Quality of higher education is often assumed to be linked to the size of the faculty. Therefore, ... more Quality of higher education is often assumed to be linked to the size of the faculty. Therefore, this study tested the hypothesis whether Bachelor's theses in ecology at a large, old research university would have more connection to theory than those at a small, young university college. The results revealed no significant difference between the universities. One potential explanation for these results is that theory is more likely to depend on the individual supervisor who may demand a clear connection to theory in Bachelor's theses. However, in the group of theses categorized as without a clear connection to theory, there were significant differences between the two universities regarding whether students were testing/developing a method or performing a case study. At the large, well-equipped research university, Bachelor's theses were significantly more likely to be based on developing/testing methods, while those at the university college more often comprised inexpen...
A lab-scale acidogenic sulfate-reducing reactor with N 2 stripping was continuously operated to u... more A lab-scale acidogenic sulfate-reducing reactor with N 2 stripping was continuously operated to uncover its microbial mechanism treating highly sulfate-containing organic wastewaters. Results showed that sulfate reduction efficiency decreased with the influent COD/sulfate ratios. Microbial community analysis showed that VFA accumulation mainly caused by the predominance of fermentative bacteria including Streptococcus and Oceanotoga. Genus Desulfovibrio was the most predominant SRB and enriched at low influent COD/sulfate ratios. Although Bifidobacterium, Atopobium, Wohlfahrtiimonas, Dysgonomonas etc. had low average abundance, they were identified keystone genera by the co-occurrence network analysis. The functions of the microbial community were not insignificantly influenced by COD/sulfate ratios. All predicted functional genes involved in dissimilatory sulfate reduction reached their maximum abundances at influent COD/sulfate ratio of 1.5, while the assimilatory sulfate reduction was favored at the COD/sulfate ratio lower than 2.
Implementation of a clean air policy in China has high national importance. Here, we analyzed tem... more Implementation of a clean air policy in China has high national importance. Here, we analyzed tempo-spatial characteristics of the concentrations of PM 2.5 (PM 2.5 _C), PM 10 (PM 10 _C), SO 2 (SO 2 _C), NO 2 (NO 2 _C), CO (CO _C), and maximum 8-h average O 3 (O 3 _8h_C), monitored at 22 stations throughout the mega-city of Wuhan from January 2016 to December 2020, and their correlations with the meteorological and socioeconomic factors. PM 2.5 _C, PM 10 _C, SO 2 _C, NO 2 _C, and CO _C showed similar monthly and seasonal trends, with minimum value in summer and maximum value in winter. However, O 3_ 8h_C showed an opposite monthly and seasonal change pattern. In 2020, compared to the other years, the annual average PM 2.5 _C, PM 10 _C, SO 2 _C, NO 2 _C, and CO _C were lower. PM 2.5 _C and PM 10 _C were higher in urban and industrial sites and lower in the control site. The SO 2 _C was higher in industrial sites. The NO 2 _C was lower, and O 3_ 8h_C was higher in suburban sites, while CO showed no spatial differences in their concentrations. PM 2.5 _C, PM 10 _C, SO 2 _C, NO 2 _C, and CO _C had positive correlations with each other, while O 3_ 8h_C showed more complex correlations with the other pollutants. PM 2.5 _C, PM 10 _C, SO 2 _C, and CO _C presented a significantly negative association with temperature and precipitation, while O 3 was significantly positively associated with temperature and negatively associated with relative air humidity. There was no significant correlation between air pollutants and wind speed. Gross domestic product, population, number of automobiles, and energy consumption play an important role in the dynamics of air quality concentrations. These all provided important information for the decision and policy-makers to effectively control the air pollution in Wuhan. In past decades, the deterioration of air quality caused by increased human activity and manufacturing has attracted wide concern worldwide 1,2. This not only reduces the visibility of the air atmosphere 3 but also significantly harms human health 4 and endangers the sustainable development of society and the economy 5. High concentrations of PM 2.5 and PM 10 would reduce atmospheric visibility and increase the occurrence of traffic accidents, while excessive exposure to polluted air could cause many kinds of cardiovascular and chronic respiratory diseases (e.g. asthma) 6 or even lead to premature death and cancer 2. High concentrations of SO 2 and NO x could cause acid rain and bring serious adverse ecosystem effects, such as the corrosion of buildings, soil acidification, and damage to crops and the aquatic environment 7,8. Therefore, it is urgent to reduce air pollutants and improve air quality. Urban air quality is influenced by various factors, including socioeconomic factors (e.g., the level of economic development, urban population, car ownership, fuel emission, and usage of fossil resources, etc.) and meteorological factors (e.g., temperature, relative air humidity, wind speed, and precipitation, etc.) 9,10. Socioeconomic factors are the main pollution sources affecting urban air quality 11,12 , while meteorological conditions also influence air quality when the main pollution sources are relatively stable 13-16. For example, urban emissions from human activity and manufacturing could cause environmental problems, such as photochemical smog, ozone layer depletion, acid rain, toxic chemical pollution, and global climate warming 17,18. Monthly or seasonal air quality variations are caused by pollutant-intensive emission sources and meteorological conditions 13,19,20. Therefore, strict and effective regulations and measures for air pollution prevention have begun to be implemented worldwide 21,22. China has suffered serious environmental degradation and air pollution, accompanying rapid economic growth and urbanization in recent decades. Population growth, energy consumption, motor vehicle increment,
International Journal of Climatology, May 13, 2021
Mountain ecosystems are sensitive to climate change, and vegetation phenology provides one of the... more Mountain ecosystems are sensitive to climate change, and vegetation phenology provides one of the best signals to exemplify ecosystem responses to climate change. Vegetation phenology of mountain ecosystems is usually characterized with an elevational pattern, with the growing season starts earlier and ends later in lower versus higher elevations. With climate change, this elevational gradient of vegetation phenology is likely to shift as well. However, both the patterns and the underlying driving forces for potential changes in this elevational gradient of vegetation phenology are still unclear. Here, we used 500‐m resolutioned normalized difference vegetation index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS) for the period of 2001 to 2017 to investigate changes in the start of growing season (SOS) along the elevational gradient for six mountains in northern China dominated by broadleaf deciduous forests. We found that while SOS consistently advanced for most of the pixels, the elevational lapse rate of SOS (SE) showed various trends for different mountains. Specifically, SE showed a significant (p‐value < .05) decreasing trend for the two southernmost mountains, indicating an increasing elevational synchronization in SOS. However, such phenological synchronization was not found in other temperate mountains. As warming has caused relatively consistent increases in heat forcing across different elevations and among different mountains but has led to highly various changes in chilling hours between high and low elevations, we suggested that the distinctive pattern in elevational synchronicity of spring phenology between southern and northern mountains in temperate China was primarily due to their different recent changes in chilling hours. Our work provides a novel key hypothesis for explaining the divergent changes in elevational gradients of vegetation phenology that can be tested in other regions for mountain ecosystems.
To improve understanding of how global warming may affect competitive interactions among plants, ... more To improve understanding of how global warming may affect competitive interactions among plants, information on the responses of plant functional traits across species to long-term warming is needed. Here we report the effect of 23 years of experimental warming on plant traits across four different alpine subarctic plant communities: tussock tundra, Dryas heath, dry heath and wet meadow. Open-top chambers (OTCs) were used to passively warm the vegetation by 1.5-3 °C. Changes in leaf width, leaf length and plant height of 22 vascular plant species were measured. Long-term warming significantly affected all plant traits. Overall, plant species were taller, with longer and wider leaves, compared with control plots, indicating an increase in biomass in warmed plots, with 13 species having significant increases in at least one trait and only three species having negative responses. The response varied among species and plant community in which the species was sampled, indicating community-warming interactions. Thus, plant trait responses are both species-and community-specific. Importantly, we show that there is likely to be great variation between plant species in their ability to maintain positive growth responses over the longer term, which might cause shifts in their relative competitive ability. Recent anthropogenic global warming is likely to pose a major threat to biodiversity 1. Global warming is predicted to be one of the main drivers of future species extinction 2. Warming may alter species interactions and could thereby cause local extinction of species 3. Significant changes in community structure can occur due to warming mediated through changes in plant interactions and growth 4. Plant distribution, abundance, and phenology are also likely to be significantly affected by climate change in the Arctic 5, 6. From the Arctic tundra to tropical regions, changes in plant diversity and community structure have already been reported 7, 8. Particularly, in Arctic tundra, studies have reported that there has been a shift from non-woody to woody vegetation 9, 10. Species functional traits and interactions with other species are fundamental in driving community assembly 11, 12. To successfully predict future changes in community structure, a critical step is to determine how the current anthropogenic changes could affect plant performance and fitness. There is evidence that functional traits directly affect plant physiology and performance, with implications for competitive interactions between plant species 13-16. Thus in order to predict future changes in species abundance, it is crucial to understand how environmental changes could affect such traits. Recent modelling studies based on plant functional trait and co-occurrence data have shown that unexpected climate-driven community changes can occur, that interactive indirect effects can overcome direct effects and that the timing of species responses is an important driver of community dynamics 17. Functional trait-based modelling methods have been shown to be more accurate in modelling vegetation distribution and analysing vegetation sensitivity than models built on plant functional type schemes 18. Such dynamic global vegetation models built on plant functional traits are helpful for assessing vegetation sensitivity to different climatic scenarios. Functional trait plasticity can also be used to asses vulnerability to climate change 19 .
Changing vegetation affects microclimates, groundwater tables, deserti cation, and biodiversity a... more Changing vegetation affects microclimates, groundwater tables, deserti cation, and biodiversity at the landscape level. The objective of this study is to assess the land cover dynamics and local perception of the in uence of land use on vegetation change in Katsina State, Nigeria. Remote sensing and Geographic Information System (GIS)-based analysis, key informant interviews, and a semi-structured questionnaire covering 400 households were used to examine the driving forces behind vegetation change across Katsina State. As a result of the household survey, 86.5% (n = 400) of respondents reported a decline in vegetation in the study area, aligning with the Land Use Land Cover analysis phase of the study. The key drivers behind the observed vegetation depletion in the study area include rewood collection, charcoal production, and population growth. There has been an increasing awareness that education has emerged as one of the most signi cant socioeconomic factors in uencing respondents' perceptions of these drivers. In spite of this, the unsustainable vegetation changes observed in this study have a negative impact on rural livelihoods and the management of natural resources in rural areas. This study recommends the implementation of sustainable land use policies that promote land-use practises that support economic growth and development.
Recreational activities worldwide have major impacts on the environment. This study examined the ... more Recreational activities worldwide have major impacts on the environment. This study examined the impact of different kinds of recreational activities on plant communities in a highly visited park in Mashhad, Iran. Vegetation in the park was sampled along 41 random 10-m transects with different human disturbances (trails, dirt roads, campsites) and undisturbed communities. Life form spectrum, species composition, species and phylogenetic diversity were determined for all communities. Disturbance increased the frequency of therophytes, but decreased the frequency of chamaephytes and percentage vegetated area. Recreational-mediated disturbance had variable impact on species composition, but decreased species and phylogenetic diversity compared with undisturbed areas. Roads and campsites caused the greatest damage, while trails had the smallest negative impact on vegetation. This study showed that damage to (semi-)natural park vegetation differs with recreation activity. This finding can help prioritise management activities to minimise negative impacts of recreation activities on local vegetation. The current visitor load to the urban park studied here appears too high to be sustainable over time, so better monitoring and restrictions on visitor numbers may be needed to minimise the negative impacts on park vegetation. The camping impacts can be managed by creating clusters of designated campsites to spatially concentrate the impact area. Lowimpact practices should be communicated to visitors. Natural areas used as outdoor recreation destinations suffer various adverse environmental impacts from visitor activities 1,2. Among outdoor activities, hiking and camping are popular worldwide 3. There is a large body of literature describing the adverse effects of these two activities on natural vegetation and soil in different regions 4-6. Frequently reported negative impacts of hiking and camping on the vegetation in recreation destinations include changes in species composition, reduced biodiversity, shorter vegetation, more patches of bare soil and complete removal of vegetation 2,4,5,7-10. Recreation activities are a major source of disturbance in arid regions, and their impacts on arid ecosystems are poorly understood 11-13. There is a geographical bias in recreation ecology studies, with few published reports from developing countries 6,14. Moreover, impacts of recreation vary greatly as a response to disturbance intensity and vegetation type 15. Managers in developing countries have to refer to studies in other parts of the world with a different evolutionary history of natural ecosystems and thus the results can be misleading for these managers, especially in preparing a proper conservation programme 2,14. An appropriate management strategy should preserve recreation values to enhance positive social impacts 16. Iran occupies an area of around 1.64 million km 2 and has a diverse flora 17. Approximately 30% of 8000 recorded plant species in Iran are endemic and some habitats in the country are located in the Irano-Anatolian and Caucasus global biodiversity hotspots 18. Land use changes and grazing are the major threats to the habitats of Iran 18-22. These disturbances, together with lack of knowledge 23 , make it difficult to plan appropriate management programmes for Iran's natural habitats. Mashhad, located in north eastern Iran, is the second-largest and most-visited city in the country. It is also among the most visited religious cities in the world 19. Recreation destinations in Mashhad are visited by large
Climate change is rapidly warming high latitude and high elevation regions influencing plant comm... more Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment. We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analyzed based on a seven-year Community-Level Interaction Program experiment. The communities had distinct soil moisture conditions, leading to community-specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs, and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.
There is increasing interestin broad‐scale analysis, modeling, and prediction of the distribution... more There is increasing interestin broad‐scale analysis, modeling, and prediction of the distribution and composition of plant species assemblages under climatic, environmental, and biotic change, particularly for conservation purposes. We devised a method to reliably predict the impact of climate change on large assemblages of plant communities, while also considering competing biotic and environmental factors. To this purpose, we first used multilabel algorithms in order to convert the task of explaining a large assemblage of plant communities into a classification framework able to capture with high cross‐validated accuracy the pattern of species distributions under a composite set of biotic and abiotic factors. We applied our model to a large set of plant communities in the Swiss Alps. Our model explained presences and absences of 175 plant species in 608 plots with >87% cross‐validated accuracy, predicted decreases in α, β, and γ diversity by 2040 under both moderate and extreme climate scenarios, and identified likely advantaged and disadvantaged plant species under climate change. Multilabel variable selection revealed the overriding importance of topography, soils, and temperature extremes (rather than averages) in determining the distribution of plant species in the study area and their response to climate change. Our method addressed a number of challenging research problems, such as scaling to large numbers of species, considering species relationships and rarity, and addressing an overwhelming proportion of absences in presence–absence matrices. By handling hundreds to thousands of plants and plots simultaneously over large areas, our method can inform broad‐scale conservation of plant species under climate change because it allows species that require urgent conservation action (assisted migration, seed conservation, and ex situ conservation) to be detected and prioritized. Our method also increases the practicality of assisted colonization of plant species by helping to prevent ill‐advised introduction of plant species with limited future survival probability.
Urban agglomeration will be the main mode of future urbanization in China, greatly in uencing soc... more Urban agglomeration will be the main mode of future urbanization in China, greatly in uencing social & economic development and ecosystem protection at the whole city cluster scale. It is important to analyze the impacts of large-scale, scattered land use and cover change (LUCC) consisting of one-polemulti-point urbanization in city clusters on regional ecosystem services (ESs), so as to increase ecological security and maintain ESs levels. Using the urban-rural gradient analysis method (UGAM), this study examined driver-response mechanisms of large-scale, scattered agglomeration urbanization on ESs along an urban-rural gradient and at regional scale. This was done by simulating and analyzing tempospatial variations in ESs characteristics along concentric ring gradients in Central Yunnan City Cluster (CYCC) under its present urbanization path. The results showed that rapid urban sprawl is the main driver affecting the integral value of ESs in CYCC and that ESs trade-offs (through LUCC caused by urbanization) between adjacent zones along the urban-rural gradient will particularly exacerbate degradation of integral ESs levels. Hence, CYCC should follow a sustainable, eco-friendly urbanization path and should consider ecological principles and the impact of LUCC on regional ESs along the urbanrural gradient in top-level design and decision-making on urban planning and strategic land use management. Differentiated regional development policies should be formulated for each areas, the urban-rural development pattern and layout optimized, the scale of construction land rationally controlled, and the overall e ciency of land use improved. Ecological buffers should be set up around areas with sharp and obvious changes in land use, to alleviate the negative impact of large-scale, decentralized city cluster urbanization on regional ESs.
Background and aim Global warming is expected to have large impacts on high alpine and Arctic eco... more Background and aim Global warming is expected to have large impacts on high alpine and Arctic ecosystems in future. Here we report the effects of 18 years of experimental warming on two contrasting high alpine plant communities in subarctic Sweden.Methods Using open-top chambers (OTCs), we analysed the effects of long-term passive experimental warming on two high alpine plant communities, a species- and nutrient-poor heath and a more nutrient- and species-rich mesic meadow. We determined the impact on species composition, species diversity (at the level of rare, frequent and dominant species in each community), and phylogenetic and functional diversity.Key results Long-term warming drove differentiation in the species composition in both heath and meadow vegetation, with the warmed plots having distinctly different species composition in 2013 compared with 1995. In addition, variability in species composition increased in the meadow, while it decreased in the heath. The long-term warming had a significant negative effect on the three orders of phylogenetic Hill diversity in the meadow. There was a similar tendency in the heath, but only the phylogenetic diversity of dominant species was significantly affected. Long-term warming caused a reduction in graminoids in the heath, while deciduous shrubs increased. In the meadow, cushion-forming plants showed an increase in abundance from 2001 to 2013 in the warmed plots. Conclusions Responses in species and phylogenetic diversity to experimental warming varied over both time (medium vs long-term responses) and space (i.e. between the two neighbouring plant communities heath and meadow). The meadow community was more negatively affected in terms of species and phylogenetic diversity than the heath community. A potential driver for the changes in the meadow may be decreased soil moisture caused by the long-term warming.
Quality of higher education is often assumed to be linked to the size of the faculty. Therefore, ... more Quality of higher education is often assumed to be linked to the size of the faculty. Therefore, this study tested the hypothesis whether Bachelor's theses in ecology at a large, old research university would have more connection to theory than those at a small, young university college. The results revealed no significant difference between the universities. One potential explanation for these results is that theory is more likely to depend on the individual supervisor who may demand a clear connection to theory in Bachelor's theses. However, in the group of theses categorized as without a clear connection to theory, there were significant differences between the two universities regarding whether students were testing/developing a method or performing a case study. At the large, well-equipped research university, Bachelor's theses were significantly more likely to be based on developing/testing methods, while those at the university college more often comprised inexpen...
A lab-scale acidogenic sulfate-reducing reactor with N 2 stripping was continuously operated to u... more A lab-scale acidogenic sulfate-reducing reactor with N 2 stripping was continuously operated to uncover its microbial mechanism treating highly sulfate-containing organic wastewaters. Results showed that sulfate reduction efficiency decreased with the influent COD/sulfate ratios. Microbial community analysis showed that VFA accumulation mainly caused by the predominance of fermentative bacteria including Streptococcus and Oceanotoga. Genus Desulfovibrio was the most predominant SRB and enriched at low influent COD/sulfate ratios. Although Bifidobacterium, Atopobium, Wohlfahrtiimonas, Dysgonomonas etc. had low average abundance, they were identified keystone genera by the co-occurrence network analysis. The functions of the microbial community were not insignificantly influenced by COD/sulfate ratios. All predicted functional genes involved in dissimilatory sulfate reduction reached their maximum abundances at influent COD/sulfate ratio of 1.5, while the assimilatory sulfate reduction was favored at the COD/sulfate ratio lower than 2.
Implementation of a clean air policy in China has high national importance. Here, we analyzed tem... more Implementation of a clean air policy in China has high national importance. Here, we analyzed tempo-spatial characteristics of the concentrations of PM 2.5 (PM 2.5 _C), PM 10 (PM 10 _C), SO 2 (SO 2 _C), NO 2 (NO 2 _C), CO (CO _C), and maximum 8-h average O 3 (O 3 _8h_C), monitored at 22 stations throughout the mega-city of Wuhan from January 2016 to December 2020, and their correlations with the meteorological and socioeconomic factors. PM 2.5 _C, PM 10 _C, SO 2 _C, NO 2 _C, and CO _C showed similar monthly and seasonal trends, with minimum value in summer and maximum value in winter. However, O 3_ 8h_C showed an opposite monthly and seasonal change pattern. In 2020, compared to the other years, the annual average PM 2.5 _C, PM 10 _C, SO 2 _C, NO 2 _C, and CO _C were lower. PM 2.5 _C and PM 10 _C were higher in urban and industrial sites and lower in the control site. The SO 2 _C was higher in industrial sites. The NO 2 _C was lower, and O 3_ 8h_C was higher in suburban sites, while CO showed no spatial differences in their concentrations. PM 2.5 _C, PM 10 _C, SO 2 _C, NO 2 _C, and CO _C had positive correlations with each other, while O 3_ 8h_C showed more complex correlations with the other pollutants. PM 2.5 _C, PM 10 _C, SO 2 _C, and CO _C presented a significantly negative association with temperature and precipitation, while O 3 was significantly positively associated with temperature and negatively associated with relative air humidity. There was no significant correlation between air pollutants and wind speed. Gross domestic product, population, number of automobiles, and energy consumption play an important role in the dynamics of air quality concentrations. These all provided important information for the decision and policy-makers to effectively control the air pollution in Wuhan. In past decades, the deterioration of air quality caused by increased human activity and manufacturing has attracted wide concern worldwide 1,2. This not only reduces the visibility of the air atmosphere 3 but also significantly harms human health 4 and endangers the sustainable development of society and the economy 5. High concentrations of PM 2.5 and PM 10 would reduce atmospheric visibility and increase the occurrence of traffic accidents, while excessive exposure to polluted air could cause many kinds of cardiovascular and chronic respiratory diseases (e.g. asthma) 6 or even lead to premature death and cancer 2. High concentrations of SO 2 and NO x could cause acid rain and bring serious adverse ecosystem effects, such as the corrosion of buildings, soil acidification, and damage to crops and the aquatic environment 7,8. Therefore, it is urgent to reduce air pollutants and improve air quality. Urban air quality is influenced by various factors, including socioeconomic factors (e.g., the level of economic development, urban population, car ownership, fuel emission, and usage of fossil resources, etc.) and meteorological factors (e.g., temperature, relative air humidity, wind speed, and precipitation, etc.) 9,10. Socioeconomic factors are the main pollution sources affecting urban air quality 11,12 , while meteorological conditions also influence air quality when the main pollution sources are relatively stable 13-16. For example, urban emissions from human activity and manufacturing could cause environmental problems, such as photochemical smog, ozone layer depletion, acid rain, toxic chemical pollution, and global climate warming 17,18. Monthly or seasonal air quality variations are caused by pollutant-intensive emission sources and meteorological conditions 13,19,20. Therefore, strict and effective regulations and measures for air pollution prevention have begun to be implemented worldwide 21,22. China has suffered serious environmental degradation and air pollution, accompanying rapid economic growth and urbanization in recent decades. Population growth, energy consumption, motor vehicle increment,
International Journal of Climatology, May 13, 2021
Mountain ecosystems are sensitive to climate change, and vegetation phenology provides one of the... more Mountain ecosystems are sensitive to climate change, and vegetation phenology provides one of the best signals to exemplify ecosystem responses to climate change. Vegetation phenology of mountain ecosystems is usually characterized with an elevational pattern, with the growing season starts earlier and ends later in lower versus higher elevations. With climate change, this elevational gradient of vegetation phenology is likely to shift as well. However, both the patterns and the underlying driving forces for potential changes in this elevational gradient of vegetation phenology are still unclear. Here, we used 500‐m resolutioned normalized difference vegetation index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS) for the period of 2001 to 2017 to investigate changes in the start of growing season (SOS) along the elevational gradient for six mountains in northern China dominated by broadleaf deciduous forests. We found that while SOS consistently advanced for most of the pixels, the elevational lapse rate of SOS (SE) showed various trends for different mountains. Specifically, SE showed a significant (p‐value < .05) decreasing trend for the two southernmost mountains, indicating an increasing elevational synchronization in SOS. However, such phenological synchronization was not found in other temperate mountains. As warming has caused relatively consistent increases in heat forcing across different elevations and among different mountains but has led to highly various changes in chilling hours between high and low elevations, we suggested that the distinctive pattern in elevational synchronicity of spring phenology between southern and northern mountains in temperate China was primarily due to their different recent changes in chilling hours. Our work provides a novel key hypothesis for explaining the divergent changes in elevational gradients of vegetation phenology that can be tested in other regions for mountain ecosystems.
To improve understanding of how global warming may affect competitive interactions among plants, ... more To improve understanding of how global warming may affect competitive interactions among plants, information on the responses of plant functional traits across species to long-term warming is needed. Here we report the effect of 23 years of experimental warming on plant traits across four different alpine subarctic plant communities: tussock tundra, Dryas heath, dry heath and wet meadow. Open-top chambers (OTCs) were used to passively warm the vegetation by 1.5-3 °C. Changes in leaf width, leaf length and plant height of 22 vascular plant species were measured. Long-term warming significantly affected all plant traits. Overall, plant species were taller, with longer and wider leaves, compared with control plots, indicating an increase in biomass in warmed plots, with 13 species having significant increases in at least one trait and only three species having negative responses. The response varied among species and plant community in which the species was sampled, indicating community-warming interactions. Thus, plant trait responses are both species-and community-specific. Importantly, we show that there is likely to be great variation between plant species in their ability to maintain positive growth responses over the longer term, which might cause shifts in their relative competitive ability. Recent anthropogenic global warming is likely to pose a major threat to biodiversity 1. Global warming is predicted to be one of the main drivers of future species extinction 2. Warming may alter species interactions and could thereby cause local extinction of species 3. Significant changes in community structure can occur due to warming mediated through changes in plant interactions and growth 4. Plant distribution, abundance, and phenology are also likely to be significantly affected by climate change in the Arctic 5, 6. From the Arctic tundra to tropical regions, changes in plant diversity and community structure have already been reported 7, 8. Particularly, in Arctic tundra, studies have reported that there has been a shift from non-woody to woody vegetation 9, 10. Species functional traits and interactions with other species are fundamental in driving community assembly 11, 12. To successfully predict future changes in community structure, a critical step is to determine how the current anthropogenic changes could affect plant performance and fitness. There is evidence that functional traits directly affect plant physiology and performance, with implications for competitive interactions between plant species 13-16. Thus in order to predict future changes in species abundance, it is crucial to understand how environmental changes could affect such traits. Recent modelling studies based on plant functional trait and co-occurrence data have shown that unexpected climate-driven community changes can occur, that interactive indirect effects can overcome direct effects and that the timing of species responses is an important driver of community dynamics 17. Functional trait-based modelling methods have been shown to be more accurate in modelling vegetation distribution and analysing vegetation sensitivity than models built on plant functional type schemes 18. Such dynamic global vegetation models built on plant functional traits are helpful for assessing vegetation sensitivity to different climatic scenarios. Functional trait plasticity can also be used to asses vulnerability to climate change 19 .
Changing vegetation affects microclimates, groundwater tables, deserti cation, and biodiversity a... more Changing vegetation affects microclimates, groundwater tables, deserti cation, and biodiversity at the landscape level. The objective of this study is to assess the land cover dynamics and local perception of the in uence of land use on vegetation change in Katsina State, Nigeria. Remote sensing and Geographic Information System (GIS)-based analysis, key informant interviews, and a semi-structured questionnaire covering 400 households were used to examine the driving forces behind vegetation change across Katsina State. As a result of the household survey, 86.5% (n = 400) of respondents reported a decline in vegetation in the study area, aligning with the Land Use Land Cover analysis phase of the study. The key drivers behind the observed vegetation depletion in the study area include rewood collection, charcoal production, and population growth. There has been an increasing awareness that education has emerged as one of the most signi cant socioeconomic factors in uencing respondents' perceptions of these drivers. In spite of this, the unsustainable vegetation changes observed in this study have a negative impact on rural livelihoods and the management of natural resources in rural areas. This study recommends the implementation of sustainable land use policies that promote land-use practises that support economic growth and development.
Recreational activities worldwide have major impacts on the environment. This study examined the ... more Recreational activities worldwide have major impacts on the environment. This study examined the impact of different kinds of recreational activities on plant communities in a highly visited park in Mashhad, Iran. Vegetation in the park was sampled along 41 random 10-m transects with different human disturbances (trails, dirt roads, campsites) and undisturbed communities. Life form spectrum, species composition, species and phylogenetic diversity were determined for all communities. Disturbance increased the frequency of therophytes, but decreased the frequency of chamaephytes and percentage vegetated area. Recreational-mediated disturbance had variable impact on species composition, but decreased species and phylogenetic diversity compared with undisturbed areas. Roads and campsites caused the greatest damage, while trails had the smallest negative impact on vegetation. This study showed that damage to (semi-)natural park vegetation differs with recreation activity. This finding can help prioritise management activities to minimise negative impacts of recreation activities on local vegetation. The current visitor load to the urban park studied here appears too high to be sustainable over time, so better monitoring and restrictions on visitor numbers may be needed to minimise the negative impacts on park vegetation. The camping impacts can be managed by creating clusters of designated campsites to spatially concentrate the impact area. Lowimpact practices should be communicated to visitors. Natural areas used as outdoor recreation destinations suffer various adverse environmental impacts from visitor activities 1,2. Among outdoor activities, hiking and camping are popular worldwide 3. There is a large body of literature describing the adverse effects of these two activities on natural vegetation and soil in different regions 4-6. Frequently reported negative impacts of hiking and camping on the vegetation in recreation destinations include changes in species composition, reduced biodiversity, shorter vegetation, more patches of bare soil and complete removal of vegetation 2,4,5,7-10. Recreation activities are a major source of disturbance in arid regions, and their impacts on arid ecosystems are poorly understood 11-13. There is a geographical bias in recreation ecology studies, with few published reports from developing countries 6,14. Moreover, impacts of recreation vary greatly as a response to disturbance intensity and vegetation type 15. Managers in developing countries have to refer to studies in other parts of the world with a different evolutionary history of natural ecosystems and thus the results can be misleading for these managers, especially in preparing a proper conservation programme 2,14. An appropriate management strategy should preserve recreation values to enhance positive social impacts 16. Iran occupies an area of around 1.64 million km 2 and has a diverse flora 17. Approximately 30% of 8000 recorded plant species in Iran are endemic and some habitats in the country are located in the Irano-Anatolian and Caucasus global biodiversity hotspots 18. Land use changes and grazing are the major threats to the habitats of Iran 18-22. These disturbances, together with lack of knowledge 23 , make it difficult to plan appropriate management programmes for Iran's natural habitats. Mashhad, located in north eastern Iran, is the second-largest and most-visited city in the country. It is also among the most visited religious cities in the world 19. Recreation destinations in Mashhad are visited by large
Climate change is rapidly warming high latitude and high elevation regions influencing plant comm... more Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment. We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analyzed based on a seven-year Community-Level Interaction Program experiment. The communities had distinct soil moisture conditions, leading to community-specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs, and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.
There is increasing interestin broad‐scale analysis, modeling, and prediction of the distribution... more There is increasing interestin broad‐scale analysis, modeling, and prediction of the distribution and composition of plant species assemblages under climatic, environmental, and biotic change, particularly for conservation purposes. We devised a method to reliably predict the impact of climate change on large assemblages of plant communities, while also considering competing biotic and environmental factors. To this purpose, we first used multilabel algorithms in order to convert the task of explaining a large assemblage of plant communities into a classification framework able to capture with high cross‐validated accuracy the pattern of species distributions under a composite set of biotic and abiotic factors. We applied our model to a large set of plant communities in the Swiss Alps. Our model explained presences and absences of 175 plant species in 608 plots with >87% cross‐validated accuracy, predicted decreases in α, β, and γ diversity by 2040 under both moderate and extreme climate scenarios, and identified likely advantaged and disadvantaged plant species under climate change. Multilabel variable selection revealed the overriding importance of topography, soils, and temperature extremes (rather than averages) in determining the distribution of plant species in the study area and their response to climate change. Our method addressed a number of challenging research problems, such as scaling to large numbers of species, considering species relationships and rarity, and addressing an overwhelming proportion of absences in presence–absence matrices. By handling hundreds to thousands of plants and plots simultaneously over large areas, our method can inform broad‐scale conservation of plant species under climate change because it allows species that require urgent conservation action (assisted migration, seed conservation, and ex situ conservation) to be detected and prioritized. Our method also increases the practicality of assisted colonization of plant species by helping to prevent ill‐advised introduction of plant species with limited future survival probability.
Urban agglomeration will be the main mode of future urbanization in China, greatly in uencing soc... more Urban agglomeration will be the main mode of future urbanization in China, greatly in uencing social & economic development and ecosystem protection at the whole city cluster scale. It is important to analyze the impacts of large-scale, scattered land use and cover change (LUCC) consisting of one-polemulti-point urbanization in city clusters on regional ecosystem services (ESs), so as to increase ecological security and maintain ESs levels. Using the urban-rural gradient analysis method (UGAM), this study examined driver-response mechanisms of large-scale, scattered agglomeration urbanization on ESs along an urban-rural gradient and at regional scale. This was done by simulating and analyzing tempospatial variations in ESs characteristics along concentric ring gradients in Central Yunnan City Cluster (CYCC) under its present urbanization path. The results showed that rapid urban sprawl is the main driver affecting the integral value of ESs in CYCC and that ESs trade-offs (through LUCC caused by urbanization) between adjacent zones along the urban-rural gradient will particularly exacerbate degradation of integral ESs levels. Hence, CYCC should follow a sustainable, eco-friendly urbanization path and should consider ecological principles and the impact of LUCC on regional ESs along the urbanrural gradient in top-level design and decision-making on urban planning and strategic land use management. Differentiated regional development policies should be formulated for each areas, the urban-rural development pattern and layout optimized, the scale of construction land rationally controlled, and the overall e ciency of land use improved. Ecological buffers should be set up around areas with sharp and obvious changes in land use, to alleviate the negative impact of large-scale, decentralized city cluster urbanization on regional ESs.
Background and aim Global warming is expected to have large impacts on high alpine and Arctic eco... more Background and aim Global warming is expected to have large impacts on high alpine and Arctic ecosystems in future. Here we report the effects of 18 years of experimental warming on two contrasting high alpine plant communities in subarctic Sweden.Methods Using open-top chambers (OTCs), we analysed the effects of long-term passive experimental warming on two high alpine plant communities, a species- and nutrient-poor heath and a more nutrient- and species-rich mesic meadow. We determined the impact on species composition, species diversity (at the level of rare, frequent and dominant species in each community), and phylogenetic and functional diversity.Key results Long-term warming drove differentiation in the species composition in both heath and meadow vegetation, with the warmed plots having distinctly different species composition in 2013 compared with 1995. In addition, variability in species composition increased in the meadow, while it decreased in the heath. The long-term warming had a significant negative effect on the three orders of phylogenetic Hill diversity in the meadow. There was a similar tendency in the heath, but only the phylogenetic diversity of dominant species was significantly affected. Long-term warming caused a reduction in graminoids in the heath, while deciduous shrubs increased. In the meadow, cushion-forming plants showed an increase in abundance from 2001 to 2013 in the warmed plots. Conclusions Responses in species and phylogenetic diversity to experimental warming varied over both time (medium vs long-term responses) and space (i.e. between the two neighbouring plant communities heath and meadow). The meadow community was more negatively affected in terms of species and phylogenetic diversity than the heath community. A potential driver for the changes in the meadow may be decreased soil moisture caused by the long-term warming.
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Papers by Juha Alatalo