The year 2025 marks the 75th anniversary of the establishment of diplomatic relations between China and Vietnam and the China-Vietnam People-to-People Exchange Year.Over the last 75 years,China has always regarded Vie...The year 2025 marks the 75th anniversary of the establishment of diplomatic relations between China and Vietnam and the China-Vietnam People-to-People Exchange Year.Over the last 75 years,China has always regarded Vietnam as a priority in its neighborhood diplomacy,and Vietnam has regarded its relations with China as the top priority in its independent,all-round,and diversified foreign policy.The two sides have continuously strengthened mutually beneficial cooperation in various fields and elevated their comprehensive strategic partnership to new heights to build a China-Vietnam community with a shared future with strategic significance.展开更多
Tree rings provide long-term records of tree growth and climate changes,which makes them ideal benchmarks for forest modeling.Tree-ring information has greatly improved the reliability of 3-PG,which is one of the most...Tree rings provide long-term records of tree growth and climate changes,which makes them ideal benchmarks for forest modeling.Tree-ring information has greatly improved the reliability of 3-PG,which is one of the most commonly used process-based forest growth models.Here,we strengthen 3-PG's ability to simulate tree-ring width and stable carbon isotopes(δ^(13)C)by enhancing its descriptions of tree physiology.The major upgrade was adding a carbon storage pool for tree-ring formation using stored carbohydrates.We also incorporated previous modifications(replacing the age modifier with a height modifier)of 3-PG and tested their efficacy in improving tree-ring simulations.We ran the model based on two grand fir(Abies grandis)stands.The updated model greatly improved the simulations for both tree-ring widths andδ^(13)C.The results represent one of the best tree-ringδ^(13)C simulations,which accurately captured the amplitude in annual variations ofδ^(13)C.The correlations(R^(2))between simulations and observations reached 0.50 and 0.73 at two stands,respectively.The new model also greatly improved the simulations of raw tree-ring widths and detrended ring-width index(RWI).Because of better descriptions of tree physiology and more accurate simulations of tree rings than the previous model version,the updated 3-PG should provide more reliable simulations than previous 3-PG versions when tree-ring information is used as a benchmark in future studies.展开更多
Central Asia,located in the innermost part of the Eurasian continent,has experienced“warming and humidification”in recent decades,with potentially important implications for tree growth in alpine forests,which are c...Central Asia,located in the innermost part of the Eurasian continent,has experienced“warming and humidification”in recent decades,with potentially important implications for tree growth in alpine forests,which are critical for regional water reserves.We use nested principal component analysis to assess tree radial growth patterns and reveal significant positive trends since the 20th century across Central Asian alpine forests(0.076 per decade during 1900-2021,p=0.003).Regional hydroclimatic variations affect the greening of these alpine forests,especially with extreme droughts being the most damaging.Growth acceleration is driven by low-latitude warming,which enhances regional temperatures and precipitation.The warming ocean centers alter atmospheric circulation patterns,leading to more moisture being transported to the Central Asian alpine forests,thereby increasing regional precipitation and promoting tree growth.Our model projections indicate that growth rates will continue to rise in the future.However,unprecedented warming may eventually lead to growth deterioration if negative effects,such as insufficient precipitation,occur due to breakdown signs of positive feedback mechanisms,such as moisture transport driven by low-latitude warming.Our study highlights the beneficial,but not unlimited,influences of climate warming on tree growth in Central Asian alpine forests,with implications for the sustainability of water resources.However,as urban and agricultural demands escalate,a holistic,long-term perspective is recommended to mitigate the adverse effects of temperature increases.展开更多
Correlating tree-ring parameters with daily resolved climate data is becoming increasingly common for understanding the complex relationships between tree growth and the surrounding environment.However,with an increas...Correlating tree-ring parameters with daily resolved climate data is becoming increasingly common for understanding the complex relationships between tree growth and the surrounding environment.However,with an increased number of calculated correlations,there is an inherent risk of spurious significance.In this study,we present an analysis using synthetic weather and tree-ring data mimicking the statistical properties of ten real-world sites across Europe to quantify the extent to which numerous comparisons may inflate maximum correlations.Comparisons of different tree-ring proxies,considering varying overlapping period lengths and seasons,revealed 95th percentile correlation differences reaching 0.25 by chance.Using synthetic tree-ring chronologies with an assigned non-signal(r=0.00),spurious correlations can reach statistical significance in over 60%of tests.Correlation inflation is greater when:(1)the climate-proxy relationship is weaker;(2)comparison periods are shorter;and(3)the length of seasonal windows is longer.Autocorrelation in the proxy records does not appear to have a major effect.These findings indicate that caution should be exercised when computing high numbers of correlations with limited observations.We provide tables listing correlation inflations for precipitation-and temperature-sensitive tree-ring chronologies that can inform interpretations of significance.展开更多
Sequencing of environmental samples has great potential for biodiversity research,but its application is limited by the lack of reliable DNA barcode databases for species identifications.Such a database has been creat...Sequencing of environmental samples has great potential for biodiversity research,but its application is limited by the lack of reliable DNA barcode databases for species identifications.Such a database has been created for epiphytic lichens of Europe,allowing us to compare the results of environmental sequencing with standard taxonomic surveys.The species undetected by taxonomic surveys(what we term the ghost component)amount to about half of the species actually present in hectare plots of Central European forests.Some of these,which currently occur only as diaspores or weakly developed thalli,are likely to be favoured in the course of global change.The ghost component usually represents a larger fraction in managed forests than in old-growth unmanaged forests.The total species composition of different plots is much more similar than suggested by taxonomic surveys alone.On a regional scale,this supports the well-known statement that“everything is everywhere,but,the environment selects”.展开更多
The study investigates the potential of UAV-based remote sensing technique for monitoring of Norway spruce health condition in the affected forest areas.The objectives are:(1)to test the applicability of UAV visible a...The study investigates the potential of UAV-based remote sensing technique for monitoring of Norway spruce health condition in the affected forest areas.The objectives are:(1)to test the applicability of UAV visible an near-infrared(VNIR)and geometrical data based on Z values of point dense cloud(PDC)raster to separate forest species and dead trees in the study area;(2)to explore the relationship between UAV VNIR data and individual spruce health indicators from field sampling;and(3)to explore the possibility of the qualitative classification of spruce health indicators.Analysis based on NDVI and PDC raster was successfully applied for separation of spruce and silver fir,and for identification of dead tree category.Separation between common beech and fir was distinguished by the object-oriented image analysis.NDVI was able to identify the presence of key indicators of spruce health,such as mechanical damage on stems and stem resin exudation linked to honey fungus infestation,while stem damage by peeling was identified at the significance margin.The results contributed to improving separation of coniferous(spruce and fir)tree species based on VNIR and PDC raster UAV data,and newly demonstrated the potential of NDVI for qualitative classification of spruce trees.The proposed methodology can be applicable for monitoring of spruce health condition in the local forest sites.展开更多
Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence...Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(Ⅱ)-citrate-oxalate-H_2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.展开更多
AIM: To describe the clinical characteristics and analyze prognostic factors that influence visual outcome in 669 patients with intraocular foreign bodies(IOFBs).METHODS: Medical records of 669 patients with IOFBs fro...AIM: To describe the clinical characteristics and analyze prognostic factors that influence visual outcome in 669 patients with intraocular foreign bodies(IOFBs).METHODS: Medical records of 669 patients with IOFBs from West China Hospital were reviewed. Best corrected visual acuity(BCVA) values were recorded using standard Snellen acuity chart and were converted to logarithm of the minimum angle of resolution(log MAR) scale for statistical analysis. The visual outcome was defined by the final BCVA(excellent visual outcome: final BCVA of 20/40 or better;poor visual outcome: final BCVA less than 20/200). Statistical analysis of collected data was performed using IBM SPSS Statistics version 23. A 2-tailed P value of less than 0.05 was considered statistically significant throughout the study. RESULTS: The average age ranged from 1 to 79 years old(mean age, 34.8±12.7 SD) and the majority of patients were men(626, 93.6%). The major cause of ocular injury was hammering(383, 57.2%). Almost all the patients(97.8%) underwent surgeries(97.8%) and the average time interval between injury and surgery was 26.4±322.3 d(0-7300), while 327 patients received surgeries within 24 h(48.9%) and 590 patients received surgeries within seven days(88.2%) after IOFBs injury. The poor BCVA was associated with older age(P=0.013), larger IOFBs size(P<0.001), presence of complications(P<0.001) and worse presenting BCVA(P<0.001). On the contrary, younger age(P=0.005), smaller IOFBs size(P<0.001), absence of complications(P<0.001) and better presenting BCVA(P<0.001) were considered to relate to excellent BCVA.CONCLUSION: Multiple prognostic factors may influence the final visual outcome, including age, size of IOFBs, complications and presenting BCVA. Meanwhile, further education and promotion on eye protection should be taken for the improvement on self-protection and selfhealth awareness.展开更多
Switchgrass（Panicum virgatum L.） is a perennial C_4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide（CO_2） f...Switchgrass（Panicum virgatum L.） is a perennial C_4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide（CO_2） fluxes and mitigate climate change. However, information on how these CO_2 fluxes respond to changing climate is still lacking. In this study, CO_2 fluxes were monitored continuously from 2011 through 2014 using high frequency measurements from Switchgrass land seeded in 2008 on an experimental site that has been previously used for soybean（Glycine max L.） in South Dakota, USA. DAYCENT, a process-based model, was used to simulate CO_2 fluxes. An improved methodology CPTE[Combining Parameter estimation（PEST） with ＂Trial and Error＂ method] was used to calibrate DAYCENT. The calibrated DAYCENT model was used for simulating future CO_2 emissions based on different climate change scenarios. This study showed that：（i） the measured soil CO_2 fluxes from Switchgrass land were higher for 2012 which was a drought year, and these fluxes when simulated using DAYCENT for long-term（2015–2070） provided a pattern of polynomial curve;（ii） the simulated CO_2 fluxes provided different patterns with temperature and precipitation changes in a long-term,（iii） the future CO_2 fluxes from Switchgrass land under different changing climate scenarios were not significantly different, therefore, it can be concluded that Switchgrass grown for longer durations could reduce changes in CO_2 fluxes from soil as a result of temperature and precipitation changes to some extent.展开更多
Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observin...Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observing the patterns of species richness, abundances and species composition of epiphytic orchids and ferns in two subtropical forests in Nepal. We also studied the relationship of host plants(Schima wallichii and Quercus lanata) and epiphyte species. Data were collected in Naudhara community forest(CF) and the national forest(NF) in Shivapuri Nagarjun National Park. The data were analyzed using univariate and multivariate tests. In total, we recorded 41 species of epiphytes(33 orchid and 8 fern species). Orchid species abundance is significantlyhigher in CF compared to NF. Orchid species richness and abundance increased with increasing southern aspect whereas it decreased with increasing canopy cover, and fern species richness increased with host bark roughness. Orchid abundance was positively correlated with increasing bark p H, stem size, tree age and tree height and negatively correlated with increasing steepness of the area. Likewise, fern abundances were high in places with high canopy cover, trees that were tall and big, but decreased with increasing altitude and southern aspect. The composition of the orchid and fern species was affected by altitude, aspect, canopy cover, DBH, number of forks and forest management types. We showed that the diversity of orchid and fern epiphytes is influenced by host characteristics as well as host types. The most important pre-requisite for a high epiphyte biodiversity is the presence of oldrespectively tall trees, independent of the recent protection status. This means:(i) for protection, e.g.in the frame of the national park declaration, such areas should be used which host such old tall trees;and(ii) also in managed forests and even in intensively used landscapes epiphytes can be protected by letting a certain number of trees be and by giving them space to grow old and tall.展开更多
One of the greatest threats posed by ongoing climate change may be regarded the drought caused by changes in precipitation distribution. The aim of presented study was to characterize reactions to dry conditions and c...One of the greatest threats posed by ongoing climate change may be regarded the drought caused by changes in precipitation distribution. The aim of presented study was to characterize reactions to dry conditions and conditions without drought stress on gross primary production (GPP) and net ecosystem production (NEP) of spruce and beech forests, as these two species dominate within the European continent. Daily courses of GPP and NEP of these two species were evaluated in relation to an expected decrease in CO2 uptake during dry days. The occurrence of CO2 uptake hysteresis in daily production was also investigated. Our study was performed at Bily Kriz(spruce) and Stitna(beech) mountain forest sites during 2010–2012 period. We applied eddy covariance technique for the estimation of carbon fluxes, vapor pressure deficit and precipitation characteristics together with the SoilClim model for the determination of drought conditions, and the inverse of the Penman–Monteith equation to compute canopy conductance. Significant differences were found in response to reduced water supply for both species. Spruce reacts by closing its stomata before noon and maintaining a reduced photosynthetic activity for the rest of the day, while beech keeps its stomata open as long as possible and slightly reduces photosynthetic activity evenly throughout the entire day. In the spruce forest, we found substantial hysteresis in the light response curve of GPP. In the beech forest, the shape of this curve was different: evening values exceeded morning values.展开更多
Climate change has major impacts on the livelihoods of forest-dependent communities.The unpredictable weather conditions in rural Nepal have been attributed to a changing climate.This study explored the climate change...Climate change has major impacts on the livelihoods of forest-dependent communities.The unpredictable weather conditions in rural Nepal have been attributed to a changing climate.This study explored the climate change adaptation and coping strategies that rural communities adopt for the conservation of natural resources and livelihoods in the mid-hills of Nepal.This paper explored major climatic hazards,assessed different coping and adaptation measures,and barrier faced to climate change adaptation based on perceptions by forest-dependent communities.We conducted focus group discussions,questionnaire surveys,and semistructured interviews with local communities and stakeholders.The results showed that rural communities had experienced significant impacts of climate change and variability.In response,they are practicing diverse coping and adaptation strategies,including the construction of bioengineering structures and planting different species that grow quickly and establish promptly.展开更多
Glacial lake outburst floods(GLOFs)represent one of the most serious hazard and risk in deglaciating high mountain regions worldwide and the need for GLOF hazard and risk assessment is apparent.As a consequence,numero...Glacial lake outburst floods(GLOFs)represent one of the most serious hazard and risk in deglaciating high mountain regions worldwide and the need for GLOF hazard and risk assessment is apparent.As a consequence,numerous region-and nation-wide GLOF assessment studies have been published recently.These studies cover large areas and consider hundreds to thousands of lakes,prioritizing the hazard posed by them.Clearly,certain simplification is required for executing such studies,often resulting in neglecting qualitative characteristics which would need manual assignment.Different lake dam types(e.g.,bedrock-dammed,moraine-dammed)are often not distinguished,despite they control GLOF mechanism(dam overtopping/dam breach)and thus GLOF magnitude.In this study,we explore the potential of easily measurable quantitative characteristics and four ratios to approximate the lake dam type.Our dataset of 851 lakes of the Cordillera Blanca suggests that while variances and means of these characteristics of individual lake types differ significantly(F-test,t-test),value distribution of different geometrical properties can’t be used for the originally proposed purpose along the spectra.The only promising results are obtained for extreme values(selected bins)of the ratios.For instance,the low width to length ratio indicates likely morainedammed lake while the high value of ratio indicating round-shape of the lake indicates increased likelihood of bedrock-dammed lake.Overall,we report a negative result of our experiment since there are negligible differences of relative frequencies in most of the bins along the spectra.展开更多
Natural disasters and finding suitable areas to dispose of municipal solid waste (MSW) are two major global challenges, both of which have several influences in the water resources and are related to climatic change, ...Natural disasters and finding suitable areas to dispose of municipal solid waste (MSW) are two major global challenges, both of which have several influences in the water resources and are related to climatic change, especially in developing countries like Brazil. Currently the risk of natural disasters is not utilized in the process of locating areas to dispose of MSW. This study, using geographic information system (GIS), analyzed spatially the susceptibility for landslide and flooding hazards in MSW disposal sites in S?o Paulo state, Brazil. The results showed that more than 90% of sanitary and ditch landfills are located in null, very low and low hazard classes (P0, P1 and P2). However, in this remaining 10% of landfills we still have approximately 55% of the total municipal solid waste disposed into susceptible areas with middle, high and very high hazard classes (P3, P4 and P5). This shows that S?o Paulo MSW disposal sites need more attention and control to prevent the occurrence of landslide/flooding and consequently the mitigation of environmental, economic and social impacts. In addition, the use of GIS is proved to be an appropriate tool to carry out this type of analysis, so we recommend that the risk of natural disasters should be taken into consideration in the process of finding landfill areas. Mainly, because, there is a tendency for extreme weather events to increase causing more flood and landslide events and consequently contributing to water scarcity and water degradation.展开更多
The large excess of solid waste generated in cities is a result of population growth and economic development. Properly managing this municipal solid waste (MSW) is a challenge, mainly in underdeveloped and developing...The large excess of solid waste generated in cities is a result of population growth and economic development. Properly managing this municipal solid waste (MSW) is a challenge, mainly in underdeveloped and developing countries where financial concerns are an added problem. From the environmental point of view, a major issue is properly disposing MSW taking into consideration a wide range of factors, and working with different spatial data. In this study, we used geographic information system (GIS) to perform multi-criteria decision analysis (MCDA) conducted by analytical hierarchy process (AHP). The development of the environmental impact susceptibility model (EISM) for municipal solid waste disposal sites (MSWDS) applied to the state of Sao Paulo, Brazil considered factors such as geology, pedology, geomorphology, water resources, and climate represented by fifteen associated sub-factors. The results indicated that more than 82% of Sao Paulo’s territory is situated in areas with very low, low, and medium environmental impact susceptibility categories. However, in the remaining 18% of the state land area, 85 landfills are located in areas with high and very high environmental impact susceptibility categories. These results are alarming because these 85 landfills receive approximately 17,886 tons of MSW on a daily basis, which corresponds to 46% of all municipal solid waste disposed in Sao Paulo state. Therefore, decision makers, urban planners and policymakers could use the findings of the EISM towards mitigating the environmental impacts caused by MSWDS.展开更多
The stability of monocultural,even-aged spruce forests at lower altitudes in Central Europe is seriously threatened by the prospects of global climate change.The thermostability and water use efficiency of their photo...The stability of monocultural,even-aged spruce forests at lower altitudes in Central Europe is seriously threatened by the prospects of global climate change.The thermostability and water use efficiency of their photo synthetic apparatus might play a vital role in their successful acclimation.In this study,photo systemⅡ(PSⅡ)performance(OJIP transient,rapid light curves)and thermostability were analyzed in Norway spruce(Picea abies(L.)Karst.)throughout the growing season of the exceptionally warm year 2018(May-September)in the Western Carpathians,Slovakia.These measurements were accompanied by analysis of pigment concentrations in the needles.In addition,gas-exchange temperature curves were produced weekly from June until September to obtain intrinsic water use efficiencies.At the beginning of the growing season,needles exposed to heat stress showed significantly higher basal fluorescence and lower quantum yield,performance index,critical temperature thresholds of PSII inactivation and nonphotochemical yield in comparison to other months.The overall thermostability(heat-resistance)of PSII peaked in July and August,reflected in the lowest basal fluorescence and the highest quantum yield of PSII,critical temperature thresholds and yield of non-photochemical quenching under heat stress.Additionally,the ratio between chlorophyll and carotenoids was the highest in August and had a positive impact on PSII thermostability.Moreover,the high-temperature intrinsic water use efficiency was significantly higher during July and August than in June.Results show that15-year-old trees of Picea abies at 840 m a.s.l.exhibited acclimative seasonal responses of PSII thermostability and intrinsic water use efficiency during an exceptionally warm year.Our results suggest that mountainous P.abies at lower altitudes can acclimate their photosynthetic apparatus to higher temperatures during summer.展开更多
The study assesses the functional status of the University of Energy and Natural Resources’ (UENR) bat sanctuary by examining its floral diversity and carbon stocks. Twenty-nine sampling points (plots) were randomly ...The study assesses the functional status of the University of Energy and Natural Resources’ (UENR) bat sanctuary by examining its floral diversity and carbon stocks. Twenty-nine sampling points (plots) were randomly generated by using the ArcGIS random sampling algorithm. Using a three-nest sampling plot of 100m2, 25m2, and 1m2 quadrat, the enumeration of trees (DBH>10cm), saplings (>2cm DBH 0.05) between the 10m buffer created and the core area with respect to species diversity and carbon stocks. The study has provided valuable information on the functional status of the bat sanctuary which will help promote its conservation for sustained provision of ecosystem services.展开更多
Mountain forests are more prone to environmental predispositions(EPs)than submountain ones.While remote sensing of mountain forests enables instantaneous damage mapping,the investigation of the causes requires field d...Mountain forests are more prone to environmental predispositions(EPs)than submountain ones.While remote sensing of mountain forests enables instantaneous damage mapping,the investigation of the causes requires field data.However,a local field or regionally modeled environmental characteristics influence remote data evaluation differently.This study focused on the evaluation of EPs effects damaging mountain forests between various spatial resolutions during environmental change.The evaluation was divided into managed and natural forests in the Hruby Jeseník Mts.(Czech Republic;240-1491 m a.s.l.;50.082°N,17.231°E).Damage was assessed through the discrimination analysis of the normalised difference vegetation index(NDVI)by MODIS VI during alternating drought and flood periods 2003-2014.The local environmental influence was assessed using the discrimination function(DF)separability of forest damage in the training sets.The regional influence was assessed through map algebra estimated via the DF and a forest decline spatial model based on EPs from differences between risk growth conditions and biomass fuzzy sets.Management,EPs and soil influenced forest NDVI at different levels.The management afflicted the NDVI more than the EPs.The EPs afflicted the NDVI more than the soil groups.Strong winters and droughts had a greater influence on the NDVI than the flood events,with the winter of 2005/2006 inverting the DF direction,and the 2003 drought increasing differences in managed forest biomass and decreasing differences in natural forest biomasses.More than 50% of declining managed forests in the training sets occurred on Leptosols,Podzols and Histosols.On a regional scale,the soil influence was eliminated by multiple predispositions.The EPs influenced 96% of natural forest and 65% of managed forest,though managed forest damage was more evident.The mountain forest NDVI decline was dependent on both management and risk predispositions.展开更多
Friendly exchanges between China and Malaysia date back more than 2,000 years,and a profound traditional friendship has been forged between the two countries.By adhering to the principles of mutual trust,win-win coope...Friendly exchanges between China and Malaysia date back more than 2,000 years,and a profound traditional friendship has been forged between the two countries.By adhering to the principles of mutual trust,win-win cooperation,and equal assistance,China and Malaysia have become good neighbors,good friends,and good partners.In 2013,China and Malaysia established a comprehensive strategic partnership,accelerating the development of bilateral relations.展开更多
文摘The year 2025 marks the 75th anniversary of the establishment of diplomatic relations between China and Vietnam and the China-Vietnam People-to-People Exchange Year.Over the last 75 years,China has always regarded Vietnam as a priority in its neighborhood diplomacy,and Vietnam has regarded its relations with China as the top priority in its independent,all-round,and diversified foreign policy.The two sides have continuously strengthened mutually beneficial cooperation in various fields and elevated their comprehensive strategic partnership to new heights to build a China-Vietnam community with a shared future with strategic significance.
基金supported by the National Natural Science Foundation of China(Nos.42271048,42430503,and 31971492).
文摘Tree rings provide long-term records of tree growth and climate changes,which makes them ideal benchmarks for forest modeling.Tree-ring information has greatly improved the reliability of 3-PG,which is one of the most commonly used process-based forest growth models.Here,we strengthen 3-PG's ability to simulate tree-ring width and stable carbon isotopes(δ^(13)C)by enhancing its descriptions of tree physiology.The major upgrade was adding a carbon storage pool for tree-ring formation using stored carbohydrates.We also incorporated previous modifications(replacing the age modifier with a height modifier)of 3-PG and tested their efficacy in improving tree-ring simulations.We ran the model based on two grand fir(Abies grandis)stands.The updated model greatly improved the simulations for both tree-ring widths andδ^(13)C.The results represent one of the best tree-ringδ^(13)C simulations,which accurately captured the amplitude in annual variations ofδ^(13)C.The correlations(R^(2))between simulations and observations reached 0.50 and 0.73 at two stands,respectively.The new model also greatly improved the simulations of raw tree-ring widths and detrended ring-width index(RWI).Because of better descriptions of tree physiology and more accurate simulations of tree rings than the previous model version,the updated 3-PG should provide more reliable simulations than previous 3-PG versions when tree-ring information is used as a benchmark in future studies.
基金supported by Excellent Research Group Program for Tibetan Plateau Earth System(continuation grant NSFC project No.41988101)the National Natural Science Foundation of China(Nos.U1803341 and 32061123008)+1 种基金the National Key R&D Program of China(No.2018YFA0606401)the National Youth Talent Support Program.
文摘Central Asia,located in the innermost part of the Eurasian continent,has experienced“warming and humidification”in recent decades,with potentially important implications for tree growth in alpine forests,which are critical for regional water reserves.We use nested principal component analysis to assess tree radial growth patterns and reveal significant positive trends since the 20th century across Central Asian alpine forests(0.076 per decade during 1900-2021,p=0.003).Regional hydroclimatic variations affect the greening of these alpine forests,especially with extreme droughts being the most damaging.Growth acceleration is driven by low-latitude warming,which enhances regional temperatures and precipitation.The warming ocean centers alter atmospheric circulation patterns,leading to more moisture being transported to the Central Asian alpine forests,thereby increasing regional precipitation and promoting tree growth.Our model projections indicate that growth rates will continue to rise in the future.However,unprecedented warming may eventually lead to growth deterioration if negative effects,such as insufficient precipitation,occur due to breakdown signs of positive feedback mechanisms,such as moisture transport driven by low-latitude warming.Our study highlights the beneficial,but not unlimited,influences of climate warming on tree growth in Central Asian alpine forests,with implications for the sustainability of water resources.However,as urban and agricultural demands escalate,a holistic,long-term perspective is recommended to mitigate the adverse effects of temperature increases.
基金supported partly by the ERC Advanced Grant Monostar(AdG 882727)the co funded EU project AdAgriF(CZ.02.01.01/00/22_008/0004635).
文摘Correlating tree-ring parameters with daily resolved climate data is becoming increasingly common for understanding the complex relationships between tree growth and the surrounding environment.However,with an increased number of calculated correlations,there is an inherent risk of spurious significance.In this study,we present an analysis using synthetic weather and tree-ring data mimicking the statistical properties of ten real-world sites across Europe to quantify the extent to which numerous comparisons may inflate maximum correlations.Comparisons of different tree-ring proxies,considering varying overlapping period lengths and seasons,revealed 95th percentile correlation differences reaching 0.25 by chance.Using synthetic tree-ring chronologies with an assigned non-signal(r=0.00),spurious correlations can reach statistical significance in over 60%of tests.Correlation inflation is greater when:(1)the climate-proxy relationship is weaker;(2)comparison periods are shorter;and(3)the length of seasonal windows is longer.Autocorrelation in the proxy records does not appear to have a major effect.These findings indicate that caution should be exercised when computing high numbers of correlations with limited observations.We provide tables listing correlation inflations for precipitation-and temperature-sensitive tree-ring chronologies that can inform interpretations of significance.
基金supported by the Technology Agency of the Czech Republic(Grant Nos.SS01010270,SS06010420)by a long-term research development grant RVO(Grant No.67985939)。
文摘Sequencing of environmental samples has great potential for biodiversity research,but its application is limited by the lack of reliable DNA barcode databases for species identifications.Such a database has been created for epiphytic lichens of Europe,allowing us to compare the results of environmental sequencing with standard taxonomic surveys.The species undetected by taxonomic surveys(what we term the ghost component)amount to about half of the species actually present in hectare plots of Central European forests.Some of these,which currently occur only as diaspores or weakly developed thalli,are likely to be favoured in the course of global change.The ghost component usually represents a larger fraction in managed forests than in old-growth unmanaged forests.The total species composition of different plots is much more similar than suggested by taxonomic surveys alone.On a regional scale,this supports the well-known statement that“everything is everywhere,but,the environment selects”.
基金This work was supported by the Ministry of Education,Youth and Sports of the Czech Republic within the National Programme for Sustainability I[grant number LO1415]partly by EEA Grants if Iceland,Liechtenstein and Norway[grant number EHP-CZ02-OV-1-019-2014].
文摘The study investigates the potential of UAV-based remote sensing technique for monitoring of Norway spruce health condition in the affected forest areas.The objectives are:(1)to test the applicability of UAV visible an near-infrared(VNIR)and geometrical data based on Z values of point dense cloud(PDC)raster to separate forest species and dead trees in the study area;(2)to explore the relationship between UAV VNIR data and individual spruce health indicators from field sampling;and(3)to explore the possibility of the qualitative classification of spruce health indicators.Analysis based on NDVI and PDC raster was successfully applied for separation of spruce and silver fir,and for identification of dead tree category.Separation between common beech and fir was distinguished by the object-oriented image analysis.NDVI was able to identify the presence of key indicators of spruce health,such as mechanical damage on stems and stem resin exudation linked to honey fungus infestation,while stem damage by peeling was identified at the significance margin.The results contributed to improving separation of coniferous(spruce and fir)tree species based on VNIR and PDC raster UAV data,and newly demonstrated the potential of NDVI for qualitative classification of spruce trees.The proposed methodology can be applicable for monitoring of spruce health condition in the local forest sites.
文摘Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(Ⅱ)-citrate-oxalate-H_2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.
文摘AIM: To describe the clinical characteristics and analyze prognostic factors that influence visual outcome in 669 patients with intraocular foreign bodies(IOFBs).METHODS: Medical records of 669 patients with IOFBs from West China Hospital were reviewed. Best corrected visual acuity(BCVA) values were recorded using standard Snellen acuity chart and were converted to logarithm of the minimum angle of resolution(log MAR) scale for statistical analysis. The visual outcome was defined by the final BCVA(excellent visual outcome: final BCVA of 20/40 or better;poor visual outcome: final BCVA less than 20/200). Statistical analysis of collected data was performed using IBM SPSS Statistics version 23. A 2-tailed P value of less than 0.05 was considered statistically significant throughout the study. RESULTS: The average age ranged from 1 to 79 years old(mean age, 34.8±12.7 SD) and the majority of patients were men(626, 93.6%). The major cause of ocular injury was hammering(383, 57.2%). Almost all the patients(97.8%) underwent surgeries(97.8%) and the average time interval between injury and surgery was 26.4±322.3 d(0-7300), while 327 patients received surgeries within 24 h(48.9%) and 590 patients received surgeries within seven days(88.2%) after IOFBs injury. The poor BCVA was associated with older age(P=0.013), larger IOFBs size(P<0.001), presence of complications(P<0.001) and worse presenting BCVA(P<0.001). On the contrary, younger age(P=0.005), smaller IOFBs size(P<0.001), absence of complications(P<0.001) and better presenting BCVA(P<0.001) were considered to relate to excellent BCVA.CONCLUSION: Multiple prognostic factors may influence the final visual outcome, including age, size of IOFBs, complications and presenting BCVA. Meanwhile, further education and promotion on eye protection should be taken for the improvement on self-protection and selfhealth awareness.
基金supported by the South Dakota State University (SDSU) and North Central Regional Sun Grant Center at SDSU through a grant provided by the US Department of Energy Bioenergy Technologies Office under award number DE-FC36-05GO85041
文摘Switchgrass（Panicum virgatum L.） is a perennial C_4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide（CO_2） fluxes and mitigate climate change. However, information on how these CO_2 fluxes respond to changing climate is still lacking. In this study, CO_2 fluxes were monitored continuously from 2011 through 2014 using high frequency measurements from Switchgrass land seeded in 2008 on an experimental site that has been previously used for soybean（Glycine max L.） in South Dakota, USA. DAYCENT, a process-based model, was used to simulate CO_2 fluxes. An improved methodology CPTE[Combining Parameter estimation（PEST） with ＂Trial and Error＂ method] was used to calibrate DAYCENT. The calibrated DAYCENT model was used for simulating future CO_2 emissions based on different climate change scenarios. This study showed that：（i） the measured soil CO_2 fluxes from Switchgrass land were higher for 2012 which was a drought year, and these fluxes when simulated using DAYCENT for long-term（2015–2070） provided a pattern of polynomial curve;（ii） the simulated CO_2 fluxes provided different patterns with temperature and precipitation changes in a long-term,（iii） the future CO_2 fluxes from Switchgrass land under different changing climate scenarios were not significantly different, therefore, it can be concluded that Switchgrass grown for longer durations could reduce changes in CO_2 fluxes from soil as a result of temperature and precipitation changes to some extent.
基金“Bauer-Stiftung und Glaser-Stiftung im Stifterverband für die Deutsche Wissenschaft” Project No. T237/24905/2013/Kg for the research grantgrant number 14-36098G of the Czech Science Foundation and the institutional support RVO 67985939
文摘Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observing the patterns of species richness, abundances and species composition of epiphytic orchids and ferns in two subtropical forests in Nepal. We also studied the relationship of host plants(Schima wallichii and Quercus lanata) and epiphyte species. Data were collected in Naudhara community forest(CF) and the national forest(NF) in Shivapuri Nagarjun National Park. The data were analyzed using univariate and multivariate tests. In total, we recorded 41 species of epiphytes(33 orchid and 8 fern species). Orchid species abundance is significantlyhigher in CF compared to NF. Orchid species richness and abundance increased with increasing southern aspect whereas it decreased with increasing canopy cover, and fern species richness increased with host bark roughness. Orchid abundance was positively correlated with increasing bark p H, stem size, tree age and tree height and negatively correlated with increasing steepness of the area. Likewise, fern abundances were high in places with high canopy cover, trees that were tall and big, but decreased with increasing altitude and southern aspect. The composition of the orchid and fern species was affected by altitude, aspect, canopy cover, DBH, number of forks and forest management types. We showed that the diversity of orchid and fern epiphytes is influenced by host characteristics as well as host types. The most important pre-requisite for a high epiphyte biodiversity is the presence of oldrespectively tall trees, independent of the recent protection status. This means:(i) for protection, e.g.in the frame of the national park declaration, such areas should be used which host such old tall trees;and(ii) also in managed forests and even in intensively used landscapes epiphytes can be protected by letting a certain number of trees be and by giving them space to grow old and tall.
基金supported by the Ministry of Education,Youth and Sports of CR within the National Sustainability Program I(NPU I),(No.LO1415)within the CzeCOS program(No.LM2015061)
文摘One of the greatest threats posed by ongoing climate change may be regarded the drought caused by changes in precipitation distribution. The aim of presented study was to characterize reactions to dry conditions and conditions without drought stress on gross primary production (GPP) and net ecosystem production (NEP) of spruce and beech forests, as these two species dominate within the European continent. Daily courses of GPP and NEP of these two species were evaluated in relation to an expected decrease in CO2 uptake during dry days. The occurrence of CO2 uptake hysteresis in daily production was also investigated. Our study was performed at Bily Kriz(spruce) and Stitna(beech) mountain forest sites during 2010–2012 period. We applied eddy covariance technique for the estimation of carbon fluxes, vapor pressure deficit and precipitation characteristics together with the SoilClim model for the determination of drought conditions, and the inverse of the Penman–Monteith equation to compute canopy conductance. Significant differences were found in response to reduced water supply for both species. Spruce reacts by closing its stomata before noon and maintaining a reduced photosynthetic activity for the rest of the day, while beech keeps its stomata open as long as possible and slightly reduces photosynthetic activity evenly throughout the entire day. In the spruce forest, we found substantial hysteresis in the light response curve of GPP. In the beech forest, the shape of this curve was different: evening values exceeded morning values.
文摘Climate change has major impacts on the livelihoods of forest-dependent communities.The unpredictable weather conditions in rural Nepal have been attributed to a changing climate.This study explored the climate change adaptation and coping strategies that rural communities adopt for the conservation of natural resources and livelihoods in the mid-hills of Nepal.This paper explored major climatic hazards,assessed different coping and adaptation measures,and barrier faced to climate change adaptation based on perceptions by forest-dependent communities.We conducted focus group discussions,questionnaire surveys,and semistructured interviews with local communities and stakeholders.The results showed that rural communities had experienced significant impacts of climate change and variability.In response,they are practicing diverse coping and adaptation strategies,including the construction of bioengineering structures and planting different species that grow quickly and establish promptly.
基金the financial support by the University of Grazpartly supported by the Ministry of Education,Youth and Sports of the Czech Republic within the National Sustainability Programme I(NPU I),grant number LO1415Supporting perspective human resources Programme of the Czech Academy of Sciences,project"Dynamics and spatiotemporal patterns of glacial lakes evolution and their implications for risk management and adaptation in recently deglaciated areas"awarded to AE。
文摘Glacial lake outburst floods(GLOFs)represent one of the most serious hazard and risk in deglaciating high mountain regions worldwide and the need for GLOF hazard and risk assessment is apparent.As a consequence,numerous region-and nation-wide GLOF assessment studies have been published recently.These studies cover large areas and consider hundreds to thousands of lakes,prioritizing the hazard posed by them.Clearly,certain simplification is required for executing such studies,often resulting in neglecting qualitative characteristics which would need manual assignment.Different lake dam types(e.g.,bedrock-dammed,moraine-dammed)are often not distinguished,despite they control GLOF mechanism(dam overtopping/dam breach)and thus GLOF magnitude.In this study,we explore the potential of easily measurable quantitative characteristics and four ratios to approximate the lake dam type.Our dataset of 851 lakes of the Cordillera Blanca suggests that while variances and means of these characteristics of individual lake types differ significantly(F-test,t-test),value distribution of different geometrical properties can’t be used for the originally proposed purpose along the spectra.The only promising results are obtained for extreme values(selected bins)of the ratios.For instance,the low width to length ratio indicates likely morainedammed lake while the high value of ratio indicating round-shape of the lake indicates increased likelihood of bedrock-dammed lake.Overall,we report a negative result of our experiment since there are negligible differences of relative frequencies in most of the bins along the spectra.
文摘Natural disasters and finding suitable areas to dispose of municipal solid waste (MSW) are two major global challenges, both of which have several influences in the water resources and are related to climatic change, especially in developing countries like Brazil. Currently the risk of natural disasters is not utilized in the process of locating areas to dispose of MSW. This study, using geographic information system (GIS), analyzed spatially the susceptibility for landslide and flooding hazards in MSW disposal sites in S?o Paulo state, Brazil. The results showed that more than 90% of sanitary and ditch landfills are located in null, very low and low hazard classes (P0, P1 and P2). However, in this remaining 10% of landfills we still have approximately 55% of the total municipal solid waste disposed into susceptible areas with middle, high and very high hazard classes (P3, P4 and P5). This shows that S?o Paulo MSW disposal sites need more attention and control to prevent the occurrence of landslide/flooding and consequently the mitigation of environmental, economic and social impacts. In addition, the use of GIS is proved to be an appropriate tool to carry out this type of analysis, so we recommend that the risk of natural disasters should be taken into consideration in the process of finding landfill areas. Mainly, because, there is a tendency for extreme weather events to increase causing more flood and landslide events and consequently contributing to water scarcity and water degradation.
文摘The large excess of solid waste generated in cities is a result of population growth and economic development. Properly managing this municipal solid waste (MSW) is a challenge, mainly in underdeveloped and developing countries where financial concerns are an added problem. From the environmental point of view, a major issue is properly disposing MSW taking into consideration a wide range of factors, and working with different spatial data. In this study, we used geographic information system (GIS) to perform multi-criteria decision analysis (MCDA) conducted by analytical hierarchy process (AHP). The development of the environmental impact susceptibility model (EISM) for municipal solid waste disposal sites (MSWDS) applied to the state of Sao Paulo, Brazil considered factors such as geology, pedology, geomorphology, water resources, and climate represented by fifteen associated sub-factors. The results indicated that more than 82% of Sao Paulo’s territory is situated in areas with very low, low, and medium environmental impact susceptibility categories. However, in the remaining 18% of the state land area, 85 landfills are located in areas with high and very high environmental impact susceptibility categories. These results are alarming because these 85 landfills receive approximately 17,886 tons of MSW on a daily basis, which corresponds to 46% of all municipal solid waste disposed in Sao Paulo state. Therefore, decision makers, urban planners and policymakers could use the findings of the EISM towards mitigating the environmental impacts caused by MSWDS.
基金the Ministry of Education,Youth and Sports of CR within the CzeCOS program(grant number LM2018123)the Slovak Grant Agency for Science(no.VEGA 1/0535/20)+1 种基金Slovak Research and Development Agency(APVV-17-0644)project FORRES,ITMS:313011T678(20%)supported by the Operational Programme Integrated Infrastructure(OPII)funded by the ERDF。
文摘The stability of monocultural,even-aged spruce forests at lower altitudes in Central Europe is seriously threatened by the prospects of global climate change.The thermostability and water use efficiency of their photo synthetic apparatus might play a vital role in their successful acclimation.In this study,photo systemⅡ(PSⅡ)performance(OJIP transient,rapid light curves)and thermostability were analyzed in Norway spruce(Picea abies(L.)Karst.)throughout the growing season of the exceptionally warm year 2018(May-September)in the Western Carpathians,Slovakia.These measurements were accompanied by analysis of pigment concentrations in the needles.In addition,gas-exchange temperature curves were produced weekly from June until September to obtain intrinsic water use efficiencies.At the beginning of the growing season,needles exposed to heat stress showed significantly higher basal fluorescence and lower quantum yield,performance index,critical temperature thresholds of PSII inactivation and nonphotochemical yield in comparison to other months.The overall thermostability(heat-resistance)of PSII peaked in July and August,reflected in the lowest basal fluorescence and the highest quantum yield of PSII,critical temperature thresholds and yield of non-photochemical quenching under heat stress.Additionally,the ratio between chlorophyll and carotenoids was the highest in August and had a positive impact on PSII thermostability.Moreover,the high-temperature intrinsic water use efficiency was significantly higher during July and August than in June.Results show that15-year-old trees of Picea abies at 840 m a.s.l.exhibited acclimative seasonal responses of PSII thermostability and intrinsic water use efficiency during an exceptionally warm year.Our results suggest that mountainous P.abies at lower altitudes can acclimate their photosynthetic apparatus to higher temperatures during summer.
文摘The study assesses the functional status of the University of Energy and Natural Resources’ (UENR) bat sanctuary by examining its floral diversity and carbon stocks. Twenty-nine sampling points (plots) were randomly generated by using the ArcGIS random sampling algorithm. Using a three-nest sampling plot of 100m2, 25m2, and 1m2 quadrat, the enumeration of trees (DBH>10cm), saplings (>2cm DBH 0.05) between the 10m buffer created and the core area with respect to species diversity and carbon stocks. The study has provided valuable information on the functional status of the bat sanctuary which will help promote its conservation for sustained provision of ecosystem services.
基金the support by the Project LM2018123 Cze COS of the Ministry of Education,Youth and Sports of the Czech Republic。
文摘Mountain forests are more prone to environmental predispositions(EPs)than submountain ones.While remote sensing of mountain forests enables instantaneous damage mapping,the investigation of the causes requires field data.However,a local field or regionally modeled environmental characteristics influence remote data evaluation differently.This study focused on the evaluation of EPs effects damaging mountain forests between various spatial resolutions during environmental change.The evaluation was divided into managed and natural forests in the Hruby Jeseník Mts.(Czech Republic;240-1491 m a.s.l.;50.082°N,17.231°E).Damage was assessed through the discrimination analysis of the normalised difference vegetation index(NDVI)by MODIS VI during alternating drought and flood periods 2003-2014.The local environmental influence was assessed using the discrimination function(DF)separability of forest damage in the training sets.The regional influence was assessed through map algebra estimated via the DF and a forest decline spatial model based on EPs from differences between risk growth conditions and biomass fuzzy sets.Management,EPs and soil influenced forest NDVI at different levels.The management afflicted the NDVI more than the EPs.The EPs afflicted the NDVI more than the soil groups.Strong winters and droughts had a greater influence on the NDVI than the flood events,with the winter of 2005/2006 inverting the DF direction,and the 2003 drought increasing differences in managed forest biomass and decreasing differences in natural forest biomasses.More than 50% of declining managed forests in the training sets occurred on Leptosols,Podzols and Histosols.On a regional scale,the soil influence was eliminated by multiple predispositions.The EPs influenced 96% of natural forest and 65% of managed forest,though managed forest damage was more evident.The mountain forest NDVI decline was dependent on both management and risk predispositions.
文摘Friendly exchanges between China and Malaysia date back more than 2,000 years,and a profound traditional friendship has been forged between the two countries.By adhering to the principles of mutual trust,win-win cooperation,and equal assistance,China and Malaysia have become good neighbors,good friends,and good partners.In 2013,China and Malaysia established a comprehensive strategic partnership,accelerating the development of bilateral relations.
