Modeling of the Potential Geographical Distribution of Three Fritillaria Species Under Climate Change

Future of Three Endemic Woody Species of Colutea (Fabaceae) in a Changing Climate in Iran

Woody plants offer valuable services to ecosystems, including providing useful products, stabilizing ecosystems, and mitigating climate and pollution effects. However, they face significant abiotic and biotic stresses, with climate change being the most critical challenge. It is essential to understand that reducing populations of woody species, particularly those found only in a specific area, can have severe and irreversible effects on the entire ecosystem. Therefore, exploring the potential influence of climate change on the distribution of endemic woody species is an appealing subject for conservation researchers. This study investigates how climate change affects the distribution of three endemic species of woody plants in the genus Colutea in Iran. The MaxEnt model was used to analyze the data, and the results showed that the model was effective for predicting the impact of climate change on the plants (AUC ≥ 0.9). The distribution of C. persica was significantly affected by solar radiation, Precipitation of Wettest Month, sand, and silt content. C. porphyrogamma's distribution was impacted by Mean Temperature of Coldest Quarter, Precipitation of Driest Month, and Cation Exchange Capacity, while C. triphylla was most affected by Precipitation Seasonality, Precipitation of Driest Quarter, and Isothermality. According to the findings, the distribution of these species is expected to decrease in the 2050s and 2070s due to climate change, based on the RCP4.5 and RCP8.5 climate scenarios. These findings can be useful for developing strategies to manage the impacts of climate change on these species.

Current and Projected Future Spatial Distribution Patterns of Prunus microcarpa in the Kurdistan Region of Iraq

Prunus microcarpa is an endemic species prevalent throughout the highlands of the Kurdistan Region of Iraq. Conservation, introduction, and restoration efforts require an in-depth understanding of the species' current and future habitat distributions under different climate change scenarios. This study utilized field observations, species distribution modeling, geospatial techniques, and environmental predictors to analyze the distribution and forecast potential habitats for P. microcarpa in the highlands of Iraq. Findings indicate that, according to the global climate models (i.e., BCC-CSM2-MR and MRI-ESM2.0), the reduction in habitat for the species is projected to be more than the potential expansion. Specifically, the area of habitat is expected to reduce by 2351.908 km2 (4.6%) and 2216.957 km2 (4.3%), while it could increase by 1306.384 km2 (2.5%) and 1015.612 km2 (2.0%) for the respective climate models. Topographic features such as elevation and slope, climatic conditions, precipitation seasonality, and annual mean temperature relatively shape the distribution of P. microcarpa. The modeling demonstrated good predictive capability (area under the curve (AUC) score = 0.933). The total study area is approximately 51,558.327 km2, with around 20.5% (10,602 km2) identified as suitable habitat for P. microcarpa. These findings offer essential baseline information for conservation strategies and provide new insights into where the species currently resides and where it could be found in the future. This underscores how combining distribution modeling with geospatial techniques can be effective, particularly in data-deficient regions like Iraq.

Fritillaria steroidal alkaloids and their multi-target therapeutic mechanisms: insights from network pharmacology

Medicinal Fritillaria herbs, known for their rich content of steroidal alkaloids, have emerged as promising candidates in the treatment of chronic diseases due to their diverse pharmacological properties. Leveraging advancements in network pharmacology and molecular docking, this study explores the multi-target mechanisms through which these alkaloids exert therapeutic effects. The integration of bioinformatics, systems biology, and pharmacology in drug discovery has provided insights into the molecular interactions and pathways influenced by Fritillaria steroidal alkaloids. This review synthesizes comprehensive literature from 1985 to 2024, revealing the potential of these compounds in addressing respiratory diseases, inflammation, and cancer. The integration of traditional Chinese medicine (TCM) with modern pharmacological techniques underscores the relevance of these compounds in next-generation drug discovery. While initial findings are promising, further empirical validation is necessary to fully harness the therapeutic potential of Fritillaria steroidal alkaloids.

UDP-glucosyltransferases from UGT73 family catalyze 3-O-glucosylation of isosteroidal and steroidal alkaloids in Fritillaria unibracteata var. wabuensis

Fritillaria unibracteata var. wabuensis is an important resource plant for the famous traditional Chinese medicine Fritillariae cirrhosae bulbus ("Chuanbeimu" in Chinese). F. cirrhosae bulbus is the dried bulbs of several species from Fritillaria genus, with isosteroidal alkaloids components assumed as the bioactive ingredients. However, the biosynthesis pathway of isosteroidal alkaloids remains elusive. Here, we adopted F. unibracteata var. wabuensis as a material to identify genes involved in the biosynthesis of isosteroidal alkaloids. We first constructed the multi-tissue metabolome and transcriptome dataset of F. unibracteata var. wabuensis. Interestingly, imperialine-3-β-d-glucoside, an isosteroidal glycoalkaloid, was found to be the major tissue-specific accumulated alkaloid. Through phylogenetic and co-expression analysis, we identified two UDP-glucosyltransferases from UGT73 family catalyzing 3-O-glucosylation of isosteroidal and steroidal alkaloids: imperialine 3-O-glucosyltransferase (FuwI3GT) can use both isosteroidal alkaloid imperialine and steroidal alkaloid solanidine as substrates, while solanidine 3-O-glucosyltransferase (FuwS3GT) can only use steroidal alkaloid solanidine as a substrate. We further approved that the W201 residue of FuwI3GT determined its substrate preference of isosteroidal alkaloids. Overall, our results identified enzymes involved in 3-O-glucosylation of isosteroidal and steroidal alkaloids in F. unibracteata var. wabuensis and paved the way to fully elucidate the isosteroidal alkaloid biosynthesis pathway in Fritillaria species.

Prediction of change in suitable habitats of Senna obtusifolia and Senna tora under climate change

Senna obtusifolia (L.) Irwin & Barneby and Senna tora (L.) Roxb represent important medicinal resources in traditional Chinese medicine for more than two millennia. Sustainable resource utilization and preservation strategies for Senna species necessitate a thorough understanding of the climatic factors governing their distribution patterns. Therefore, this study aimed to identify the key climate variables shaping the current and potential future global distribution of both Senna species. To achieve this, the MaxEnt ecological niche model was employed, integrating species occurrence data with relevant environmental variables. The results indicated that Bio13 and Bio14 were the most critical variables affecting distribution of S. tora, while Bio6 and Bio14 were crucial for S. obtusifolia. The moderate and high suitability habitats of S. obtusifolia and S. tora consist of ca. 189.69 × 104 km2 and 129.07 × 104 km2, respectively, under current situation. Moreover, the global distribution of both species under various climate scenarios revealed that the suitable habitats of both Senna species will reach the maximum during the 2081-2100 period under the SSP585 scenario. Projections across all four climate scenarios indicate a general northward migration in the core distribution of both Senna species. Intriguingly, the observed high degree of ecological niche overlap between the two species aligns with their close phylogenetic relationship. These findings provide valuable insights into the potential future distribution and ecological niche of Senna species, informing sustainable utilization and preservation strategies for Senna resources.

Geographical Distribution Dynamics of Acorus calamus in China Under Climate Change

Acorus calamus, a perennial emergent herb, is highly valued for its ornamental appeal, water purification ability, and medicinal properties. However, there is a significant contradiction between the rapidly increasing demand for A. calamus and the diminishing wild resources. Understanding its geographical distribution and the influence of global climate change on its geographical distribution is imperative for establishing a theoretical framework for the conservation of natural resources and the expansion of its cultivation. In this study, 266 distribution records of A. calamus and 18 selected key environmental factors were utilized to construct an optimal MaxEnt model via the ENMeval package. We simulated the potential geographical distributions under current conditions and under three different climate scenarios (SSP126, SSP370, and SSP585) in the 2050s, 2070s, and 2090s. Additionally, we employed the jackknife method and response curves to identify the environmental factors with the greatest influence on the distribution of A. calamus, and their response intervals. The results indicate that the regularization multiplier (RM) of 3.5 and the feature combinations (FC) of linear (L), quadratic (Q), hinge (H), and product (P) are the optimal model parameter combinations. With these parameters, the model predictions are highly accurate, and the consistency of the results is significant. The dominant environmental factors and their thresholds affecting the distribution of A. calamus are the precipitation of the wettest month (≥109.87 mm), human footprint (≥5.39), annual precipitation (≥388.56 mm), and mean diurnal range (≤12.83 °C). The primary land use types include rivers and channels, reservoirs and ponds, lakes, urban areas, marshes, other constructed lands, rice fields, forested areas, and shrublands. Under current climate conditions, the suitable geographical distribution of A. calamus in China is clearly located east of the 400 mm precipitation line, with high- and low-suitability areas covering 121.12 × 104 km2, and 164.20 × 104 km2, respectively. Under future climate conditions, both high- and low- suitability areas are projected to increase significantly, whereas unsuitable areas are expected to decrease, with the centroid of each suitability zone shifting northward. This study provides a theoretical foundation for sustainable utilization, future production planning, and the development of conservation strategies for wild germplasm resources of A. calamus.

Integrated approach to predicting habitat suitability and evaluating quality variations of Notopterygium franchetii under climate change

The impact of climate change on medicinal plants has significantly altered their suitable environments, thereby affecting the quality of herbal medicines. Notopterygium franchetii (N. franchetii), a medicinal plant intricately linked to its natural habitat, exhibits substantial quality variations influenced by the ecological conditions of its native region. In this study, comprehensive field surveys were conducted to gather occurrence records and samples of N. franchetii. The Maxent model and ArcGIS software were employed to predict the suitable habitats of N. franchetii during different time periods. A high-performance liquid chromatography (HPLC) method was developed to establish the chemical fingerprints of 21 sample batches. Fourteen common peaks were subjected to cluster analysis, principal component analysis, and orthogonal partial least squares-discriminant analysis. The findings revealed quality variations correlated with their geographic origins, identifying peaks 10, 1, 14, 3, and 4 as crucial for quality differentiation. The study indicates that precipitation, temperature, and altitude significantly influence the distribution of N. franchetii. Under current climate conditions, the suitable habitat area for N. franchetii is estimated to be approximately 94,637.33 km2. However, projections under three future climate scenarios suggest a declining trend in suitable habitat areas. A quality zoning map of N. franchetii was developed, integrating a correlation model between chemical composition and environmental variables with the spatial analysis and visualization capabilities of ArcGIS. The high-quality regions for N. franchetii are predominantly located in the Gannan, Linxia, Dingxi, Longnan, and Wuwei districts. These research outcomes offer a valuable reference for identifying suitable cultivation areas and assessing the quality of N. franchetii in Gansu Province.

Predicting the geographical distribution and niche characteristics of Cotoneaster multiflorus based on future climate change

Introduction

Arid and semi-arid regions are climate-sensitive areas, which account for about 40% of the world's land surface area. Future environment change will impact the environment of these area, resulting in a sharp expansion of arid and semi-arid regions. Cotoneaster multiflorus is a multi-functional tree species with extreme cold, drought and barren resistance, as well as ornamental and medicinal functions. It was found to be one of the most important tree species for ecological restoration in arid and semi-arid areas. However, bioclimatic factors play an important role in the growth, development and distribution of plants. Therefore, exploring the response pattern and ecological adaptability of C. multiflorus to future climate change is important for the long-term ecological restoration of C. multiflorus in arid and semi-arid areas.

Methods

In this study, we predicted the potential distribution of C. multiflorus in China under different climate scenarios based on the MaxEnt 2.0 model, and discussed its adaptability and the major factors affecting its geographical distribution.

Results

The major factors that explained the geographical distribution of C. multiflorus were Annual precipitation (Bio12), Min air temperature of the coldest month (Bio6), and Mean air temperature of the coldest quarter (Bio11). However, C. multiflorus could thrive in environments where Annual precipitation (Bio12) >150 mm, Min air temperature of the coldest month (Bio6) > -42.5°C, and Mean air temperature of the coldest quarter (Bio11) > -20°C, showcasing its characteristics of cold and drought tolerance. Under different future climate scenarios, the total suitable area for C. multiflorus ranged from 411.199×104 km² to 470.191×104 km², which was 0.8~6.14 percentage points higher than the current total suitable area. Additionally, it would further shift towards higher latitude.

Discussion

The MaxEnt 2.0 model predicted the potential distribution pattern of C. multiflorus in the context of future climate change, and identified its ecological adaptability and the main climatic factors affecting its distribution. This study provides an important theoretical basis for natural vegetation restoration in arid and semi-arid areas.

The relationship between niche breadth and phylogenetic characteristics of eight species of rhubarb on the Qinghai-Tibet Plateau, Asia

The relationship between spatial distribution and phylogeny has been widely debated in recent decades. To understand biogeographic and evolutionary history relationships and to explore the interspecific similarities and phylogenetic correlations of niche characteristics, we collected and recorded all distribution points for eight species of rhubarb on the Qinghai-Tibet Plateau, used different methods to describe the ecological niche, and explored the relationship between phylogeny, ecological niche, and distribution range. The results reveal that: (1) the ranges of optimal environmental variables for species with close kinship are not exactly the same, ecologically similar species are not necessarily sister species, and the overlap of rhubarb has no significant correlation with phylogeny. Therefore, the impact of ecological dimensions on species formation is greater than that of geographical latitude for the eight species of rhubarb. (2) Among the eight species of rhubarb, the breadth of ecological niche is positively correlated with the current suitable habitat area and negatively correlated with fluctuations in future suitable habitat area. In the future, except for Rheum tanguticum and Rheum palmatum, the suitable planting areas for the other six species of rhubarb will decrease as greenhouse gas emissions concentrations and time increase. Therefore, species with smaller ecological niches are at a greater risk of habitat loss compared to species with larger ecological niches. (3) In both existing and future distribution prediction models of rhubarb, we observed that both the widely distributed Rheum spiciforme and the niche narrow Rheum nobile, all eight species of rhubarb are present in the Hengduan Mountains, based on our analysis, we propose that the Hengduan Mountains should be regarded as a priority conservation area for rhubarb, to preserve the species' biodiversity. Our study lays the groundwork for identifying evolutionary trends in ecological specialization.

Bioinformatic Analysis of Codon Usage Bias of HSP20 Genes in Four Cruciferous Species

Heat shock protein 20 (HSP20) serves as a chaperone and plays roles in numerous biological processes, but the codon usage bias (CUB) of its genes has remained unexplored. This study identified 140 HSP20 genes from four cruciferous species, Arabidopsis thaliana, Brassica napus, Brassica rapa, and Camelina sativa, that were identified from the Ensembl plants database, and we subsequently investigated their CUB. As a result, the base composition analysis revealed that the overall GC content of HSP20 genes was below 50%. The overall GC content significantly correlated with the constituents at three codon positions, implying that both mutation pressure and natural selection might contribute to the CUB. The relatively high ENc values suggested that the CUB of the HSP20 genes in four cruciferous species was relatively weak. Subsequently, ENc exhibited a negative correlation with gene expression levels. Analyses, including ENc-plot analysis, neutral analysis, and PR2 bias, revealed that natural selection mainly shaped the CUB patterns of HSP20 genes in these species. In addition, a total of 12 optimal codons (ΔRSCU > 0.08 and RSCU > 1) were identified across the four species. A neighbor-joining phylogenetic analysis based on coding sequences (CDS) showed that the 140 HSP20 genes were strictly and distinctly clustered into 12 subfamilies. Principal component analysis and cluster analysis based on relative synonymous codon usage (RSCU) values supported the fact that the CUB pattern was consistent with the genetic relationship at the gene level and (or) species levels. These results will not only enrich the HSP20 gene resource but also advance our understanding of the CUB of HSP20 genes, which may underlie the theoretical basis for exploration of their genetic and evolutionary pattern.

Biomod2 modeling for predicting the potential ecological distribution of three Fritillaria species under climate change

The Fritillaria species ranked as a well-known traditional medicine in China and has become rare due to excessive harvesting. To find reasonable strategy for conservation and cultivation, identification of new ecological distribution of Fritillaria species together with prediction of those responses to climate change are necessary. In terms of current occurrence records and bioclimatic variables, the suitable habitats for Fritillaria delavayi, Fritillaria taipaiensis, and Fritillaria wabuensis were predicted. In comparison with Maxent and GARP, Biomod2 obtained the best AUC, KAPPA and TSS values of larger than 0.926 and was chosen to construct model. Temperature seasonality was indicated to put the greatest influence on Fritillaria taipaiensis and Fritillaria wabuensis, while isothermality was of most importance for Fritillaria delavayi. The current suitable areas for three Fritillaria species were distributed in south-west China, accounting for approximately 17.72%, 23.06% and 20.60% of China's total area, respectively. During 2021-2100 period, the suitable habitats of F. delavayi and F. wabuensis reached the maximum under SSP585 scenario, while that of F. taipaiensis reached the maximum under SSP126 scenario. The high niche overlap among three Fritillaria species showed correlation with the chemical composition (P ≤ 0.05), while no correlation was observed between niche overlap and DNA barcodes, indicating that spatial distribution had a major influence on chemical composition in the Fritillaria species. Finally, the acquisition of species-specific habitats would contribute to decrease in habitat competition, and future conservation and cultivation of Fritillaria species.

Impacts of Climate Changes on Geographic Distribution of Primula filchnerae, an Endangered Herb in China

Primula filchnerae, an endangered plant endemic to China, has drawn people's attention in recent years due to its ornamental value in flower. It was rarely recorded since being described in 1902, but it was rediscovered in 2009 and is now known from a limited number of sites located in Hubei and Shaanxi Provinces. Since the species is still poorly known, a number of unanswered questions arise related to it: How has P. filchnerae responded to past climate change and how might it respond in the future? Why was P. filchmerae so rarely collected during the past century? We assembled geographic coordinates for P. filchnerae through the field surveys and website searches, and then used a maximum entropy model (MaxEnt) to simulate its potential suitable distribution in six periods with varied carbon emission levels by combining bioclimatic and environmental factors. MaxEnt showed that Min Temperature of the Coldest Month (bio6) and Precipitation of the Coldest Quarter (bio19) affected P. filchnerae's distribution most, with an aggregate contribution >60% and suitable ranges above -5 °C and below 40 mm, respectively. We also analyzed potential habitat distribution in various periods with differing impacts of climate change compared to today's suitable habitats, and in most cases, Shaanxi and Sichuan remained the most stable areas and with possible expansion to the north under various carbon emission scenarios, but the 2050s SSP5-8.5 scenario may be an exception. Moreover, we used MaxEnt to evaluate population shifts, with various scenarios indicating that geometric center would be concentrated in Sichuan Province in China. Finally, conservation strategies are suggested, including the creation of protected areas, long-term monitoring, raising public awareness of plant conservation, situ conservation measures, assisted migration, and species introduction. This study demonstrates how P. filchnerae may have adapted to changes in different periods and provides a scientific basis for germplasm conservation and management.

Integrated transcriptomic and metabolomic analysis reveals the molecular basis of tissue-specific accumulation of bioactive steroidal alkaloids in Fritillaria unibracteata

Fritillaria unibracteata is an endangered medicinal plant whose bulb has been used as a Chinese herb to suppress cough, asthma and excessive phlegm for centuries. Steroidal alkaloids, which are synthesized via the steroid synthesis pathways, are their significant bioactive constituents. However, few studies on genes involved in steroidal alkaloid biosynthesis in F. unibracteata have been reported, mainly due to the lack of the F. unibracteata genome. In this paper, comparative transcriptomic and metabolomic analyses of four different tissues of F. unibracteata (leaves, flowers, stems, and bulbs) were performed. Imperialine, peiminine, and peimisine were among the significant bioactive compounds that were considerably abundant in bulb tissue, according to the metabolomic findings. Then, 83.60 Gb transcriptome sequencing of four different tissues was performed, of which one gene encoding phosphomevalonate kinase was directly functionally characterized to verify the accuracy of sequences obtained from the transcriptome. A total of 9217 differentially expressed unigenes (DEGs) were identified in four different tissues of F. unibracteata. GO and KEGG enrichments revealed that phenylpropanoid biosynthesis, MVA-mediated terpenoid backbone biosynthesis, and steroid biosynthesis were enriched in bulb tissue, whereas enrichment of MEP-mediated terpenoid backbone biosynthesis, photosynthesis, photosynthesis-antenna protein and carotenoid biosynthesis was observed in aerial tissues. Moreover, clustering analysis indicated that the downstream steroid biosynthesis pathway was more important in steroidal alkaloid biosynthesis compared to the upstream terpenoid backbone biosynthesis pathway. Hence, MVA-mediated biosynthesis of steroidal alkaloids was proposed, in which 15 bulb-clustered DEGs were positively correlated with a high accumulation of bioactive steroid alkaloids, further validating our proposal. In addition, 36 CYP450s showing a positive correlation with bioactive steroidal alkaloids provided candidate enzymes to catalyze the subsequent steps of steroidal alkaloid biosynthesis. In addition, the transcription factors and ABC transporters clustered in bulb tissue might be responsible for the regulation and transportation of steroidal alkaloid biosynthesis. Protein-protein interaction analysis implied a highly complex steroid alkaloid biosynthesis network in which delta (24)-sterol reductase might be one of the central catalysts. Based on the integrated transcriptome and metabolome, this current study is a first step in understanding the tissue-specific biosynthesis of steroidal alkaloids in F. unibracteata. Furthermore, key genes and regulators identified herein could facilitate metabolic engineering to improve steroidal alkaloids in F. unibracteata.

Rapid Test for Adulteration of Fritillaria Thunbergii in Fritillaria Cirrhosa by Laser-Induced Breakdown Spectroscopy

Fritillaria has a long history in China, and it can be consumed as medicine and food. Owing to the high cost of Fritillaria cirrhosa, traders sometimes mix it with the cheaper Fritillaria thunbergii powder to make profit. Herein, we proposed a laser-induced breakdown spectroscopy (LIBS) technique to test the adulteration present in the sample of Fritillaria cirrhosa powder. Experimental samples with different adulteration levels were prepared, and their LIBS spectra were obtained. Partial least squares regression (PLSR) was adopted as the quantitative analysis model to compare the effects of four data standardization methods, namely, mean centring, normalization by total area, standard normal variable, and normalization by the maximum, on the performance of the PLSR model. Principal component analysis and least absolute shrinkage and selection operator (LASSO) were utilized for feature extraction and feature selection, and the performance of the PLSR model was determined based on its quantitative analysis. Subsequently, the optimal number of features was determined. The residuals were corrected using support vector regression (SVR). The mean absolute error and root mean square error of prediction obtained from the quantitative analysis results of the combined LASSO-PLSR-SVR model for the test set data were 5.0396% and 7.2491%, respectively, and the coefficient of determination R² was 0.9983. The results showed that the LIBS technique can be adopted to test adulteration in the sample of Fritillaria cirrhosa powder and has potential applications in drug quality control.

Modeling of the potential geographical distribution of naked oat under climate change

INTRODUCTION

Naked oat (Avena sativa L.), is an important miscellaneous grain crop in China, which is rich in protein, amino acids, fat and soluble dietary fiber. The demand for functional foods is gradually increasing as living standards rise, and the output of minor cereals in China is increasing annually. The planting layout of naked oat is scattered and lacks planning, which seriously restricts the development of the naked oat industry. The increase in miscellaneous grain production will not only be impacted by cultivation methods and management techniques, but the potential impact of global climate change needs to be considered. North China is the main area for naked oat production, worldwide.

METHODS

In this study, the potential distribution range of naked oat in North China was forecast based on historical distribution data and the Maxent model under climate change conditions. The performance of the model was relatively high.

RESULTS

The results indicated that the most suitable area for the potential geographic distribution of naked oat in North China was 27.89×104 km², including central and northeastern Shanxi, and northeastern and western Hebei and Beijing, gradually moving northward. The core suitable area increased, and the distribution of naked oat had an obvious regional response to climate warming; the main environmental factors affecting the potential geographic distribution were precipitation factor variables (precipitation seasonality (variation coefficient)), terrain factor variables (elevation) and temperature factor variables (temperature seasonality (Standard Deviation*100)).

DISCUSSION

In this study, the Maxent model was used to analyze and predict suitable areas for naked oat in North China, and the distribution of suitable areas was accurately divided, and the main climatic factors affecting the distribution of naked oat were identified. This research provides data support and theoretical support for the optimal planting zone of naked oat in North China.

Predicting the distribution of suitable habitat of the poisonous weed Astragalus variabilis in China under current and future climate conditions

Astragalus variabilis is a locoweed of northwest China that can seriously impede livestock development. However, it also plays various ecological roles, such as wind protection and sand fixation. Here, we used an optimized MaxEnt model to predict the distribution of suitable habitat of A. variabilis under current (1970-2000) conditions and future (2021-2080) climate change scenarios based on recent occurrence records. The most important environmental variables (suitability ranges in parentheses) affecting the distribution of A. variabilis were average maximum temperature of February (-2.12-5.34^°C), followed by total precipitation of June (2.06-37.33 mm), and topsoil organic carbon (0.36-0.69%). The habitat suitability of A. variabilis was significantly correlated with the frequency of livestock poisoning (p < 0.05). Under current climate conditions, the suitable environment of A. variabilis was distributed in central and western Inner Mongolia, Ningxia, central and northwestern Gansu, central and northwestern Qinghai, and the four basins around the Tianshan Mountains in Xinjiang. Under future climate conditions, the suitable habitat of A. variabilis shifted to higher latitudes and altitudes. No previous studies have used niche models to predict the suitable environment of this species nor analyzed the relationship between the habitat suitability of poisonous plants and the frequency of animal poisoning. Our findings provide new insights that will aid the prevention of livestock animal poisoning and the control of poisonous plants, promote the development of the livestock husbandry industry, and provide basic information that will facilitate the maintenance of the ecological balance of grassland ecosystems.

Predicting the potential distribution of four endangered holoparasites and their primary hosts in China under climate change

Climate change affects parasitic plants and their hosts on distributions. However, little is known about how parasites and their hosts shift in distribution, and niche overlap in response to global change remains unclear to date. Here, the potential distribution and habitat suitability of four endangered holoparasites and their primary hosts in northern China were predicted using MaxEnt based on occurrence records and bioclimatic variables. The results indicated that (1) Temperature annual range (Bio7) and Precipitation of driest quarter (Bio17) were identified as the common key climatic factors influencing distribution (percentage contribution > 10%) for Cynomorium songaricum vs. Nitraria sibirica (i.e., parasite vs. host); Temperature seasonality (Bio4) and Precipitation of driest month (Bio14) for Boschniakia rossica vs. Alnus mandshurica; Bio4 for Cistanche deserticola vs. Haloxylon ammodendron; Precipitation of warmest quarter (Bio18) for Cistanche mongolica vs. Tamarix ramosissima. Accordingly, different parasite-host pairs share to varying degree the common climatic factors. (2) Currently, these holoparasites had small suitable habitats (i.e., moderately and highly) (0.97-3.77%), with few highly suitable habitats (0.19-0.81%). Under future scenarios, their suitable habitats would change to some extent; their distribution shifts fell into two categories: growing type (Boschniakia rossica and Cistanche mongolica) and fluctuating type (Cynomorium songaricum and Cistanche deserticola). In contrast, the hosts' current suitable habitats (1.42-13.43%) varied greatly, with highly restricted suitable habitats (0.18-1.00%). Under future scenarios, their suitable habitats presented different trends: growing type (Nitraria sibirica), declining type (Haloxylon ammodendron) and fluctuating type (the other hosts). (3) The niche overlaps between parasites and hosts differed significantly in the future, which can be grouped into two categories: growing type (Boschniakia rossica vs. Alnus mandshurica, Cistanche mongolica vs. Tamarix ramosissima), and fluctuating type (the others). Such niche overlap asynchronies may result in severe spatial limitations of parasites under future climate conditions. Our findings indicate that climate factors restricting parasites and hosts' distributions, niche overlaps between them, together with parasitic species identity, may jointly influence the suitable habitats of parasitic plants. Therefore, it is necessary to take into account the threatened holoparasites themselves in conjunction with their suitable habitats and the parasite-host association when developing conservation planning in the future.

The Future Potential Distribution and Sustainable Management of Ancient Pu’er Tea Trees (Camellia sinensis var. assamica (J. W. Mast.) Kitam.)

Ancient Pu’er tea trees (Camellia sinensis var. assamica (J. W. Mast.) Kitam.) are an important ecological resource with high economic value. Knowledge of the environmental variables shaping the original distribution and the effects of climate change on the future potential distribution of these trees, as well as the identification of sustainable management approaches, is essential for ensuring their future health and production. Here, we used 28 current environmental variables and the future climate data to model the suitable areas for ancient Pu’er tea trees. We also compared the health of these ancient trees in areas under different local management strategies. The results suggested the general distribution is likely to remain stable, but there are environmentally suitable areas outside its current habitats. To achieve more sustainable management, the main areas in which the management of poorly-managed trees can be improved include learning from managers of well-managed trees and following the common technical management regulations stipulated by the local government. The suitable value ranges for environmental factors, potentially suitable areas under climate change, and assessment of management approaches will aid the future cultivation and transplantation of ancient Pu’er tea trees. The methodology includes management-level analysis and provides practical insights that could be applied to regions outside the most suitable areas identified.