不同干扰下阿拉善荒漠啮齿动物优势种对气候变化的响应

Many studies focus on rodent community pattern and changing at present in the world, but most of them are conducted in small plots. Few studies investigated the rodent community classification and diversity in semi-desert and desert areas at regional scale, although some researchers started to study the change of animal community patterns on a large scale. We investigated rodent communities in desert, non-irrigated farming land and desert steppe of Inner Mongolia, covering an area of 380,000 km2 from May to August in 1988-1993 and in 1998-2003, respectively, in order to reveal the changing characteristics of zonal rodent communities. The community classification and diversity of rodents were analyzed in research areas. The results suggested that the communities could be classified in 9 zonal types. Spermophilus dauricus, Cricetulus longicaudatus and Eutamias sibiricus were dominant species in Community I; Phodopus roborovskii, Cricetulus barabansis and Cricetulus longicaudatus were dominant in Community II; Meriones unguiculatus, Phodopus roborovskii and Cricetulus longicaudatus were dominant in Community III; Allactaga sibirica, Allactaga bullata and Spermophilus dauricus were dominant in Community IV; Allactaga bullata, Dipus sagitta and Meriones unguiculatus were dominant in Community V; Meriones meridianus, Spermophilus dauricus and Allactaga bullata were dominant in Community VI; Allactaga sibirica, Allactaga bullata and Dipus sagitta were dominant in Community VII; Phodopus roborovskii, Dipus sagitta and Allactaga sibirica were dominant in Community VIII; Meriones meridianus, Dipus sagitta and Allactaga sibirica were dominant in Community IX. The community diversity and evenness analysis showed that the edge effect of community, the effect of disturbance and habitat fragmentation and scale effect were significantly correlated with community diversity in the semi-desert and desert regions. The ordinal results of 9 zonal rodent communities were in accordance with the results analyzed with similar community indices, showing the habitat change in the characteristics of the above-mentioned groups.

Benthic diatoms are an indispensable link of the water ecological system in terms of energy flow and material cycling, and they directly or indirectly reflect the status of the water environment. We sampled benthic diatoms and environmental factors from April to May of 2013 from 53 sites along the Ying River to study their application in local water trophic status assessment, with a focus on the dominant benthic diatom species, their composition and distribution pattern, and the relationship between benthic diatoms and environmental factors. A total of 370 species and varieties were identified, belonging to 56 genera and six orders. The dominant species were as follows: Nitzschia inconspicua Grunow, Achnanthidium minutissimum (Kützing) Czarnecki, Navicula aitchelbee L. L. Bahls, Nitzschia palea (Kützing) Smith, Cyclotella meneghiniana Kützing, Navicula submuralis Hustedt and Mayamaea atomus (Kützing) Lange-Bertalot. The Ying River was divided into five orders using the Strahler method and three regions according to total nitrogen, total phosphorus and ammonia nitrogen. In region Y-1, which had the lowest nutrient level, the dominant species was Achnanthidium minutissimum. In region Y-2, which had the highest nutrient level, Navicula aitchelbee, Nitzschia palea, and Cyclotella meneghiniana were dominant, while in region Y-3, which had moderate nutrient levels, Nitzschia inconspicua was dominant. Pearson’s correlation analysis and canonical correspondence analysis (CCA) revealed a significant correlation between the environmental factors with dominant species and diatom indices (especially the SPI). Our study indicates that dominant species and diatom indices can, to some extent, indicate the environment, especially nutrient distribution.

Acknowledgement to reviewers

The broadleaved Korean pine forest is the zonal climax vegetation in the eastern mountainous region of Northeast China, and it has been subjected to intense human disturbance and largely replaced by extensive secon-dary forests and plantations since the last century. Investigating the spatial distribution patterns of dominant species and their interspecific associations in secondary forests is crucial for elucidating community assembly mechanisms and ecological processes. Based on data from a 25 hm2 permanent secondary forest plot in the Xiaoxing'an Mountains, we analyzed population structures of dominant woody species with DBH≥1 cm, explored the ecological processes influencing their spatial distributions by different null models. A total of 70611 woody plants (DBH ≥1 cm) were recorded, belonging to 48 species, 39 genera, and 23 families. Acer pictum subsp. mono and Pinus koraiensis exhibited an inverted "J"-shaped diameter distribution, while Betula platyphylla, Tilia amurensis, and Betula costata displayed approximately normal distributions in diameter classes, and Corylus mandshurica displayed an "L"-shaped patttern. Under the complete spatial randomness model, C. mandshurica, P. koraiensis, and B. costata showed aggregated distributions across all scales (0-100 m), B. platyphylla, A. pictum subsp. mono, and T. amurensis showed aggregated distributions at scales of 0-81 m, 0-94 m, and 0-48 m, and random distributions at other scales. Under the Poisson cluster model, C. mandshurica, A. pictum subsp. mono, T. amurensis, and P. koraiensis showed aggregated distributions at the 0-5 m scale, B. platyphylla showed an aggregated distribution at the 0-2 m scale, B. costata showed random distributions across all scales. Under the heterogeneous Poisson model, the degree of aggregation decreased, tending toward random and uniform distributions. Interspecific associations among dominant species were primarily positive or negative. Evergreen and deciduous species mainly showed positive associations, while dominant tree species and shrubs predominantly exhibited negative associations. In conclusion, the secondary forest community showed good regeneration, with dispersal limitation and habitat heterogeneity driving the spatial patterns of dominant species. The associations among dominant species reflected a coexistence of competition and mutualism mechanisms.

Cattle grazing has been shown to alter various features of desert communities that may impact microhabitats required by various species of desert rodents, with unknown implications for desert rodent communities. We conducted a series of studies at heavily and lightly grazed sites to investigate effects of cattle grazing on desert rodent relative abundances, home range sizes and microhabitat use in salt desert shrub communities of the western Great Basin Desert. Monitoring of rodent populations with repeated live trapping showed that different levels of grazing were associated with differences in relative abundances of some species of rodents. Specifically, Dipodomys merriami was significantly more abundant in heavily grazed areas, and Perognathus longimembris was significantly more abundant in lightly grazed areas. Our studies showed that cattle, by preferentially feeding on certain plants, can create conditions that are more suitable for some species of rodents, while reducing important microhab...

Global climate change is significantly altering the large scale distributions of plants and animals. The Earth has warmed by 0.7°C during the last century. The consequences are already apparent in forest ecosystems as species are responding to the changing climate with shifts in their phenology and geographic distributions. The potential for large increases in global mean temperatures (e.g., 4.3 ± 0.7°C) by 2100 has significant implications for forest species and ecosystems. Under these varying climatic conditions, some species may go extinct either locally or regionally, with climate change acting synergistically with other extinction drivers. Tropical Asian forests contain several biodiversity hotspots and species-rich ecoregions. Our understanding of species’ and forest ecosystems’ vulnerability to global climate change in this region is limited. Addressing this problem is a critical task for current tropical Asian ecological research.The overall aim of this PhD thesis is to investigate the current and potential effects of climate change on the geographic distribution and composition of selected plant and mammal species in tropical Asian forests. The selected plants include Sal (Shorea robusta), Garjan (Dipterocarpus turbinatus) and Teak (Tectona grandis). These all are ecologically and economically important timber trees and are distributed widely across South and Southeast Asia. The selected mammals include Asiatic black bear (Ursus thibetanus), Asian elephant (Elephas maximus), Western hoolock gibbon (Hoolock hoolock) and Bengal tiger (Panthera tigris tigris). These threatened large mammals are of high conservation concern and are typically targeted by international conventions. I present a comprehensive review of the previous literature and new predictive models of species distributions that quantify potential climate change impacts on tropical forests. My results show that projected changes in temperature and rainfall extremes are potential threats to the diverse and species-rich forest ecoregions of tropical Asia.I used bio-climatic models and two scenarios of climate change (a moderate and an extreme Representative Concentration Pathway (RCP) scenario) to assess climate change impacts on the continental scale distributions of two threatened Dipterocarp trees Sal and Garjan, and the valuable timber species, Teak. Annual precipitation was the key bioclimatic variable for explaining the current and future distributions of Sal and Garjan. Suitable habitat conditions for Sal will decline by 24% and 34% by 2070 under the RCP4.5 and RCP8.5 scenarios, respectively. In contrast, the consequences of climate change appear less severe for Garjan, with a decline of 17% and 27% under RCP4.5 and RCP8.5, respectively. Changes in annual precipitation, precipitation seasonality and annual mean actual evapotranspiration may result in shifts in the distributions of Teak across tropical Asia. These findings can contribute to conservation planning for the species and their management under future climates.I developed habitat suitability models for the four large threatened mammals (Asiatic black bear, Asian elephant, Western hoolock gibbon and Bengal tiger), across their entire distributions in Asia. The results suggest that changes in annual precipitation, annual mean temperature, precipitation and temperature seasonality, and land use/land cover change could reduce suitable habitat for these large mammals and therefore increase their extinction risks. It can be concluded that increasing climate stress on tropical forests could lead to greater extinction risks of these threatened large mammals.The findings of this thesis provide a fundamental basis for further studies of climate change impacts on species distribution in tropical Asia, and highlight the conservation importance of the plant and animal species in the region. The modelling outputs can be used to categorize the natural habitats of Sal, Garjan and Teak as low to high risk under changing climates to inform conservation planning and forest management. Given the conservation importance of the threatened large mammals for maintaining a healthy forest ecosystem, the findings of the models can be used to categorize the likely suitable habitats under changing climates and preparing proper guidelines to reduce their extinction risks. To ensure wider applicability to conservation planning for species vulnerable to global climate change, the methods and analyses presented here for tropical Asia could be applied to other tropical regions (i.e., in Africa and the Americas), using different species groups and forest types.

Effect of land-based solar power development on ecosystem functions in global terrestrial ecosystems.

According to the mean seasonal and annual temperature and precipitation from Nielamu and Dingri meteorological stations in the periods of 1967–2019, the variability of temperature and precipitation and their trends are analyzed in the Mount Qomolangma region. The biggest fluctuation of precipitation occured in winter on the seasonal scale, the mean annual temperature showed a wavelike decrease change before 1997 and a wavelike increase change after 1997, the mean seasonal and annual temperature are increased with the increasing of age. There is an increasing trend in mean seasonal and annual temperatures during this period in the Mount Qomolangma region, and the increasing trends in winter seem more significant than those in the other three seasons. The research in this paper showed the seasonal and annual precipitation are no obvious variation in the Mount Qomolangma region. On the other hand, there is obvious local change characteristics for temperature and precipitation in the Mount Qomolangma region. The results of this study would be helpful for the understanding of the climatic characteristics on the Tibetan Plateau, and it could provide a reference for the Second Tibetan Plateau Scientific Expedition and Research (STEP).

Influence of climatic and geographic factors on the spatial distribution of Qinghai spruce forests in the dryland Qilian Mountains of Northwest China

Vegetation around the Daihai Lake, northern China, is very sensitive to climate changes. In this paper, pollen-based quantitative climate reconstructions using three methods [weighted averaging partial least squares method (WAPLS), modern analog technique (MAT), and pollen response surface method (PRS)] were conducted to obtain robust reconstructions of Holocene climate changes in the Daihai Lake area. The result obtained by the three methods all consistently show the annual precipitation to have been 50–100 mm lower in the early Holocene, 100–200 mm higher in the Mid-Holocene, and 50–100 mm lower again in the late Holocene than at present. The WAPLS and the MAT methods also show quasi-synchronous oscillations of the mean annual temperature (Ta); 1°–2°C lower in the Early Holocene and 1°–3°C higher in the Mid-Holocene than today. The time period from 6200 to 5100 cal yr BP was the wettest and the warmest interval, with an annual precipitation (Pa) greater than 550 mm and mean annual temperature Ta higher than 6.5°C. Several cold and dry events can be identified to occur about 8200, 6000, and 4400 cal yr BP, with an annual precipitation less than 400 mm and a mean annual temperature colder than 4.5°C, respectively. The mean temperature of the warmest month (Tw) as reconstructed using both WAPLS and MAT methods was relatively stable during the Holocene, fluctuating about ±2°C relative to the present level, but the PRS method suggests more varied Tw values in both amplitude and frequency. After 1500 cal yr BP, no consistent pattern can be observed from these three different analyses, probably because of the impact of intensified human disturbances on the natural vegetation. The fluctuations of annual precipitation (Pa) correspond to that observed in Dongge Cave in southern China. The differences might be linked to Indian monsoon and East Asia monsoon climates or caused by the different degree of dating precision, different temporal resolution, and different sensitive response of climate proxies to the climate variations.

Several rodent species damage rice crops and commensal rodents cause damage to stored produce and infrastructure, hygienic problems and they can transmit zoonotic pathogens. In the first such study in Sri Lanka, we identified the main rodent and shrew species and the extent of post-harvest damage caused in rice storage facilities of smallholder farmers. Netting of rice bags was trialled as a new measure of protection. Field experiments were performed in the three main agro-ecological zones of Sri Lanka.Five rodent species and one shrew species were captured in storage facilities. Rattus rattus, Bandicota indica and Suncus murinus were the dominant species in storage facilities. The small mammal composition was more related to season than to region. In storage, depending on region, 3.2–9.1% (mean 7.6%) of rice was lost to rodents when rice was stored indoors in unprotected polyethylene bags. Netting around bags reduced damage by 89% - equivalent to the annual rice consumption of one person per storage facility, reduced the presence of rodent droppings by 92% and the bag area damaged by rodents by 96%.Our findings clearly show the considerable amount of damage caused by rodents to rice post-harvest across three agro-ecological zones of Sri Lanka and indicate that netting bags considerably reduces damage and contamination. This netting can be used to aid the development of an ecologically-based rodent management (EBRM) program tailored to local conditions. More detailed studies are needed to fully understand the population and breeding ecology of the relevant rodent pest species in relation to damage patterns to optimize management beyond individual structural measures.

Ecosystem organic carbon storage and their drivers across the drylands of China

The responses of dominant tree species to climate warming at the treeline on the eastern edge of the Tibetan Plateau

AimGlobal flux data analyses have shown a significant positive and linear relationship between site‐scale photosynthetic optimum temperature (Topt‐s) and averaged temperature variables. However, as existing studies have not fully considered species composition, it remains unclear to what extent the change in Topt‐s is derived from intraspecific plasticity or from a difference in species with a consistent species‐specific Topt‐s. We tested these two hypotheses using the satellite‐derived enhanced vegetation index (EVI).LocationSubalpine and temperate forests in Japan.Time period2001–2020.Major taxa studiedThirty‐three tree species.MethodsBased on an in situ vegetation survey dataset, we identified 1814 EVI cells (250 m × 250 m) that were characteristic of the spectral reflectance of a single dominant species. For each cell, we pooled EVIs from 2001 to 2020 and estimated the temperature at the time of EVI peak as a species‐specific Topt‐s. We tested our hypotheses by fitting linear regression models to the Topt‐s and mean annual temperature (MAT). A positive slope indicated support for the intraspecific plasticity hypothesis.ResultsFor 32 of the 33 tree species, the Topt‐s increased with an increase in MAT. A linear mixed‐effect model provided a good explanation of the variation in the Topt‐s based on the MAT (intercept = 14.63, slope = 0.58, marginal R2 = .78), with minimal effect of species difference (conditional R2 = .75).Main conclusionsOur results support the intraspecific plasticity hypothesis. At least in East Asian subalpine and temperate forests, the Topt‐s can be estimated from the MAT, irrespective of the dominant canopy species. The observed MAT–Topt‐s relationship is consistent with the findings of previous photosynthetic studies and has important implications for the establishment of new algorithms for estimating gross primary productivity that can account explicitly for spatial and temporal differences in temperature‐dependent photosynthetic responses.

Ethiopian woodlands offer a variety of cultural, social, and economic advantages. However, human disturbances, climate change, and changes in land use may have influences on the benefits and services that woodlands currently provide. Furthermore, the distribution of plant ecosystems can be influenced by ecological characteristics. This study aimed to identify the types of plant communities, the relationships between plant communities and environmental conditions, the diversity, composition, and structure of woody plant species, and the regeneration status of woody species in the Basso Subwatershed. To gather information on vegetation and environmental conditions, systematic random sampling was employed. Fifty-two 20 m × 20 m sample quadrats were set up to assess trees and shrubs, and five 5 × 5 m subplots were created to assess seedlings and saplings. Woody species diversity was evaluated using the Shannon–Weiner diversity index, species richness, and Shannon evenness. Canonical correspondence analysis was used to examine links between vegetation and the environmental factors. In this study, a total of 28 plant species that belong to 17 families and five different plant community types were identified. The richness and diversity of species differed depending on the type of community. The overall Shannon–Wiener diversity index (2.65), species richness (25), and the Shannon evenness value (0.84) of the woodland were recorded in the subwatershed. Findings show that slope, disturbance, and grazing intensity reflected significant effects on woody vegetation patterns in the Basso Subwatershed (p < 0.01). However, altitude, aspect, and human impacts did not show significant effects on woody vegetation patterns in the Basso Subwatershed (p > 0.01). The most dominant woody species in the subwatershed were Acalypha fruticosa, Terminalia brownii, Combretum molle, and Balanites aegyptiaca. In the future, rehabilitation and sustainable vegetation management techniques will take into consideration significant environmental factors, particularly for species with low rates of regeneration like Dichrostachys cinerea, Grewia bicolor, and Maytenus senegalensis.