Separation of the bioclimatic spaces of Himalayan tree rhododendron species predicted by ensemble suitability models

Projecting the global potential distribution of nine Rhododendron Subgenus Hymenanthes species under different climate change scenarios

As one of China's most treasured traditional flowers, Rhododendron Subgen. Hymenanthes is renowned worldwide for its evergreen foliage, vibrant flowers, and significant ornamental, landscaping, and economic value. However, climate change poses a serious threat to its future, leading to population declines and endangerment of some species. Despite the ecological and economic importance of Rhododendron Subgen. Hymenanthes, the future distribution of suitable habitats and the most effective strategies for its conservation and utilization remain unclear. This study employs the MaxEnt model, which is well-known for its reliability in predicting species distribution under changing environmental conditions, to predict the potential global distribution of nine species of Rhododendron Subgen. Hymenanthes. The goal is to provide a solid foundation for their conservation, cultivation management, and breeding. The results indicate that, under future climate scenarios, suitable habitat areas for four species (R. irroratum, R. agastum, R. decorum, and R. arboreum) will significantly decrease, while suitable habitats for the remaining five species (R. delavayi, R. fortunei, R. calophytum, R. simiarum, and R. wardii) will experience slight expansion. Temperature and precipitation are identified as key environmental factors influencing the growth and distribution of these species, affecting their ability to colonize new regions. The migration direction of the expanding regions for all nine species is consistent, with their centroids shifting towards the northwest. These findings provide critical insights for developing targeted conservation strategies, including identifying potential refugia and prioritizing conservation areas under future climate conditions.

Assessing the role of Alnus nepalensis D. Don in stabilizing landslide and its potential distribution: a case study from Uttarakhand, Western Himalaya

The rising frequency and severity of landslides in the vulnerable Himalayan region of India threaten human settlements and critical infrastructure. This growing issue demands urgent action and innovative strategies to mitigate risks and bolster the resilience of affected communities and infrastructure in this fragile area. The research explores the use of Alnus nepalensis for slope stabilization, illustrated by a case study near Ukhimath, Uttarakhand, India, and elucidates the potential ecological niche of Alnus in the temperate region of Uttarakhand using well-dispersed species occurrence records along with environment. The study used Sentinel-2 (2021) data for land use and land cover (LULC) mapping and Landsat 4-5, Sentinel-2, and Google Earth imagery from 1998, 2004, 2015, 2019, and 2020 for landslide slope recovery assessment. The Ukhimath landslide, spanning 54.61 ha in August 1998, demonstrated a remarkable recovery, with 98.20% coverage of Alnus by 2020, showcasing the species efficacy in stabilizing slopes without human intervention. The research forecasts a total potential distribution area of Alnus in the temperate region (1,000-2,500 m·asl [above mean sea level]) of Uttarakhand as ∼7,833 km2, with 782.30  km2 highly suitable, 2,104.33  km2 moderately suitable, and the rest showing low suitability. These distribution insights provide a foundation for in situ planning to leverage Alnus-based bioengineering for early slope stabilization, which is especially relevant in landslide-prone areas like Uttarakhand. The study provides a comprehensive and scientifically rigorous strategy for achieving sustainable outcomes in landslide-prone areas, particularly in the lower temperate region of the Himalaya.

Aging varies greatly within a single genus: A demographic study of Rhododendron spp. in botanic gardens

PREMISE

There is mounting evidence that age matters in plant demography, but also indications that relationships between age and demographic rates may vary significantly among species. Age-based plant demographic data, however, are time-consuming to collect and still lacking for most species, and little is known about general patterns across species or what may drive differences.

METHODS

We used individual birth and death records for 12 Rhododendron species from botanic gardens and conducted Bayesian survival trajectory analyses to assess how mortality changed with age. We calculated the demographic measures of aging rate, life-span equality, and life expectancy for each species, and assessed their relationships with the climatic conditions at species' sites of ancestral origin and with taxonomic group (subgenus).

RESULTS

We found substantial among-species variation in survival trajectories, with mortality increasing, decreasing, or remaining constant with advancing age. Moreover, we found no relationships between demographic measures and ancestral climatic conditions but there were statistically significant differences among taxonomic groups in the rate of change in mortality with age (aging rate).

CONCLUSIONS

We conclude that demographic consequences of aging can differ qualitatively, even among species in the same genus. In addition, taxonomic trends in aging rates indicate they may be genetically determined, though evolutionary drivers are still unclear. Furthermore, we suggest there is untapped potential in using botanic garden records in future studies on plant life history.

TreeGOER: A database with globally observed environmental ranges for 48,129 tree species

The TreeGOER (Tree Globally Observed Environmental Ranges) database provides information for most known tree species of their environmental ranges for 38 bioclimatic, eight soil and three topographic variables. It is based on species distribution modelling analyses of more than 44 million occurrences. The database can be accessed from https://doi.org/10.5281/zenodo.7922927. Statistics that include 5% and 95% quantiles were estimated for a cleaned and taxonomically standardized occurrence data set with different methods of outlier detection, with estimates for roughly 45% of species being based on 20 or more observation records. Where sufficient representative observations are available, the ranges provide useful preliminary estimates of suitable conditions particularly for lesser-known species under climate change. Inferred core bioclimatic ranges of species along global temperature and moisture index gradients and across continents follow the known global distribution of tree diversity such as its highest levels in moist tropical forests and the 'odd man out' pattern of lower levels in Africa. To demonstrate how global analyses for large numbers of tree species can easily be done in R with TreeGOER, here I present two case studies. The first case study investigated latitudinal trends of tree vulnerability and compared these with previous results obtained for urban trees. The second case study focused on tropical areas, compared trends in different longitudinal zones and investigated patterns for the moisture index. TreeGOER is expected to benefit researchers conducting biogeographical and climate change research for a wide range of tree species at a variety of spatial and temporal scales.

Seeing from space makes sense: Novel earth observation variables accurately map species distributions over Himalaya

Topical advances in earth observation have enabled spatially explicit mapping of species' fundamental niche limits that can be used for nature conservation and management applications. This study investigates the possibility of applying functional variables of ecosystem retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) onboard sensor data to map the species distribution of two alpine treeline species, namely Betula utilis D.Don and Rhododendron campanulatum D.Don over the Himalayan biodiversity hotspot. In this study, we have developed forty-nine Novel Earth Observation Variables (NEOVs) from MODIS products, an asset to the present investigation. To determine the effectiveness and ecological significance of NEOVs combinations, we built and compared four different models, namely, a bioclimatic model (BCM) with bioclimatic predictor variables, a phenology model (PhenoM) with earth observation derived phenological predictor variables, a biophysical model (BiophyM) with earth observation derived biophysical predictor variables, and a hybrid model (HM) with a combination of selected predictor variables from BCM, PhenoM, and BiophyM. All models utilized topographical variables by default. Models that include NEOVs were competitive for focal species, and models without NEOVs had considerably poor model performance and explanatory strength. To ascertain the accurate predictions, we assessed the congruence of predictions by pairwise comparisons of their performance. Among the three machine learning algorithms tested (artificial neural networks, generalised boosting model, and maximum entropy), maximum entropy produced the most promising predictions for BCM, PhenoM, BiophyM, and HM. Area under curve (AUC) and true skill statistic (TSS) scores for the BCM, PhenoM, BiophyM, and HM models derived from maximum entropy were AUC ≥0.9 and TSS ≥0.6 for the focal species. The overall investigation revealed the competency of NEOVs in the accurate prediction of species' fundamental niches, but conventional bioclimatic variables were unable to achieve such a level of precision. A principal component analysis of environmental spaces disclosed that niches of focal species substantially overlapped each other. We demonstrate that the use of satellite onboard sensors' biotic and abiotic variables with species occurrence data can provide precision and resolution for species distribution mapping at a scale that is relevant ecologically and at the operational scale of most conservation and management actions.

Identification of suitable habitat for Taxus wallichiana and Abies pindrow in moist temperate forest using maxent modelling technique

Conservation of any species necessitates knowledge of its biology and natural history, as well as prospective locations or newer adaptive landscapes where the species can survive and thrive. This study presents habitat suitability and local conservation status of Taxus wallichiana and Abies pindrow in moist temperate forest of Hazara division, Pakistan. Data was collected through field surveys based on 363 samples from field, topographical and bioclimatic variables. In the present study, we employed the MaxEnt model exclusively for each tree species along with 23 independent or environment variables (19 bioclimatic and 4 topographic). The jackknife test was used to demonstrate the significance of variables with the highest gain, and it was found that overall tree cover, annual temperature range was the factors with the highest gain, while slope was amongst the least important. The MaxEnt model produced high accuracy for each tree species, with receiver operating characteristic (ROC), area under the curve (AUC), training mean testing values for Taxus wallichiana was 0.966 followed by 0.944 for Abies pindrow. Local conservation status of Taxus wallichiana and Abies pindrow was evaluated using IUCN criteria 2001. Taxus wallichiana was declared critically endangered locally as the population size reduced by 87%. In contrast, Abies pindrow was declared as endangered as population size reduced by 69% falling under endangered criteria A of IUCN. The decline in population size of Taxus wallichiana and Abies pindrow species were due to human cause anthropogenic activities such as exploitation and loss of habitat, the extent of occurrence, and slow regeneration of tree species. Results and field-based observation revealed that suitable habitat modeling showed unsuitable (0.0–0.2), less suitable (0.2–0.4), moderately (0.4–0.6), highly (0.6–0.7), and very highly (0.7–1.0) suitable habitat for Taxus wallichiana and Abies pindrow. Results also revealed that both species were distributed irregularly in the moist temperate forest of Hazara division. Habitat suitability of Taxus wallichiana and Abies pindrow can be considered one of most significant points toward conserving these tree species. Habitat loss is a major threat to their occurrence, which should be overcome by ensuring the protection of suitable habitat and conservation approaches. Considering the species ecological and economic value, it is essential to understand how the species distribution may vary as a result of climate change to establish effective conservation policies. This study also includes significant environmental elements that influence species distribution, which could help locate regions where the species could be planted. Forest tree species require effective, scientific, and long-term management and conservation techniques in the study area. Furthermore, the formulation and implementation of protective laws and policies are required to conserve and protect both the conifer species.

Predicting the distributional range shifts of Rhizocarpon geographicum (L.) DC. in Indian Himalayan Region under future climate scenarios

Himalaya, the highest mountain system in the world and house of important biodiversity hotspot, is sensitive to projected warming by climate change. Rhizocarpon geographicum (map lichen), a crustose lichen, grows in high mountain ranges, is a potential indicator species of climate change. In the present study, MaxEnt species distribution modeling algorithm was used to predict the suitable habitat for R. geographicum in current and future climate scenarios. Nineteen bioclimatic variables from WorldClim database, along with elevation, were used to predict the current distribution and three representative concentration pathway (RCP) scenarios by integrating three general circulation models (GCMs) for future distribution of species covering years 2050 and 2070. Furthermore, we performed change analysis to identify the precise difference between the current and future distribution of suitable areas of the species for delineating habitat range expansion (gain), habitat contraction (loss), and stable habitats. The final ensemble model obtained had average test value 0.968, and its predicted ~ 27.5% of the geographical area in the Indian Himalayan Region is presently climatically suitable for the species. The predicted highly suitable area for R. geographicum is observed to be declining in Northwestern Himalaya, and it is shifting towards the higher elevation areas of the Eastern Himalaya. The projected distribution in future under the RCP scenarios (RCP 4.5, 6.0, and 8.5) showed the range expansion towards higher elevations, and it is more pronounced for the extreme future scenarios (RCP 8.5) than for the moderate and intermediate climate scenarios (RCP 4.5 and RCP 6.0). However, assuming that species can migrate to previously unoccupied areas, the model forecasts a habitat loss of 10.86-16.51% for R. geographicum, which is expected due to increase in mean annual temperature by 1.5-3.7 °C. The predictive MaxEnt modeling approach for mapping lichen will contribute significantly to the understanding of the impact of climate change in Himalayan ecosystems with wide implications for drawing suitable conservation plans and to take adaptation and mitigation measures.

Rhododendron arboreum: A Critical Review on Phytochemicals, Health Benefits and Applications in the Food Processing Industries

Abstract:

Rhododendron is a resourceful, evergreen shrub or a small tree with an ornate display of scarlet red or pale pink flowers that belongs to the family Ericaceae. Rhododendron plants are traditionally used to treat numerous human ailments like blood dysentery, headache, asthma, cough, stomachache, fever, inflammation and fungal infections. Rhododendron also has economic, medicinal, and pharmacological importance. Rhododendron has been regarded as a rich source of secondary metabolites. Apart from aesthetic and sacred values, from past times, Rhododendron juice was prepared from the flowers to curb allergies, treat diabetes and deal with inflammations. Recent studies have shown several promising activities particularly relaxant, digestive enzyme, antioxidant, antimicrobial, antispasmodic, anticancer and antagonistic effects. With the rapidly growing popularity of Rhododendron arboreum, it is important to have a comprehensive reference for its nutritional benefits with the growing search for natural and healthy foods. This work aimed to review the recent advances in research carried out to date for the purposive evaluation of the nutritional quality and potential health benefits of Rhododendron arboreum for its utilization in food processing industries for composing novel value- added products, to achieve high consumer acceptability and health benefits.

Potential habitat distribution of Himalayan red panda and their connectivity in Sakteng Wildlife Sanctuary, Bhutan

Survival of endangered Himalayan red panda is threatened by ever-growing anthropogenic activities leading to an unprecedented rate of habitat degradation and loss. However, limited studies have been conducted in the context of the spatial distribution of habitats and habitat connectivity for the species in the landscape of Sakteng Wildlife Sanctuary (SWS). Lack of such information remains a challenge while implementing effective and holistic conservation initiatives. Therefore, this study identifies the distribution of potential habitats and their connectivity using maxent and linkage mapper, respectively. Precipitation-related predictor variables exhibited a significant influence on the prediction of habitat distribution. The model predicted 27.7% of the SWS as a potential habitat (fundamental niche). More than 75% of the predicted habitats fall outside the existing core zones where anthropogenic disturbance is relatively high, indicating the need to reassess existing management options. In SWS, 15 core habitats (CH) are predicted which are connected by a least-cost corridor (length µ = 2.91 km) with several pinch points in it. Centrally located CH5 and CH11 are identified as the most important habitat in maintaining overall connectivity within SWS. However, CH located in the peripheries could be equally important in facilitating the transboundary movement of the species. Overall, SWS can play a critical role as a connecting link between the larger landscape of Bhutan and the adjacent Indian state of Arunachal Pradesh in the conservation of Himalayan red panda that exhibits narrow dispersal with special habitat needs. Based on our findings, we recommend initiating GPS/satellite telemetry of the species to enable SWS to understand the precise interaction of Himalayan red panda to widespread herder communities, livestock, and free-roaming dogs dwelling in the same landscape. It will also help to evaluate the functionality of the predicted habitats, linkages, and feasibility of transboundary conservation initiatives.

Synthesis, characterization and cellular mineral absorption of nanoemulsions of Rhododendron arboreum flower extracts stabilized with gum arabic

To assess the cellular mineral uptake and oxidative stability of flower extract, a nanoscale gum arabic stabilized Rhododendron arboreum flower extract emulsion was formulated. Four different concentrations of flower extract (1-5%) were used for the optimization of the nanoemulsion. A significant (P < 0.05) difference was observed in average droplet size (43.51-55.87 nm) of the nanoemulsion. FTIR spectrum confirmed mainly C=C, aliphatic C-H, aliphatic and aromatic galacto-proteins, and polymeric-OH groups present in nanoemulsion. Smooth type of nanoemulsion was confirmed by inverted light microscopy. Ionic strength was evaluated and significant (P < 0.05) increase in particles size was attributed, whereas significant (P < 0.05) decrease in zeta potential was observed by increased NaCl concentration. Iron and calcium showed a non-significant difference in terms of mineral bioavailability. Calcium revealed significantly higher cellular uptake (52.11%) in comparison with iron (50.25%) and zinc (45.32%) during transwell assay. Higher cellular iron uptake unveiled a satisfactory amount of ferritin content.

Species-Level Vegetation Mapping in a Himalayan Treeline Ecotone Using Unmanned Aerial System (UAS) Imagery

Understanding ecological patterns and response to climate change requires unbiased data on species distribution. This can be challenging, especially in biodiverse but extreme environments like the Himalaya. This study presents the results of the first ever application of Unmanned Aerial Systems (UAS) imagery for species-level mapping of vegetation in the Himalaya following a hierarchical Geographic Object Based Image Analysis (GEOBIA) method. The first level of classification separated green vegetated objects from the rest with overall accuracy of 95%. At the second level, seven cover types were identified (including four woody vegetation species). For this, the suitability of various spectral, shape and textural features were tested for classifying them using an ensemble decision tree algorithm. Spectral features alone yielded ~70% accuracy (kappa 0.66) whereas adding textural and shape features marginally improved the accuracy (73%) but at the cost of a substantial increase in processing time. Contrast in plant morphological traits was the key to distinguishing nearby stands as different species. Hence, broad-leaved versus fine needle leaved vegetation were mapped more accurately than structurally similar classes such as Rhododendron anthopogon versus non-photosynthetic vegetation. Results highlight the potential and limitations of the suggested UAS-GEOBIA approach for detailed mapping of plant communities and suggests future research directions.

Predicting the potential distribution of the endangered red panda across its entire range using MaxEnt modeling

An upsurge in anthropogenic impacts has hastened the decline of the red panda (Ailurus fulgens). The red panda is a global conservation icon, but holistic conservation management has been hampered by research being restricted to certain locations and population clusters. Building a comprehensive potential habitat map for the red panda is imperative to advance the conservation effort and ensure coordinated management across international boundaries. Here, we use occurrence records of both subspecies of red pandas from across their entire range to build a habitat model using the maximum entropy algorithm (MaxEnt 3.3.3k) and the least correlated bioclimatic variables. We found that the subspecies have separate climatic spaces dominated by temperature-associated variables in the eastern geographic distribution limit and precipitation-associated variables in the western distribution limit. Annual precipitation (BIO12) and maximum temperature in the warmest months (BIO5) were major predictors of habitat suitability for A. f. fulgens and A. f. styani, respectively. Our model predicted 134,975 km2 of red panda habitat based on 10 percentile thresholds in China (62% of total predicted habitat), Nepal (15%), Myanmar (9%), Bhutan (9%), and India (5%). Existing protected areas (PAs) encompass 28% of red panda habitat, meaning the PA network is currently insufficient and alternative conservation mechanisms are needed to protect the habitat. Bhutan's PAs provide good coverage for the red panda habitat. Furthermore, large areas of habitat were predicted in cross-broader areas, and transboundary conservation will be necessary.

Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal

Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in MaxEnt software using a subset of least correlated bioclimatic variables for current conditions (1950-2000), topographic variables (DEM derived) and Landuse Landcover (LULC) data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models (ESM) were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western Nepal. The major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.

Synergizing community-based forest monitoring with remote sensing: a path to an effective REDD+ MRV system

BACKGROUND

The reliable monitoring, reporting and verification (MRV) of carbon emissions and removals from the forest sector is an important part of the efforts on reducing emissions from deforestation and forest degradation (REDD+). Forest-dependent local communities are engaged to contribute to MRV through community-based monitoring systems. The efficiency of such monitoring systems could be improved through the rational integration of the studies at permanent plots with the geospatial technologies. This article presents a case study of integrating community-based measurements at permanent plots at the foothills of central Nepal and biomass maps that were developed using GeoEye-1 and IKONS satellite images.

RESULTS

The use of very-high-resolution satellite-based tree cover parameters, including crown projected area (CPA), crown density and crown size classes improves salience, reliability and legitimacy of the community-based survey of 0.04% intensity at the lower cost than increasing intensity of the community-based survey to 0.14% level (2.5 USD/ha vs. 7.5 USD/ha).

CONCLUSION

The proposed REDD+ MRV complementary system is the first of its kind and demonstrates the enhancement of information content, accuracy of reporting and reduction in cost. It also allows assessment of the efficacy of community-based forest management and extension to national scale.

Suitability Analysis and Projected Climate Change Impact on Banana and Coffee Production Zones in Nepal

The Government of Nepal has identified opportunities in agricultural commercialization, responding to a growing internal demand and expansion of export markets to reduce the immense trade deficit. Several cash crops, including coffee and bananas, have been identified in the recently approved Agriculture Development Strategy. Both of these crops have encouraged smallholder farmers to convert their subsistence farming practices to more commercial cultivation. Identification of suitable agro-ecological zones and understanding climate-related issues are important for improved production and livelihoods of smallholder farmers. Here, the suitability of coffee and banana crops is analyzed for different agro-ecological zones represented by Global Environmental Stratification (GEnS). Future shifts in these suitability zones are also predicted. Plantation sites in Nepal were geo-referenced and used as input in species distribution modelling. The multi-model ensemble model suggests that climate change will reduce the suitable growing area for coffee by about 72% across the selected emission scenarios from now to 2050. Impacts are low for banana growing, with a reduction in suitability by about 16% by 2050. Bananas show a lot of potential for playing an important role in Nepal as a sustainable crop in the context of climate change, as this study indicates that the amount of area suited to banana growing will grow by 40% by 2050. Based on our analysis we recommend possible new locations for coffee plantations and one method for mitigating climate change-related problems on existing plantations. These findings are expected to support planning and policy dialogue for mitigation and support better informed and scientifically based decision-making relating to these two crops.