CLIMEX Model Research Articles

Application of true skill statistics as a practical method for quantitatively assessing CLIMEX performance

The species distribution model (SDM) predicts the potential distribution of a species as a function of abiotic variables. CLIMEX is a SDM that mechanistically evaluates the climatic suitability of a species in a specific area. However, compared with other SDMs, the metrics for quantitatively evaluating CLIMEX performance are limited. Hence, this study quantitatively evaluated the performance of the CLIMEX models of six example species by applying the metrics used for machine-learning-based SDMs. The results showed that the performance of CLIMEX had a minimum true skill statistic (TSS) of 0.35 and a maximum of 0.78 depending on the species. Depending on the scale of the prediction area, number of occurrence coordinates, and classification threshold, CLIMEX performance can be evaluated by applying true skill statistics (TSS). Although this method is not perfect because of the characteristics of CLIMEX modeling, we expect it to be a useful option before conceiving the best method to evaluate mechanistic SDM.

Predicting the potential global distribution of an invasive alien pest Trioza erytreae (Del Guercio) (Hemiptera: Triozidae)

The impact of invasive alien pests on agriculture, food security, and biodiversity conservation has been worsened by climate change caused by the rising earth’s atmospheric greenhouse gases. The African citrus triozid, Trioza erytreae (Del Guercio; Hemiptera: Triozidae), is an invasive pest of all citrus species. It vectors the phloem-limited bacterium “Candidatus Liberibacter africanus”, a causal agent of citrus greening disease or African Huanglongbing (HLB). Understanding the global distribution of T. erytreae is critical for surveillance, monitoring, and eradication programs. Therefore, we combined geospatial and physiological data of T. erytreae to predict its global distribution using the CLIMEX model. The model’s prediction matches T. erytreae present-day distribution and shows that parts of the Mediterranean region have moderate (0 < EI < 30) to high (EI > 30) suitability for the pest. The model predicts habitat suitability in the major citrus-producing countries, such as Mexico, Brazil, China, India, and the USA. In the Special Report on Emissions Scenarios (SRES) A1B and A2 scenarios, the model predicts a reduction in habitat suitability from the current time to 2070. The findings show that global citrus production will continue to be threatened by T. erytreae. However, our study provides relevant information for biosecurity and risk assessment.

Spatial and climatic analyses for predicting potential distribution of an invasive ant, Linepithema humile (Hymenoptera: Formicidae)

AbstractThe Argentine ant (Linepithema humile) is an invasive species that rapidly enters into new areas, causing worldwide ecological concern. Early assessment of its potential habitat could indicate areas that we need to pay attention to in advance, to prevent its invasion; therefore, in this study we aimed to predict the potential spatial distribution of the Argentine ant and analyze the climatic characteristics of its occurrence sites. The CLIMEX model was used to predict the spatial distribution of this ant species, while the probability density function was employed to extract climatic preferences in places where their main habitats are located. High climatic suitability was predicted in the eastern United States, eastern South America, central Africa, eastern Australia, and a few regions in India and China, suggesting the high possibility of its invasion worldwide. The frequency of occurrence was highest at approximately 20°C monthly average maximum temperature, 8°C monthly average minimum temperature, and 10 mm monthly precipitation. In addition, the occurrence records of Argentine ants were mostly shown to be above sub‐zero temperatures. We expect that these results can be used to identify new areas exposed to the risk of Argentine ant invasion and for further application to establish monitoring strategies in advance.

The Impacts of Climate Change on the Potential Distribution of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) in China.

Simple SummaryPlodia interpunctella (Hübner) is an important grain storage pest in China that is distributed in almost every province and that has caused huge economic losses. In this study, we adjusted the biological parameters of the Indian grain borer and then used the CLIMEX model to predict the detailed potential distribution of P. interpunctella in China under current and future conditions. Under historical climatic conditions, the central, northeastern, and southern regions of China are highly suitable habitats for it. Because of temperature change in the future climate, suitable habitats will increase in the eastern part of Qinghai and will decrease in the mid-eastern, northeastern, and southeastern parts of China. This study provides important information for controlling the further spread of the Indian corn borer in China.The Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is a notorious stored-grain pest that can be found in most parts of China. The corpses, excretions, and other secretions of P. interpunctella larvae cause serious grain pollution, seriously affecting the nutritional and economic value of stored grain in China. To elucidate the potential distribution of P. interpunctella in China, we used the CLIMEX 4.0 model to project the potential distribution of the pest using historical climate data (1960–1990) and estimated future climate data (2030, 2050, and 2070). Under the historical climate situation, P. interpunctella was distributed in most areas of China, and its highly favorable habitats account for 48.14% of its total potential distribution. Because of temperature change in the future climate, suitable habitats will increase in the eastern part of Qinghai and will decrease in the mid-eastern, northeastern, and southeastern parts of China. Under these scenarios, the area of this pest’s highly favorable habitat will be reduced by 1.24 million km2, and its proportion will decrease to about 28.48%. These predicted outcomes will help to distinguish the impact of climate change on the potential distribution of P. interpunctella, thereby providing important information to design early forecasting and strategies to prevent pest harm to stored grain.

Potential Distribution of Invasive Boxwood Blight Pathogen (Calonectriapseudonaviculata) as Predicted by Process-Based and Correlative Models.

Simple SummaryKnowledge of where invasive species could potentially establish (potential distribution) is critical to prioritizing and addressing biological invasion threats. In this study, we predicted the potential distribution of Calonectria pseudonaviculata (Cps), an invasive fungal pathogen that blights boxwood, an iconic landscape plant, major evergreen nursery crop, and keystone forest species. We used climate data, presence records from Europe and western Asia, and multiple modeling approaches to predict the potential distribution of Cps at regional and global scales and to explore the roles of temperature and moisture in shaping its distribution. Model predictions were validated using an independent presence record dataset. A consensus map of model predictions revealed that Cps could potentially spread and establish well beyond its currently invaded range in Europe, western Asia, New Zealand, United States and Canada. These include a number of not-yet-invaded areas in eastern and southern Europe, North America, and many regions of the world where boxwood is native. This knowledge informs policymakers and other stakeholders in these areas on the need for implementing a strict phytosanitary protocol for risk mitigation of accidental introduction, having an effective surveillance for early detection, and developing a recovery plan for the pathogen when accidental introductions occur.Boxwood blight caused by Cps is an emerging disease that has had devastating impacts on Buxus spp. in the horticultural sector, landscapes, and native ecosystems. In this study, we produced a process-based climatic suitability model in the CLIMEX program and combined outputs of four different correlative modeling algorithms to generate an ensemble correlative model. All models were fit and validated using a presence record dataset comprised of Cps detections across its entire known invaded range. Evaluations of model performance provided validation of good model fit for all models. A consensus map of CLIMEX and ensemble correlative model predictions indicated that not-yet-invaded areas in eastern and southern Europe and in the southeastern, midwestern, and Pacific coast regions of North America are climatically suitable for Cps establishment. Most regions of the world where Buxus and its congeners are native are also at risk of establishment. These findings provide the first insights into Cps global invasion threat, suggesting that this invasive pathogen has the potential to significantly expand its range.

Spatial assessment of potential areas at risk from blueberry gall midge distribution in South Korea

AbstractDasineura oxycoccana, the blueberry gall midge, has damaged domestic blueberry cultivation since its presence was confirmed in Korea. In this study, the domestic climatic suitability of D. oxycoccana was evaluated using the CLIMEX model, which comprehensively integrates the species biology and regional climate. In addition, we derived the risk posed to major areas of blueberry cultivation by considering the domestic potential distribution of D. oxycoccana based on climatic suitability D. oxycoccana showed the highest occurrence suitability on the southern coast under the current climate, and its population is expected to gradually increase inland due to climate change. Jeju and the southern coast were the major areas that were presently found to be at risk from D. oxycoccana; the area at risk from D. oxycoccana is expected to extend to southern Gyeonggi‐do and Ganwon‐do by 2040 and 2060, respectively. D. oxycoccana was predicted to occur throughout the country according to climate change, suggesting increase in its infestation in blueberry cultivation. Therefore, we expected this study provides precautionary evaluation for monitoring and controlling the pest.

Malice at the Gates of Eden: current and future distribution of Agrilus mali threatening wild and domestic apples.

The apple buprestid, Agrilus mali Matsumura, that was widespread in north-eastern China, was accidently introduced to the wild apple forest ecosystem in mountainous areas of Xinjiang, China. This invasive beetle feeds on domesticated apples and many species of Malus and presents a serious threat to ancestral apple germplasm sources and apple production worldwide. Estimating the potential area at risk of colonization by A. mali is crucial for instigating appropriate preventative management strategies, especially under global warming. We developed a CLIMEX model of A. mali to project this pest's potential distribution under current and future climatic scenarios in 2100 using CSIRO-Mk 3.0 GCM running the SRES A1B emissions scenario. Under current climate, A. mali could potentially invade neighbouring central Asia and eventually the mid-latitude temperate zone, and some subtropical areas and Pampas Steppe in the Southern Hemisphere. This potential distribution encompasses wild apples species, the ancestral germplasm for domesticated apples. With global warming, the potential distribution shifts to higher latitudes, with the potential range expanding slightly, though the overall suitability could decline in both hemispheres. In 2100, the length of the growing season of this pest in the mid-latitude temperature zone could increase by 1-2 weeks, with higher growth rates in most sites compared with current climate in mid-latitudes, at least in China. Our work highlights the need for strategies to prevent the spread of this pest, managing the threats to wild apples in Tian Shan Mountain forests in Central Asia, and commercial apple production globally. We discuss practical management tactics to reduce the spread of this pest and mitigate its impacts.

Climate change effects on the global distribution and range shifts of citrus longhorned beetle Anoplophora chinensis

AbstractThe citrus longhorned beetle (CLB) (Anoplophora chinensis) is an important quarantine pest of main Citrus crops. Its potential distribution and invasion under climate change scenarios have important economic implications for many countries. We used the ensemble maps from both the CLIMEX and MaxEnt models to obtain CLB’s potential distribution in climate‐suitable regions under historical and future climate conditions. Global broadleaved forest cover was overlaid with CLB’s ensemble distributions to further assess the effects of host range. The ensemble models’ projected climate‐suitable regions by 2040–2060 and 2060–2070 under different emission scenarios were used to analyze range shifts. Our results indicate that projected climate‐suitable regions of the CLIMEX are much wider than that of the MaxEnt, but both of them would lose areas with climate change. The global ensemble distributions of CLB concentrated in eastern Asia, central and western Europe and eastern North America, and would shift northward in the future time. Broadleaved forests would cover most of the projected climate‐suitable regions, which provide essential hosts for CLB’s establishment. The ensemble predictive results from the correlative model and mechanistic model highlight the necessity of increasing control, monitoring and quarantine efforts on the pest in the threatened areas.

Evaluation of the suitability of potato cultivation areas in South Korea based on climate and soil conditions.

Changes in dietary patterns have led to a decrease in rice consumption, raising demands for the cultivation of alternative crops that meet the current requirements. Potatoes are highly productive and can be stored for a relatively long period, thereby ensuring adequate income for farmers; however, optimal cultivation is necessary to maximize yield. This study proposes optimal cultivation regions for potato considering climate and soil conditions. The CLIMEX model was developed to evaluate climatic suitability, while the soil suitability was scored based on five soil characteristics. The final areal suitability for potato cultivation was classified into 4 levels: very suitable, suitable, marginal, and unsuitable. Overall, 36.5% of South Korea had very suitable climate, but areas with the best values for soil conditions were approximately 10% of the climatically suitable areas. When considering the climate and soil conditions simultaneously, climatic suitability and soil condition were inversely related, resulting in only 1.2% of optimal areas with Jeju Island as the most suitable area. Because both climate and soil conditions need to be suitable for growing crops, this study can provide potential paddy-cultivation areas for potato cultivation and a method for evaluating suitable areas for crop cultivation.

Potential distribution of fall armyworm in Africa and beyond, considering climate change and irrigation patterns

The fall armyworm, Spodoptera frugiperda (FAW), first invaded Africa in 2016 and has since become established in many areas across the continent where it poses a serious threat to food and nutrition security. We re-parameterized the existing CLIMEX model to assess the FAW global invasion threat, emphasizing the risk of transient and permanent population establishment in Africa under current and projected future climates, considering irrigation patterns. FAW can establish itself in almost all countries in eastern and central Africa and a large part of western Africa under the current climate. Climatic barriers, such as heat and dry stresses, may limit the spread of FAW to North and South Africa. Future projections suggest that FAW invasive range will retract from both northern and southern regions towards the equator. However, a large area in eastern and central Africa is projected to have an optimal climate for FAW persistence. These areas will serve as FAW ‘hotspots’ from where it may migrate to the north and south during favorable seasons and then pose an economic threat. Our projections can be used to identify countries at risk for permanent and transient FAW-population establishment and inform timely integrated pest management interventions under present and future climate in Africa.

Climate Change Impacts on the Potential Distribution of Apocheima cinerarius (Erschoff) (Lepidoptera: Geometridae)

Simple SummaryApocheima cinerarius (Erschoff) is an important forest pest in China. It has many hosts and occurs in 20 provinces of China, causing huge economic and ecological losses. The northern temperate zone (north latitude 30–50° N) and the south temperate zone (south latitude 20–60° S) are areas suitable for this pest, although with irrigation, suitability is reduced and the suitable area is smaller, and so superimposed irrigation will make the suitable area smaller. With projected climate change, the suitable area of A. cinerarius will move northward. A model based on climate and available hosts for A. cinerarius indicates potential for its diffusion and colonization. This research provides a theoretical basis for preventing and controlling the invasion and spread of A. cinerarius.Among the impacts of ongoing and projected climate change are shifts in the distribution and severity of insect pests. Projecting those impacts is necessary to ensure effective pest management in the future. Apocheima cinerarius (Erschoff) (Lepidoptera: Geometridae) is an important polyphagous forest pest in China where causes huge economic and ecological losses in 20 provinces. Under historical climatic conditions, the suitable areas for A. cinerarius in China are mainly in the northern temperate zone (30–50° N) and the southern temperate zone (20–60° S). Using the CLIMEX model, the potential distribution of the pest in China and globally, both historically and under climate change, were estimated. Suitable habitats for A. cinerarius occur in parts of all continents. With climate change, its potential distribution extends northward in China and generally elsewhere in the northern hemisphere, although effects vary depending on latitude. In other areas of the world, some habitats become less suitable for the species. Based on the simulated growth index in CLIMEX, the onset of A. cinerarius would be earlier under climate change in some of its potential range, including Spain and Korea. Measures should anticipate the need for prevention and control of A. cinerarius in its potential extended range in China and globally.

Distribution analysis of Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae) in South Korea using climate and host plant ensemble maps

Spatial ensemble modeling by overlaying host distribution and climatic suitability predicted by the developed CLIMEX model to evaluate the potential distribution of Leptoglossus occidentalis in South Korea. • We develop the CLIMEX model suitable for L. occidentalis distribution. • The model could predict 99% of actual distribution in North America. • The developed model was applied to predict L. occidentalis in South Korea. • Ensemble map combining climatic suitability and coniferous forests was constructed. • L. occidentalis distribution would decrease by climate change in South Korea. Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae) is a notorious pest that causes irreversible damage to coniferous forests in South Korea. However, an effective control strategy is still under development. In this study, we used CLIMEX to analyze the potential distribution of L. occidentalis in relation to climate and host plants in South Korea for the identification of effective control spots. The climate needs of L. occidentalis under current and future climate conditions were analyzed and projected on a map along with the distribution of coniferous forests. The CLIMEX model projected that the area of L. occidentalis distribution would decrease slightly in 2060 compared with that at present. However, it was projected that occurrence in mountainous regions would be sustained, suggesting continued damage to coniferous forests in South Korea.

Potential distribution and biosecurity risks from three economically important plant‐parasitic nematodes

AbstractThe plant‐parasitic nematodes (PPNs), Heterodera zeae, Hirschmanniella oryzae and Meloidogyne graminicola, are economically important pests of major grain crops. Each of these species is still absent from the majority of countries, so there is great concern about their spread. However, the areas particularly at risk of invasion and the potential global distributions of these nematode pests are yet to be identified. This paper identifies these areas, together with the main factors that could facilitate establishment in new areas using CLIMEX models. Parameterised using published studies of species phenology and global species distributions, the models correctly identified the areas invaded recently by M. graminicola and H. zeae. The vast majority of the areas of the world under wheat, rice and maize were identified as suitable for the nematodes. The nematodes are not yet established in many of these areas, suggesting that biosecurity measures may be particularly warranted to prevent the spread of these species to the new suitable areas identified. Intensive cropping systems under irrigation were identified as being at much greater risk than rain‐fed cropping systems. The potential detrimental effects from introduction and local spread of PPNs in irrigation water could undermine suggested potential gains from using irrigation to increase world food production and meet increasing demand. These results mean that biosecurity measures for PPNs are justified.

Optimised and systematic suitable climate modelling confirms future longitudinal-trends for growing oil palm in Africa

Palms are iconic plants. Oil palms are very important economically and originate in Africa where they can act as a model for palms in general. The effect of future climate on the growth of oil palm will be very detrimental. Latitudinal migration of tropical crops to climate refuges may be impossible, and longitudinal migration has only been confirmed for oil palm, of all the tropical crops. The previous method to determine the longitudinal trend for oil palm used the longitudes of various countries in Africa and plotted these against the percentage suitable climate for growing oil palms in each country. An increasing longitudinal trend was observed from west to east. However, the longitudes of the countries were randomly distributed which may have introduced bias and the procedure was time consuming. The present report presents an optimised and systematic procedure that divided the regions, as presented on a map derived from a CLIMEX model, into ten equal sectors and the percentage suitable climates for growing oil palm were determined for each sector. This approach was quicker, systematic and straight forward and will be useful for management of oil palm plantations under climate change. The method confirmed and validated the trends reported in the original method although the suitability values were often lower and there was less spread of values around the trend. The values for the CSIRO MK3.0 and MIROC H models demonstrated considerable similarities to each other, contributing to validation of the method. The procedure of dividing maps equally into sectors derived from models, could be used for other crops, regions, or systems more generally, where the alternative may be a more superficial visual examination of the maps. Methods are required to mitigate the effects of climate change and stakeholders need to contribute more actively to the current climate debate with tangible actions.

Methodological analysis of bioclimatic variable selection in species distribution modeling with application to agricultural pests (Metcalfa pruinosa and Spodoptera litura)

MaxEnt is a machine-learning-based species distribution modeling tool that is widely used to evaluate the occurrence possibility of a species. The characteristics of the algorithm requires that bioclimatic variables are appropriately selected in order for the model to predict species occurrence as precisely as possible without overfitting to the training data. In this study, we developed MaxEnt models with six different variable selection methods for two major pests, Metcalfa pruinosa and Spodoptera litura, which are differentially distributed worldwide. It was found that when evaluated by model performance indices that consider both the actual distribution and size of the prediction area, correlation-based screening, and principal component analysis-based variable reconstruction generally returned a better prediction accuracy. However, the optimal method was different for each species, indicating that the variable selection might depend on the target species and its distribution pattern, i.e., the presence data. In addition, we combined the two best MaxEnt models with a previously developed CLIMEX model, demonstrating the effectiveness of ensemble modeling in assessing species distribution. Although it was impossible to identify a single method for MaxEnt variable selection, this study provides insights on how to statistically select the bioclimatic variables and evaluate the performance between different models.

Biology, Ecology and Management of the Invasive Navua Sedge (Cyperus aromaticus)-A Global Review.

Navua sedge (Cyperus aromaticus (Ridley) Mattf. & Kukenth) is an invasive perennial sedge, native to tropical Africa, which is threatening many natural ecosystems and agroecosystems, especially in northern Queensland, Australia. Crop and pasture production have been impacted by Navua sedge and it is also directly causing reductions in dairy and beef production in affected regions. This review documents the biology, ecology and potential management options to minimise the spread and impact of Navua sedge. The weed reproduces both sexually (seeds) and vegetatively (via underground rhizomes). Its tiny seeds can be spread easily via wind, water, vehicles, farm machinery and animals, whilst the rhizomes assist with establishment of dense stands. The CLIMEX model (which uses distribution and climate data in native and novel ranges) indicates that in Australia, Navua sedge has the potential to spread further within Queensland and into the Northern Territory, New South Wales and Victoria. Several management strategies, including mechanical, chemical and agronomic methods, and their integration will have to be used to minimise agricultural production losses caused by Navua sedge, but most of these methods are currently either ineffective or uneconomical when used alone. Other management approaches, including biological control and mycoherbicides, are currently being explored. We conclude that a better understanding of the interaction of its physiological processes, ecological patterns and genetic diversity across a range of conditions found in the invaded and native habitats will help to contribute to and provide more effective integrated management approaches for Navua sedge.

Ensemble evaluation of the potential risk areas of yellow-legged hornet distribution.

Invasion of alien species facilitated by climate change and human assistant is one of global threats that cause irreversible damages on the local flora and fauna. One of these issued species, Vespa velutina nigrithoraxdu Buysson, 1905 (Hymenoptera:Vespidae), is a significant threat to entomofauna, including honeybees, in the introduced regions. This wasp is still expanding its habitats, prioritizing the development of a reliable species distribution model based on recently updated occurrence data. Therefore, the aim of this study was to evaluate the potential areas that are climatically exposed to V. v. nigrithorax invasion globally and in South Korea, where the wasp has caused severe damage to local ecosystems and apiculture after its recent introduction. We developed a new global scale ensemble model based on CLIMEX and Maxent models and applied it to South Korea using field survey data. As a result, risky areas were predicted to be temperate and subtropical climate regions, including the eastern USA, western Europe, Far East Asia, and small areas in South America and Australia. In particular, South Korea has a high potential risk throughout the country. We expect that this study would provide fundamental data for monitoring the environmental risks caused by V. v. nigrithorax using advanced species distribution modeling.

Potential displacement of the native Tenuisvalvae notata by the invasive Cryptolaemus montrouzieri in South America suggested by differences in climate suitability.

Tenuisvalvae notata (Mulsant) (Coccinellidae) is a predatory ladybird beetle native to South America. It specializes in mealybugs prey (Pseudococcidae), but relatively little is known about its ecology. In contrast, the ladybird beetle Cryptolaemus montrouzieri Mulsant (Coccinellidae) is indigenous to Australia and has been introduced to many countries worldwide including Brazil for biological control of mealybugs. The potential impacts of these introductions to native coccinellids have rarely been considered. The software CLIMEX estimated the climate suitability for both species as reflected in the Ecoclimatic Index (EI). Much of South America, Africa, and Australia can be considered climatically suitable for both species, but in most cases, the climate is considerably more favorable for C. montrouzieri than T. notata, especially in South America. The CLIMEX model also suggests seasonal differences in growth conditions (e.g. rainfall and temperature) that could affect the phenology of both species. These models suggest that few locations in South America would be expected to provide T. notata climatic refugia from C. montrouzieri. Although other ecological factors will also be important, such as prey availability, this analysis suggests a strong potential for displacement of a native coccinellid throughout most of its range as a consequence of the invasion by an alien competitor.

Establishment of the biological control agent Hypocosmiapyrochroma for Dolichandraunguis‐cati (Bignoniaceae) is limited by microclimate

AbstractCat's claw creeper, Dolichandra unguis‐cati (Bignoniaceae), a perennial woody vine native to tropical America, is a target for biological control in Australia and South Africa. The cat's claw creeper leaf‐tying moth Hypocosmia pyrochroma (Lepidoptera: Pyralidae) from tropical South America was released as a biological control agent for cat's claw creeper in Australia from 2007 to 2010. A total of 2,277 adults, 837 pupae and 77,250 larvae were released at 40 sites in Queensland and New South Wales. Releases were made mostly in open fields (85%), and at limited sites (15%) in insect‐proof cages erected over naturally occurring cat's claw creeper infestations in the field. Sampling was conducted annually in spring and autumn to monitor the establishment and dispersal of H. pyrochroma. Establishment of H. pyrochroma was first noticed in 2012 at three release sites and since then the number of established sites has increased to 80 in 2020. Establishment was evident on both ‘short‐pod’ and ‘long‐pod’ forms of cat's claw creeper and was more widespread in sites where releases were made within insect‐proof field cages (50%) than in sites with open field releases (9%). The moth was active from late spring to late autumn with peak larval activity in late summer. To date, all field establishments have been in areas predicted by a CLIMEX model as climatically suitable but restricted mostly to riparian environment (93% of establishment), where the moth has continued to spread from 1.5 to 23 km from release sites. In contrast, there is the only limited establishment and spread in non‐riparian corridors, highlighting the role of microclimate (riparian) as a limiting factor for establishment and spread. Future efforts will focus on redistribution of the agent to river/creek systems where the moth is currently not present.

Production suitability of date palm under changing climate in a semi-arid region predicted by CLIMEX model

ObjectivesDate palm (Phoenix dactylifera L.), a member of the Arecaceae family is grown on large areas in the world with varying climatic and soil conditions. However, date palm productivity is severely being affected by ongoing climate changes. Identifying suitable production areas for date palm under changing climatic conditions could help to sustain its production. The objective of the current study was to predict the range expansion/contraction in the production areas of date palm in a semi-arid region. MethodsCLIMEX model was used to estimate the expected expansion/contraction in the potential distribution areas of date palm under current and future climatic conditions. Two climate change scenarios [(CCSs) i.e., A1B and A2] were used and production suitability was predicted for three timespans [i.e., 2030 (early-century), 2050 (mid-century) and 2100 (late century)]. ResultsThe model estimated significant suitable area (71.21%) for date palm cultivation under current climatic conditions. Climate change seemed to have no impact on production areas until early-century. However, range contraction (8 and 10% decline under A1B and A2 scenarios, respectively) in the suitable areas was predicted for mid-century. Nonetheless, severe range contraction (27.98 and 33% decline under A1B and A2 scenarios, respectively) was predicted in the production areas for late-century. Most of the climatically suitable areas during early-century became unsuitable during late-century. Moreover, the model predicted northward shift in the production areas for date palm. The range contraction was higher under A2 climate change scenario due to higher warming trend compared to A1B scenario. ConclusionThe results of the current study indicate that plenty of areas are suitable for date palm cultivation. Thus, date palm cultivation could be increased in these areas for augmenting the production. Climate warming will result in the range shifts; thus, cultivation of future orchards should be planned in the most suitable areas in order to avoid the negative consequences of climate change on date palm production in the country.