Ailao Mountains Research Articles

Habitat suitability of neotenic net‐winged beetles (Coleoptera: Lycidae) in China using combined ecological models, with implications for biological conservation

AbstractAimChina has dozens of well‐recognized biodiversity hotspots, but many more potential areas have not been estimated thoroughly, which is unfavourable for biodiversity conservation. Neotenic net‐winged beetles with limited dispersal ability generally occur in restricted ranges but rarely occur in China, which makes them ideal models for biogeographical studies to define biodiversity hotspots. This study will explore the potential distribution patterns of neotenic Lycidae in China to provide basic data for the implementation of biological conservation.LocationChina.MethodsWe conducted maximum entropy (MaxEnt) and random forest (RF) modelling to simulate the habitat suitability for neotenic Lycidae occurring in China under different climate scenarios by using all available distribution information in Southeast Asia (a total of 305 occurrence records) and several environmental variables. The dynamic changes in the potentially suitable habitats and centroids of neotenic Lycidae were simulated under all climate scenarios.ResultsThe results indicated that potentially suitable habitats for neotenic Lycidae were mostly located in the montane areas and mountainous islands in southern China, including the eastern Himalayas, Gaoligong Mountains, Ailao Mountains, Hengduan Mountains, Wumeng Mountains, Miaoling Mountains, Daba Mountains, Wu Mountains, Yunkai Mountains, Wuzhi Mountains and Central Mountains. In addition, the dynamic analyses showed that their changes also occurred in montane areas, whose affinity and significance were confirmed in the biological conservation.Main conclusionsTaking the unique neotenic Lycidae as the subject, we verify that several montane areas are biodiversity hotspots that have already been well‐recognized, while it is determined that some additional mountains could be potential hotspots. Therefore, more attention and biological conservation efforts should be used in these areas. In addition, using the ensemble modelling approach to identify potential distributions is a helpful tool to develop strategies for biological conservation, even if it has several limitations.

Responses of Nitrogen-Fixing Bacteria Communities to Elevation, Season, and Slope Aspect Variations in Subtropical Forests of Yunnan, China

Nitrogen-fixing bacteria play a significant role in tropical forest ecosystems. However, little is known about the comprehensive effects of altitude gradient (1000–2600 m), seasons (October, January, April, and July), and slope aspects (east and west) on the abundance and diversity of nitrogen-fixing bacteria in subtropical forest. Q-PCR and PCR-DGGE methods were performed to explore the abundance and diversity of nitrogen-fixing bacteria, respectively, in the Ailao Mountain subtropical forest. Our results showed that the abundance of nitrogen-fixing bacteria was highest in October and December, whereas it was lowest in April and July. Moreover, there was no difference in the total number of soil nitrogen-fixing bacteria on the eastern and western slopes. The diversity of soil nitrogen-fixing bacteria is higher at low and medium altitudes, but lower at high and medium altitudes with increasing altitude, and similar variation in the eastern and western slopes as well. Moreover, the most influential factors affecting the abundance of nitrogen-fixing bacteria was NH4+-N and herbal coverage, while those most affecting the diversity of nitrogen-fixing bacteria were NH4+-N and NO3−-N. In addition, permutational multivariate analysis demonstrated that the season had the greatest effects on the abundance of nitrogen-fixing, whereas altitude had the greatest effects on the diversity of nitrogen-fixing bacteria. These findings provide evidence that the variation in nitrogen-fixing bacteria is affected by multiple factors (altitudes, seasons and slope aspects) in the subtropical forests of Yunnan, China.

Response strategies of N-fixation by epiphytic bryophytes to water change in a subtropical montane cloud forest

Water changes are predicted to regulate physiological activities of bryophytes characterized by poikilohydric gametophytes. In montane forest ecosystems, nitrogen(N)–fixing bryophyte–cyanobacteria associations are main N resources. The aim of this study was to assess how bryophyte–associated microbiomes and their nitrogenase activity response to instant or long-term water content changes. We investigated the cyanobacterial colonization and nitrogenase activity of four epiphytic bryophyte species in a subtropical montane cloud forest during the dry and rainy seasons in Ailao Mountains, Yunnan, southwestern China. We also evaluated the nitrogenase activity of bryophyte–cyanobacteria associations in response to different water contents in laboratory experiment. The degree of cyanobacterial colonization was evaluated using ultraviolet fluorescence microscopy, and nitrogenase activity of bryophyte–cyanobacteria associations were measured using the acetylene reduction assay (ARA). Cyanobacteria showed an association with all four bryophyte species, with 1.04–3.37% area colonized of the shoot and 10.16–20.21 nmol C2H4·g−1·h−1 average nitrogenase activity. Nitrogenase activity was positively related to cyanobacterial colonization (R = 0.742; P = 0.0349). The relationship between water content and nitrogenase activity was unimodal, and both water surplus and shortage inhibited N fixation. Furthermore, long–term drought conditions reduced the degree of cyanobacteria colonization on bryophyte shoots, resulting in decreased nitrogenase activity in the dry season. These results indicate that different response strategies of N fixation operate in bryophyte–cyanobacteria associations to cope with instant and long–term changes in water availability. Our data suggest that both extreme precipitation and drought have a negative impact on N fixation of cyanobacteria–bryophyte associations.

Fast restore of the structure and composition of hemiepiphytes after a heavy-snowfall event in a subtropical forest

Since epiphytes mainly obtain water and nutrients from surrounding air, they are extremely sensitive to environmental changes, making them reliable bio-indicators for monitoring climate change. Hemiepiphytes are one common form of epiphytic plants, consisting of primary and secondary hemiepiphytes. It is thus reasonable to suppose that the hemiepiphytes should respond strongly to an extreme change in local climatic conditions. Based on survey data of hemiepiphytes (all the investigated species are primary hemiepiphytes) on trees before (2014) and after (2018) a heavy snowfall event (2015, depth of 50 cm), we examined differences in the distribution and abundance of individuals, population structure, and the general network structure of hemiepiphyte–host associations in a subtropical forest in the Ailao Mountains (Yunnan Province, in southwest China). Contrary to our hypothesis, the results revealed no significant changes for the distribution and abundance of this hemiepiphyte community before and after the heavy-snowfall event. The population structure of all hemiepiphytes (pooled) shifted from a dynamic to a stable state, but did not change on a per species basis. According to the constructed network's parameters, no significant differences were found between years, except for changed web asymmetry, linkage density, and interaction evenness. Our results suggest hemiepiphytes are highly resilient to extreme weather perturbations: within just four years after the snowfall, the community was nearly fully restored to its prior composition and structure. We propose this resilience capability is linked to their ecophysiological characteristics and distributions on host trees.

U-Pb Detrital Zircon Ages and Geochemical Features of the Jingxing Formation, (Qamdo Basin, Tibet: Implications): Inferences for the Metallogenic Model of the East Tethys Evaporite

Qamdo basin is located between the suture zone of Jinsha River (Ailao Mountains) and that of Ban Gong Lake (Nujiang) in the eastern Tethys. Part of the Jingxing Formation is deposited in the southwest of the basin. In this study, two profiles were investigated from the north and south of Qamdo basin. The characteristics of detrital zircon LA-ICP-MS U-Pb age, and the main and trace elements of sandstone were analyzed. The characteristics of major and trace elements showed that the tectonic setting of the study area is mainly composed of a relatively stable active continental margin and a passive continental margin, showing characteristics of a continental island arc. The weathering degree of Jingxing Formation in the Qamdo area is lower than that in the Lanping-Simao area, which may be closer to the origin. The age distribution characteristics of detrital zircon grains indicate that the Qiangtang Block, Youjiang basin, and Yangtze area jointly constitute the provenance of the Qamdo-Lanping-Simao basin. Both basins may be part of a large marine basin with unified water conservancy connection before evaporite deposition. Metamorphic seawater from the Qamdo basin may migrate to the Lanping-Simao basin and even the Khorat basin, where evaporite was deposited.

Spatial Distribution Trends and Influencing Factors of Typical Heavy Metals in Subtropical Alpine Forest Soils: A Case Study from Ailao Mountain in Yunnan Province

In this study, we hypothesized that the distribution patterns of trace metal elements in montane regions would be controlled by the local climate, human activities, vegetation distribution and soil development. Hence, we selected nine forest sites among the elevation of 850 m to 2650 m on the windward (western slope) and leeward (eastern slope) slopes of Ailao Mountain in Yunnan Province of China to determine the typical heavy metal concentrations in forest surface soils, and their differences for distribution trends along with the increasing elevations, and the corresponding environmental factors. The results showed that surface soil Cd, Sb, As, Cr, and Pb had relatively higher concentrations and distinct enrichment factors both on eastern and western slopes. Specifically, the concentrations of Cd and Sb in surface soils of the eastern and western slopes and Pb on the western slope all had obvious altitude distribution trends, which showed their concentrations increased with the increasing elevation. In addition, we found the concentrations of Cd, Sb, As, and Cr in surface soils of the western slope were significantly higher than those of the eastern slope at the same altitude. The correlation analysis and principal component analysis further depicted that the elevation trends of Cd and Sb were mainly controlled by the strong combining effects from long-range atmospheric input and soil organic matter strong absorption, and there was an obvious "cold trapping" effect in high altitude areas. The distribution variations of As and Cr were mainly derived from the weathering difference of soil parent material, while the variations for Pb were controlled by the weathering of bedrock minerals. This study highlights the important role of combining effects from long-range atmospheric input, and from precipitation and vegetation (such as "cold trapping" effect, promoting canopy filtration, litterfall deposition and bedrock weathering) on the distribution trends of trace metals in remote alpine soils.

Chthonobacter rhizosphaerae sp. nov., a bacterium isolated from rhizosphere soil of Citrus sinenesis.

A Gram-staining negative, facultative anaerobic, motile and short rod-shaped bacterium, designated strain yh7-1T, was isolated from rhizosphere soil of Citrus sinenesis collected from the garden of Citrus sinenesis in Ailao Mountain, south-west China. Cells grew at 15-45°C, pH 5.0-9.0 and were able to tolerate up to 1% (w/v) NaCl on R2A medium. The respiratory lipoquinone was Q-10 and the major cellular fatty acids contained summed feature 8 (C18:1 ω7c or C18:1 ω6c) and C18:0. Polar lipids in the cellular membrane were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and one unidentified aminophospholipid. The genomic DNA G+C content was 69.9mol%. On basis of 16S rRNA gene sequence analysis, strain yh7-1T showed the highest similarities with Chthonobacter albigriseus KCTC 42450T (97.6%), Mongoliimonas terrestris KCTC 42635T (97.0%) and lower than 97.0% to other species. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain yh7-1T clustered with C. albigriseus KCTC 42450T. The ANI values ranged between 78.1 and 82.7% for C. albigriseus KCTC 42450T, M. terrestris KCTC 42635T and strain yh7-1T, which were lower than the prokaryotic species delineation threshold of 95.0-96.0%. The digital DNA-DNA hybridization values between C. albigriseus KCTC 42450T, M. terrestris KCTC 42635T and strain yh7-1T indicated that the new isolate represents a novel genomic species. According to the phenotypic and genotypic characteristics, strain yh7-1T should belong to the genus Chthonobacter, for which the name Chthonobacter rhizosphaerae sp. nov. (type strain yh7-1T = CGMCC 1.17236T = CCTCC AB 2019258T = KCTC 82185T) is proposed.

Translocation and distribution of mercury in biomasses from subtropical forest ecosystems: evidence from stable mercury isotopes

To understand its source, distribution, storage, and translocation in the subtropical forest ecosystems, mercury (Hg) concentrations and stable isotopes in forest biomass tissues (foliage, branch, bark, and trunk) were investigated at Ailao Mountain National Nature Reserve, Southwest China. The total Hg (THg) concentrations in the samples show the following trend: mature foliage (57 ± 19 ng g−1) > bark (11 ± 4.0 ng g−1) > branch (5.4 ± 2.5 ng g−1) > trunk (1.6 ± 0.7 ng g−1). Using the measured THg concentrations and the quantity of respective biomasses, the Hg pools in the forest are: wood (60 ± 26 μg m−2) > bark (51 ± 18 μg m−2) > foliage (41 ± 11 μg m−2) > branch (26 ± 8.3 μg m−2). The tree biomasses displayed negative δ202Hg (− 1.83‰ to − 3.84‰) and ∆199Hg (− 0.18‰ to − 0.62‰). The observed ∆200Hg (− 0.08‰ to 0.04‰) is not significantly from zero. A ∆199Hg/∆201Hg ratio of 1.05 was found in tree biomasses, suggesting that mercury has undergone Hg(II) photoreduction processes. A Hg-isotope based binary mixing model suggests that Hg in the tree biomasses mainly originated from foliage uptake of atmospheric Hg0, constituting 67%, 80%, and 77% of Hg in wood, branch, and bark, respectively. Our study sheds new light on the transportation and sources of Hg in the subtropical forest ecosystems.

Decomposition of roots of different diameters in response to different drought periods in a subtropical evergreen broad-leaf forest in Ailao Mountain

Root decomposition plays an essential role in the terrestrial carbon cycle, but the responses of roots of different diameters to varying drought periods are unclear. Therefore, artificial drought experiments were conducted to investigate the effects of different drought periods on the decomposition rates of roots with different diameters. In this study, <2 mm, 2–5 mm and 5–10 mm root decomposition experiments were conducted in control (CK), short-term drought (STD, drought during one rainy season), and long-term drought (LTD, two-year drought) treatments. The drought treatments significantly reduced the soil water content by 52.5% and 83.6%, respectively, but had little effect on the soil temperature. According to the decomposition coefficient (k value), the root decomposition rate decreased significantly with increasing diameter, and STD and LTD significantly reduced root decomposition of different diameters by 30.4–41.7% and 47.8–70.8%, respectively. The analysis of covariance (ANCOVA) revealed that diameter, treatments and their interaction had significant effects on the k values. The linear regression showed that the dependence of the stage root decomposition rate (SRDR) and k value of fine roots on the soil water content were higher than that of coarse roots. Therefore, fine roots were more sensitive to the soil water content and drought, thereby affecting the nutrient cycle and health of forest ecosystems under drought. This study provides new insight into the impact of climate change on root decomposition and the carbon cycle.

Change of rhizospheric bacterial community of the ancient wild tea along elevational gradients in Ailao mountain, China

The rhizospheric microbial community is one of the major environmental factors affecting the distribution and fitness of plants. Ancient wild tea plants are rare genetic resource distributed in Southwest China. In this study, we investigated that rhizospheric bacterial communities of ancient wild tea plants along the elevational gradients (2050, 2200, 2350 and 2500 m) in QianJiaZhai Reserve of Ailao Mountains. According to the Illumina MiSeq sequencing of 16 S rRNA gene amplicons, Proteobacteria, Acidobacteria and Actinobacteria were the dominant phyla with the relative abundance 43.12%, 21.61% and 14.84%, respectively. The Variibacter was the most dominant genus in rhizosphere of ancient wild tea plant. Phylogenetic null modeling analysis suggested that rhizospheric bacterial communities of ancient wild tea plants were more phylogenetically clustered than expected by chance. The bacterial community at 2050 m was unique with the highest alpha diversity, tend to cluster the nearest taxon and simple co-occurrence network structure. The unique bacterial community was correlated to multiple soil factors, and the content soil ammonium nitrogen (NH4+-N) was the key factor affecting the diversity and distribution of bacterial community along the elevational gradients. This study provided the necessary basic information for the protection of ancient tea trees and cultivation of tea plants.

Organic Carbon Storage and 14C Apparent Age of Upland and Riparian Soils in a Montane Subtropical Moist Forest of Southwestern China

Upland and riparian soils usually differ in soil texture and moisture conditions, thus, likely varying in carbon storage and turnover time. However, few studies have differentiated their functions on the storage of soil organic carbon (SOC) in sub-tropical broad-leaved evergreen forests. In this study, we aim to uncover the SOC storage and 14C apparent age, in the upland and riparian soils of a primary evergreen broad-leaved montane subtropical moist forest in the Ailao Mountains of southwestern China. We sampled the upland and riparian soils along four soil profiles down to the parent material at regular intervals from two local representative watersheds, and determined SOC concentrations, δ13C values and 14C apparent ages. We found that SOC concentration decreased exponentially and 14C apparent age increased linearly with soil depth in the four soil profiles. Although, soil depth was deeper in the upland soil profiles than the riparian soil profiles, the weighted mean SOC concentration was significantly greater in the riparian soil (25.7 ± 3.9 g/kg) than the upland soil (19.7 ± 2.3 g/kg), but has an equal total SOC content per unit of ground area around 21 kg/m2 in the two different type soils. SOC δ13C values varied between −23.7 (±0.8)‰ and −33.2 (±0.2)‰ in the two upland soil profiles and between −25.5 (±0.4)‰ and −36.8 (±0.4)‰ along the two riparian soil profiles, with greater variation in the riparian soil profiles than the upland soil profiles. The slope of increase in SOC 14C apparent age along soil depth in the riparian soil profiles was greater than in the upland soil profiles. The oldest apparent age of SOC 14C was 23,260 (±230) years BP (before present, i.e., 1950) in the riparian soil profiles and 19,045 (±150) years BP in the upland soil profiles. Our data suggest that the decomposition of SOC is slower in the riparian soil than in the upland soil, and the increased SOC loss in the upland soil from deforestation may partially be compensated by the deposition of the eroded upland SOC in the riparian area, as an under-appreciated carbon sink.

Cenozoic magmatic activity and oblique uplifting of the Ailao Mountain: Evidence from a short-period dense seismic array

Geological studies show that the southern part of Ailaoshan-Red River shear zone (ALSRRSZ) has experienced complex metallogenic processes and multi-stage non-uniform uplifting, called oblique uplifting since the Cenozoic. To detect the deep structure and geodynamic background beneath Daping, Chang’an and other gold and polymetallic deposits in this area, we carried out a high-density short-period seismic array survey in southern Yunnan province. The array used is approximately 240 km long with an interval of 500 m between two adjacent stations. Based on the data collected by the array, we used H-κ stacking and common conversion point (CCP) methods of receiver functions to reveal the fine crustal structure beneath this array, which was located from Lvchun (western end) to the east and ended in Maguan. The three main conclusions are as follows. (1) The average crustal thickness is approximately 37 km and the Vp/Vs ratio is 1.75. However, the thickness and Vp/Vs ratio of the Ailao Mountain are rather greater or higher than those of the western Lanping-Simao Basin and eastern South-China block. These results may indicate that the crust is rich in ferromagnesian minerals or has a thermal fluid anomaly after orogenic movement. (2) There are two obvious inclined interfaces beneath the Ailao Mountain in the mid-upper crust, which suggests that strong deformation occurred there during the orogenic period. Some evidences, such as the weak converted-wave Pms phase from the Moho, low P-wave velocities of the upper mantle, high surface heat flow values, and generally developed hot springs, indicate that a strong crust-mantle interaction exists in the southern segments of the Ailaoshan-Red River shear zone. These interactions include a diapir of mantle-sourced magma (stronger in the east than that in the west), lateral collision from the Indian Plate, and the differential uplift caused by the strike-slip movement of the Red River Fault. All of above deep processes led to the Cenozoic oblique uplifting of Ailao Mountain. (3) By combining the location of the deposits on the surface, characteristics of the average crustal Vp/Vs ratio, hypocenters of the small earthquakes along the research profile, Moho shape, and horizontal variations of the Pms phase amplitudes, we speculate that the Ailaoshan Fault was the upgoing conduit for metallogenic magma and played a significant role in the Cenozoic development of the multiform metal deposits around the Ailao Mountain area.

A combination of morphological and photosynthetic functional traits maintains the vertical distribution of bryophytes in a subtropical cloud forest.

The distribution and performance of bryophyte species vary with vertical gradients, as a result of changes in environmental factors, especially light. However, the morphological and physiological drivers of bryophyte distribution along forest vertical gradients are poorly understood. For 18 species of mosses and liverworts distributed among three vertical microhabitats (ground, tree trunk, and branch, variance in 28 morphological and photosynthetic functional traits was comparatively analyzed among the microhabitats and bryophyte life-forms in a subtropical cloud forest in Ailao Mountain, Yunnan, southwestern China. Principal component analysis (PCA) was used to summarize trait differences among bryophyte species. In contrast to trunk and ground dwellers, branch dwellers tended to reduce light interception (smaller leaf and cell sizes, lower chlorophyll content), protect against damage from intense irradiation (higher ratios of carotenoids to chlorophyll), raise light energy use (higher photosynthetic capacity), and cope with lower environmental moisture (pendant life-forms, thicker cell walls). The PCA showed that ecological strategies of bryophytes in response to levels of irradiation were specialized in branch dwellers, although those of ground and trunk dwellers were less distinct. Environmental filtering shaped the combination of functional traits and the spatial distribution of bryophytes along the vertical gradients. Bryophyte species from the upper canopy of cloud forests show narrow variation in functional traits in high-light intensity, whereas species in the lower vertical strata associated with low-light intensity used contrasting, but more diverse ecological strategies.

Strong genetic differentiation among populations of Cheirotonus gestroi (Coleoptera: Euchiridae) in its native area sheds lights on species conservation

The long-armed scarab (Cheirotonus gestroi) is an endangered large insect in southwestern China and neighboring countries; however, limited information is available regarding its population genetics, hindering conservation efforts. Therefore, we investigated the population genetic structure and evolutionary history of C. gestroi in southwestern China. Twenty-five haplotypes were obtained from 47 specimens across five populations. The Dawei Mountain (DWS) population differed from other populations by a high genetic distance. Population structure analysis generated three distinct clades, corresponding to Hengduan Mountains (HM), Ailao Mountains (AM), and Dawei Mountains (DM), and high-level genetic diversity was found in two HM populations. Collectively, the strong genetic differentiation among populations might be due to limited gene flow, geographical isolation, and habitat fragmentation. Therefore, while developing a conservation strategy, HM, AM, and DM groups should be defined as separate management units. Additionally, the DWS population should be given priority protection due to its uniqueness and low genetic diversity.

Relationships among different types of ecosystem service in Southwest China

Understanding the relationships among different ecosystem services is the basis for optimizing ecological protection strategy and achieving sustainable ecological management. Based on the ecosystem services and their spatial patterns in Southwest China, we analyzed tradeoffs and synergies of five ecosystem regulation services (water retention, soil retention, carbon sequestration, biodiversity conservation, and water purification) and five provision services (rice production, wheat production, corn production, vegetable production, and fruit production) using statistical analysis, ArcGIS technology and GeoDa software. Further, we identified the win-win areas of ecosystem servi-ces through overlay analysis, and discussing the influence of ecosystem types on win-win pattern. There were synergistic relationships among different types of regulation or provision services in Southwest China, while there were both synergies and trade-offs between regulation and provision services. The high win-win areas of the total ecosystem services in Southwest China were mainly distributed in Qionglai Mountains, Ailao Mountains, Dayao Mountains, as well as Lujiang River and Lancang River basins. The proportion of forest and farmland areas significantly affected all kinds of win-win trend.

Impacts of moisture sources on the temporal and spatial heterogeneity of monsoon precipitation isotopic altitude effects

Moisture sources affect the temporal variations of the elevation effects on the stable isotopes in monsoon precipitation. However, whether it will lead to spatial variations and form a specific spatial-temporal heterogeneity pattern remains to be explored. Based on the monthly precipitation samples collected in Ailao Mountains of East Asian monsoon region, we computed and identified five moisture source regions to facilitate its comparison to the monthly oxygen isotope composition (δ18O) of precipitation with HYSPLIT model. We analysed the influence mechanisms of the moisture sources on the temporal and spatial heterogeneity of the elevation effect on the hydrogen and oxygen stable isotopes during dry and rainy seasons. We found that the temporal heterogeneity of the elevation effects on the precipitation 18O depends on the proportion of the moisture sources in the dominant direction, and as the proportion increases, the elevation effect becomes more significant. The spatial heterogeneity depends on the combination complexity of the moisture sources, the simpler the combinations, the more significant the elevation effects. The results demonstrate that for precipitation δ18O in Ailao Mountains, the dominant of monsoon moisture sources (the ratio higher than 50%) can result in significant elevation effects, while the mixtures of multiple moisture sources and the dominant of local moisture sources will lead to no elevation effects. Future studies should pay more attention to the influence mechanism of the spatial and temporal heterogeneity of the elevation effects on a relatively larger or global scale.

哀牢山中山湿性常绿阔叶林木径向生长季节动态及其对气候因子的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 哀牢山中山湿性常绿阔叶林木径向生长季节动态及其对气候因子的响应 DOI: 10.5846/stxb201901070057 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（31770533）；国家自然科学基金国际（地区）合作项目（31861133007）；国家重点研发计划第五课题（2016YFC0502105） Intra-annual radial growth of evergreen and deciduous tree species and their response to climatic factors in a montane moist evergreen broad-leaved forest in the Ailao Mountains, Southwest China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究采用树木生长环在哀牢山中山湿性常绿阔叶林持续9年（2009-2017年）监测了2个常绿树种（厚皮香，Ternstroemia gymnanthera；南亚枇杷，Eriobotrya bengalensis）和2个落叶树种（西桦，Betula alnoides；珍珠花，Lyonia ovalifolia）的树干月生长量，采用逻辑斯蒂生长模型（Logistic model）模拟树木径向生长量和物候参数，并分析了年、季尺度上径向生长与主要气候因子的关系。结果表明：1）4个树种年平均生长量为6.3 mm，落叶树种年平均生长量（10.6 mm/a）显著高于常绿树种（3.0 mm/a）；2）雨季（5-10月）是哀牢山中山湿性常绿阔叶林树木生长的主要时期，4个树种雨季平均生长量为5.9 mm，占全年总生长量的93%，其中落叶树种雨季生长量占全年的96%，而常绿树种雨季生长量占全年的86%；3）常绿树种生长季长度为169天，长于落叶树种（137天），而落叶树种最大生长速率（0.14 mm/d）显著高于常绿树种（0.03 mm/d），最大径向生长速率能很好地预测树种年生长量；4）低温、雾日和光合有效辐射是影响哀牢山亚热带常绿阔叶林4个研究树种径向生长的重要环境因子，其中温度对常绿树种径向生长具有显著影响，而雨日、雾日与空气湿度等水分因子对落叶树种径向生长更为重要。常绿树种年生长量对旱季气候因子的响应相比落叶树种更为敏感，树木旱季生长量除了受低温限制外，也受到水分供给的影响。气候变化可能改变不同物候类型树种在哀牢山中山湿性常绿阔叶林中的生长状态与分布格局。 Abstract:This study monitored intra-annual stem diameter growth of two evergreen (Ternstroemia gymnanthera, Eriobotrya bengalensis) and two deciduous tree species (Betula alnoides, Lyonia ovalifolia) for a 9-year period (2009-2017) in a montane moist evergreen broad-leaved forest in the Ailao Mountains, southwest China. The metal band-dendrometer technique was used to measure stem diameter. We modeled growth phenology (i.e., start day, stop day, growth duration, and annual growth) with a logistic model, and analyzed the associations between annual and seasonal growth and climate factors over the study period. The deciduous trees had an average annual growth rate of 10.6 mm over the study period, and the evergreen trees had an average annual growth rate of 3.0 mm. The average annual growth rate of all four species was 6.3 mm. On average, trees grew 5.9 mm during the rainy season, which accounted for nearly 93% of annual growth. Deciduous trees showed higher growth rates than evergreen trees during the rainy season. Compared with deciduous trees, evergreen trees started growth earlier and stopped growth later. Annual total growth of the four studied species were highly related to their maximum growth rates during the rainy season, but less correlated with the length of the growing season. Temperature was the main limiting factor for stem growth of evergreen tree species, while precipitation days, fog days, and relative humidity were more important for stem growth of deciduous tree species. The different growth-climate relationships between evergreen and deciduous tree species implies that ongoing climate change may alter tree growth rates and species composition of subtropical evergreen broad-leaved forests. 参考文献 相似文献 引证文献

Driving forces underlying the beta diversity of tree species in subtropical mid-mountain moist evergreen broad-leaved forests in Ailao Mountains

Driving forces underlying the beta diversity of tree species in subtropical mid-mountain moist evergreen broad-leaved forests in Ailao Mountains

Intra-Annual Radial Growth of Pinus kesiya var. langbianensis Is Mainly Controlled by Moisture Availability in the Ailao Mountains, Southwestern China

Intra-annual monitoring of tree growth dynamics is increasingly applied to disentangle growth-change relationships with local climate conditions. However, such studies are still very limited in subtropical regions which show a wide variety of climate regimes. We monitored stem radius variations (SRV) of Pinus kesiya var. langbianensis (Szemao pine) over five years (2012–2015 and 2017) in the subtropical monsoon mountain climate of the Ailao Mountains, Yunnan Province, southwest China. On average, the stem radial growth of Szemao pine started in early March and ended in early October, and the highest growth rates occurred during May to June. Stem radius increments were synchronous with precipitation events, while tree water deficit corresponded to the drought periods. Correlation analysis and linear mixed-effects models revealed that precipitation and relative humidity are the most important limiting factors of stem radial increments, whereas air temperature and vapor pressure deficit significantly affected tree water balance and may play an important role in determining the growing season length and seasonality (i.e., duration, start, and cessation). This study reveals that moisture availability plays a major role for tree growth of P. kesiya var langbianensis in the Ailao Mountains, southwest China.

Ecological risk assessment of landslide disasters based on potential loss of ecosystem services

Landslides are common geological calamities in mountainous regions, which not only threaten social and economic development and residents' safety but also cause ecosystem damage, with consequences on human welfare. A more comprehensive and systematic reference for disaster prevention and mitigation with ecosystem services loss as an index for the potential damage of ecosystem could aid the progress of landslide ecological risk assessment. Five provinces in Southwest China (Sichuan, Yunnan, Guizhou, Guangxi and Chongqing) have diverse landforms, complex stratum and lithology, and active geological tectonic movements, which are the most landslide prone areas in China. In this study, the ecological risk assessment framework, model and indicator were constructed from three dimensions, including disaster risk, vulnerability and potential loss of the ecosystem. Disaster risk was based on the comprehensive analysis of factors such as geology, topo-graphy, landform, precipitation, and their mutual relationship. The vulnerability of the ecosystem was characterized by landscape patterns indices. The potential loss was measured by ecosystem service to evaluate the ecological risk associated with landslide hazards in the five provinces of Southwest China. The results showed that the areas with high potential loss of ecosystem services were mainly distributed in the south of Ailao Mountain in Yunnan Province, Qionglai Mountain of Sichuan Pro-vince, Hengduan Mountains, Dadu River Basin, Northwest Guangxi Autonomous Region, and eastern area of Dayao Mountain. The high ecological risk of landslide hazard in the study area mainly distributed in the areas of Min Mountain, Qionglai Mountain, Wuliang Mountain, Ailao Mountain, Miao Ridge, Leigong Mountain, and Dadu River basin. With respect to altitude, 500-1500 m was the main high-risk areas, accounting for 37.9% of the high-risk area. In terms of ecosystem types, forests are the high-risk areas, accounting for 66.4% of the high-risk areas. Landslide monitoring and early warning in the high ecological risk areas should be strengthened, through strengthening ecosystem protection in the region and improving the stability and resistance of ecosystems.