Search

There are increasing concerns about regional ecosystem shifts in the Arctic due to climate change. Notably, warming-induced increases in Arctic vegetation cover can have important consequences for surface energy balance, habitat changes, permafrost, and more. Mammalian herbivory is an important potential force to counteract this effect. In this systematic literature review, we examine the role of terrestrial mammalian herbivory on warming-induced increases in Arctic vegetation. We analyse the effects of terrestrial mammalian herbivory on vegetation cover, abundance, growth, survival, and ecosystem productivity. Our results show that herbivory has an overall significant negative influence on Arctic vegetation, particularly on vegetation biomass, growth, and productivity, as indicated by the Normalised Difference Vegetation Index (NDVI). Importantly, we demonstrated a significant role of herbivores in controlling carbon dioxide exchange and carbon uptake, whilst acknowledging that the relationship between herbivory and ecosystem productivity is highly complex and site-dependent. Our results confirm the important role that herbivory can play in buffering observed and predicted warming-induced Arctic vegetation increases. We also find that this is strongly affected by plant palatability, trampling occurrence, and herbivore density. [ABSTRACT FROM AUTHOR]

Ecological disturbances driving state changes in ecosystems are likely to be exacerbated with climate shifts during this century. Temperate montane ecosystems of the Western United States (Mountain West) are especially vulnerable due to their low fertility, heterogeneous landscapes, and tight coupling between terrestrial and aquatic components. We review how catchment level pulse and press disturbances will intensify, and how they are reflected by coupled measurements of stream water chemistry and flow. Detecting effects on watershed processes can be complex and depend on the type and extent of disturbance. Within this context, we discuss the impacts of wildfire (pulse), bark beetle outbreaks (pulse), snowpack shifts (press), and progressive vegetation community shifts (press) on streamflow and chemistry dynamics (hydrochemographs). We used long-term data from three mid- to high-elevation watersheds as examples of how disturbances may influence stream hydrochemographs, including increased variability in winter nitrate export in more recent years with extremes in snowmelt runoff export; variable nitrate export when snow water equivalent was abnormally high or low; and high nitrate flux in the years immediately following sudden forest loss. These examples illustrate the need for long-term continuous monitoring to fill the gap in our understanding of the short- and long-term consequences of climate change-induced disturbances to watersheds. As disturbances increase in severity and frequency and induce ecological state changes, it is critical that we develop our understanding of impacts on downstream communities that depend sociologically and economically on water availability and quality. [ABSTRACT FROM AUTHOR]

Climate change and human activities such as overgrazing and rapid development of tourism simultaneously affected the vegetation of the Zoige Plateau. However, the spatiotemporal variations of vegetation and the relative contributions of climate change and human activities to these vegetation dynamics remain unclear. Therefore, clarifying how and why the vegetation on the Zoige Plateau changed can provide a scientific basis for the sustainable development of the region. Here, we investigate NDVI trends using the Normalized Difference Vegetation Index (NDVI) as an indicator of vegetation greenness and distinguish the relative effects of climate changes and human activities on vegetation changes by utilizing residual trend analysis and the Geodetector. We find a tendency of vegetation greening from 2001 to 2020, with significant greening accounting for 21.44% of the entire region. However, browning area expanded rapidly after 2011. Warmer temperatures are the primary driver of vegetation changes in the Zoige Plateau. Climatic variations and human activities were responsible for 65.57% and 34.43% of vegetation greening, and 39.14% and 60.86% of vegetation browning, respectively, with browning concentrated along the Yellow, Black and White Rivers. Compared to 2001–2010, the inhibitory effect of human activity and climate fluctuations on vegetation grew dramatically between 2011 and 2020. [ABSTRACT FROM AUTHOR]

In the arid southwestern U.S., urban greening strategies have been promoted to alleviate ecosystem disservices associated with lawns, including the adoption of xeric yards with desert-adapted floras and gravel groundcover and wildlife-friendly yards with complex vegetation structure and composition. Scant studies have investigated the extent of different vegetation changes in urban greening practices and the complexity of associated human drivers. We addressed this gap by analyzing survey data from two survey periods (2017 and 2021) to answer the following questions: to what extent have residents from metropolitan Phoenix made different vegetation changes in their yards over the last decade, and how do multi-scalar human drivers affect different vegetation changes? We found a sustainable trajectory for residential vegetation changes in Phoenix since mid-2010s, with declining additions of grass and increases in trees and desert plants across residential neighborhoods. Esthetics was an influential driver of both tree planting and native gardening. Additionally, tree planting was associated with anthropocentric values (i.e., low-maintenance needs), while desert plant additions reflected the appreciation of nature (i.e., attitudes towards the desert) and environmental concerns (i.e., supporting wildlife). Institutions such as local government programs might shape residents' vegetation choices, as tree planting differed among municipalities. We also found counterintuitive influences of residential tenure controls on landscaping decisions. Specifically, renters were more likely to add yard trees compared to homeowners. Our results inform landscape sustainability by identifying potential pathways to residential yard changes that offer a multitude of services while being appreciated and maintained by residents. [ABSTRACT FROM AUTHOR]

The eastern part of the Benoue River bank is undergoing degradation marked by a significant decrease in vegetation cover and woody resources due to anthropogenic activities and climatic. The main objective of this study is to analyze the farmers' knowledge of vegetation evolution and the dynamics of land use using satellite images in the east of the bank of the Benoue. The methodological approach used is an integrated one combining field surveys, remote sensing, mapping, and modeling. The results obtained show that 88% of the population surveyed believe that the area covered by vegetation has decreased. The reasons for this decrease are numerous, but the main one remains the strong anthropic activity that would be at the origin of the progressive degradation of the land. The evolutionary trend of plant formations is essentially regressive for natural formations from 1991 to 2021. The analysis of the evolution of land use showed that in the Rey-Bouba district during 1991, 58.24% of the area formerly made up of dense woody formations regressed considerably to 25.77% in 2021. The same is true for the Bibemi district where the area of wooded zone has decreased from 65.47% in 1991 to 28.45% of the total area in 2021. This regression of the surface area of wooded formations was done to the benefit of anthropized occupation classes whose area has increased. They suggest an effective awareness in the monitoring of the dynamics of the vegetation cover subjected to anthropic pressures and climatic variations for a better-integrated management of the vegetation of this area. [ABSTRACT FROM AUTHOR]

Subarctic ecosystems are subjected to increasing nitrogen (N) enrichment and disturbances that induce particularly strong effects on plant communities when occurring in combination. There is little experimental evidence on the longevity of these effects. We applied N-fertilization (40 kg urea-N ha−1 year−1 for 4 years) and disturbance (removal of vegetation and organic soil layer on one occasion) in two plant communities in a subarctic forest-tundra ecotone in northern Finland. Within the first four years, N-fertilization and disturbance increased the share of deciduous dwarf shrubs and graminoids at the expense of evergreen dwarf shrubs. Individual treatments intensified the other's effect resulting in the strongest increase in graminoids under combined N-fertilization and disturbance. The re-analysis of the plant communities 15 years after cessation of N-fertilization showed an even higher share of graminoids. 18 years after disturbance, the total vascular plant abundance was still substantially lower and the share of graminoids higher. At the same point, the plant community composition was the same under disturbance as under combined N-fertilization and disturbance, indicating that multiple perturbations no longer reinforced the other's effect. Yet, complex interactions between N-fertilization and disturbance were still detected in the soil. We found higher organic N under disturbance and lower microbial N under combined N-fertilization and disturbance, which suggests a lower bioavailability of N sources for soil microorganisms. Our findings support that the effects of enhanced nutrients and disturbance on subarctic vegetation persist over decadal timescales. However, they also highlight the complexity of plant–soil interactions that drive subarctic ecosystem responses to multiple perturbations across varying timescales. [ABSTRACT FROM AUTHOR]

The rapid urbanization observed in various regions worldwide has led to the transformation of agricultural, forest, and green spaces into grey areas. The expansion of these grey areas contributes to heat wave events and an overall increase of average temperatures in specific regions due to their high reflectance properties. This study focuses on analyzing the heat island phenomenon resulting from urban growth and vegetation change over the past 30 years (1990–2020) in three key districts, namely Sheikhupura, Chiniot, and Pakpattan, located in the Punjab province. Landsat data is utilized to assess the urban heat island (UHI) effect caused by land cover changes in these regions. The maximum likelihood classification method is employed to classify remote sensing data, enabling the identification of heat islands based on surface emissivity. The UHI has main influence on built-up land areas therefore, to forecast future scenarios of LULC and their impact on LST, the study employs cellular automata (CA) modeling and incorporates several spatial variables to predict LULC for the year 2050. Four primary land cover classes, namely vegetation including cropland, built-up, water, and barren land, are utilized to examine temperature differences across different land cover types, aiming to understand the impact of land cover changes on temperature patterns. The findings also indicate that barren land and urban areas exhibit the highest thermal reflectivity, contributing significantly to increased surface temperatures. Over the past three decades, the surface temperature has risen by 1.65 °C in Chiniot, 0.86 °C in Sheikhupura, and experienced a slight decrease of – 0.04 °C in Pakpattan. The temperature decrease in Pakpattan can be attributed to a substantial reduction in barren land, which has been converted into agricultural and urban areas. This indicates a negative correlation between land surface temperature (LST) and vegetation cover. The changes in land use and land cover (LULC) in the study area are found to be relatively insignificant. [ABSTRACT FROM AUTHOR]

The succession process in terms of species composition and stand structure was directly tracked for 10 years in permanent plots of five Korean cool-temperate forests having different stand ages and topography: Pinus-Quercus forest (PQ), Quercus-Tilia forest (QT), Broadleaved-Abies mixed forest (BA), Populus-Salix forest (PS), and subalpine forest (SA). Although the 10-year change in mature forests was small, succession was detected by applying the pre-developed climax index. The species composition based on the climax index implied that PQ is at pioneer stage, QT and PS are at intermediate stage, while BA and SA are at the late-successional stage. The stems were regulated in a density-dependent manner; severer in forests such as PQ and QT with high initial densities, and severer in the dense mid-story than in the upper-story. Consequently, the basal area increased in the upper-story and decreased in the mid-story. As the abundance of species with higher climax index increased, succession exhibited a progressive direction. However, SA suffered chronic disturbances, and showed fluctuations. During the study, BA and PS were also damaged but they were resilient to site-related natural disturbances. Our findings through a 10-year permanent-plot study may have meaningful implications for explaining mature forest succession in other regions of Korea. [ABSTRACT FROM AUTHOR]

Vegetation is an essential component of terrestrial ecosystems, influenced by climate change and human activities. Quantifying the relative contributions of climate change and human activities to vegetation dynamics is crucial for addressing global climate change. Sichuan Province is one of the essential ecological functional areas in the upper reaches of the Yangtze River, and its vegetation change is of great significance to the environmental function and ecological security of the Yangtze River Basin and southwest China. In this paper, the modified Carnegie-Ames-Stanford Approach(CASA) model was used to estimate the monthly NPP (Net Primary Productivity) of vegetation in Sichuan Province from 2000 to 2018, and the univariate linear regression analysis was used to analyze the temporal and spatial variation of vegetation NPP in Sichuan Province from 2000 to 2018. In addition, taking vegetation NPP as an index, Pearson correlation analysis, partial correlation analysis, and second-order partial correlation analysis were carried out to quantitatively analyze the contribution of climate change and human activities to vegetation NPP. Finally, the Hurst index and nonparametric Man-Kendall significance test were used to predict the future change trend of vegetation NPP in Sichuan Province. The results show that (1) from 2000 to 2018, the NPP of vegetation in Sichuan Province has a significant increasing trend (Slope = 6.09gC·m−2·a−1), with a multi-year average of 438.72 gC·m−2·a−1, showing a trend of low in the east and high in the middle. The response of vegetation NPP to altitude is different at different elevations; (2) the contribution rates of climate change and human activities to vegetation NPP change are 4.12gC·m−2·a−1 and 1.97gC·m−2·a−1, respectively. In contrast, the impact of human activities on NPP is more significant than climate change. Human activities are the main factors affecting vegetation restoration and degradation in Sichuan Province. However, the positive contribution to NPP change is less than climate change; (3) the future vegetation NPP change trend in Sichuan Province is mainly rising, and the same direction change trend is much larger than the reverse change trend. The areas with an increasing trend in the future account for 89.187% of the total area. This research helps understand the impact of climate change and human activities on vegetation change in Sichuan Province. It offers scientific bases for vegetation restoration and ecosystem management in Sichuan and the surrounding areas. [ABSTRACT FROM AUTHOR]

Investigating the dynamics of vegetation is an essential basis to know how to protect ecological environments and to help predict any changes in trend. Because of its fragile alpine ecosystem, the Tibetan Plateau is a particularly suitable area for studying vegetation changes and their driving factors. In this study, we present a high-resolution pollen record covering the last two centuries extracted from Gongzhu Co on the western Tibetan Plateau. Alpine steppe is the predominant vegetation type in the surrounding area throughout the past 250 years with stable vegetation composition and abundance, as revealed by pollen spectra dominated by Artemisia, Ranunculaceae, Cyperaceae, and Poaceae. Detrended canonical correspondence analysis (DCCA) of the pollen data reveals low turnover in compositional species (0.41 SD), suggesting that the vegetation in the Gongzhu catchment had no significant temporal change, despite climate change and population increases in recent decades. We additionally ran DCCA on ten other pollen records from the Tibetan Plateau with high temporal resolution (1–20 years) covering recent centuries, and the results also show that compositional species turnover (0.15–0.81 SD) is relatively low, suggesting that the vegetation stability may have prevailed across the Tibetan Plateau during recent centuries. More high-resolution pollen records and high taxonomic-resolution palaeo-vegetation records (such as sedaDNA), however, are needed to confirm the vegetation stability on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Reconstructing the Holocene megaflood history is a key component of understanding the mechanism of past climate change and assessing the potential impact of future catastrophic events. The Pearl River is the longest watercourse in southern China, and its lower reach has been identified as one of the world's most vulnerable regions for flood exposure. However, there is a complete lack of millennial-scale geological records of paleomegafloods for the future prediction of once-in-a-hundred (even once-in-a-thousand) year floods in southern China. Here, we identified a series of paleomegaflood deposits interbedded with wood-rich peat layers in the lower West Pearl River area. All paleoflood layers have been well dated using AMS 14C dating method. According to the regional correlation of the flood sequence, sediment characteristics and provenance analysis, there have been at least 7 megafloods corresponding to once-in-a-thousand-year events in the lower reaches of the West Pearl River during the past 6000 years, with an average return period of approximately 855 years. The identified paleomegafloods were coeval with periods of strong El Niño-Southern Oscillation (ENSO), indicating that weakening of the Asian summer monsoon, associated with enhanced ENSO variability, may have triggered abnormally high precipitation leading to flooding of exceptional magnitude in southern China. In addition, the most prominent paleomegafloods identified in the lower Pearl River coincided with intervals of lower precipitation and fewer storms in central-eastern China, indicating the intensification of the meridional "tripole" pattern of precipitation across eastern China during the latter half of the Holocene. Increased land use and deforestation over the last 2000 years have resulted in soil loss and rapid degradation of local primeval forest ecosystems, leading to more catastrophic flooding. Large amounts of rice pollen in the uppermost flood layer during the Song Dynasty indicate that this megaflood may have inundated a large area of cultivated land. The periodic occurrence of Holocene megafloods not only caused damage to human existence, but also affected the evolution of local civilization. This study reveals for the first time a series of Holocene millennial-scale megafloods and sheds new light on the importance of atmosphere-ocean interactions in the tropical Pacific and monsoon subtropical climate dynamics for precipitation anomalies in East Asia. Our data yield valuable information for future research into climate extremes and hazard prevention. [ABSTRACT FROM AUTHOR]

This paper assessed the expansion of land use and land cover that occurred in Oyo State, Southwestern Nigeria, over a period of thirty-year. This was to assess urban expansion, landuse dynamics and their effects on land surface temperature in the area. The study used four multi-date imageries of the area. Landsat 7 ETM + , 1990, 2000, 2012, and Landsat 8 OLI/TIR, 2021 were collected from the United States Geological Survey (USGS) website were used. The ArcGIS 10.1 environment was utilised to clip the area of interest, and ERDAS Imagine remote sensing software was employed to efficiently improve and categorise the images. The images were then divided into five major: cultivation, built-up area, vegetation, water body, and bare soil using a maximum likelihood supervised classification algorithm. These categories were then utilised to conduct time series analysis or change detection analysis. Results of this study revealed that the built-up area has changed over the preceding three decades because of urban expansion. The built-up area increased from 19.83 km2 to 35.67 km2 in 2012 and 44.84 km2 in 2021, indicating increases of 14.93% to 79.87% and 25.71%, respectively, whereas the vegetative land cover decreased from -0.11% to -3.01 48% and 12.75% during the study period. Findings revealed that anthropogenic factors including urbanisation and agricultural expansion, have significantly altered the surface and atmospheric characteristics of the study area, causing a variety of heat patterns within the area. The built-up area had average temperatures between 35.05 °C and 36.16 °C between 1990 and 2021, which indicated a higher temperature with evidence of an urban heat island. This study concludes that the city's land surface temperature is rising and that the expanding built-up area's density and a corresponding decline in vegetation over time significantly impact it. Therefore, the study suggests cultivating and maintaining trees, promoting green environment,, public awareness, campaigns and education on actions that aggravate high temperatures are also required. [ABSTRACT FROM AUTHOR]

Quantifying the contributions of climate change (CC) and human activities (HA) to streamflow alteration is significant for effective water resources management. However, numerous studies fail to differentiate the individual impacts of various HA on streamflow. In this study, a comprehensive streamflow attribution framework that incorporates climate, vegetation, and water withdrawal (WW) was proposed. In this framework, traditional streamflow attribution methods such as statistical analysis (Double Mass Curve and Slope Change Ratio of Accumulative Quantity), elasticity (Budyko), and modeling simulation (Variable Infiltration Capacity and Long Short-term Memory) are employed to separate the influence of meteorological factors (MF) on streamflow. Subsequently, the impacts of WW on streamflow are assessed using global WW data. The Residual Analysis method is utilized to quantify the effects of vegetation alteration caused by both CC (Lcc) and HA (Lha) on streamflow alteration. To demonstrate the applicability of our proposed framework, two stations, Xianyang and Huaxian, located within the Weihe River Basin in Northwest China were selected as the case study area. The results demonstrated that compared to the baseline period (1961–1990), the average contributions of MF, Lcc, Lha, and WW to streamflow reduction during the variation periods (1991–2019) were as follows: for the Xianyang station, 26.0%, 13.5%, 30.9%, and 29.6% respectively; and for the Huaxian station, 28.9%, 5.5%, 17.7%, and 47.9% respectively. Additionally, during the variation periods, the contributions of CC and HA to vegetation variation were 30.5% and 69.5% respectively in Xianyang, and 23.7% and 76.3% respectively in Huaxian. The framework developed herein also provides a solution for quantifying the indirect effects of CC on streamflow through vegetation. [ABSTRACT FROM AUTHOR]

Vegetation is an important indicator of global climate change and an indispensable natural resource in the human living environment. This study used trend analysis to examine the spatial and temporal changes in the vegetation in East Africa, and then used coefficient of variation method and partial correlation analysis to investigate the effects of climate change and human activity on regional vegetation changes. The findings indicated that vegetation in East Africa exhibited an increasing spatial trend from north to south and that NDVI changes from 2001 to 2021 generally showed a weak upwards trend; however, 2005 was a significant year in the NDVI time series, and the NDVI fluctuations increased. Whereas the surface temperature showed varying degrees of the opposite tendency during the 21 years, the changes in vegetation and precipitation in East Africa were essentially coordinated, both indicating a fluctuating increasing trend. In East Africa, both surface mean temperature and precipitation had a significant impact on the NDVI, with precipitation having a marginally stronger impact than surface mean temperature. The partial correlations between the NDVI and surface temperature and precipitation were strongest in the RS2 (October to December) and DS1 (January to February) seasons, respectively. The results of the study provide a valuable reference for the future development of vegetation in East Africa. [ABSTRACT FROM AUTHOR]

Resilience of plant communities to disturbance is supported by multiple mechanisms, including ecological legacies affecting propagule availability, species' environmental tolerances, and biotic interactions. Understanding the relative importance of these mechanisms for plant community resilience supports predictions of where and how resilience will be altered with disturbance. We tested mechanisms underlying resilience of forests dominated by black spruce (Picea mariana) to fire disturbance across a heterogeneous forest landscape in the Northwest Territories, Canada. We combined surveys of naturally regenerating seedlings at 219 burned plots with experimental manipulations of ecological legacies via seed addition of four tree species and vertebrate exclosures to limit granivory and herbivory at 30 plots varying in moisture and fire severity. Black spruce recovery was greatest where it dominated pre-fire, at wet sites with deep residual soil organic layers, and fire conditions of low soil or canopy combustion and longer return intervals. Experimental addition of seed indicated all species were seed-limited, emphasizing the importance of propagule legacies. Black spruce and birch (Betula papyrifera) recruitment were enhanced with vertebrate exclusion. Our combination of observational and experimental studies demonstrates black spruce is vulnerable to effects of increased fire activity that erode ecological legacies. Moreover, black spruce relies on wet areas with deep soil organic layers where other species are less competitive. However, other species can colonize these areas if enough seed is available or soil moisture is altered by climate change. Testing mechanisms underlying species' resilience to disturbance aids predictions of where vegetation will transform with effects of climate change. [ABSTRACT FROM AUTHOR]

Island avifauna suffer high rates of extinction and decline. North Island in the Houtman Abrolhos Archipelago, Western Australia, supports one of three populations of the Abrolhos Painted Button-quail (Turnix varius scintillans), a subspecies determined to be the 5th most likely taxon to become extinct in Australia. T. v. scintillans were last recorded on North Island in 2006. Vegetation declines on North Island due to introduced tammar wallabies (Notamacropus eugenii derbianus) and predation by introduced house mice (Mus musculus) are implicated as major threats. Between 2018 and 2021, 12,820 camera trap-nights on North Island failed to detect any signs of T. v. scintillans, suggesting local extinction. We deployed rodent chew cards at each camera site and analysed rainfall and vegetation cover data to identify potential causes of decline. Vegetation cover change was related to tammar wallaby density and was highly correlated with rainfall (r2 = 0.75). At the time of the last button-quail sighting in 2006, tammar wallaby numbers were at their peak, and annual rainfall was near its lowest level. Introduced tammar wallabies and house mice in tandem with reduced rainfall have likely resulted in degradation of habitat critical for T. v. scintillans, which is now confined to just two islands. Preventing further introductions of mice, rats and feral cats is a high priority for limiting further declines of this subspecies. [ABSTRACT FROM AUTHOR]

Vegetation change is of significant concern because it plays a crucial role in the global carbon cycle and climate. Many studies have examined recent changes in vegetation growth and the associated drivers. These drivers include both natural and human activities, but few studies have identified the regulation factors. By employing normalized difference vegetation index (NDVI) data, we analyzed the spatiotemporal pattern of vegetation change in China and then explored the driving factors. It was found that the overall greening of China has improved significantly, especially in the Loess Plateau and southwest China. The Yangtze River Delta and Bohai Rim, however, have not seen as much growth. Natural conditions are conducive to vegetation growth. Although socioeconomic development will be more beneficial for vegetation restoration, the current level and speed of development have a negative effect on vegetation. The regulation factors are considered separately since they affect both directly and indirectly. Regulation factors have accelerated vegetation growth. By understanding the factors affecting the current vegetation growth, we can provide a guide for future vegetation recovery in China and other similar countries. [ABSTRACT FROM AUTHOR]

The study presents a GIS- and RS-based diagnostic model to determine the changes in the existing vegetation in the Urla, Çeşme, and Karaburun peninsulas, Turkey, between 2002 and 2017 after the installation of 239 wind power plants (WPP). The vegetation changes in 7 CORINE land cover classes within the 0–1 km (facility zone) and 1–2 km (control zone) buffer zones were detected in relation with the slope and aspect groups using NDVI analysis. The highest amount of negative change in broad-leaved forests, coniferous forests, and land principally occupied by agriculture, with significant areas of natural vegetation, was detected in the 3–5% slope group, while pasture lands, sclerophyllous vegetation and transitional woodland-shrubs showed the highest degradation in 1–2% slope areas. Negative changes in complex cultivation patterns were found to be on the flat surfaces. Except for the pasture lands and sclerophyllous vegetation classes, the highest degradations were observed on north-facing aspects. In all land cover classes, the most degraded areas were found to be within the facility zone. The results and the proposed model are expected to facilitate planning and decision-making processes for locations with similar landscape characteristics. [ABSTRACT FROM AUTHOR]

Deforestation and fragmentation threaten biodiversity owing to their impacts on many species. To prevent and minimise the problem, protected areas have been created with the aim of conserving biodiversity, and parts of continental territories have been designated for this purpose. However, these areas are not exempt from forest loss and can be directly and indirectly disturbed by surrounding territories, natural disasters, climate, and human actions. In addition, the management quality of many protected areas is unknown. Thus, forest change detection using remote sensing data has been implemented as an approach to assess forest loss in conservation areas, since it generates spatio-temporal information about the protected forest area, which can then be used to improve forest management and decision making. This article reviews the approaches that have been implemented to study forest changes in protected areas. [ABSTRACT FROM AUTHOR]

We investigated recent changes in spatial patterning of fen and bog zones in five boreal aapa mire complexes (mixed peatlands with patterned fen and bog parts) in a multiproxy study. Comparison of old (1940–1970s) and new aerial images revealed decrease of flarks (wet hollows) in patterned fens by 33–63% in middle boreal and 16–42% in northern boreal sites, as lawns of bog Sphagnum mosses expanded over fens. Peat core transects across transformed areas were used to verify the remote sensing inference with stratigraphic analyses of macrofossils, hyperspectral imaging, and age-depth profiles derived from 14C AMS dating and pine pollen density. The transect data revealed that the changes observed by remote sensing during past decades originated already from the end of the Little Ice Age (LIA) between 1700–1850 CE in bog zones and later in the flarks of fen zones. The average lateral expansion rate of bogs over fen zones was 0.77 m y−1 (range 0.19–1.66) as estimated by remote sensing, and 0.71 m y−1 (range 0.13–1.76) based on peat transects. The contemporary plant communities conformed to the macrofossil communities, and distinct vegetation zones were recognized as representing recently changed areas. The fen-bog transition increased the apparent carbon accumulation, but it can potentially threaten fen species and habitats. These observations indicate that rapid lateral bog expansion over aapa mires may be in progress, but more research is needed to reveal if ongoing fen-bog transitions are a commonplace phenomenon in northern mires. [ABSTRACT FROM AUTHOR]

Pollen, spores, and microscopic charcoal from the sediments of Grosssee (1,619 m a.s.l.), a small lake in the lower subalpine vegetation zone of the Glarus Alps, Switzerland, were analysed to reconstruct vegetation patterns and land use over the past ca. 12,300 calibrated 14C years bp (cal bp). Pollen data revealed an open landscape covered with grasses and herbs such as Artemisia during the Late Glacial Period. The catchment was likely initially afforested with Betula and Pinus cembra or Pinus sylvestris during the Early Holocene. Thermophilous taxa such as Ulmus, Tilia, and Alnus glutinosa-type expanded from ca. 11,000–9,200 cal bp, and mesophyllic Picea abies and Fagus sylvatica followed, and expanded beginning from ca. 8,000–7,600 cal bp. Interestingly, Alnus viridis (synonym: A. alnobetula) expanded about 2,000 years earlier than at comparable sites in the northern Swiss Alps. Its expansion was profound and persistent, and percentages > 15% were already achieved by ca. 7,000 cal bp. Local erosion events that followed are well explained by vegetation changes and inferred human land use activities at Grosssee. In particular, this led to a more open landscape, and land uses (e.g. grazing) intensified from the Mid- to Late Holocene. Indicators of environmental disturbance including persistently high levels of A. viridis, monolete fern spores, and microscopic charcoal were pronounced after ca. 4,000 cal bp. At that time, high influxes of spores from coprophilous fungi and the consistent presence of cultural indicators (Cerealia-type, Plantago lanceolata) indicate increased grazing and high levels of human impact. Land use and grazing activities seemed to have been particularly pronounced and to have promoted diversity in the vegetation over the past 1,000 years. [ABSTRACT FROM AUTHOR]

Climate and vegetation are important components of a changing environment that have synergistic effects on surface runoff. To date, few researchers have included the synergistic effects of changes in climate and vegetation in runoff simulation studies. In this study, a water-heat balance model based on the Budyko hypothesis was established, and an empirical formula for estimating model parameters based on the Normalized Difference Vegetation Index was proposed. This Normalized Difference Vegetation Index-climate relationship model allowed the synergistic effects of changes in climate and vegetation on runoff trends to be analyzed. The model was tested in the Fen River Basin, China. The results showed that the annual runoff would be 15.4%–39.5% (between 2020 and 2100) higher under two climate change scenarios than in the baseline period (2006–2015). Climate-driven change in the vegetation cover accounted for 8.0%–19.6% of the total variation in the runoff. The change in the vegetation cover inhibited the increase in runoff. To improve the accuracy of models and avoid overestimates, synergistic changes in vegetation and climate should be included in model simulations. [ABSTRACT FROM AUTHOR]

Naturalistic grazing by large herbivores is an increasingly practiced way of managing habitats with conservational value. It has the potential to restore and enhance biodiversity, creating self-sustainable environments vital for organisms requiring regular disturbances to moderate and/or reverse successional changes. European bison, Exmoor pony, and Tauros cattle were introduced in 2015 to a former military training area in Milovice, Czech Republic. The prevailing vegetation type is a forest-steppe savanna with Bromus erectus-dominated xeric grasslands mixed with deciduous shrubs and trees. After the cessation of military use, the area was abandoned which led to successional changes, including the dominance of tall grasses, litter accumulation, and bush encroachment. In 2017–2021, we monitored grassland vegetation in 30 grazed permanent plots (2 × 2 m) and 5 control plots representative of ungrazed, abandoned vegetation adjacent to the grazed areas. Naturalistic grazing increased species richness and the cover of forbs, while the cover of grasses and legumes was minimally affected. Grazing increased functional diversity of plant community, promoted a compositional change to small statured species and an increased incidence of red-list species. Seven years of continuous grazing increased the conservation value of this forest-steppe vegetation, a habitat type rapidly declining in Europe. [ABSTRACT FROM AUTHOR]

Vegetation plays an important role in the dry deposition of particles with significant spatial variability, but the magnitude remains unclear at the global scale. With the aid of satellite products, this study estimated the vegetation-related dry deposition of fine particulate matter (PM2.5). Methodologically, dry deposition was first calculated using an empirical algorithm. Then, deposition on the leaf surface was estimated to evaluate the influence of vegetation. Our results showed that the mean deposition velocity (Vd) of global PM2.5 was 0.91×10−3 µg·m−2·s−1, with high velocities observed in sparsely vegetated regions because of the high friction velocity. Under the combined effect of the PM2.5 mass concentration and deposition velocity, the global mean dry deposition reached 0.47 g·m−2·yr−1. Global vegetation absorbed 0.26 g·m−2·yr−1 from PM2.5 pollution sources, contributing 54.98% of the total dry deposition. Spatially, vegetation-related dry deposition was high in the Amazon, Central Africa and East China due to dense vegetation coverage or serious pollution. Temporally, the increasing trends were mainly in Central Africa and India because of worsening air pollution. The results of this study helped to clarify the impact of vegetation on air pollution, which supported related land management and planning for air quality improvement. [ABSTRACT FROM AUTHOR]

Understanding the impact of management interventions on the environment over decadal and longer timeframes is urgently required. Longitudinal or large-scale studies with consistent methods are best practice, but more commonly, small datasets with differing methods are used to achieve larger coverage. Changes in methods and interpretation affect our ability to understand data trends through time or across space, so an ability to understand and adjust for such discrepancies between datasets is important for applied ecologists. Calibration or double sampling is the key to unlocking the value from disparate datasets, allowing us to account for the differences between datasets while acknowledging the uncertainties. We use a case study of livestock grazing impacts on riparian vegetation in southeastern Australia to develop a flexible and powerful approach to this problem. Using double sampling, we estimated changes in vegetation attributes over a 12-year period using a pseudo-quantitative visual method as the starting point, and the same technique plus point-intercept survey for the second round. The disparate nature of the datasets produced uncertain estimates of change over time, but accounting for this uncertainty explicitly is precisely the objective and highlights the need to look more closely at this very common problem in environmental management, as well as the potential benefits of the double sampling approach. [ABSTRACT FROM AUTHOR]

The effects of sea level rise and coastal saltwater intrusion on wetland plants can extend well above the high-tide line due to drought, hurricanes, and groundwater intrusion. Research has examined how coastal salt marsh plant communities respond to increased flooding and salinity, but more inland coastal systems have received less attention. The aim of this study was to identify whether ground layer plants exhibit threshold responses to salinity exposure. We used two vegetation surveys throughout the Albemarle-Pamlico Peninsula (APP) of North Carolina, USA to assess vegetation in a low elevation landscape (≤ 3.8 m) experiencing high rates of sea level rise (3–4 mm/year). We examined the primary drivers of community composition change using Non-metric Multidimensional Scaling (NMDS) and used Threshold Indicator Taxa Analysis (TITAN) to detect thresholds of compositional change based on indicator taxa, in response to potential indicators of exposure to saltwater (Na, and the Σ Ca + Mg) and elevation. Salinity and elevation explained 64% of the variation in community composition, and we found two salinity thresholds for both soil Na+ (265 and 3843 g Na+/g) and Ca+ + Mg+ (42 and 126 µeq/g) where major changes in community composition occur on the APP. Similar sets of species showed sensitivity to these different metrics of salt exposure. Overall, our results showed that ground layer plants can be used as reliable indicators of salinity thresholds in coastal wetlands. These results can be used for monitoring salt exposure of ecosystems and for identifying areas at risk for undergoing future community shifts. [ABSTRACT FROM AUTHOR]

As the source of the Yellow River, Yangtze River, and Lancang River, the Three-River Source Region (TRSR) in China is very important to China's ecological security. In recent decades, TRSR's ecosystem has degraded because of climate change and human disturbances. Therefore, a range of ecological projects were initiated by Chinese government around 2000 to curb further degradation. Current research shows that the vegetation of the TRSR has been initially restored over the past two decades, but the respective contribution of ecological projects and climate change in vegetation restoration has not been clarified. Here, we used the Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) to assess the spatial-temporal variations in vegetation and explore the impact of climate and human actions on vegetation in TRSR during 2001–2018. The results showed that about 26.02% of the TRSR had a significant increase in EVI over the 18 yr, with an increasing rate of 0.010/10 yr (P < 0.05), and EVI significantly decreased in only 3.23% of the TRSR. Residual trend analysis indicated vegetation restoration was jointly promoted by climate and human actions, and the promotion of human actions was greater compared with that of climate, with relative contributions of 59.07% and 40.93%, respectively. However, the degradation of vegetation was mainly caused by human actions, with a relative contribution of 71.19%. Partial correlation analysis showed that vegetation was greatly affected by temperature (r = 0.62, P < 0.05) due to the relatively sufficient moisture but lower temperature in TRSR. Furthermore, the establishment of nature reserves and the implementation of the Ecological Protection and Restoration Program (EPRP) improved vegetation, and the first stage EPRP had a better effect on vegetation restoration than the second stage. Our findings identify the driving factors of vegetation change and lay the foundation for subsequent effective management. [ABSTRACT FROM AUTHOR]

The karst region of Southwest China is one of the largest in the world. Due to the effects of human activities and climate change, rocky desertification has become the primary ecological disaster which has significantly hindered the economic growth in Southwest China. In recent decades, the Chinese government has carried out a number of ecological restoration projects in Southwest China. This study aims to analyze the changes in vegetation coverage and its main driving factors in the Southwest China and the karst region of Southwest China from 2001 to 2015 through trend analysis, Hurst index correlation analysis, correlation analysis, and residual analysis. The results showed that (1) both Southwest China and the karst region of Southwest China experienced significant increasing trends in annual fractional vegetation cover, at a rate of 0.0028 year−1 and 0.0029 year−1, respectively; (2) the NDVI of the Southwest China and the karst region of Southwest China was stable, and the vegetation coverage areas showed low to medium fluctuations, accounting for 97.17% and 98.32% respectively; (3) the NDVI of the Southwest China and the karst region of Southwest China had strong sustainability, and the sustainable and improved regions account for 74.79% and 75.77% respectively; and (4) climate change had little influence on vegetation restoration, and human activities had a great influence on vegetation restoration. The relative contribution rates of human activities and climate change to vegetation NDVI changes in the Southwest China were 86% and 14%, respectively, and 90% and 10% in karst regions of Southwest China. Our findings contribute to a better understanding of the mechanisms of vegetation change in karst region and may provide scientific support for local vegetation restoration and conservation policies. [ABSTRACT FROM AUTHOR]

Context: Spatial patterns of vegetation change and fire severity are influenced by fire exclusion, topography and weather conditions during a fire. Since the late nineteenth century, fire exclusion has increased vegetation cover which could influence fire severity and post-fire vegetation composition. Objectives: We use field measurements and remote sensing of a 2011 wildfire to answer the following questions: (1) How did twentieth century vegetation change influence fire severity patterns? (2) What were the key drivers of wildfire severity? (3) Did initial post-fire development indicate stability or a shift in woody plant composition. Methods: Repeat aerial photography and pre and post fire field measurements were used to quantify twentieth century vegetation change and measure wildfire effects. Spatial controls on 2011 fire severity were determined using geospatial layers of vegetation type and change, topography, fire weather, daily fire extent, and fire severity. Results: Vegetation changes since 1935 increased area of closed woodlands and shrublands and the 2011 fire reversed this trend and increased heterogeneity of vegetation types. Vegetation in plots experienced a post-fire shift towards resprouting species. At the landscape scale, terrain and weather were the main variables controlling fire severity with modest contribution by vegetation type and areas with vegetation change since 1935. Conclusions: Our findings indicate that wildfire severity in this landscape is strongly influenced by weather and terrain and wildfires reverse the effects of fire exclusion. Using terrain based landscape compartments for prescribed and wildfire management would help maintain the heterogeneous effects of the 2011 fire into future. [ABSTRACT FROM AUTHOR]

Space technology offers effective tools to monitor the status of World Natural Heritage sites. East Rennell Island, which covers approximately 37,000 hectares (ha) and a marine area extending three nautical miles into the sea, was added to the list of endangered World Natural Heritage sites in 2013. Deforestation and natural disasters have increasingly threatened sustainable development on the island. Based on analyses of multi-source time series of remote sensing data (e.g., MODIS and Worldview), the forest cover change on Rennell Island from 2000 to 2020 and its future trends were mapped and analysed using Sen + Mann–Kendall and Hurst index models. A land cover classification system derived from high-resolution Worldview images was developed as a baseline for monitoring and analysing future forest cover changes on the island. Our results showed that (1) the areas of vegetation degradation and improvement were basically equal from 2000 to 2020. (2) The forest cover change trend had weak continuity, and significant improvements could be achieved in areas with damaged vegetation given sufficient protection measures and financial input. (3) This heritage site has a strong vegetation regeneration ability, and human activities such as mining, logging, and road construction, which could greatly disturb the unique ecosystem, should be restricted. [ABSTRACT FROM AUTHOR]

It has been established that resurvey of historical vegetation stands, even those not marked permanently, could foster our understanding of vegetation dynamics and changes in structure and composition over time. However, such studies are poorly available, particularly in remote landscapes of the Indian Himalaya. There exists a complete lack of resurveys, which has limited our ability to provide reliable evidence of changes over the decades. This study, for the first time in the Indian Himalaya, considered repeat surveys (nearly after 25 years) of vegetation stands in eleven forest communities of the buffer zone of NDBR (Nanda Devi Biosphere Reserve). Thirty historical forest stands, earlier studied in 1988–1990, were revisited during 2012–2014 and investigated using the same survey methods as used in the previous study. We found that previously reported dominant tree species, i.e., Alnus nepalensis, Acer cappadocicum, Quercus floribunda, Quercus semecarpifolia, Hippophae salicifolia, and Betula utilis, in nine out of eleven communities in the study area are continuing to exhibit dominance in the community. However, a significant increase in species richness and density in the seedling and sapling layer in Quercus floribunda, Quercus semecarpifolia, Rhododendron arboreum, and Abies pindrow is indicative of the ongoing process of change in forest composition. The compositional features of plant communities, when analyzed through Community Change Sensitivity (CCS) approach, identified Quercus floribunda, mixed Quercus—deciduous spp., Hippophae salicifolia, and Abies pindrow as the most change-sensitive communities in the study area and thus can be prioritized as the long-term ecological monitoring sites in the west Himalaya to understand intensity and patterns of changes. The potential changes based on the ecological information from two time period compositional data sets, having conservation and management implications, should be accommodated in the long-term perspective plans of the reserve. [ABSTRACT FROM AUTHOR]

Chaparral shrubs in southern California may be vulnerable to frequent fire and severe drought. Drought may diminish postfire recovery or worsen impact of short-interval fires. Field-based studies have not shown the extent and magnitude of drought effects on recovery, which may vary among chaparral types and climatic zones. We tracked regional patterns of shrub cover based on June-solstice Landsat Normalized Difference Vegetation Index series, compared between the periods 1984–1989 and 2014–2018. High spatial resolution ortho-imagery was used to map shrub cover in distributed sample plots, to empirically constrain the Landsat-based estimates of mature-stage lateral canopy recovery. We evaluated precipitation, climatic water deficit (CWD), and Palmer Drought Severity Index in summer and wet seasons preceding and following fire, as regional predictors of recovery in 982 locations between the Pacific Coast and inland deserts. Wet-season CWD was the strongest drought-metric predictor of recovery, contributing 34–43% of explanatory power in multivariate regressions (R2 = 0.16–0.42). Limited recovery linked to drought was most prevalent in transmontane chamise chaparral; impacts were minor in montane areas, and in mixed and montane chaparral types. Elevation was correlated negatively to recovery of transmontane chamise; this may imply acute drought sensitivity in resprouts which predominate seedlings at higher elevations. Landsat Visible Atmospherically Resistant Index (sensitive to live-fuel moisture) was evaluated as a landscape-scale predictor of recovery and explained the greatest amount of variance in a multivariate regression (R2 = 0.53). We find that drought severity was more closely related to recovery differences among twice-burned sites than was fire-return interval. Summarily, drought has a major role in long-term shrub cover reduction within xeric chaparral ecotones bounding the Mojave Desert and Colorado Desert, likely in tandem with other global change stressors. [ABSTRACT FROM AUTHOR]

The process of urbanization is the most important human activity since the twentieth century. Due to the unique environmental problems brought about by urbanization, urban heat islands not only affect regional economic development and regional climate but also bring comfort to urban residents and energy consumption. The negative impact is obvious, so the study of urban heat island effect is very important to monitor regional and even global climate change and guide urban development plans. First of all, this paper takes the coastal megacities along the Belt and Road as the research object, based on MODIS surface temperature products and Landsat land use classification data, and uses urban heat island intensity as an indicator to analyze the heat islands of 10 megacities from an interannual and seasonal perspective from 2004 to 2020. The effect of the spatio-temporal pattern changes; then, taking a city as an example, based on Landsat land use classification data, RS and GIS technology is used to analyze the land use cover change and urban expansion of a city in the past 30 years; finally, according to Landsat surface temperature data and land using classified data, the impact of land use and cover characteristics on urban heat islands in a city was investigated. Outdoor sports organizations and operators in SD coastal cities found that the outdoor sports organizations and operators in SD coastal cities did not make full use of the geographical environment, economic development, and cultural environment of coastal cities and fully analyzed the comprehensive and systematic problems in the organization and management of outdoor sports, so that outdoor sports organizations and operators in SD coastal cities can give full play to their advantages. Through this research, we will promote a more comprehensive understanding of the healthy and sustainable development of outdoor sports and promote the organization and development of outdoor sports. Management research provides a theoretical basis. [ABSTRACT FROM AUTHOR]

Meteorological conditions have an important impact on changes of vegetation in ecologically fragile karst areas. This study aims to explore a method for quantitative evaluation of these meteorological conditions. We analyzed the changing trend of vegetation during 2000–2018 and the correlations between vegetation changes and various meteorological factors in karst rocky areas of Guangxi Zhuang Autonomous Region, China. Key meteorological factors in vegetation areas with varying degrees of improvement were selected and evaluated at seasonal timescale. A quantitative evaluation model of comprehensive influences of meteorological factors on vegetation was built by using the partial least-square regression (PLS). About 91.45% of the vegetation tended to be improved, while only the rest 8.55% showed a trend of degradation from 2000 to 2018. Areas with evident vegetation improvement were mainly distributed in the middle and northeast, and those with obvious vegetation degradation were scattered. Meteorological factors affecting vegetation were significantly different among the four seasons. Overall, high air humidity, small temperature difference in spring and autumn, and low daily minimum temperature and air pressure were favorable conditions. Low temperature in winter as well as high temperature in summer and autumn were unfavorable conditions. The Climate Vegetation Index (CVI) model was established by PLS using the maximum, minimum, and average temperatures; vapor pressure; rainfall; and air pressure as key meteorological factors. The Enhanced Vegetation Index (EVI) was well fitted by the CVI model, with the average coefficient of determination (r2) and root mean square error (RMSE) of 0.856 and 0.042, respectively. Finally, an assessment model of comprehensive meteorological conditions was built based on the interannual differences in CVI. The meteorological conditions in the study area in 2014 were successfully evaluated by combining the model and selected seasonal key meteorological factors. [ABSTRACT FROM AUTHOR]

Managed wildfire is an increasingly relevant management option to restore variability in vegetation structure within fire-suppressed montane forests in western North America. Managed wildfire often reduces tree cover and density, potentially leading to increases in soil moisture availability, water storage in soils and groundwater, and streamflow. However, the potential hydrologic impacts of managed wildfire in montane watersheds remain uncertain and are likely context dependent. Here, we characterize the response of vegetation and soil moisture to 47 years (1971–2018) of managed wildfire in Sugarloaf Creek Basin (SCB) in Sequoia-Kings Canyon National Park in the Sierra Nevada, California, USA, using repeat plot measurements, remote sensing of vegetation, and a combination of continuous in situ and episodic spatially distributed soil moisture measurements. We find that, by comparison to a nearby watershed with higher vegetation productivity and greater fire frequency, the managed wildfire regime at SCB caused relatively little change in dominant vegetation over the 47 year period and relatively little response of soil moisture. Fire occurrence was limited to drier mixed-conifer sites; fire-caused overstory tree mortality patches were generally less than 10 ha, and fires had little effect on removing mid- and lower strata trees. Few dense meadow areas were created by fire, with most forest conversion leading to sparse meadow and shrub areas, which had similar soil moisture profiles to nearby mixed-conifer vegetation. Future fires in SCB could be managed to encourage greater tree mortality adjacent to wetlands to increase soil moisture, although the potential hydrologic benefits of the program in drier basins such as this one may be limited. [ABSTRACT FROM AUTHOR]

Accurate information on the location and magnitude of vegetation change in scenic areas can guide the configuration of tourism facilities and the formulation of vegetation protection measures. High spatial resolution remote sensing images can be used to detect subtle vegetation changes. The major objective of this study was to map and quantify forest vegetation changes in a national scenic location, the Purple Mountains of Nanjing, China, using multi-temporal cross-sensor high spatial resolution satellite images to identify the main drivers of the vegetation changes and provide a reference for sustainable management. We used Quickbird images acquired in 2004, IKONOS images acquired in 2009, and WorldView2 images acquired in 2015. Four pixel-based direct change detection methods including the normalized difference vegetation index difference method, multi-index integrated change analysis (MIICA), principal component analysis, and spectral gradient difference analysis were compared in terms of their change detection performances. Subsequently, the best pixel-based detection method in conjunction with object-oriented image analysis was used to extract subtle forest vegetation changes. An accuracy assessment using the stratified random sampling points was conducted to evaluate the performance of the change detection results. The results showed that the MIICA method was the best pixel-based change detection method. And the object-oriented MIICA with an overall accuracy of 0.907 and a kappa coefficient of 0.846 was superior to the pixel-based MIICA. From 2004 to 2009, areas of vegetation gain mainly occurred around the periphery of the study area, while areas of vegetation loss were observed in the interior and along the boundary of the study area due to construction activities, which contributed to 79% of the total area of vegetation loss. During 2009–2015, the greening initiatives around the construction areas increased the forest vegetation coverage, accounting for 84% of the total area of vegetation gain. In spite of this, vegetation loss occurred in the interior of the Purple Mountains due to infrastructure development that caused conversion from vegetation to impervious areas. We recommend that: (1) a local multi-agency team inspect and assess law enforcement regarding natural resource utilization; and (2) strengthen environmental awareness education. [ABSTRACT FROM AUTHOR]

Knowledge of historical changes in moisture within semi-arid and arid regions is the basis of climatic change predictions and strategies in response to long-term drought. In this study, a multiproxy peat record with high-resolution from Sichanghu in the northern Tianshan was used to document the changes in vegetation and climate over the past 450 years in the arid Central Asia. The pollen, grain size, and loss on ignition (LOI) records indicate that the productivity of local peat began to increase at ∼1730 AD. The vegetation in the Sichanghu area experienced several transitions, from temperate desert to dense desert, marsh meadow, and steppe desert vegetation. The climate in the study area was extremely dry during the early stages of the Little Ice Age (LIA) (before 1730 AD) and relatively wet during the late stages (1730–1880 AD). The inferred changes in the moisture conditions of the Sichanghu peatland since the LIA may have been controlled by the extent of Arctic sea ice, the North Atlantic Oscillation, and the Siberian High via the connections of large-scale atmospheric circulations such as the Westerlies. [ABSTRACT FROM AUTHOR]

Knowledge of long-term change in vegetation and climate in semi-arid/arid regions is essential for the study of current climate and development of mitigation strategies against severe drought. Here, a fossil pollen record of annually-varved core from Sugan Lake in interior Qaidam Basin was quantitatively analyzed to reconstruct changes in vegetation, floristic diversity and drought frequency. Results of biomization suggested that regional vegetation was desert vegetation with three short-term occupations of temperate steppe/xerophytic shrub during the last 2700 years. Floristic diversity generally increased/decreased with the expansion/degradation of desert vegetation. Moisture fluctuations showed three distinct stages (extremely dry between 742BC and ∼AD500, relatively wet with an increasing trend between ∼AD500 and 1200 and relatively wet with frequent fluctuations after AD1200), interrupted by 14 drought events. Spectral analysis and continuous wavelet transform of moisture variation revealed 200- and 120-year cycles. According to cross-wavelet transform analysis, major drought frequency of ∼200-year was explicitly correlated to solar activity. It's suggested that the centennial-scale drought frequency was mainly driven by solar activity, through modulation of large-scale atmospheric circulation. Furthermore, the effect of surface temperature-evaporation and uplifting/subsiding air flow should be notable. The climatic drought in interior Qaidam Basin could be intensified under the continuous global warming. [ABSTRACT FROM AUTHOR]

Changes in Arctic vegetation can have important implications for trophic interactions and ecosystem functioning leading to climate feedbacks. Plot-based vegetation surveys provide detailed insight into vegetation changes at sites around the Arctic and improve our ability to predict the impacts of environmental change on tundra ecosystems. Here, we review studies of changes in plant community composition and phenology from both long-term monitoring and warming experiments in Arctic environments. We find that Arctic plant communities and species are generally sensitive to warming, but trends over a period of time are heterogeneous and complex and do not always mirror expectations based on responses to experimental manipulations. Our findings highlight the need for more geographically widespread, integrated, and comprehensive monitoring efforts that can better resolve the interacting effects of warming and other local and regional ecological factors. [ABSTRACT FROM AUTHOR]

Mangrove forest encroachment into coastal marsh habitats has been described in subtropical regions worldwide in recent decades. To better understand how soil processes may influence vegetation change, we studied soil surface elevation change, accretion rates, and soil subsurface change across a coastal salinity gradient in Florida, USA, an area with documented mangrove encroachment into saline marshes. Our aim was to identify if variations in the soil variables studied exist and to document any associated vegetation shifts. We used surface elevation tables and marker horizons to document the soil variables over 5 years in a mangrove-to-marsh transition zone or ecotone. Study sites were located in three marsh types (brackish, salt, and transition) and in riverine mangrove forests. Mangrove forest sites had significantly higher accretion rates than marsh sites and were the only locations where elevation gain occurred. Significant loss in surface elevation occurred at transition and salt marsh sites. Transition marshes, which had a significantly higher rate of shallow subsidence compared to other wetland types, appear to be most vulnerable to submergence or to a shift to mangrove forest. Submergence can result in herbaceous vegetation mortality and conversion to open water, with severe implications to the quantity and quality of wetland services provided. [ABSTRACT FROM AUTHOR]

Glacier recession is a globally occurring trend. Although a rich body of work has documented glacial response to climate warming, few studies have assessed vegetation cover change in recently deglaciated areas, especially using geospatial technologies. Here, vegetation change at two glacier forefronts in Glacier National Park, Montana, U.S.A. was quantified through remote sensing analysis, fieldwork validation, and statistical modeling. Specifically, we assessed the spatial and temporal patterns of landcover change at the two glacier forefronts in Glacier National Park and determined the role of selected biophysical terrain factors (elevation, slope, aspect, solar radiation, flow accumulation, topographic wetness index, and surficial geology) on vegetation change (from non-vegetated to vegetated cover) at the deglaciated areas. Landsat imagery of the study locations in 1991, 2003, and 2015 were classified and validated using visual interpretation. Model results revealed geographic differences in biophysical correlates of vegetation change between the study areas, suggesting that terrain variation is a key factor affecting spatial-temporal patterns of vegetation change. At Jackson Glacier forefront, increases in vegetation over some portion or all of the study period were negatively associated with elevation, slope angle, and consolidated bedrock. At Grinnell Glacier forefront, increases in vegetation associated negatively with elevation and positively with solar radiation. Integrated geospatial and field approaches to the study of vegetation change in recently deglaciated terrain are recommended to understand and monitor processes and patterns of ongoing habitat change in rapidly changing mountain environments. [ABSTRACT FROM AUTHOR]

Vegetation changes in the Poyang Lake wetland related to the construction of the Three Gorges Dam (TGD) and climate change have received increasing attention in recent decades. However, due to the high spatial heterogeneity, the changes in wetland vegetation have not been well quantified at a large spatial scale. We addressed this challenge by using Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2000 to 2012. Using a Mann-Kendall (MK) test, statistically significant decreasing trends were found in the Enhanced Vegetation Index (EVI) at the upper edge of the Poyang Lake wetland. In contrast, the vegetation distributed at lower elevations experienced a significant increasing trend during the study period. Downward boundaries of wetland vegetation in response to declining water levels could partially explain the increases in vegetation coverage. Vegetation colonized the non-vegetation area more quickly after the implementation of the TGD due to the earlier recession of the lake level during the recession period. Our findings suggested that hydrological changes caused by the lake decline might be the main factors driving the vegetation area changes. The information provided in this study is critical for future conservation and restoration efforts in the Poyang Lake wetland ecosystem. [ABSTRACT FROM AUTHOR]

This study investigates the palynological remains (both fossil pollen and charcoal) recovered from the Thundiy shell midden deposit, Bentinck Island, Gulf of Carpentaria, northern Australia, to provide a vegetation and fire record for this site, which sheds light on human occupation of the southern Wellesley Archipelago over the late Holocene. Results show that the development of a high-density shell deposit by human activities was directly responsible for pollen preservation, possibly through the creation of a moist, anaerobic environment that reduces oxidation of pollen grains. The presence of recoverable pollen from a shell midden deposit from Bentinck Island provides a valuable new proxy to provide greater context for archaeological records, particularly in terms of local vegetation information and potential insight into human land management practices. [ABSTRACT FROM AUTHOR]

In urban areas, the consistent and positive association between vegetation density and household income has been explained historically by either the capitalization of larger lawns and lower housing densities or landscaping and lifestyle districts that convey prestige. Yet cities with shrinking populations and rising land burdens often exhibit high vegetation density in declining neighborhoods. Because the observed associations do not directly address the causal connection between measures of social privilege and vegetation in urban landscapes, it is difficult to understand the forces that maintain them. Here, we compare patterns of household income with new measures derived from housing market data and other parcel-level sources—sale prices, tax foreclosures, new housing construction, demolitions, and the balance of construction and demolition. Our aim is to evaluate whether these spatially, temporally and semantically finer measures of neighborhood social conditions are better predictors of the distribution of urban vegetation. Furthermore, we examine how these relationships differ at two scales: within the City of Detroit and across the Detroit metropolitan area. We demonstrate, first, that linear relationships between income or home values and urban vegetation, though evident at broad metropolitan scales, do not explain recent variations in vegetation density within the City of Detroit. Second, we find that the real estate and demolition records demonstrate a stronger relationship with changes in vegetation density than corresponding changes in US Census measures like income, which suggests they hold at least as much interest for understanding how the relationships between biophysical changes and neighborhood change processes come about. [ABSTRACT FROM AUTHOR]

There has been regulatory concern over the appropriate length of time to monitor wetland sites restored or created as compensation for impacts permitted by a U.S. Clean Water Act permit. However there is very little longitudinal research on wetland compensation sites, and conclusions on compensation site development are usually drawn from the analysis of a chronosequence of sites of different ages. This approach has limitations, given the extent of changes in wetland compensation practices and performance standards over the past few decades. In this study we conducted vegetation surveys of 22 wetland compensation sites in a rapidly developing part of the Minneapolis-St. Paul metropolitan area in 1997 and 2010. We present data on changes over time in floristic richness and cover at the site level and at the level of wetland community type within each site. Our findings do not support the assumption that wetland compensation sites progress on a trajectory toward increasing diversity, floristic quality, or native cover over time. We find that, when data from all sites are considered together, emergent communities have suffered significant declines in both floristic quality and native plant cover, while wet meadow communities have gained species richness but not species diversity. There is some evidence that site richness and cover characteristics are converging toward a regional mean over time, as the species composition of wet meadows became significantly more similar over the survey period, and all community types have significant increases in woody cover. Our study suggests the importance of selecting appropriate compensation sites that avoid foreseeable hydrologic stresses, and does not support the position that 5 years of monitoring can assure the ongoing biotic integrity of wetland compensation sites. [ABSTRACT FROM AUTHOR]

Changes to vegetation structure and composition in forests adapted to frequent fire have been well documented. However, little is known about changes to the spatial characteristics of vegetation in these forests. Specifically, patch sizes and detailed information linking vegetation type to specific locations and growing conditions on the landscape are lacking. We used historical and recent aerial imagery to characterize historical vegetation patterns and assess contemporary change from those patterns. We created an orthorectified mosaic of aerial photographs from 1941 covering approximately 100,000 ha in the northern Sierra Nevada. The historical imagery, along with contemporary aerial imagery from 2005, was segmented into homogenous vegetation patches and classified into four relative cover classes using random forests analysis. A generalized linear mixed model was used to compare topographic associations of dense forest cover on the historical and contemporary landscapes. The amount of dense forest cover increased from 30 to 43% from 1941 to 2005, replacing moderate forest cover as the most dominant class. Concurrent with the increase in extent, the area-weighted mean patch size of dense forest cover increased tenfold, indicating greater continuity of dense forest cover and more homogenous vegetation patterns across the contemporary landscape. Historically, dense forest cover was rare on southwesterly aspects, but in the contemporary forest, it was common across a broad range of aspects. Despite the challenges of processing historical air photographs, the unique information they provide on landscape vegetation patterns makes them a valuable source of reference information for forests impacted by past management practices. [ABSTRACT FROM AUTHOR]

Long-term analyses of vegetation succession after catastrophic events are of high interest for an improved understanding of succession dynamics. However, in many studies such analyses were restricted to plot-based measurements. Contrarily, spatially continuous observations of succession dynamics over extended areas and time-periods are sparse. Here, we applied a change vector analysis (CVA) to investigate vegetation succession dynamics at Mount St. Helens after the great volcanic eruption in 1980 using Landsat. We additionally applied a supervised random forest classification using Sentinel-2 data to map the currently prevailing vegetation types. Change vector analysis was performed with the normalized difference vegetation index (NDVI) and the urban index (UI) for three subsequent decades after the eruption as well as for the whole observation time between 1984 and 2016. The influence of topography on the current vegetation distribution was examined by comparing altitude, slope angles and aspect values of vegetation classes derived by the random forest classification. Wilcox- Rank-Sum test was applied to test for significant differences between topographic properties of the vegetation classes inside and outside of the areas affected by the eruption. For the full time period, a total area of 516 km2 was identified as re-vegetated, whereas the area and magnitude of re-growing vegetation decreased during the three decades and migrated closer to the volcanic crater. Vegetation losses were mainly observed in regions unaffected by the eruption and related mostly to timber harvesting. The vegetation type classification reached a high overall accuracy of approximately 90%. 36 years after the eruption, coniferous and deciduous trees have established at formerly devastated areas dominating with a proportion of 66%, whereas shrubs are more abundant in riparian zones. Sparse vegetation dominates at regions very close to the crater. Elevation was found to have a great influence on the reestablishment and distribution of the vegetation classes within the devastated areas showing in almost all cases significant differences in altitude distribution. Slope was less important for the different classes - only representing significantly higher values for meadows, whereas aspect seems to have no notable influence on the reestablishment of vegetation at Mount St. Helens. We conclude that major vegetation succession dynamics after catastrophic events can be assessed and characterized over large areas from freely available remote sensing data and hence contribute to an improved understanding of succession dynamics. [ABSTRACT FROM AUTHOR]

Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38°C/10yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming. [ABSTRACT FROM AUTHOR]

To advance predictive ecology, the hypothesis of hierarchical predictability proposes that community measures for which species are interchangeable (e.g., structure and species richness) are more predictable than measures for which species identity matters (e.g., community composition). Predictability is hypothesized to decrease for response measures in order of the following categories: structure, species richness, function, and species composition. We tested this hypothesis using a 14-year, oak savanna–prairie restoration experiment that removed non-native pine plantations at 24 sites in northwestern Ohio, USA. Based on 24 response measures, the data showed minimal support for the hypothesis, because response measures varied in predictability within categories. Half of response measures had over half their variability modeled using fixed (restoration treatment and year) and random plot effects, and these “predictable” measures occurred in all four categories. Pine basal area, environment (e.g., soil texture), and antecedent vegetation accounted for over half the variation in change within the first three post-restoration years for 77% of response measures. Change between the 3rd and 14th years was less predictable, but most restoration measures increased favorably via sites achieving them in unique ways. We propose that variation will not conform with the hypothesis of hierarchical predictability in ecosystems with vegetation dynamics driven by stochastic processes such as seed dispersal, or where vegetation structure and species richness are influenced by species composition. The ability to predict a community measure may be more driven by the number of combinations of casual factors affecting a measure than by the number of values it can have. [ABSTRACT FROM AUTHOR]

Secondary forests account for a large amount of subtropical forest due to persistent anthropogenic disturbance in China. The interaction between vegetation and soil during recovery process is rather complex and dependent on forest conditions. Understanding how vegetation and soil properties changes and how their relationship develops in secondary forests is key to effective forest restoration and management. Here we explored the patterns of vegetation and soil properties as well as their correlations during forest recovery process in a subtropical forest in south China. Plots of three forest types, i.e., broadleaf-conifer mixed forest, broadleaved forest and old growth stand, were established to represent the recovery stages. The results showed that diversity patterns in the tree, shrub and herb layers were different: in the tree layer the species diversity peaked at the intermediate stage, while in the understory layers it decreased chronologically. Most of the soil factors showed an increasing trend, and different effects of soil factors were found for the three layers as well as for the two spatial scales. Together, our results suggested that vegetation and soil might be interdependent during the recovery course. Further studies are needed on exploring how vegetation interplays with soil at different scales and how nutrient limitations affects the vegetation development in a chronosequence. [ABSTRACT FROM AUTHOR]