Detecting latitudinal and altitudinal expansion of invasive bamboo Phyllostachys edulis and Phyllostachys bambusoides (Poaceae) in Japan to project potential habitats under 1.5°C–4.0°C global warming

Rapid expansion of exotic bamboos has lowered species diversity in Japan's ecosystems by hampering native plant growth. The invasive potential of bamboo, facilitated by global warming, may also affect other countries with developing bamboo industries. We examined past (1975–1980) and recent (2012) distributions of major exotic bamboos (Phyllostachys edulis and P. bambusoides) in areas adjacent to 145 weather stations in central and northern Japan. Bamboo stands have been established at 17 sites along the latitudinal and altitudinal distributional limit during the last three decades. Ecological niche modeling indicated that temperature had a strong influence on bamboo distribution. Using mean annual temperature and sun radiation data, we reproduced bamboo distribution (accuracy = 0.93 and AUC (area under the receiver operating characteristic curve) = 0.92). These results infer that exotic bamboo distribution has shifted northward and upslope, in association with recent climate warming. Then, we simulated future climate data and projected the climate change impact on the potential habitat distribution of invasive bamboos under different temperature increases (i.e., 1.5°C, 2.0°C, 3.0°C, and 4.0°C) relative to the preindustrial period. Potential habitats in central and northern Japan were estimated to increase from 35% under the current climate (1980–2000) to 46%–48%, 51%–54%, 61%–67%, and 77%–83% under 1.5°C, 2.0°C, 3.0°C, and 4.0°C warming levels, respectively. These infer that the risk areas can increase by 1.3 times even under a 1.5°C scenario and expand by 2.3 times under a 4.0°C scenario. For sustainable ecosystem management, both mitigation and adaptation are necessary: bamboo planting must be carefully monitored in predicted potential habitats, which covers most of Japan.     

Potential Distribution Predicted for Rhynchophorus ferrugineus in China under Different Climate Warming Scenarios

As the primary pest of palm trees, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) has caused serious harm to palms since it first invaded China. The present study used CLIMEX 1.1 to predict the potential distribution of R. ferrugineus in China according to both current climate data (1981–2010) and future climate warming estimates based on simulated climate data for the 2020s (2011–2040) provided by the Tyndall Center for Climate Change Research (TYN SC 2.0). Additionally, the Ecoclimatic Index (EI) values calculated for different climatic conditions (current and future, as simulated by the B2 scenario) were compared. Areas with a suitable climate for R. ferrugineus distribution were located primarily in central China according to the current climate data, with the northern boundary of the distribution reaching to 40.1°N and including Tibet, north Sichuan, central Shaanxi, south Shanxi, and east Hebei. There was little difference in the potential distribution predicted by the four emission scenarios according to future climate warming estimates. The primary prediction under future climate warming models was that, compared with the current climate model, the number of highly favorable habitats would increase significantly and expand into northern China, whereas the number of both favorable and marginally favorable habitats would decrease. Contrast analysis of EI values suggested that climate change and the density of site distribution were the main effectors of the changes in EI values. These results will help to improve control measures, prevent the spread of this pest, and revise the targeted quarantine areas.     

Predation by polyphagous carabid beetles on eggs of a pest slug: Potential implications of climate change

Harpalus rufipes and Poecilus cupreus are two widespread polyphagous carabids which are known to destroy eggs of the pest slug Deroceras reticulatum in the laboratory. To examine the effect of temperature on the predation of the eggs of D. reticulatum by H. rufipes and P. cupreus, a laboratory experiment with different temperatures and a semi‐field experiment including simulated warming were performed. In both experiments, H. rufipes killed more eggs than P. cupreus, and the predatory activity of the former increased significantly with increasing temperature. To our knowledge, this is the first study on predatory activity of polyphagous carabids on the eggs of a pest slug performed under a climate warming scenario. Results suggest that biological pest control performed by polyphagous carabids such as H. rufipes upon pest slugs may be enhanced under predicted climate warming conditions.     

Climate warming effects on grape and grapevine moth (Lobesia botrana) in the Palearctic region

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Reef‐coral refugia in a rapidly changing ocean

This study sought to identify climate‐change thermal‐stress refugia for reef corals in the Indian and Pacific Oceans. A species distribution modeling approach was used to identify refugia for 12 coral species that differed considerably in their local response to thermal stress. We hypothesized that the local response of coral species to thermal stress might be similarly reflected as a regional response to climate change. We assessed the contemporary geographic range of each species and determined their temperature and irradiance preferences using a k‐fold algorithm to randomly select training and evaluation sites. That information was applied to downscaled outputs of global climate models to predict where each species is likely to exist by the year 2100. Our model was run with and without a 1 °C capacity to adapt to the rising ocean temperature. The results show a positive exponential relationship between the current area of habitat that coral species occupy and the predicted area of habitat that they will occupy by 2100. There was considerable decoupling between scales of response, however, and with further ocean warming some ‘winners’ at local scales will likely become ‘losers’ at regional scales. We predicted that nine of the 12 species examined will lose 24–50% of their current habitat. Most reductions are predicted to occur between the latitudes 5–15°, in both hemispheres. Yet when we modeled a 1 °C capacity to adapt, two ubiquitous species, Acropora hyacinthus and Acropora digitifera, were predicted to retain much of their current habitat. By contrast, the thermally tolerant Porites lobata is expected to increase its current distribution by 14%, particularly southward along the east and west coasts of Australia. Five areas were identified as Indian Ocean refugia, and seven areas were identified as Pacific Ocean refugia for reef corals under climate change. All 12 of these reef‐coral refugia deserve high‐conservation status.     

Temperature,invaders and patchy habitat interact to limit the distribution of a vulnerable freshwater fish

Interacting global‐change drivers such as invasive species and climate warming are likely to have major and potentially unexpected influences on aquatic ecosystems. In river networks, modified water temperature combined with patchy physical conditions will likely cause shifts in the amount and distribution of suitable habitat, with influential invasive species further altering habitat availability. We examined how distributions of a thermally sensitive galaxiid fish native to the alpine rivers of New Zealand, Galaxias paucispondylus, were influenced by these drivers using spatially extensive presence–absence electrofishing surveys of 46 sites spread over four subcatchments. A unimodal response to water temperature and an interaction with substratum size meant G. paucispondylus were limited to streams with average summer water temperatures between 10.6 and 13.8 °C and were absent when average substratum sizes were <36 mm, regardless of temperature. In addition, non‐native trout >150 mm long excluded G. paucispondylus, but were only found in streams with average summer water temperatures <10.6 °C. These influences of trout likely strengthened the unimodal temperature response of G. paucispondylus and led to a very small G. paucispondylus realized niche. When predicted temperature increases were applied to catchment models, G. paucispondylus distributions were patchy and variable across subcatchments. Moreover, local physical characteristics of river networks were particularly important because of the non‐linear and interactive influences of temperature and substratum size on the outcome of species interactions. Therefore, substratum sizes, water temperature and a non‐native predator combined to influence the distribution of this thermally sensitive fish, illustrating how the effects of climate warming will likely be strongly context‐dependent and interactive.     

Behavioral buffering of global warming in a cold‐adapted lizard

Alpine lizards living in restricted areas might be particularly sensitive to climate change. We studied thermal biology of Iberolacerta cyreni in high mountains of central Spain. Our results suggest that I. cyreni is a cold‐adapted thermal specialist and an effective thermoregulator. Among ectotherms, thermal specialists are more threatened by global warming than generalists. Alpine lizards have no chance to disperse to new suitable habitats. In addition, physiological plasticity is unlikely to keep pace with the expected rates of environmental warming. Thus, lizards might rely on their behavior in order to deal with ongoing climate warming. Plasticity of thermoregulatory behavior has been proposed to buffer the rise of environmental temperatures. Therefore, we studied the change in body and environmental temperatures, as well as their relationships, for I. cyreni between the 1980s and 2012. Air temperatures have increased more than 3.5°C and substrate temperatures have increased by 6°C in the habitat of I. cyreni over the last 25 years. However, body temperatures of lizards have increased less than 2°C in the same period, and the linear relationship between body and environmental temperatures remains similar. These results show that alpine lizards are buffering the potential impact of the increase in their environmental temperatures, most probably by means of their behavior. Body temperatures of I. cyreni are still cold enough to avoid any drop in fitness. Nonetheless, if warming continues, behavioral buffering might eventually become useless, as it would imply spending too much time in shelter, losing feeding, and mating opportunities. Eventually, if body temperature exceeds the thermal optimum in the near future, fitness would decrease abruptly.     

Effects of temperature on life histories of three endangered Japanese diving beetle species

To elucidate population-increasing factors in the diving beetle Cybister tripunctatus lateralis (Fabricius) (Coleoptera: Dytiscidae) in Japan in recent years, life histories and oviposition patterns were compared among three endangered diving beetle species, Cybister brevis Aubé (qualified by the Japanese Red Data List as ‘near threatened’), Cybister chinensis Motschulsky (vulnerable), and C. tripunctatus lateralis (vulnerable). Oviposition in C. brevis, C. chinensis, and C. tripunctatus lateralis was observed from late April to mid-June, from late April to early July, and from late May to mid-August, respectively, under semi-outdoor conditions. There were no interspecies differences in total hatchling production during the reproductive season. In rearing experiments at various temperatures (20, 23, 25, 28, and 30 °C), the mortality of C. tripunctatus lateralis larvae was higher at 20 °C, and gradually lower with increasing temperature up to 30 °C. Adult body size of females in C. tripunctatus lateralis is larger than that of males but there were no significant differences among temperatures (25–30 °C). Cybister brevis had a higher emergence rate at 23–28 °C than at 20 and 30 °C. In C. brevis, the body size of adults reared at 25 or 28 °C was significantly larger than at other temperatures. Cybister chinensis did not differ in emergence rate and adult body size among the five temperature conditions. The developmental zero (i.e., the lower developmental threshold) from the first instar to adult emergence was 11.1 °C for C. brevis, 8.7 °C for C. chinensis, and 16.8 °C for C. tripunctatus lateralis. We speculate how the influence of global warming may have a positive impact on the growth and survival of C. tripunctatus lateralis.     

Non‐native fishes and climate change: predicting species responses to warming temperatures in a temperate region

1. Temperate regions with fish communities dominated by cold‐water species (physiological optima <20 °C) are vulnerable to the effects of warming temperatures caused by climate change, including displacement by non‐native cool‐water (physiological optima 20–28 °C) and warm‐water fishes (physiological optima >28 °C) that are able to establish and invade as the thermal constraints on the expression of their life history traits diminish. 2. England and Wales is a temperate region into which at least 38 freshwater fishes have been introduced, although 14 of these are no longer present. Of the remaining 24 species, some have persisted but failed to establish, some have established populations without becoming invasive and some have become invasive. The aim of the study was to predict the responses of these 24 non‐native fishes to the warming temperatures of England and Wales predicted under climate change in 2050. 3. The predictive use of climate‐matching models and an air and water temperature regression model suggested that there are six non‐native fishes currently persistent but not established in England and Wales whose establishment and subsequent invasion would benefit substantially from the predicted warming temperatures. These included the common carp Cyprinus carpio and European catfish Silurus glanis, fishes that also exert a relatively high propagule pressure through stocking to support angling and whose spatial distribution is currently increasing significantly, including in open systems. 4. The potential ecological impacts of the combined effects of warming temperatures, current spatial distribution and propagule pressure on the establishment and invasion of C. carpio and S. glanis were assessed. The ecological consequences of C. carpio invasion were assessed as potentially severe in England and Wales, with impacts likely to relate to habitat destruction, macrophyte loss and increased water turbidity. However, evidence of ecological impacts of S. glanis elsewhere in their introduced range was less clear and so their potential impacts in England and Wales remain uncertain.     

Adaptation of soil microbial growth to temperature: Using a tropical elevation gradient to predict future changes

Terrestrial biogeochemical feedbacks to the climate are strongly modulated by the temperature response of soil microorganisms. Tropical forests, in particular, exert a major influence on global climate because they are the most productive terrestrial ecosystem. We used an elevation gradient across tropical forest in the Andes (a gradient of 20°C mean annual temperature, MAT), to test whether soil bacterial and fungal community growth responses are adapted to long‐term temperature differences. We evaluated the temperature dependency of soil bacterial and fungal growth using the leucine‐ and acetate‐incorporation methods, respectively, and determined indices for the temperature response of growth: Q₁₀ (temperature sensitivity over a given 10oC range) and T_min (the minimum temperature for growth). For both bacterial and fungal communities, increased MAT (decreased elevation) resulted in increases in Q₁₀ and T_min of growth. Across a MAT range from 6°C to 26°C, the Q₁₀ and T_min varied for bacterial growth (Q_10–20 = 2.4 to 3.5; T_min = ?8°C to ?1.5°C) and fungal growth (Q_10–20 = 2.6 to 3.6; T_min = ?6°C to ?1°C). Thus, bacteria and fungi did not differ significantly in their growth temperature responses with changes in MAT. Our findings indicate that across natural temperature gradients, each increase in MAT by 1°C results in increases in T_min of microbial growth by approximately 0.3°C and Q_10–20 by 0.05, consistent with long‐term temperature adaptation of soil microbial communities. A 2°C warming would increase microbial activity across a MAT gradient of 6°C to 26°C by 28% to 15%, respectively, and temperature adaptation of microbial communities would further increase activity by 1.2% to 0.3%. The impact of warming on microbial activity, and the related impact on soil carbon cycling, is thus greater in regions with lower MAT. These results can be used to predict future changes in the temperature response of microbial activity over different levels of warming and over large temperature ranges, extending to tropical regions.     

The capacity to cope with climate warming declines from temperate to tropical latitudes in two widely distributed Eucalyptus species

As rapid climate warming creates a mismatch between forest trees and their home environment, the ability of trees to cope with warming depends on their capacity to physiologically adjust to higher temperatures. In widespread species, individual trees in cooler home climates are hypothesized to more successfully acclimate to warming than their counterparts in warmer climates that may approach thermal limits. We tested this prediction with a climate‐shift experiment in widely distributed Eucalyptus tereticornis and E. grandis using provenances originating along a ~2500 km latitudinal transect (15.5–38.0°S) in eastern Australia. We grew 21 provenances in conditions approximating summer temperatures at seed origin and warmed temperatures (+3.5 °C) using a series of climate‐controlled glasshouse bays. The effects of +3.5 °C warming strongly depended on home climate. Cool‐origin provenances responded to warming through an increase in photosynthetic capacity and total leaf area, leading to enhanced growth of 20–60%. Warm‐origin provenances, however, responded to warming through a reduction in photosynthetic capacity and total leaf area, leading to reduced growth of approximately 10%. These results suggest that there is predictable intraspecific variation in the capacity of trees to respond to warming; cool‐origin taxa are likely to benefit from warming, while warm‐origin taxa may be negatively affected.     

Larval development of Empoasca vitis and Edwardsiana rosae (Homoptera: Cicadellidae) at different temperatures on grapevine leaves

The grape leafhopper Empoasca vitis (Homoptera: Cicadellidae) is regarded as a major insect pest in many European grapevine growing areas, with an increasing importance realized in recent years maybe as a result of climatic change. Both larvae and adults feed on the phloem vessels of the leaves, causing characteristic symptoms also referred to as hopperburn. Phenology of adult leafhoppers was monitored in one vineyard in three successive years and indicated that immigration of a few hibernated E. vitis individuals into vineyards might take place already quite early in the year depending on winter temperatures and starts to progress in substantial numbers right at grapevine bud burst. In addition, these monitoring studies have shown that there are several other leafhopper species occurring on grapevine plants besides E. vitis, such as the rose leafhopper Edwardsiana rosae (Homoptera: Cicadellidae). Here, we report on the development of larval instars of both leafhopper species, E. vitis and E. rosae on grapevine leaves under different temperature regimes in the laboratory. Shortest larval developmental time was observed at night temperatures of 13–15°C and day temperatures of 23–25°C, which was in agreement with predicted optimal temperatures for both species. At the temperature regime of 20°C night and 30°C day temperature, either no egg hatch was observed or early development of first‐instar larvae was not successful for both species. These results suggest that warm (18°C) nights and moderately warm (28°C) days are representing the upper thermal threshold for development of both E. vitis and E. rosae embryonic stages on grapevine leaves, questioning current assumptions of an increasing importance of E. vitis as a grapevine pest under future climate change.     

Prediction of the potential global distribution of the Asian longhorned beetle Anoplophora glabripennis (Coleoptera: Cerambycidae) under climate change

1. The Asian longhorned beetle (ALB) Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) is an important wood-boring pest that has caused substantial damage to broadleaf trees in Asia, North America, and Europe.
2. We used the modelling software CLIMEX to project the potential global distribution of ALB based on both historical (1987–2016) and future (2021–2050) climate conditions. ALB has possible hosts in 37 genera, and their known distributions were incorporated into the model to assess their effect on pest distribution.
3. Suitable regions for ALB are predicted to be widely distributed under both historical and future climate conditions, and across all continents except Antarctica. With climate change, climate suitability would increase in the regions north of 30°N and decline in most regions south of 30°N.
4. The area of most climate-suitable regions would be covered by potential hosts, and optimum hosts would dominate. The possibility of ALB outbreaks in the Northern Hemisphere is much higher than in the Southern Hemisphere, owing to the richer abundance of hosts.
5. These results provide theoretical guidance for developing effective ALB monitoring and mitigation measures.

     

Rapid loss of an ecosystem engineer: Sphagnum decline in an experimentally warmed bog

Sphagnum mosses are keystone components of peatland ecosystems. They facilitate the accumulation of carbon in peat deposits, but climate change is predicted to expose peatland ecosystem to sustained and unprecedented warming leading to a significant release of carbon to the atmosphere. Sphagnum responses to climate change, and their interaction with other components of the ecosystem, will determine the future trajectory of carbon fluxes in peatlands. We measured the growth and productivity of Sphagnum in an ombrotrophic bog in northern Minnesota, where ten 12.8‐m‐diameter plots were exposed to a range of whole‐ecosystem (air and soil) warming treatments (+0 to +9°C) in ambient or elevated (+500 ppm) CO₂. The experiment is unique in its spatial and temporal scale, a focus on response surface analysis encompassing the range of elevated temperature predicted to occur this century, and consideration of an effect of co‐occurring CO₂ altering the temperature response surface. In the second year of warming, dry matter increment of Sphagnum increased with modest warming to a maximum at 5°C above ambient and decreased with additional warming. Sphagnum cover declined from close to 100% of the ground area to <50% in the warmest enclosures. After three years of warming, annual Sphagnum productivity declined linearly with increasing temperature (13–29 g C/m² per °C warming) due to widespread desiccation and loss of Sphagnum. Productivity was less in elevated CO₂ enclosures, which we attribute to increased shading by shrubs. Sphagnum desiccation and growth responses were associated with the effects of warming on hydrology. The rapid decline of the Sphagnum community with sustained warming, which appears to be irreversible, can be expected to have many follow‐on consequences to the structure and function of this and similar ecosystems, with significant feedbacks to the global carbon cycle and climate change.     

石山苣苔属的潜在适生区特征及其环境驱动变量

石山苣苔属(Petrocodon Hance)是著名的观赏花卉之一，但气候动荡和人类活动的强烈干扰，使其绝大部分被评估为极危(CR),至少也是易危(VU)以上。为重建末次间冰期以来石山苣苔属潜在适生区的时空变化，探讨适生区对环境变化的响应关系，为石山苣苔属的起源、地理分化研究和中国特有种质资源保护、园林开发利用提供理论指导，该研究结合120个分布记录和17个环境变量，应用优化的MaxEnt模型和地理信息技术(ArcGIS)对石山苣苔属在中国及中南半岛的适生区及其分布格局进行模拟，并基于逐步多元线性回归分析、冗余分析和蒙特卡洛检验评估影响石山苣苔属当前地理分布的主导变量。结果表明：(1)优化的MaxEnt模型的预测精度高，AUC值大于0.96;石山苣苔属当前适生区从中国西南部连续分布至越南北部，零散分布于中国中部和南部、块状分布于缅甸北部，其中以中国云贵高原南部为最佳适生区。(2)制约石山苣苔属当前地理分布的主导环境变量为最干月降雨量(bio14)、最热季度平均降雨量(bio18)、最湿季降雨量(bio16)、温度变化方差(bio4)、最冷月最低温度(bio6)、海拔(alt)。(3)在...     

Sustainability potential for Ginkgo biloba L. plantations under climate change uncertainty: An ex-situ conservation perspective

G. biloba is native to China and one of the oldest living species. It has high economic value and has been used for medicinal, ornamental and other purposes. The current study sought to assess the potential sustainability of the plantations of the endangered species under climate change scenarios. The sustainability of the existing small wild population and plantations of the species worldwide were evaluated by assessing the changes in the climatic suitability of the areas to be used for the species plantations under different emission scenarios. A survey for the species distribution worldwide showed that it is currently planted in 29 botanic gardens. In Egypt only 31 trees exist in private and public botanic gardens. Propagation and germination experiments have been tested in 4 successive years to assess the effect of climate changes on germination requirements and phenology of the species. Propagation trials showed that seeds that were grown in soil media for 5 months under 25 °C attained high germination rate (>60%). Propagation trials in the nursery by stem cuttings gave promising results (100%) in 2015–2016. Using SDMs approach for assessing the change in the potential climatically suitable areas for the plantations and ex situ conservation of G. biloba under different climate change and emission scenarios, revealed that overall G. biloba is predicted to gain more climatically suitable areas under the four representative concentration pathway scenarios (RCP 2.6, 4.5, 6.0 and 8.5), however, a gain in the climatically suitable areas for the species is expected under the low and moderate emission scenarios and a decline is expected under the more warming scenarios. Also, a northwards shift is predicted in the climatic suitability for the plantations of the species. The projected latitudinal shift needs to be considered by mangers of G. biloba plantations. The provided predictions can guide the managers in developing short- and long-term plans for sustaining the plantations of the species under a precipitously changing climate.     

Prediction of climate warming impacts on plant species could be more complex than expected. Evidence from a case study in the Himalaya

Many studies have investigated the possible impact of climate change on the distributions of plant species. In the present study, we test whether the concept of potential distribution is able to effectively predict the impact of climate warming on plant species.Using spatial simulation models, we related the actual (current species distribution), potential (modelled distribution assuming unlimited dispersal) and predicted (modelled distribution accounting for wind-limited seed dispersal) distributions of two plant species under several warming scenarios in the Sagarmatha National Park (Nepal). We found that the two predicted distributions were, respectively, seven and nine times smaller than the potential ones. Under a +3 °C scenario, both species would likely lose their actual and predicted distributions, while their potential distributions would remain partially safe. Our results emphasize that the predicted distributions of plant species may diverge to a great extent from their potential distributions, particularly in mountain areas, and predictions of species preservation in the face of climate warming based on the potential distributions of plant species are at risk of producing overoptimistic projections.We conclude that the concept of potential distribution is likely to lead to limited or inefficacious conservation of plant species due to its excessively optimistic projections of species preservation. More robust strategies should utilize concepts such as “optimal reintroduction”, which maximizes the benefit–cost ratio of conservation activities by limiting reintroduction efforts to suitable areas that could not otherwise be reached by a species; moreover, such strategies maximize the probability of species establishment by excluding areas that will be endangered under future climate scenarios.     

Climate-based ensemble modelling to evaluate the global distribution of Anoplophora glabripennis (Motschulsky)

1. Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) is a forest pest that damages a wide range of trees in areas where it has recently been introduced, demanding a proactive evaluation of its possible future distribution.
2. This study aimed to project the potential distribution of A. glabripennis using species distribution modelling and constructed an ensemble map for evaluating global risk areas.
3. We used CLIMEX and MaxEnt to evaluate the potential distribution of A. glabripennis as a function of current and future climates.
4. The results showed that the models predicted a high probability of A. glabripennis distribution where this species is currently found, and the suitable climate was shifted northward due to climate change.
5. The projected area differed between the models because of different modelling algorithm and climate change scenario; thus, an ensemble map projecting the consensus areas from two models was constructed to identify the risk areas that corresponded to the eastern United States, Europe, and native countries, Korea and China, and nearby Japan.
6. From the perspective of ensemble modelling for evaluating species distributions with reduced uncertainties, this study will enhance the model reliability for defining areas at risk of A. glabripennis occurrence.

     

Effects of climate warming on plant autotoxicity in forest evolution: a case simulation analysis for Picea schrenkiana regeneration

In order to explore how plant autotoxicity changes with climate warming, the autotoxicity of P. schrenkiana needles' water extract, organic extract fractions, and key allelochemical DHAP was systemically investigated at the temperature rising 2 and 4°C based on the data‐monitored soil temperature during the last decade in the stage of Schrenk spruce regeneration (seed germination and seedling growth). The results showed that the criterion day and night temperatures were 12°C and 4°C for seed germination, and 14°C and 6°C for seedling growth, respectively. In the presence of water extract, the temperature rise of 2°C significantly inhibited the germination vigor and rate of P. Schrenkiana seed, and a temperature rise of 4°C significantly increased the inhibition to the seedling growth (P < 0.05). Among the three organic fractions, the low‐polar fraction showed to be more phytotoxic than the other two fractions, causing significant inhibitory effects on the seed germination and growth even at low concentration of 0.1 mg/mL, and the inhibition effect was enhanced as temperature increased. The temperature rise significantly enhanced the promotion effect of DHAP, while the inhibition effect of temperature rise became less important with increasing concentration of DHAP. This investigation revealed that autotoxicity of P. schrenkiana was affected by the climate warming. As expected, it provided an insight into the mechanism and effectiveness of allelopathy in bridging the causal relationship between forest evolution and climate warming.     

Effect of temperature on survival and immature development of Arma chinensis

Arma chinensis (Fallou) is a predaceous pentatomid with the potential to control a wide range of insect pests. In this study, the stage-specific temperature-dependent development and survival of A. chinensis was investigated under seven constant temperatures (range 18–35 °C) when fed with yellow mealworm (Tenebrio molitor L.). Developmental times (in days) for the immature stage, entire nymphal stage, and egg-to-adult development were inversely proportional to temperatures between 18 and 33 °C (30 °C for eggs and 1st instar nymphs). The lowest survival rate of A. chinensis was observed at 18 °C (6.7%), whereas it was the highest (80–93.3%) at temperatures ranging from 21 to 24 °C. The low temperature thresholds for the egg, entire nymph stage, and egg-to-adult development were 14.3, 12.28, and 12.8 °C, respectively, while the thermal constants for these stages were estimated to be 85.47, 334.9, and 423.8° days. Among the three non-linear models examined, the Taylor model showed the best fit for the egg data, the Briére1 model was the best fit for the 1st instar nymph stage, and the Lactin1 model was more approprate for all the other instar stages, the entire nymphal stage, and overall development. The upper temperature thresholds estimated using the Lactin1 model for eggs, overall nymphal stage, and egg-to-adult development were 38.57, 38.9, and 40.0 °C. The optimal temperature for the overall egg-to-adult period was estimated to be 33.5 °C. The results of this study can be used for the mass rearing of this natural pest enemy and development of phenology models of its seasonal progress.