southern Ethiopia: Identification, seasonal characterization, and altitudinal distribution

Searching for low-cost, readily available non-conventional feeds is viewed as an alternate measure and solution in resolving feed-related difficulties. This study was conducted to investigate Commelina species feed use in Konso zone, Southern Ethiopia, by identifying available species and characterize seasonal and altitudinal distribution. The data were gathered through focus group discussions and interviews with 195 households drawn randomly from 15 villages. Five Commelina spp.; Commelina benghalensis, Commelina imberbis, Commelina diffusa, Commelina albescens, and Commelina africana were identified in the study area. C. diffusa was available year-round (88.71%) at low and mid altitudes, whereas all others show diminishing pattern with dry season. C. benghalensis, C. imberbis and C. diffusa were found in low and mid altitudes, whereas C. africana and C. albescence were found only in low altitude. Availability and distribution of commelina spp. in the study area shows variability with seasonal and altitudinal changes. The wider feed usage by livestock keepers across all the corners of the area, combined with the species’ proclivity to grow as friendly alley crops on farmland, suggests that the value of C. benghalensis and C. imberbis may extend beyond feed use. Agricultural experts must transfer intercropping trend of C. benghalensis, and C. imberbis with food crops to farmers who lack it. Nutritional quality of the species should be conducted to have a clear picture about feed value of the plants.

Composition of Stand and Growth Dynamics of Black Cardamom (Amomum subulatum) in Different Agroforestry Habitats in Bhutan

The composition and arrangement of tree species at different altitudes play a vital environmental role in the growth of Black Cardamom (Amomum subulatum) in Bhutan. The present study assesses agroforestry tree species composition and factors affecting the growth of A. subulatum in different habitat types. Altitudes were sorted into three different altitudinal bands (low, mid, and high) and each altitudinal band in three different habitats (timber tree, fodder tree, and mixed tree habitat) was assessed. The sampling of 48 plots was made for each habitat and the plot size was 20×20 m. In total, 144 plots were sampled systematically within the selected altitudinal bands in three different habitats. The 56 ecologically important agroforestry shade tree species were used for growing A. subulatum. Tree species preference of A. subulatumchanged based on different altitudes and habitat types [F(2, 33) = 45.672, P = .001]. Critical factors affecting the growth are tree canopy cover (r = –0.461) and infested A. subulatum stems (r = –0.765). The increasing number of infested stems retarded the growth and dense canopy cover or open canopy reduces the growth rate of A. subulatum. Overall, growth was suitable in timber tree habitat at mid altitudes, where Alnus nepalensis was the dominating species having 41.40% canopy cover with low pest and disease-infested A. subulatum stems. Significantly, the lower altitudinal band and the fodder tree habitats were found to be unsuitable for growth (p &lt; 0.05). Thus, appropriate site selection, canopy cover and altitude could provide optimum growth.