Regeneration potential of conifers along an elevation gradient under highly disturbed regimes in the western Himalayan region

This paper focuses on growth pattern of seedlings from tree-ring proxies and their performance at different altitudes under high disturbance regime. The disturbance is predominately anthropogenic. Four conifer species found during investigations, namely, Pinus wallichiana, Pinus roxburghii, Cedrus deodara and Abies pindrow. The parameters chosen for assessment of regeneration potential were age and growth rate. In addition, edaphic and topographic characteristics of thirty disturbed forest stands were also determined. The stands were deterministically selected because these were deteriorating with respect to tree population, biodiversity and degradation of soil. Seedling density varied in the order: P. wallichiana > Pinus roxburghii > C. deodara > Abies pindrow while the growth rate was exhibited in the order Pinus roxburghii > P. wallichiana > Abies pindrow > C. deodara. These findings suggest that Pinus roxburghii is the most suitable species (sub tropical species) at lower elevations (~1600–1900 a.s.l.) with regard to its regenerative ability and consequently potentially useful for the conservation of these forests. P. wallichiana showed highly significant (P < 0.01) correlations with PC1 (primarily controlled by total dissolved salts and water holding capacity) only whereas Abies pindrow was highly correlated (P < 0.001 and P < 0.01) with PC1 and PC2 respectively (function of oxidative-reductive potential and water holding capacity) while C. deodara and Pinus roxburghii did not show correlation with any of the PCA components. In the light of current findings, Pinus roxburghii was found to be effectively adapted to the environment of the study area. Growth rate of species steadily decreased in response to unfavorable conditions. The other pine species i.e. P. wallichiana (moist temperate species) also showed some degree of adaptability under the influence of predefined environmental attributes. Hence pines are most likely the species that can be able to retain forest cover in future and are the best choice for restoration of these forests. However, the other conifers i.e. C. deodara and Abies pindrow are also able to withstand the physiographic characteristics and the extent of perturbation and persisting possibly beyond their tolerance limits but they need to be preserved and retained in these forests. Conifers are still giving positive response with respect to growth rate and their adaptive compatibility to such an extent that this forest can recover if management and conservation strategies are implemented. Therefore, it is strongly recommended that seedlings and saplings should be conserved to assure future forest cover.     

Drought signal in the tree rings of three conifer species from Northern Pakistan

Anthropogenic and climatic stressors have affected the forests of northern Pakistan in recent decades. Several studies have been conducted to understand forest growth and its relation to the changing climate in this region, but more work needs to be done to understand this complex environment. In this study, we have collected tree core samples of three conifer species (Pinus wallichiana, Picea smithiana, and Abies pindrow) from three different sites in northern Pakistan to understand their radial growth pattern with the goal of finding a relationship between ring-width and climatic parameters (temperature, precipitation, and drought). A 610-year (AD 1406–2015), a 538-year (AD 1478–2015), and a 306-year (AD 1710–2015) long tree-ring width chronology of Pinus wallichiana, Picea smithiana, and Abies pindrow were developed, respectively, using living trees. The ring-width chronologies of these three species showed a strong positive link with the self-calibrated Palmer Drought Severity Index (scPDSI) rather than precipitation or temperature alone, indicating that soil moisture is the primary limiting climatic factor for the growth of these species in the sampling locations. The chronologies of Pinus wallichiana and Picea smithiana exhibited growth suppressions during AD 1570–1610 and the second half of 17th century while their growth was heightened from AD 1540–1560. We have found the lowest growth in Abies pindrow and Picea smithiana from AD 1900–1920, suggesting dry conditions. All three chronologies have exhibited the most rapid increase in growth during the recent decades, suggesting that this region is experiencing climate change with a strong trend towards wetter conditions.     

Habitat distribution modeling of endangered medicinal plant Picrorhiza kurroa (Royle ex Benth) under climate change scenarios in Uttarakhand Himalaya,India

Climate change has been the key factor in changing the alpine vegetation's habitat and causing it to migrate to higher latitudes. The present study aims to model the current and future potential habitat distribution of endangered medicinal plant Picrorhiza kurroa Royle ex Benth in Uttarakhand Himalaya using the maximum entropy (MaxEnt) modeling. We initially select twenty-two environmental variables (bioclimatic + topographic) got from the Fifty-four (54) species occurrence points, which were further reduced to nine variables to prevent multicollinearity. Shared Socioeconomic Pathways (SSP1–2.6 and SSP2–4.5) from the CMIP6 (BCC-CSM2-MR) climate model for the periods 2041–60 and 2061–80 were used to predict the current and future habitat distribution of P. kurroa. Results showed that the precipitation of the driest month (Bio 14; 33.8%), isothermality (Bio 3; 20.2%), mean temperature of warmest quarter (Bio 10; 12.7%), and temperature annual range (Bio 7; 12.2%) were the important bioclimatic variables influencing the habitat of P. kurroa. Overall, there is a decrease in the habitat of P. kurroa under climate change scenarios. The present results may prove insightful for the decision-makers to identify suitable sites in the wild for the further propagation of P. kurroa.     

Chloroplast population genetics reveals low levels of genetic variation and conformation to the central–marginal hypothesis in Taxus wallichiana var. mairei,an endangered conifer endemic to China

The central–marginal hypothesis predicts that geographically peripheral populations should exhibit reduced genetic diversity and increased genetic differentiation than central populations due to smaller effective population size and stronger geographical isolation. We evaluated these predictions in the endangered conifer Taxus wallichiana var. mairei. Eight plastid simple sequence repeats (cpSSRs) were used to investigate plastid genetic variation in 22 populations of Taxus wallichiana var. mairei, encompassing nearly its entire distribution range. Low levels of plastid genetic variation and differentiation were detected in the populations, and the findings were attributed to low mutation rates, small population sizes, habitat fragmentation and isolation, and effective pollen or seed dispersal. Hunan and Hubei were identified as major refugia based on the number of private haplotypes and species distribution modeling. Trends in plastid genetic diversity and genetic differentiation from central to peripheral populations supported the predictions of the central–marginal hypothesis. In scenarios wherein the future climate becomes warmer, we predict that some peripheral populations will disappear and southern and southeastern regions will become significantly less habitable. Factors that include the levels of precipitation during the driest month, annual precipitation level, and annual temperature range will be decisive in shaping the future distribution of these populations. This study provides a theoretical basis for the conservation of T. wallichiana var. mairei.     

Ecological analysis and environmental niche modelling of Dactylorhiza hatagirea (D. Don) Soo: A conservation approach for critically endangered medicinal orchid

The natural populations of Dactylorhiza hatagirea have been greatly affected due to incessant exploitation. As such, studies on its population attributes together with habitat suitability and environmental factors affecting its distribution are needed to be undertaken for its conservation in nature. Present study aimed at accessing an impact of anthropogenic pressure on population structure and locate suitable habitats for the conservation of this critically endangered orchid. Considerable changes in the phytosociological attributes were observed on account of the changing magnitude and extent of anthropogenic threat in their natural abode. The distribution pattern of species indicated that more than 90% of the populations exhibit substantially aggregated spatial distribution. Maximum Entropy (MaxEnt) distribution modelling algorithm was used to predict suitable habitat and potential area for its cultivation and reintroduction. Twenty-seven occurrence records, nineteen bioclimatic variables, altitude, and slope were used. MaxEnt map output gave the habitat suitability for this species and predicted its distribution in the North-Western Himalayas of India for approximately 616 km². Jackknifing indicated that maximum temperature of warmest month, annual mean temperature, mean temperature of the driest quarter, and mean temperature of the wettest quarter were the governing factors for its distribution and hence, presented a higher gain with respect to other variables. According to permutation importance, precipitation seasonality and mean temperature of wettest quarter shows the prominent impact on the habitat distribution. Results of AUC (area under curve) were statistically significant (0.940) and the line of predicted omission falls very close to an omission on training samples, validating a better run of the model. Response curves revealed a probable increase in the occurrence of D. hatagirea with an increase in mean temperature of the wettest quarter and maximum temperature of the warmest month contributed more than 50% to predicted habitat suitability. Direct field observations concurrent with predicted habitat suitability and google-earth images represent greater model thresholds for successful inception of the species. Together, the study proposes that the species can be conserved in or near its present-day natural habitats and is equally effective in determining the possible habitats for its cultivation and reintroduction.     

Prediction of wild pistachio ecological niche using machine learning models

Observing vegetation dynamics and determining optimum conditions for tree species are important for the long-term habitat conservation. In this study we evaluate the environmental drivers that may explain the development and geographic distribution of Pistacia atlantica Desf. (wild pistachio) in Northeastern Iran. The study uses seven machine learning models to predict the habitats of P. atlantica: multivariate adaptive regression splines (MARS), flexible discriminant analysis (FDA), boosted regression tree (BRT), maximum entropy (MaxEnt), random forest (RF), support vector machine (SVM), generalized linear model (GLM), and their ensembles (ESMs). In total, 1477 P. atlantica sites were identified, described and mapped. The most relevant determinants of the species habitat were included as 28 bioclimatic, topographic, edaphic, and geologic components. While all the models returned high accuracies, the ESMs achieved the highest AUC, TSS, and Kappa values, suggesting a good predictive performance. The most important parameters explaining the species habitat were found to be the mean diurnal temperature range, annual precipitation and slope. These results support the higher performance of ESMs to predict the spatial distribution of P. atlantica. In turn, this model may support species conservation and decision-making at the regional and national levels.     

Distribution of gymnosperms in West Pakistan

Summary In West Pakistan 17 species of Gymnosperms are found wild. Out of these 13 species belong to the conifers and 4 species are of Ephedra. In the Plains only Ephedra foliata Borss. is found. In the outer ranges of Kashmir, Murree Hills, Hazara, Swat and Dir which are under the dominant influence of summer monsoon rains only Conifers consisting of Pinus roxburgii Sarg. Pinus wallichiana A.B.Jacks., Picea smithiana Boiss., Taxus baccata L., Abies pindrow Spach., Abies spectabis Royle are found and are indigenous to the Western Himalayas with the exception of Taxus baccata L. These species show relationship with those found in the Mediterranean and temperate Central European regions. There is not much resemblance between these and the Conifers of adjoining Eastern Himalayas. The Conifers and the Ephedra species found in Quetta, Waziristan, Kurram, Chitral, Gilgit, Indus Kohistan and Upper parts of Dir, Swat, Kaghan and Kishan Ganga which are under the dominant influence of winter rains are inhibited by elements of Pak-Turanio floristic region. The species belonging to this category are Cedrus deodara Loud., Pinus gerardiana Wall., Juniperus macropoda Boiss., Juniperus communis L., Ephedra gerardiana Wall. and Ephedra intermedia Sabr. et C.A.May. Plants of this region show clear affinities with the flora of the Mediterranean region. In the northern parts like Chitral and Gilgit central Asian elements are represented by Ephedra przewalskii Stapf and Juniperus turkestanica Kom.

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Zusammenfassung In West Pakistan gibt es 17 Arten von Gymnospermen, von denen 13 Coniferen und 4 Ephedra sind. Im Flachland gibt es nur Ephedra foliata Boiss. Am äusseren Rande von Kashmir, Murree Hills, Hazara, Swat und Dir, wo der Einfluss der Sommermonsun Regen gross ist findet man Pinus roxburgii Sarg, Pinus wallichiana A.B.Jacks., Picea smithiana Boiss., Taxus baccata L. Abies pindrow Spach. und Abies spectabis Royle. Dies sind einheimische Arten aus West Himalaya mit Ausnahme von Taxus baccata L. Sie haben Verwandtschaft mit den Arten aus der Mediterran und gemässigten Zone Mitteleuropas, aber überhaupt keine mit dem benachbarten östlichen Himalaya Gebiet. Die Coniferen und Ephedra-Arten aus Quetta, Waziristan, Kurram, Chitral, Gilgit, Indus Kohistan, und dem oberen Teil aus Dir, Swat, Kaghan und Kishan Ganga stehen unter dem Einfluss der Winterregen, und bilden das Pak-Turanio floristische Gebiet. Es sind die Arten Cedrus deodara Loud., Pinus gerardiana Wall., Juniperus macropoda Boiss., Juniperus communis L., Ephedra gerardiana Wall., Ephedra intermedia Sabr. et C.A.May. Die Vegetation dieses Gebietes zeigt eindeutige Verwandtschaft mit der Vegetation des Mediterran-Gebietes. In dem nördlichen Teil, wie Chitral und Gilgit sind Ephedra przewalskii Stapf. und Juniperus turkestanica Kom. zentral-asiatische Elemente.

     

Using MaxEnt modeling to predict the potential distribution of the endemic plant Rosa arabica Crép. in Egypt

Climate change poses negative impacts on plant species, particularly for those of restricted ecology and distribution range. Rosa arabica Crép., an exclusive endemic species to Saint Catherine Protectorate in Egypt, has severely declined and become critically endangered in the last years. In this paper, we applied the maximum-entropy algorithm (MaxEnt) to predict the current and future potential distribution of this species in order to provide a basis for its protection and conservation. In total, 32 field-based occurrence points and 22 environmental variables (19 bioclimatic and three topographic) were used to model the potential distribution area under current and two future representative concentration pathways (RCP2.6 and RCP8.5) for the years 2050 and 2070. Annual temperature, annual precipitation and elevation were the key factors for the distribution of R. arabica. The response curves showed that this species prefers habitats with an annual temperature of 8.05–15.4 °C, annual precipitation of 36 to 120 mm and elevation range of 1571 to 2273 m a.s.l. Most of the potential current suitable conditions were located at the middle northern region of Saint Catherine. Prediction models under two future climate change scenarios displayed habitat range shifts through the disappearance of R. arabica in sites below 1500 m a.s.l., an altitudinal range contraction at 1500–2000 m and possible expansions towards higher elevation sites (2000–2500 m a.s.l.). Our findings can be used to define the high priority areas for reintroduction or for protection against the expected climate change impacts and future modifications.     

The impact of climate change on the distribution of rare and endangered tree Firmiana kwangsiensis using the Maxent modeling

The upsurge in anthropogenic climate change has accelerated the habitat loss and fragmentation of wild animals and plants. The rare and endangered plants are important biodiversity elements. However, the lack of comprehensive and reliable information on the spatial distribution of these organisms has hampered holistic and efficient conservation management measures. We explored the consequences of climate change on the geographical distribution of Firmiana kwangsiensis (Malvaceae), an endangered species, to provide a reference for conservation, introduction, and cultivation of this species in new ecological zones. Modeling of the potential distribution of F. kwangsiensis under the current and two future climate scenarios in maximum entropy was performed based on 30 occurrence records and 27 environmental variables of the plant. We found that precipitation‐associated and temperature‐associated variables limited the potentially suitable habitats for F. kwangsiensis. Our model predicted 259,504 km² of F. kwangsiensis habitat based on 25 percentile thresholds. However, the high suitable habitat for F. kwangsiensis is only about 41,027 km². F. kwangsiensis is most distributed in Guangxi''s protected areas. However, the existing reserves are only 2.7% of the total suitable habitat and 4.2% of the high suitable habitat for the plant, lower than the average protection area in Guangxi (7.2%). This means the current protected areas network is insufficient, underlining the need for alternative conservation mechanisms to protect the plant habitat. Our findings will help identify additional F. kwangsiensis localities and potential habitats and inform the development and implementation of conservation, management, and cultivation practices of such rare tree species.     

Structural diversity of naturally regenerating Chinese yew (Taxus wallichiana var. mairei) populations in ex situ conservation

The Chinese yew (Taxus wallichiana var. mairei) is ranked in the first class of important wild endangered plants in China. Due to overexploitation, it now occurs scattered only in the forest undergrowth along the Yangtze River Valley. To improve the conservation management of the species, we applied structural indices to investigate the structural diversity of naturally regenerating yew populations that have established via ex situ conservation. The results show that most yews had larger non‐yew tree neighbors; these were 30–70% larger than their reference trees. Collectively, the average distances between the yews and the three nearest‐neighboring trees were short ( 3 m), suggesting that the yews face strong interspecific competition from neighbors. In these two forest stands, most of the pole‐sized yews were found beneath a single tall neighboring tree (height  10 m), and their growth was enhanced under a single neighboring tree but not under two, three or zero neighboring trees. Finally, we recommend simple silvicultural measures to reduce interspecific competition and improve the vitality of the yew population; specifically, the cutting or pruning of branches of large neighboring trees in tandem with the thinning of canopy trees growing next to the mother yews.     

Preventing extinction and improving conservation status of Mesua assamica (King & Prain) Kosterm. - An endangered plant of Assam,India

Mesua assamica (King & Prain) Kosterm., commonly known as “Sia- Nahar” in Assamese is an evergreen tree belonging to family Calophyllaceae. The wood of this plant is highly preferred as fuel. However, the plant also records its significance in bearing several pharmaceutical potential components along with several traditional practices by the local people such as fish poisoning, etc. Large scale felling of the tree and clearance of habitats of the plant for extension of arable land for tea plantations and other agricultural activities, the plant has been disappearing at an alarming rate from its natural habitat and has been recorded as endangered to the area. Therefore, conservation of this potential medicinal plant with proper scientific investigation to prevent extinction in its wild habitat is urgently needed. Seed germination under natural conditions was found to be very poor for which a macropropagation protocol was standardized; saplings were raised in experimental nursery and reinforced to locations where the population size is very small in relation to other associated species. Those suitable wild habitats for reinforcement were selected by Maximum Entropy (MaxEnt) distribution modelling algorithm developed using environmental parameters and locality data in the natural range of the species. The model predicts the suitable habitats for its reintroduction to ensure its perpetuity. A total of 1000 saplings of M. assamica were reinforced to the field and the rate of survivability was measured over a period of 12 months at an interval of 60 days that revealed 75.5% survivability of the reinforced saplings. This study has proved as an effective method for improving the conservation status of the plant.     

Identifying conservation priority areas and predicting the climate change impact on the future habitats of endangered Nepenthes khasiana Hook.f. utilizing ecological niche modelling

Developing strategies for effective species conservation is necessary to counter the ever-fluctuating environmental conditions with increasing anthropogenic activities. Studies have proven Ecological Niche Modelling (ENM) as an effective tool for sustainable conservation. Nepenthes khasiana Hook.f. is an endangered pitcher plant facing a constant decline in population due to anthropogenic activities. This study aimed to locate the most suitable areas for re-establishing the species in natural habitats using Maximum Entropy (MaxEnt) modelling, and to forecast the effects of current and future climate conditions on its distribution throughout Northeast India. The potential suitable areas in future climate under three Representative Concentration Pathway (RCP) scenarios and in the current climate were predicted utilizing the 30 occurrence data, bioclimatic predictors, and variables from BCC-CSM1.1 model and WorldClim respectively. The results of the current study showed significant relationships among annual precipitation, precipitation in the driest month, seasonality of precipitation, annual range iso-thermality of temperature, mean diurnal range [Mean of monthly (max temp - min temp)], and the distribution of the analysed species. The optimum model performance was represented by the AUC value of 0.972 ± 0.007. The model predicted 10.70% of the NE Indian region as climatically suitable, which will expand under RCP4.5 and RCP6.0, reaching 15.35%, and 12.64%, respectively. However, this may degrade significantly under RCP8.5, reducing to 8.14%. Based on the analysis of modelling results it was found that the Nokrek belt and the Khasi hills as highly suitable regions for the reintroduction of the species. The study revalidated ENM as an effective means to identify new populations and predict the influence of climate change on the future habitat which can benefit the concurrent species management strategies.     

Environmental drivers inducing habitat expansion and shift of introduced alien trout in the Himalayan ecosystem and management concerns

There is a concern of the spread of introduced trout Salmo trutta and Oncorhynchus mykiss which might have potential effects on native fish species in the Himalaya. We present the first assessment of current habitat expansion of introduced trout induced by environmental drivers and posing threats to the local fish diversity. Maximum Entropy (MaxEnt) model was used and overlaid with presence-only data onto bioclimatic and environmental layers to characterize the conditions most suitable for the habitat expansion of trout. Mean AUC value for S. trutta was 0.919 and 0.881 for O. mykiss respectively showing that the MaxEnt model was highly accurate and statistically significant. The precipitation of driest quarter (Bio_17) alone accounted for 71.4% habitat expansion of S. trutta across rivers’ length and 61.1% in the case of O. mykiss. The Jackknife test of different environmental variable particularly Bio_17 and the coldest quarter (Bio_19) depicted their potential role in habitat expansion. The occurrences of trout in the Himalayan streams predicted trade-offs between few environmental variables and habitat expansion. The findings suggested that habitat expansion of trout was induced by identified environmental drivers impacting the array of biological and ecological integrity in the new geographic spaces concerning trout invasion.     

The impact of climate change on the future geographical distribution range of the endemic relict tree Gleditsia caspica (Fabaceae) in Hyrcanian forests

The Caspian locust (Gleditsia caspica) is an endemic relict tree that occurs in Hyrcanian forests. Many of its habitats have been destroyed in the last half-century. This study was performed to map past geographic distributions and estimate the suitable areas and potential risks of remaining populations under future climate change. Eight bioclimatic scenarios (one with current conditions, three with future climates, and four with past conditions) were tested using the maximum entropy algorithm. The most significant factors influencing the distributions of G. caspica were precipitation in the driest month and temperature seasonality. Even under the most optimistic model (RCP2.6), many stands of G. caspica may become endangered in the eastern and central parts of the range, and the distribution of this species will probably shift to the west of the Hyrcanian forest area. Considering the increasing destruction of habitats of this species due to human activities and the expected negative effects of climate change in the future, it is recommended that nature reserves be established to protect the habitat of G. caspica. Additionally, ex situ conservation strategies, such as storing seeds using cryopreservation techniques, can ensure the long-term survival of this species in the future.     

Identifying climate refugia and its potential impact on Tibetan brown bear (Ursus arctos pruinosus) in Sanjiangyuan National Park,China

Climate change has direct impacts on wildlife and future biodiversity protection efforts. Vulnerability assessment and habitat connectivity analyses are necessary for drafting effective conservation strategies for threatened species such as the Tibetan brown bear (Ursus arctos pruinosus). We used the maximum entropy (MaxEnt) model to assess the current (1950–2000) and future (2041–2060) habitat suitability by combining bioclimatic and environmental variables, and identified potential climate refugia for Tibetan brown bears in Sanjiangyuan National Park, China. Next, we selected Circuit model to simulate potential migration paths based on current and future climatically suitable habitat. Results indicate a total area of potential suitable habitat under the current climate scenario of approximately 31,649.46 km², of which 28,778.29 km² would be unsuitable by the 2050s. Potentially suitable habitat under the future climate scenario was projected to cover an area of 23,738.6 km². Climate refugia occupied 2,871.17 km², primarily in the midwestern and northeastern regions of Yangtze River Zone, as well as the northern region of Yellow River Zone. The altitude of climate refugia ranged from 4,307 to 5,524 m, with 52.93% lying at altitudes between 4,300 and 4,600 m. Refugia were mainly distributed on bare rock, alpine steppe, and alpine meadow. Corridors linking areas of potentially suitable brown bear habitat and a substantial portion of paths with low‐resistance value were distributed in climate refugia. We recommend various actions to ameliorate the impact of climate change on brown bears, such as protecting climatically suitable habitat, establishing habitat corridors, restructuring conservation areas, and strengthening monitoring efforts.     

Ecological characterization of Morel (Morchella spp.) habitats: A multivariate comparison from three forest types of district Swat,Pakistan

Morchella spp. are wild edible mushrooms growing ephemerally under particular environmental conditions in temperate regions of the world. The present study was aimed to outline some principal eco-edaphic characteristics influencing distribution of these mushrooms from three different forest types of Swat, Pakistan. A randomized circular plots were laid down along the transect line in 14 stands in study areas. Environmental variables were recorded and soil characteristics were determined, analyzed and compared. Five species were collected from N to NW slope at elevation range of 1100-2695m asl. Mean relative humidity of 58.7%, range of air temperature 13 °C-27 °C and soil temperature 6-26 °C were recorded at morel growing sites. A higher canopy cover (average 57%) favours sporocarp formation in morels. Soil analysis showed that morel preferably appeared in sandy loam to loamy textured soil at slightly acidic to neutral pH (mean=6.4) and with consistently higher organic matter (1.5%) and salt activities (mean = 38.8 μS) in the soil. IVI calculation showed that Pinus wallichiana A. B. Jackson, Juglans regia L., Abies pindrow Royle, Cedrus deodara (Roxb. ex D. Don) G. Don were dominant trees and Viburnum grandiflorum Wall. ex DC, Hedra nepalensis K. Koch, Hert and Sarcococca saligna (D. Don) Muell. Arg. were shrub species associated with morels. Whilst Fragaria nubicola (Hook.f.) Lindl., Viola canescens Wall ex Roxb. and Podophyllum hexandrum Roylae were the predominant herbs in morel habitat. This study will help to understand the natural habitat and to provide a base line information for the future conservation and management planning in the area.     

How much does climate change threaten European forest tree species distributions?

Although numerous species distribution models have been developed, most were based on insufficient distribution data or used older climate change scenarios. We aimed to quantify changes in projected ranges and threat level by the years 2061–2080, for 12 European forest tree species under three climate change scenarios. We combined tree distribution data from the Global Biodiversity Information Facility, EUFORGEN, and forest inventories, and we developed species distribution models using MaxEnt and 19 bioclimatic variables. Models were developed for three climate change scenarios—optimistic (RCP2.6), moderate (RCP4.5), and pessimistic (RPC8.5)—using three General Circulation Models, for the period 2061–2080. Our study revealed different responses of tree species to projected climate change. The species may be divided into three groups: “winners”—mostly late‐successional species: Abies alba, Fagus sylvatica, Fraxinus excelsior, Quercus robur, and Quercus petraea; “losers”—mostly pioneer species: Betula pendula, Larix decidua, Picea abies, and Pinus sylvestris; and alien species—Pseudotsuga menziesii, Quercus rubra, and Robinia pseudoacacia, which may be also considered as “winners.” Assuming limited migration, most of the species studied would face a significant decrease in suitable habitat area. The threat level was highest for species that currently have the northernmost distribution centers. Ecological consequences of the projected range contractions would be serious for both forest management and nature conservation.     

Neottia cordata (Orchidaceae) at its southernmost distribution border in Europe: Threat status and effectiveness of Natura 2000 Network for its conservation

Neottia cordata is an orchid species that exclusively occurs in Picea abies subsp. abies and Pinus sylvestris stands and forms its southernmost distribution limits in Greece. Over the last decade, it has been recorded in numerous sites, in which it forms small colonies, both in terms of population and area. This research re-evaluates the threat status of Neottia cordata based on updated chorological and population data; it also checks the effectiveness of the Natura 2000 Network as far as its conservation is concerned by applying the MaxEnt model. The recently collected data justify the classification of N. cordata as "Vulnerable". The most significant variables that affect its distribution were found to be the vegetation type and the precipitation of the warmest quarter. The results of the MaxEnt model suggest that: (i) the Natura 2000 Network is characterised by areas of higher habitat suitability values when compared to the areas that fall outside this network; and, (ii) Picea abies subsp. abies forests are more suitable for its conservation than those of Pinus sylvestris. It is concluded that the most appropriate management measure for the species conservation is the maintenance of the tree layer canopy closed.     

Ecological correlates of Himalayan musk deer Moschus leucogaster

Himalayan musk deer (Moschus leucogaster; hereafter musk deer) are endangered as a result of poaching and habitat loss. The species is nocturnal, crepuscular, and elusive, making direct observation of habitat use and behavior difficult. However, musk deer establish and repeatedly use the same latrines for defecation. To quantify musk deer habitat correlates, we used observational spatial data based on presence–absence of musk deer latrines, as well as a range of fine spatial‐scale ecological covariates. To determine presence–absence of musk deer, we exhaustively searched randomly selected forest trails using a 20‐m belt transect in different study sites within the Neshyang Valley in the Annapurna Conservation Area. In a subsequent way, study sites were classified as habitat or nonhabitat for musk deer. A total of 252 plots, 20 × 20 m, were systematically established every 100 m along 51 transects (each ~0.5 km long) laid out at different elevations to record a range of ecological habitat variables. We used mixed‐effect models and principal component analysis to characterize relationships between deer presence–absence data and habitat variables. We confirmed musk deer use latrines in forests located at higher elevations (3,200–4,200 m) throughout multiple seasons and years. Himalayan birch (Betula utilis) dominated forest, mixed Himalayan fir (Abies spectabilis), and birch forest were preferred over pure Himalayan fir and blue pine (Pinus wallichiana) forest. Greater crown cover and shrub diversity were associated with the presence of musk deer whereas tree height, diameter, and diversity were weakly correlated. Topographical attributes including aspect, elevation, distance to water source, and slope were also discriminated by musk deer. Over‐ and understory forest management can be used to protect forests likely to have musk deer as predicted by the models to ensure long‐term conservation of this rare deer.     

Ecological modelling for the conservation of Gluta travancorica Bedd. - An endemic tree species of southern Western Ghats,India

Endemic species are highly adapted to grow exclusively in a specific geographical area. The goal of the current study is to determine the probable habitat distribution range of the narrowly endemic species Gluta travancorica. An ecological niche modelling is carried out, using four different models viz., BioClim, MaxEnt, Random Forest and Deep Neural Networks (DNN). A total of 506 G. travancorica cluster locations were surveyed and used for this study with thirty different ecogeographic, edaphic and bioclimatic environmental parameters. After a preliminary investigation using multi-collinearity analysis, soil parameter variables like pH, cation exchange capacity (CEC), silt and clay content are used for final modelling. Factor analysis of ecological niche revealed the soil parameters like pH, CEC, silt and clay content as the key predictors. The result is validated using true skill statistics, sensitivity, specificity, kappa statistic and AUC-ROC. Results of the present study show that DNN have exceptional prediction performance, demonstrated by its AUC score of 0.959. DNN model projected 32.37% (938.18 km²) of the study region to have a ‘highly suitable habitat’, whereas 67.63% (1960.82 km²) was classified as having ‘low habitat suitability’. Besides, back-to-field assessments have also proven DNN's potential in predicting the habitat suitability of G. travancorica. The study results will facilitate the prioritization of conservation and seedling restoration strategies. The forest range explored in this work is a component of one of the most important global biodiversity hotspots, and it has significant implications for regional biodiversity conservation.