Changes In Vegetation Types Research Articles

Variations in airborne pollen and spores in urban Guangzhou and their relationships with meteorological variables

Airborne pollen causes various types of allergies in humans, and the extent of allergic infection is related to the presence of different types of sporo–pollen and existing meteorological conditions in a certain area. Therefore, an aeropalynological study of 72 airborne samples with a hydrofluoric acid (HF) treatment was conducted in the Haizhu district of Guangzhou, China, in 2016, to identify the temporal variations in airborne sporo–pollen and the relationship between airborne sporo–pollen concentrations and different meteorological variables in Guangzhou, China. Forty-five types of airborne pollen, seven types of airborne spores, and some undetermined sporo–pollen taxa were identified with two separate plant habitats occurring during this period (from January to December 2016): arboreal pollen (tree-based) and non-arboreal pollen (herb, shrub, aquatic, liane, etc.). Furthermore, the daily records of four key meteorological variables (temperature, precipitation, relative humidity, and wind speed) were acquired to distinguish the pollen seasons and correlated with Spearman's rho test to establish a pollen-weather data book with the seasonal variations. The two leading seasons were identified based on pollen abundance: spring and autumn. Among them, the primary dominant sporo–pollen families during the spring season were Poaceae, Pinaceae, Euphorbiaceae, Moraceae, Microlepia sp., and Polypodiaceae. Conversely, Artemisia sp., Asteraceae, Cyperaceae, Poaceae, Alnus sp., Corylus sp., Myrtaceae, and Rosaceae were the dominant pollen species during autumn. However, few pollen grains were identified in January, May–July, and December. The statistical analysis revealed that temperature had both positive and negative correlations with sporo–pollen concentrations. However, precipitation and relative humidity had a strong impact on the sporo–pollen dispersion and exhibited a negative correlation with the sporo–pollen concentrations. The wind speed had a positive but strong correlation with the sporo–pollen concentration during the study period. Some inconsistent results were found due to environmental variations, vegetation type, and climate change around the study area. This study will facilitate the identification of pollen seasons to prevent the occurrence of pollen-related allergies in the Guangzhou city area.

Estimating land use/land cover change impacts on vegetation response to drought under ‘Grain for Green’ in the Loess Plateau

AbstractA series of serious environmental problems have appeared in North China, especially in the Loess Plateau. The 'Grain for Green Program' project has been implemented to address issues caused by vegetation degradation. Human beings play a key moderating role between drought and vegetation; however, it is not clearly understood how typical land cover changes from human activities impact the ability of vegetation to resist drought. To represent meteorological drought and vegetation dynamics, this study applied the standardized precipitation and evapotranspiration index and solar‐induced chlorophyll fluorescence. We investigated the vegetation response relationship to drought and how changing land cover affected it. The land cover changes associated with strategic human activity were also analyzed using the response relationship and environmental characteristics. Our results showed that land cover changes contributed to abnormal changes in vegetation dynamics and type. From 2001 to 2016, meteorological drought showed an insignificant difference in Loess Plateau. To a certain extent, land cover changes could extend vegetation response time with the implementation of the 'Grain for Green Progam'. Response time to the drought of different vegetation types in both changed and unchanged land cover showed an increasing trend from early‐period to later‐period. Similar response time to drought was among cropland, forest, grassland, construction land, and desert of unchanged land cover vegetation in different Grain for Green periods. Forest cover effectively improved vegetation response time and reduced vulnerability. This study improves the understanding of vegetation change and offers guidance for environmental protection projects and evaluating ecological restoration.

Phytosociological Data in Assessment of Anthropogenic Changes in Vegetation of Rzeszów Reservoir

Phytosociological research on aquatic and marsh vegetation was conducted in Rzeszów Reservoir (SE Poland): 134 relevés according to the Braun-Blanquet method were collected there in 2016 and compared to 91 relevés published in 1994 (225 relevés in total). Changes in vegetation type, diversity measures, species composition, and Ellenberg Indicator Values (EIVs) for light, moisture, reaction, and nitrogen were analysed. Over the 22 years (1994–2016), the greatest changes were noted in communities of the classes Lemnetea and Potametea and the alliance Salicion albae. The long-term observations demonstrated the disappearance of 14 phytocoenoses and the occurrence of 12 new ones. An expansion of marsh communities (Typhetum latifoliae, Typhetum angustifoliae, Glycerietum maximae, Leersietum oryzoidis) was noted, causing a decline of several species and vegetation types. According to canonical correspondence analysis (CCA), four environmental variables (light, moisture, nitrogen, and pH) were related to plant distribution. The strong disturbances reflected in intensive eutrophication were due to human activity, which is the main factor shaping the ecological succession and overgrowing of the reservoir.

Evapotranspiration and energy partitioning across a forest-shrub vegetation gradient in a subarctic, alpine catchment

As a result of altitude and latitude amplified climate change, widespread changes in vegetation composition, density and distribution have been observed across northern regions. Despite wide documentation of shrub proliferation and treeline advance, few field-based studies have evaluated the hydrological implications of these changes. Quantification of total evapotranspiration (ET) across a range of vegetation gradients is essential for predicting water yield, yet challenging in cold alpine catchments due to heterogeneous land cover, including both boreal forest and shrub taiga ecosystems. Here, we present six years of surface energy balance components and ET dynamics at three sites along an elevational gradient in a subarctic, alpine catchment near Whitehorse, Yukon Territory, Canada. These sites span a gradient of thermal and vegetation regimes, providing a space-for-time comparison for future ecosystem shifts: 1) a low-elevation boreal white spruce forest (~12–20 m), 2) a mid-elevation subalpine taiga comprised of tall, dense willow (Salix) and birch (Betula) shrubs (~1–3 m) and 3) a high-elevation subalpine taiga with short, sparse shrub cover (<0.75 m) and moss, lichen, and bare rock. Eddy covariance instrumentation ran year-round at the forest and during the growing season at the two shrub sites. Total ET decreased and interannual variability increased with elevation, with mean May to September ET totals of 349 (±3) mm at the forest, 249 (±10) mm at the tall, dense shrub site, and 240 (±26) mm at the short, sparse shrub site. Comparatively, over the same period, ET:R ratios were the highest and most variable at the forest (2.19 ± 0.37) and similar at the tall, dense shrub (1.22 ± 0.09) and short, sparse shrub (1.14 ± 0.05) sites. Our results suggest that advances in treeline will increase overall ET and lower interannual variability; however, the large growing season water deficit at the forest indicates strong reliance on soil moisture from late fall and snowmelt recharge. In contrast, ET was considerably less at the cooler higher elevation shrub sites, which exhibited similar ET losses over 6 years despite differences in shrub height and abundance. ET rates between the two shrub sites were similar throughout the year, except during the peak growing season. Greater interannual variability in ET at the short, sparse shrub site indicates the reduced influence of vegetation controls on ET. Results suggest that predicted changes in vegetation type and structure in northern regions will have a considerable impact on water partitioning and will vary in a complex way in response to changing precipitation timing, phase and magnitude, growing season length, and vegetation snow and rain interactions.

Characteristics and metabolic patterns of soil methanogenic archaea communities in the high-latitude natural forested wetlands of China.

Soil methanogenic microorganisms are one of the primary methane‐producing microbes in wetlands. However, we still poorly understand the community characteristic and metabolic patterns of these microorganisms according to vegetation type and seasonal changes. Therefore, to better elucidate the effects of the vegetation type and seasonal factors on the methanogenic community structure and metabolic patterns, we detected the characteristics of the soil methanogenic mcrA gene from three types of natural wetlands in different seasons in the Xiaoxing'an Mountain region, China. The results indicated that the distribution of Methanobacteriaceae (hydrogenotrophic methanogens) was higher in winter, while Methanosarcinaceae and Methanosaetaceae accounted for a higher proportion in summer. Hydrogenotrophic methanogenesis was the dominant trophic pattern in each wetland. The results of principal coordinate analysis and cluster analysis showed that the vegetation type considerably influenced the methanogenic community composition. The methanogenic community structure in the Betula platyphylla–Larix gmelinii wetland was relatively different from the structure of the other two wetland types. Indicator species analysis further demonstrated that the corresponding species of indicator operational taxonomic units from the Alnus sibirica wetland and the Betula ovalifolia wetland were similar. Network analysis showed that cooperative and competitive relationships exist both within and between the same or different trophic methanogens. The core methanogens with higher abundance in each wetland were conducive to the adaptation to environmental disturbances. This information is crucial for the assessment of metabolic patterns of soil methanogenic archaea and future fluxes in the wetlands of the Xiaoxing'an Mountain region given their vulnerability.

Resource stoichiometry, vegetation type and enzymatic activity control wetlands soil organic carbon in the Herbert River catchment, North-east Queensland

Wetlands are highly productive ecosystem with great potential to store carbon (C) and retain nitrogen (N) and phosphorus (P) in their soil. Changes in vegetation type and land use can affect organic matter inputs and soil properties. This work aimed to examine how these changes affected elemental stoichiometry and C-, N-, and P- associated enzyme activities and wetland soil organic C stock. We quantified organic C concentrations, and stoichiometric ratios of C, N, and P in total and microbial biomass pools, along with the activities and ratios of C-, N-, and P-associated enzymes for soils of natural coastal wetlands with different vegetation types, namely Melaleuca wetland (Melaleuca spp), mangrove forests (Bruguiera spp), and saline marsh (Eleocharis spp). We also compared these natural wetlands to an adjacent sugarcane plantation to understand the effects of vegetation types. Hypothesis-oriented path analysis was used to explore links between these variables and soil organic C stocks. Tidal forested soils (0–30 cm) had the highest organic C, N, and P contents and potential activities of C-, N-, P- acquiring enzymes, compared with other vegetation types. Mangroves soils had the highest total soil C:N and microbial biomass C:P ratios. Microbial biomass C:P ratios were significantly and positively related to total C:P, while microbial biomass N:P ratios were positively associated with total soil C:P and N:P ratios. Path analysis suggested that soil organic C stock was largely explained by total C:P ratio, microbial biomass N:P ratios, total P content, and the ratio of C- and P-associated enzymes. Different types of wetlands have different soil properties and enzymatic activities, implying their different capacity to store and process C and N. The resource quality and stoichiometry direct influence the organic C stock.

Urban Forests as Main Regulator of the Evaporative Cooling Effect in Cities

AbstractHigher temperatures in urban areas expose a large fraction of the human population to potentially dangerous heat stress. Green spaces are promoted worldwide as local and city‐scale cooling strategies but the amount, type, and functioning of vegetation in cities lack quantification and their interaction with urban climate in different settings remains a matter of debate. Here we use state‐of‐the‐art remote sensing data from 145 city clusters to disentangle the drivers of surface urban heat islands (SUHI) intensity and quantify urban‐rural differences in vegetation cover, species composition, and evaporative cooling. We show that nighttime SUHIs are affected mostly by abiotic factors, while daytime SUHIs are highly correlated with vegetation characteristics and the wetness of the background climate. Magnitude and seasonality of daytime SUHIs are controlled by urban‐rural differences in plant transpiration and leaf area, which explain the dependence of SUHIs on wetness conditions. Leaf area differences are caused primarily by changes in vegetation type and a loss of in‐city forested areas, highlighting the importance of maintaining “natural reserves” as a sustainable heat mitigation policy.

Conversion of forest to rangelands suppress soil fauna and flora densities during long-term in mountain ecosystems

The effect of vegetation types at mountainous sites on the relationships between soil biota and environmental variables applicable for the evaluation of soil quality and functions are barely studied and remain almost unknown. In the present study, the effect of forest degradation and vegetation types changes [i.e. natural forest with dominant species of Zelkova carpinifolia (Pall.) K. Koch. and three rangelands with dominant species of Festuca ovina L. Dactylis glomerata L. and Stachys byzantina K. Koch.] on the dynamics of soil properties and density of soil organisms in northern Iran has been considered. For each studied vegetation types, three different sites (at a distance of 4–6 km) with 1 ha area were selected. In summer (August), litter or O-horizon (i.e. L, F, and H) and soil (0–10 cm) layers were collected in an area of 30 × 30 cm. Also, in order to study the dynamics of soil properties, in addition to summer, soil samples were collected in the spring (May) and autumn (November) in each of the habitats. The study area is commonly covered with snow from late December to early April every year and therefore soil sampling was not considered in the winter season. A total of 48 litters (12 samples for each of those studied vegetation types), in the summer, and a total of 144 soil [(4 vegetation types × 3 seasons × 12 samples)] samples were collected and transferred to the laboratory. According to our findings, with higher values in the autumn season, the highest density of the soil earthworm (epigeic, anecic and endogeic), microarthropods (Acarina and collembola), nematode, and protozoa were detected in the Zelkova vegetation soils. Also, the highest density of bacterial and soil fungal communities were observed, especially in summer, under the tree cover of forest habitat. Based on our data, forest degradation and vegetation type changes suppressed the density of soil biota ranked in Zelkova > Festuca > Dactylis > Stachys due to low quality of litter, soil climate, and fertility condition. Although each vegetation type plays a prominent ecological role, forest covers are worthwhile because of their capacity to create hotspots identified by soil fauna and flora densities, which play a key role in the nutrient cycle and ecosystem services, in mountain habitats.

Removing the Vegetation Effect in Mineral Maps Produced by Hyperion

Estimation of mineral quantity with the presence of dry and green vegetation at pixel level is a challenging task in hyperspectral image analysis. A multiple linear regression model was trained to remove the effect of vegetation at pixel level in Hyperion image. The main diagnostic absorption features of the minerals in the study area are in 900, 2160, 2200, 2235 nm of the VNIR spectrum. In this study, the trained models did not show high sensitivity to the presence of noise in the spectrum and the vegetation cover changes on the ground. The maximum observed amount of green vegetation, dry vegetation, and mixed green and dry vegetation were respectively 41%–60%, 59%–64%, and 61%–76% in the study area. Field spectroscopy measurements were carried out by ASD-Fieldspec-3. Vegetation Corrected Continuum Depth (VCCD) model were developed for obtaining Continuum Removed Band Depth (CRBD) of mineral diagnostic absorption features. The model efficiency was evaluated in the presence of random noise and via introducing vegetation type changes. The accuracy of results was evaluated by the petrography, XRD and XRF of collected rock samples. Our results revealed that the presence of dry vegetation leads to underestimation of the frequency of all investigated minerals; similarly, green vegetation leads to underestimation of the frequency of the minerals, with the exception of hematite and goethite. Our results also showed that linear unmixing at pixel level will increase the accuracy of the algorithm to predict kaolinite, alunite, epidote, chlorite, pyrophyllite, goethite, muscovite and hematite minerals, respectively. In this work the maximum and minimum improvements of the accuracy were obtained as 0.40 and 0.09 for epidote and hematite, respectively.

Synchronous Marine and Terrestrial Carbon Cycle Perturbation in the High Arctic During the PETM

AbstractThe Paleocene‐Eocene Thermal Maximum (PETM; 56 Ma) is considered to be one of the best analogs for future climate change. The carbon isotope composition (δ13C) of n‐alkanes derived from leaf waxes of terrestrial plants and marine algae can provide important insights into the carbon cycle perturbation during the PETM. Here, we present new organic geochemical data and compound‐specific δ13C data from sediments recovered from an early Cenozoic basin‐margin succession from Spitsbergen. These samples represent one of the most expanded PETM sites and provide new insights into the high Arctic response to the PETM. Our results reveal a synchronous ∼−6.5‰ carbon isotope excursion (CIE) in short‐chain n‐alkanes (nC19; marine algae/bacteria) with a ∼−5‰ CIE in long‐chain n‐alkanes (nC29 and nC31; plant waxes) during the peak of the PETM. Although δ13Cn‐alkanes values were potentially affected via a modest thermal effect (1‰–2‰), the relative changes in the δ13Cn‐alkanes remain robust. A simple carbon cycle modeling suggests peak carbon emission rate could be ∼3 times faster than previously suggested using δ13CTOC records. The CIE magnitude of both δ13C n‐C19 and δ13Cn‐C29 can be explained by the elevated influence of 13C‐depleted respired CO2 in the water column and increased water availability on land, elevated pCO2 in the atmosphere, and changes in vegetation type during the PETM. The synchronous decline in δ13C of both leaf waxes and marine algae/bacteria argues against a significant contribution to the sedimentary organic carbon pool from the weathering delivery of fossil n‐alkanes in the Arctic region.

Decoupling of soil nitrogen and phosphorus dynamics along a temperature gradient on the Qinghai-Tibetan Plateau

Responses of soil nitrogen (N) and phosphorus (P) dynamics to global warming have received much attention. However, there are a lot of uncertainties. Given that a large-scale field investigation along a temperature gradient can provide deep insight into the long-term effect of climate warming, we conducted a soil sampling along a temperature gradient across a 1500-km transect on the Qinghai-Tibetan Plateau. To minimize the interference of the collinearity between temperature and precipitation on the temperature patterns of soil N and P dynamics, the sampling was performed along the 400 mm isohyet. We wanted to clarify the alterations of soil N and P dynamics in response to increasing temperature when the precipitation effect was minimized. Soil N content and N storage decreased, whereas soil P content and P stocks were stable with increasing temperature, leading to a decreased soil N:P ratio along the temperature gradient. This means that soil N and P dynamics are decoupled under the condition of increasing temperature. Soil N dynamics were associated with the variations in soil organic matter content, silt content, pH and vegetation type, and the effect of temperature on soil N dynamics was mainly through the influence of temperature on soil organic matter content. Soil P dynamics were related to the changes of soil silt content, precipitation, vegetation and soil type. Our results suggest that global warming may negatively affect soil N dynamics, but have no or only a small effect on soil P dynamics, and at the same time may cause the ecosystem to change from P limited to N limited.

Comparison of changes in vegetation and land cover types between Shenzhen and Bangkok

AbstractAs important node cities in the Belt and Road region, Shenzhen and Bangkok are faced with similar environmental threats posed by the high‐speed social development process. Rapid urbanization leads to changes in vegetation growth and land cover types and then affects ecosystem services. In the current study, we used a time‐series normalized difference vegetation index dataset from 2000 to 2019 and two land cover type datasets from 2000 to 2018 to investigate and compare the spatiotemporal characteristics of the changes in vegetation and land cover types of the two cities. We found that the trend of vegetation change was mainly affected by the change in land cover types, while the interannual fluctuation of vegetation change was likely related to the extreme climate events caused by El Niño‐Southern Oscillation events. However, different urbanization strategies led to opposite vegetation change trends in Bangkok and Shenzhen after 2005. With urbanization, the vegetation coverage (Pv) of Shenzhen increased from 48% in 2000 to 62% in 2018. The total urban green spaces (except croplands) of Shenzhen have remained above 33% of the total area since 2006. However, the total urban green space in Bangkok accounted for only 8% of the total area in 2018, which was even lower than the area percentage of Shenzhen's forests in the same year. Rapid urbanization without adequate urban green spaces caused a decreasing trend of Pv in Bangkok. Green development under the Belt and Road Initiative requires serious considerations of environmental quality and urban livability during the rapid urbanization.

The Persisting Influence of Edge on Vegetation in Hemiboreal Alnus Glutinosa (L.) Gaertn. Swamp Forest Set-Asides Adjacent to Recently Disturbed Stands

To increase set-aside areas and protect biodiversity values in managed hemiboreal forest landscapes, small forest parcels called Woodland Key Habitats have been designated in Baltic and Nordic countries. The aim of this study was to investigate the persisting influence of the edge on vegetation dynamics for young, medium-old and old edges in Alnus glutinosa (L.) Gaertn. Woodland Key Habitats. All of these edges are adjacent to recently disturbed (clear-cut) stands. We surveyed edge influence on vegetation in bryophyte, herbaceous, shrub and tree layers in 90 plots in 30 set-aside forest stands in Southern Latvia. We tested the differences in the number of species and projective coverage in all vegetation layers, but plant functional types were examined—separately in the herbaceous layer. We found that edge influence in protected forest stands of A. glutinosa swamp forests reflects strong changes in vegetation and plant functional types in the herbaceous layer mostly up to 20 years after clear-cut disturbance in adjacent stands. The greatest differences were between young edges (≤20 years) and old edges (≥41 years), but there were very few significant differences between medium-old (21–40 years) and old edges which signifies more rapid changes in the early stages of edge influence and gradual stabilization of vegetation later on. We found that in edges adjacent to recently disturbed stands (up to 20 years), significantly less rare and indicator epiphytic lichen species occur, but this occurrence increases over time and edge influence is no longer present beyond 20 years after disturbance. Changes in vegetation and species occurrence found in our study indicated the need to plan the allocation of set-aside patches in production forest landscapes to ensure connectivity over longer period of time. Careful planning of clear-cuts in neighboring areas over time can significantly reduce the impact of edge effect on these set-asides.

О ПРИЧИНАХ ПОТЕПЛЕНИЯ КЛИМАТА НА ОСНОВЕ ИЗУЧЕНИЯ ИСТОРИИ ЧЕТВЕРТИЧНЫХ ОЛЕДЕНЕНИЙ КАВКАЗА (НА ПРИМЕРЕ МЕЖДУРЕЧЬЯ ТЕРЕКА И АНДИЙСКОГО КОЙСУ)

The Greater Caucasus experienced repeated glaciation during the Quaternary (early, middle, upper Pleistocene, late Glacial, and late Holocene), which occurred under changing climatic conditions and differentiated tectonic movements. These glaciations, of course, are associated with changes in terrain, the formation of new deposits, transgressions and regressions of the Caspian Sea, changes in vegetation and soil types, so the problem of glaciation affects all earth Sciences to varying degrees. The study of Quaternary glaciation, especially Holocene glaciation, is currently relevant for understanding climate change. Against the background of significant climate fluctuations within the epochs of glaciation, there are smaller cooling phases that cause the temporary onset of glaciers. Short-term climate fluctuations are manifested in oscillations – minor fluctuations in the languages of glaciers. All this indicates that the climate undergoes significant changes in a short time, which are reflected in the morphosculpture of the terrain, the latest deposits and modern precipitation. Glaciation of the Greater Caucasus in the Prikazbeksky region reached its maximum in the middle Pleistocene,when glaciers went far into the Ossetian basin. All these traces have been preserved due to the lower capacity of the Chanty-Argun glacier and its fluvioglacial flow, which developed during the late Pleistocene epoch. Volcanic activity, especially active in the late Pliocene and continuing up to the present time, is associated with the late horn stage of development of the Caucasus. The formation of the Rukhs-Dzuar molass formation more than 2 km thick in the late Pleistocene in the Ossetian basin of the Tersky-Caspian flexure is associated with the activity of volcanoes in the Kazbek volcanic region. In the early Pleistocene, volcanic activity on the BC decreased significantly. The most intense outbreak of volcanism in the Kazbek and Elbrus volcanic regions occurred at the beginning of the late Pleistocene, which roughly coincided with the maximum phase of the late Pleistocene (Bezengian) glaciation. Then, in the second half of the late Pleistocene, volcanic activity was manifested on the mount Kazbek. The last outbreak of volcanic activity occurred in the Holocene no more than 2-3 thousand years ago. Fresh lavas are available on Elbrus, Kazbek, in the Terek valley near villages. Sioni and on the Kel volcanic plateau. Fumarolic activity still continues on Elbrus. Thus, in the Kazbek region, eruptions occurred from the late Pliocene to the late Holocene inclusive. Keywords: Pleistocene, Holocene, glaciation stages, nival-glacial processes, causes of glaciations, climate change, anthropogenic factors, natural factors, Earth degassing, magmatogenic degassing branch, seismotectonic degassing branch, greenhouse gases, newest geodynamics, volcanism, mud regimes, volcanism, methane hydrates, land degradation, water reclamation.

СУММА АКТИВНЫХ ТЕМПЕРАТУР ВЫШЕ 10° С И РАЗМЕЩЕНИЕ РАСТИТЕЛЬНОСТИ В БЕКЛЕМИШЕВСКОЙ КОТЛОВИНЕ (ЗАБАЙКАЛЬСКИЙ КРАЙ)

The article analyzes the distribution of the sum of active temperatures (∑Т˃10 °) over the topography. The data obtained made it possible to obtain information on the optimal values of ∑Т˃10 ° for various types of vegetation. It was found that the steepness of the slopes has a greater effect on the type of vegetation than the exposure of the slope. The series of changes in vegetation types were constructed with a change of ∑Т˃10 ° at different values of the steepness of the slopes. Such studies are methodologically necessary for the analysis of local and short-term climate changes.

Demographic trends in community functional tolerance reflect tree responses to climate and altered fire regimes.

Forests of the western United States are undergoing substantial stress from fire exclusion and increasing effects of climate change, altering ecosystem functions and processes. Changes in broad-scale drivers of forest community composition become apparent in their effect on survivorship and regeneration, driving demographic shifts. Here we take a community functional approach to forest demography, by investigating mean drought or shade functional tolerance in community assemblages. We created the Community Mean Tolerance Index (CMTI), a response metric utilizing drought/shade tolerance trade-offs to identify communities undergoing demographic change from a functional trait perspective. We applied the CMTI to Forest Inventory and Analysis data to investigate demographic trends in drought and shade tolerance across the southern Rocky Mountains. To find the major drivers of change in community tolerance within and across forest types, we compared index trends to climate and fire-exclusion-driven disturbance, and identified areas where demographic change was most pronounced. We predicted that greater shifts in drought tolerance would occur at lower forest type ecotones where climate stress is limiting and that shifts in shade tolerance would correspond to excursions from the historic fire regime leading to greater changes in forest types adapted to frequent, low-intensity fire. The CMTI was applied spatially to identify sites likely to transition to oak shrubfield, where disturbance history combined with a species-driven demographic shift toward drought tolerance. Within forest types, lower elevations are trending toward increased drought tolerance, while higher elevations are trending toward increased shade tolerance. Across forest types, CMTI difference peaked in mid-elevation ponderosa pine and mixed-conifer forests, where fire exclusion and autecology drive demographic changes. Peak CMTI difference was associated with fire exclusion in forest types adapted to frequent fire. At higher elevations, site-level stand dynamics appear to be influencing demographic tolerance trends more than broad climate drivers. Through a community demographic approach to functional traits, the CMTI highlights areas and forest types where ecosystem function is in the process of changing, before persistent vegetation type change occurs. Applied to regional plot networks, the CMTI provides an early warning of shifts in community functional processes as climate change pressures continue.

Home range and habitat use of two sympatric crocodylians (Melanosuchus niger and Caiman yacare) under changing habitat conditions

Abstract We used radio-telemetry to record how Caiman yacare (Cy) and Melanosuchus niger (Mn) responded to the intrusion of the Maniqui river into Cedral Lagoon in the Bolivian Amazon. Nine M. niger and 3 C. yacare were followed between December 2015 and May 2016. Both species showed a gradual reduction in mean monthly range from December (19.96 ha Mn and 1.74 ha Cy) to May 2016 (0.08 ha Mn and 0.24 ha Cy). Habitat use was fairly constant throughout the months for both species, Melanosuchus niger used mainly open swampy forests and Cyperaceae Marshes, while C. yacare used more islands and flooded grasslands. This study shows that both species of caimans responded to changes in depth and vegetation types, as their habitat as a whole was changed by river intrusion.

Vulnerability of vegetation activities to drought in Central Asia

Central Asia (CA) is a continental region that is sensitive to water conditions. Hence, drought has one of the primary effects on the vegetation activities in CA and could vary with climate change. However, it is still unclear how the drought vulnerability of vegetation differs among vegetation types and varies with drought scales in CA. Therefore, this paper studied the drought vulnerability of vegetation in CA from 1982–2015. Droughts were detected by using the standardized precipitation evapotranspiration index (SPEI), and the vegetation activities were represented by the Normalized Difference Vegetation Index (NDVI). Only the areas with no change in vegetation types were analyzed, in order to avoid interference with changes in land use. Results showed that both the duration and intensity of droughts were higher in the central, southwestern, and northeastern CA. The growing season (April–October) NDVI decreased by −0.0095 ± 0.0065 per decade in response to drying trends of 0.21 ± 0.22 unit aridity index per decade in these drought-concentrated regions. Forests and savannas/woody savannas were more vulnerable to drought from July–September, and their vulnerabilities were higher to droughts with longer time scales. Shrublands and grasslands were more vulnerable to drought from April–May and May–September, respectively, and the vulnerabilities during these months were higher for the droughts at 6–12 months scales. Twelve months was the optimal (most vulnerable) drought scale for the shrublands and grasslands and the secondary drought scale for the savannas/woody savannas. Further analysis of the vulnerability of vegetation to 12 months drought found that it generally increased with the increase of the drought magnitude (duration or intensity) to some peak values and then decreased. However, the vulnerability of forests and savannas/woody savannas increased with the drought intensity. Results would help for the drought risk assessment of vegetation in CA.

Effect of Vegetation on the Temperatures of TRAPPIST-1 Planets

Abstract TRAPPIST-1 is an ultracool dwarf hosting a system consisting of seven planets. While orbital properties, radii, and masses of the planets are nowadays well constrained, one of the fascinating open issues is the possibility that an environment hospitable to life could develop on some of these planets. Here, we use a simple formulation of an energy balance model that includes vegetation coverage to investigate the possibility of life affecting the climate of the planets in the TRAPPIST-1 system. Results confirm that planet TRAPPIST-1e has the best chance to be a habitable world and indicate that vegetation coverage significantly affects the resulting temperatures and habitability properties. The influence of vegetation has been evaluated in different scenarios characterized by different vegetation types, land–sea distributions and levels of greenhouse effect. While changes in vegetation type produce small changes, about 0.1%, in the habitable surface fraction, different land–sea distributions, by also affecting the vegetation growth, produce different temperature distributions. Finally, at latitudes where vegetation grows, the lowering of local albedo still represents a relevant contribution in settling the planetary temperature profiles even when levels of greenhouse effect higher than the Earth-like case are considered.

Spatial and Temporal Characteristics of Vegetation NDVI Changes and the Driving Forces in Mongolia during 1982–2015

As a result of the unique geographical characteristics, pastoral lifestyle, and economic conditions in Mongolia, its fragile natural ecosystems are highly sensitive to climate change and human activities. The normalized difference vegetation index (NDVI) was employed in this study as an indicator of the growth status of vegetation. The Sen’s slope, Mann–Kendall test, and geographical detector modelling methods were used to assess the spatial and temporal changes of the NDVI in response to variations in natural conditions and human activities in Mongolia from 1982 to 2015. The corresponding individual and interactive driving forces, and the optimal range for the maximum NDVI value of vegetation distribution were also quantified. The area in which vegetation was degraded was roughly equal to the area of increase, but different vegetation types behaved differently. The desert steppe and the Gobi Desert both in arid regions have degraded significantly, whereas the meadow steppe and alpine steppe showed a significant upward trend. Precipitation can satisfactorily account for vegetation distribution. Changes of livestock quantity was the dominant factor influencing the changes of most vegetation types. The interactions of topographic factors and climate factors have significant effects on vegetation growth. In the region of annual precipitation between 331 mm and 596 mm, forest vegetation type and pine sandy soil type were found to be most suitable for the growth of vegetation in Mongolia. The findings of this study can help us to understand the appropriate range or type of environmental factors affecting vegetation growth in Mongolia, based on which we can apply appropriate interventions to effectively mitigate the impact of environmental changes on vegetation.