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Pollen-based vegetation, biodiversity, and biome reconstructions over the last 15,500 years from sediment core data at Mbi Crater in the Cameroon highlands (6.089273° N, 10.348549° E; 2015 m above sea level) are used to discuss the behavior of the lower edge of the Afromontane forest facing climate change. The data reveal that the post-glacial forest change gradually happened at Mbi and that the forest-wooded grassland ecotone was highly influenced by the climate variability related to the North Atlantic. The forest disruption and diversity loss intermittently occurred over the whole period, and their vegetation changes temporally match dry-cold events at the northern latitudes during the Younger Dryas, at 9.5–9.1 ka, 8.6–8.0 ka, 6.7–6.0 ka, 3.2 ka, and during the Little Ice Age (LIA). During the LIA, the mountain forest was subject to unprecedented levels of disturbance at all altitudes, unlike the seasonal lowland forests, which appears to have been only marginally affected.

International audience; While the emergence of the Acheulean is well documented in East Africa at ~1.7 Ma, subsequent developments are less well understood and to some extent controversial. Here, we provide robust evidence regarding the time period between 1.6 Ma and 1.2 Ma, based on an interdisciplinary approach to the stratigraphic sequences exposed in the Gombore gully of Melka Kunture, in the upper Awash Valley of Ethiopia. Throughout the Pleistocene, the environment differed significantly from elsewhere in Africa because of the elevation at 2000 m asl, the cooler and rainy climate, the Afromontane vegetation, the development of endemic animal species, and the recurrent impact of volcanic activity. At Gombore IB, dated ~1.6 Ma, remains of Homo erectus/ergaster have been discovered, associated with a rich early Acheulean assemblage. The techno-typological analysis of the lithic record from Gombore Iγ (~1.4 Ma) and Gombore Iδ (~1.3 Ma), where substantial areas have been excavated, and the contrasting evidence from Gombore OAM Test Pit C (~1.2 Ma), suggest that the scarcity or lack of large flakes and large cutting tools at the two earlier sites is possibly not just the outcome of sampling bias, but rather of the adaptation of H. erectus/ergaster to the local resources, in a relatively isolated environment. The sites of Gombore gully provide new evidence on the complex pattern of human evolution and adaptation in East Africa during the Lower Pleistocene.

The vicinity of the Rozprza archaeological site (central Poland) has been the area of a series of palaeoecological studies tracking the environmental history of the Luciąża River valley up to ca. 13,200 cal. BP. Numerous subfossil palaeomeanders of different sizes have been discovered in the valley floor. Here, we present the first results of multiproxy research on the paleo-oxbow lake fill, one of the oldest in the region. The wide range of palaeoecological analyses resulted in reconstructions of vegetation history, climatic, hydrological and habitat changes. The studied oxbow was an aquatic ecosystem with diverse invertebrate fauna until the end of Younger Dryas when it transformed into a limno-telmatic habitat. The sediment composition indicates active denudation processes and several episodes of turbulent hydrological conditions. Such an increased river activity could have caused flooding, resulting in an allochthonous matter supply to the oxbow lake in Late Vistulian. Environmental changes were strictly related to the regional features of the catchment, the transformation of soils, and the hydrogeological conditions. The chironomid- and pollen-inferred climatic reconstructions indicate periods of high and low continentality. The chironomid record indicates relatively cool summer conditions in the Allerød, especially ca. 13,000 cal. BP, possibly related to the Gerzensee Oscillation. On the other hand, a distinct increase of summer temperatures in Younger Dryas (up to 16 °C) was recorded. Such a situation was also confirmed in some other studies from the region, suggesting that it might be the effect of some specific, local palaeoclimatic conditions. Fundator badań: Fundator badań: Optional.empty

Site preservation and associated terrain characteristics are among the major agents controlling the spatial distribution and discoverability of late Quaternary archaeological sites. However, site expectancy in extensive areas can be determined using a combination of geoarchaeological investigation and digital spatial analysis. In that sense a prediction model, respectively the result of a Multi Criteria Decision Analysis (MCDA), is presented to highlight areas with a high potential to contain Upper Palaeolithic sites in the Eastern Mediterranean and bordering arid margins. Based on detailed on-site analysis in the Wadi Sabra region, with its many sites and the location of other well-known sites in the southern Levant, eight individual parameters, aspect (cardinal point), elevation, geomorphology, hydrogeology, drainage network, slope inclination, vegetation, and a terrain ruggedness index (TRI) are evaluated and tested for significance. The statistical results confirm a significant divergence of the spatial distribution of Upper Palaeolithic sites from the distribution of natural terrain position factors. This allows for a definition of parameter classes with a high site expectancy and their use in a predictive model. For the results map, the site expectancy factors determined in this way were intersected with each other, thus enabling a distinction between areas with a high and low site occurrence probability. The accuracy of the presented result is assessed by the implementation of another MCDA pass based on an independent dataset of archaeological survey sites and compared to the original. Both datasets complement each other and can show the potential for further investigations with more numerous site datasets as well as more detailed spatial information. A local classification based on high-resolution elevation information and field data is evaluated for the Wadi Sabra, Southern Jordan, which can confirm yet further specify the result from the MCDA.

Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment. We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analyzed based on a seven-year Community-Level Interaction Program experiment. The communities had distinct soil moisture conditions, leading to community-specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs, and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.

Pollen, sediment texture, moisture, organic/inorganic carbon content and geochemical analyses of a 1.2m in-depth sediment profile from upper Tundabhuj Lake in the Parvati Valley show that the region supported alpine-scrub vegetation. The forest elements largely consisted of Betula and its broad-leaved allies viz., Quercus, Corylus and Carpinus interspersed with meadow grasses, Asteraceae, Impatiens, etc. under a warm and moderately humid climate from around 17,100 to 14,700 cal yr BP. Additionally, the increase in organic carbon, enrichment of immobile elements (TiO2, Al2O3, Fe2O3) and moderate values of the Chemical Index of Alteration (CIA = ~72) reinforce the warm and moderately humid climate in the catchment. Subsequently, at around 14,700 to 10,600 cal yr BP, an increase in alpine-scrub vegetation dominated by Betula, Corylus and Carpinus was observed. The enrichment of (TiO2, Ni and Cr) and slightly higher CIA values (72–78) indicated relatively more humid conditions than earlier climatic conditions. The climate turned cold and dry between 10,600 and 5400 cal yr BP as deduced from the abrupt reduction in the alpine-scrubs and meadow constituents. During this period immobile elements (Al2O3, TiO2, Fe2O3, and Cr) also decreased. In contrast, mobile elements (CaO, Na2O, Sr, and Ba) increased along with a gradual decrease in CIA (minimum at 42.5 cm) and organic carbon content supporting cold and dry climatic conditions. From around 5400 until ~1600 cal yr BP, the region saw a return of alpine-scrubs and conifers, indicating a relatively warm and humid climate. Increasing CIA values, organic carbon, and concentration of immobile elements also reaffirm relatively warm and humid climatic conditions. In the most recent phase (around 1600 cal yr BP to present), the climate deteriorated as reflected by the depletion of Betula and broad-leaved associates and an increase in dry elements such as Juniperus and Ephedra. The decrease in CIA values, organic carbon and immobile elements (TiO2, Al2O3, and Fe2O3) substantiate this observation.

Detailed knowledge of the periglacial flora is essential to assess the vegetation dynamics in deglaciated regions of northern and north eastern Europe, previously covered by the ice sheet of the Late Weichselian Glaciation. Therefore, the territory of Belarus, which stretches in the periglacial zone of the Last Glaciation and the most part of which was free of ice during the Last Glacial maximum, is off particular importance in analysing the postglacial floral establishment and the subsequent vegetation dynamics in this part of the continent. In this study, results of palaeobotanical (pollen and plant macrofossil), lithological (measurements of magnetic susceptibility, MS) and isotopic (14C) investigations were obtained to fill the existing gap in reconstructing the peculiarities of the terrestrial and aquatic vegetation dynamics throughout the Lateglacial - Early Holocene period in the central Belarus. The investigated sediment profile, comprising organically enriched gyttja at 13,400–13,100 cal yr BP, carbon enriched and sandy gyttja at 13,100–9700 cal yr BP and unconsolidated mud after 9500 cal yr BP, provides clear evidence proving the flourishing of a pine-birch predominated forest with occasional spruce stands during the Allerod in area. Three occasions of change in the vegetation structure were noted within the Younger Dryas, i.e. 12,900–12,700 cal yr BP, 12,200–12,000 cal yr BP and 11,900–11,700 cal yr BP, suggesting negative climatic excursion taken place in area and facilitating flourishing of a Picea-predominating forest that culminated at about 12,300 and 12,000 cal yr BP. Pollen record suggests the Early Holocene vegetation shifts occurring at about 11,300–11,200 cal yr BP, 10,800–10,600 cal yr BP and 10,300–10,100 cal yr BP evidence the general response to the global-scale climatic events i.e. Preborael Oscillation or “10,2 ka” while fluctuations triggered by local or regional-scale climatic events have been identified as well. About 10,800–10,700 cal yr BP, formation of the forest with an increasing representation of thermophilous taxa (Ulmus, Tilia, Quercus) started in area.

This paper presents the results of the wood charcoal analyses from the Middle Paleolithic open-air site at Nesher Ramla, on the central coastal plain of Israel. The study focuses on the interpretation of the charcoals left by fires used by Middle Paleolithic hominins during early Marine Isotope Stage (MIS) 5. Moreover, this study sheds light on the arboreal taxa present in the vegetation and environmental conditions in the southern Levant during the Middle Paleolithic. A small quantity of identifiable charcoals was retrieved from the 8-m-thick archaeological sequence of the site (Units II to VI). The largest charcoal assemblage was recovered from part of the sequence dated to MIS 5e. The results show the presence of deciduous Quercus sp. and Prunus. The presence of these taxa, together with other proxies from the multidisciplinary studies at Nesher Ramla, indicate an arboreal setting with relatively humid and mild climatic conditions in MIS 5e. Our results further suggest that wood was used as fuel at Nesher Ramla. Given the scarcity of Middle Paleolithic sites in the Levant that have yielded charcoal, this new data from Nesher Ramla constitutes an important contribution to the study of past environments and the exploitation of plant resources by human groups.

Insights into the rates at which ecosystems and vegetation respond to a changing climate is fundamental to anticipating impacts of projected climate change. Characterization of vegetation change over millennia to centuries has potential to make an important contribution toward this goal, and regional scale syntheses of fossil pollen data can provide the foundation for this understanding. However, challenges of data analysis and integration are nontrivial. Here we present a case study in which publicly available fossil pollen data for California are assessed and analyzed. The data are selected according to a clearly defined selection criteria, and a Rate of Change (RoC) value is calculated to assess rates of vegetation change in California from ~15k BP (before A.D. 1950) to the present. Our results highlight several challenges presented by the extant data sets, including temporal sampling variation within and between records, large age control uncertainties, and sparse, geographically biased coverage. Recommendations for methodological refinements to better characterize ecological rates of change include increasing sampling frequency, maintaining a consistent temporal spacing within records, and applying probabilistic approaches to existing pollen data sets.

Soil erosion is a natural process, and the erosion potential of a site is the result of complex interactions among soil, vegetation, topographic position, land use and management, and climate. Soil erosion occurs when aeolian and hydrologic processes exceed a soil’s inherent resistance to these forces (figures 1 and 2). Soil erosion was recognized as a significant problem at both local and national scales in the United States in the 1920s; by 1935 soil erosion was considered a national disaster, covering over one-half of the country (Sampson and Weyl 1918; Weaver 1935), and is still a concern with 21% of the western United States degraded and vulnerable to accelerated soil erosion (Herrick et al. 2010; Weltz et al. 2014a; Duniway et al. 2019). In 1995, it was estimated that 4 × 109 t (4.4 × 109 tn) of soil was lost from US cropland (Pimentel et al. 1995). The most vulnerable areas for soil movement and thus erosion occur where annual precipitation is 100 to 400 mm y–1 (4 to 16 in yr–1), which limits soil moisture available to sustain plant growth. Anthropogenic-driven dust emissions have dramatically increased across …

This paper presents the first insight into the interpretation of the wood charcoal from the Holocene layers of Wonderwerk Cave. Situated in the Northern Cape Province in the arid interior of South Africa, the site provides a unique and valuable chronological record of past environmental fluctuations and responding human behavioural adaptations spanning the last two million years. The Holocene strata have been dated to cover the last 12.5 ka cal BP years, but exclude the last 100 years because of contamination. A sizeable amount of charcoal was recovered from these strata and remnants have been identified, described and the species composition amongst the strata compared. Most identified species are those that tolerate hot, dry conditions, signalling an arid trend during the Holocene. Comparison with present day species distributions suggests an eastwards shift in modern vegetation. The charcoal data also indicate that during the mid Holocene there was a wetter period from 6.2 to 4.5 ka cal BP, coinciding with stratum 4a.

In this study we investigate the timing and nature of moisture availability in the Late Holocene by examining a multiproxy paleoenvironmental record from Kathu Pan at the southern edge of the Kalahari. In a region where organic proxy records are scarce, Kathu Pan provides a unique record of changes in past environmental conditions. Pollen, spore, charcoal, and stable isotope records were obtained from organic deposits at Kathu Pan and examined within a radiocarbon-constrained chronological framework. The Kathu Pan record registers a relatively moist phase occurring between 4.8 ka and 2.5 ka cal BP. Local environmental conditions at Kathu Pan shift gradually beginning around the terminal Northgrippian ~4.8 ka cal BP. Kathu Pan reaches maximum moisture availability with marsh-like conditions signaled by increased organic content, dominance of Cyperaceae pollen, presence of freshwater fungi, and δ13C values consistent with local C3 vegetation, around the inception of the Meghalayan Stage, although due to uncertainties in the age-depth model these changes may have taken place 1–2 centuries on either side of the formal date for the onset of the Meghalayan at 4.2 ka cal BP. This interval also corresponds with the highest charcoal concentrations, indicating the importance of adequate moisture conditions to support the growth of biomass which eventually becomes a fuel source. The moist phase lasts ca. 2000 years until a hypothesized shift to arid conditions occurs c. 2.5 ka cal BP leading to a change in local hydroclimate that may have terminated the accumulation of organic-bearing sediments.

Palaeoecological evidence is compared with the existing archaeological record to understand how changing human activity, over the past two millennia, impacted fire regimes and vegetation dynamics in the Drakensberg Mountains, South Africa. Sediment cores from two wetland sites in the Cathedral Peak area of the northern Drakensberg, KwaZulu-Natal are dated using accelerator mass spectrometry to chronologically support biological proxy data. Fossil pollen analysis is used to detect changes in vegetation composition, and macroscopic charcoal to reconstruct changing fire regimes. Charcoal accumulation rates (CHAR) are used as a proxy for burned biomass, and charcoal width-to-length ratio (W/L) as a proxy for dominant fuel type, whether grassy or woody. Results indicate an increase in CHAR, coincident with the appearance of cereal-type grasses (>40 μm) c. 550 cal BP, suggesting a change in fire regimes associated with the arrival of early agropastoralists. A notable decline in charcoal W/L at this time indicates a shift towards a more grassy fuel type. This is consistent with a seasonal shift in the timing of ignitions from high intensity late season lightning fires to low intensity early season anthropogenic fires. The latter are less damaging to woody vegetation explaining an overall shift to a more grassy fuel type. Large scale ecosystem change is evident in the colonial period, including decreased forest pollen taxa such as Podocarpus, which may be linked to colonial period logging. The increased dominance of Pteridium spores documents the invasion trajectory of bracken fern into montane grasslands in the area, which is attributed to ecosystem disturbance in the form of colonial fire suppression. The subalpine wetland clearly documents woody encroachment of the surrounding open grassland landscape during the agropastoral and subsequent colonial periods. By contrast, at the montane wetland site, these trends appear to be overprinted by local forest dynamics and recent deforestation, likely an elevation effect. Palaeoecological evidence demonstrates how changes in fire regimes and vegetation composition in the northern Drakensberg are closely tied to human activity over the past two millennia.

International audience; The current study tries a new approach to simulating interactions between waves and seagrass through Smoothed Particle Hydrodynamics (SPH). In this model, the plants are defined as a solid that respects Hooke's law, and are assumed to have direct interaction with the fluid. Given the characteristics of the SPH method, especially in terms of computational time, the dimensions of the simulations were limited. The first goal of the current study was to optimize the approach to avoid reaching certain limits such as the rupture of the simulated plant. Plant movements under waves and/or currents have been studied by several authors in various in-situ, physical, and numerical experiments concerning various vegetation species, thus proving that plant movements can be successfully reproduced by SPH 2D/3D. Manning's roughness coefficient, n, was calculated to confirm that the results were in accordance with what had been measured in flume studies. Even though there is still room for improvement, it is shown that this method can be used to estimate Manning's coefficient for coastal vegetation (seagrass and saltmarsh vegetation) and to greatly improve the modeling and forecasting of coastal erosion and storm surge risks by including the effects of vegetation in integrated models.

In this study, we present the assimilation of data from the Orbiting Carbon Observatory-2 (OCO-2) (land nadir and glint data, version 9) to estimate the Australian carbon surface fluxes for the year 2015. To perform this estimation, we used both a regional-scale atmospheric transport–dispersion model and a four-dimensional variational assimilation scheme. Our results suggest that Australia was a carbon sink of −0.41 ± 0.08 PgC yr−1 compared to the prior estimate 0.09 ± 0.20 PgC yr−1 (excluding fossil fuel emissions). Most of the carbon uptake occurred in northern Australia over the savanna ecotype and in the western region over areas with sparse vegetation. Analysis of the enhanced vegetation index (EVI) suggests that the majority of the carbon uptake over the savanna ecosystem was due to an increase of vegetation productivity (positive EVI anomalies) amplified by an anomalous increase of rainfall in summer. Further from this, a slight increase of carbon uptake in Western Australia over areas with sparse vegetation (the largest ecosystem in Australia) was noted due to increased land productivity in the area caused by positive rainfall anomalies. The stronger carbon uptake estimate in this ecosystem was partially due to the land surface model (CABLE-BIOS3) underestimating the gross primary productivity of the ecosystem. To evaluate the accuracy of our carbon flux estimates from OCO-2 retrievals, we compare our posterior concentration fields against the column-averaged carbon retrievals from the Total Carbon Column Observing Network (TCCON) and ground-based in situ monitoring sites located around our domain. The validation analysis against TCCON shows that our system is able to reduce bias mainly in the summer season. Comparison with surface in situ observations was less successful, particularly over oceanic monitoring sites that are strongly affected by oceanic fluxes and subject to less freedom by the inversion. For stations located far from the coast, the comparison with in situ data was more variable, suggesting difficulties matching the column-integrated and surface data by the inversion, most likely linked to model vertical transport. Comparison of our fluxes against the OCO-2 model intercomparison (MIP) was encouraging. The annual carbon uptake estimated by our inversion falls within the ensemble of the OCO-2 MIP global inversions and presents a similar seasonal pattern.

This paper focuses on the environment of Ethiopia, a country highly sensitive to droughts severely affecting vegetation. Vegetation monitoring of Ethiopian Highlands requires visualization of environmental parameters to assess droughts negatively influencing agricultural sustainable management of crops. Therefore, this study presented mapping of several climate and environmental variables including Palmer Drought Severity Index (PDSI). The data were visualized and interpreted alongside the topographic data to evaluate the environmental conditions for vegetation. The datasets included WorldClim and GEBCO and Digital Chart of the World (DCW). Research has threefold objectives: i) environmental mapping; ii) technical cartographic scripting; iii) data processing. Following variables were visualized on seven new maps: 1) topography; 2) soil moisture; 3) T °C minimum; 4) T °C maximum; 5) Wind speed; 6) Precipitation; 7) Palmer Drought Severity Index (PDSI). New high-resolution thematic environmental maps are presented and the utility of GMT for mapping multi-source datasets is described. With varying degrees of soil moisture (mean value of 15.0), min T°C (−1.8°C to 24°C), max T°C (14.4°C to 40.2°C) and wind speed (0.1 to 6.1 m/s), the maps demonstrate the variability of the PDSI fields over the country area (from −11.7 to 2.3) induced by the complex sum of these variables and intensified by the topographic effects notable over the Ethiopian Highlands which can be used for vegetation analysis. The paper presents seven new maps and contributes to the environmental studies of Ethiopia.

This study was conducted during 2018–19 to evaluate the floristic composition and ecological characteristics of vegetation of Pashat valley, Bajaur. Floristic list of the valley contains 385 species distributed in 291 genera and 102 families. The dicotyledons having 83 families with 311 species and monocotyledons with 12 families contains 61 species. Pteridophytes having 05 families with 11 species and gymnosperm with a single family of two species. The leading family was Asteraceae with 42 species (10.90%) followed by Poaceae with 39 species (10.10%), Papilionaceae (Fabaceae) with 24 species (6.23%), Lamiaceae with 20 species (5. 19%) and Rosaceae with 15 species (3.90%). Therophytes 180 species (46.80%), hemicryptophytes 53 species (13.80%), nanophanerophytes 51 species (13.20%) and geophytes 35 species (9.09%) were the dominant life form groups. Leaf size class was dominated by microphylls (138 species, 35.84%) followed by nanophylls (124 species, 32.21%) and mesophylls (89 species, 23.12%). Habit wise the vegetation was mostly herbs (289 species) followed by shrubs (54 species), trees (38 species) and lianas (4 species). According to flowering phenology, most plants (62.30%) bloomed in spring followed by in summer (34%), in autumn (1.82%), in the whole year (1.30%) and in winter (0.52%). Based on chorological affinities, most of the species were bioregional in distribution (170 species, 44.15%) followed by mono-regional (157 species, 40.78%), pluri-regional (43 species, 11.17%) and cosmopolitan (15 species, 3.89%). The ecological characteristics like life form and leaf size spectra of the vegetation have a strong correlation with the prevailing environmental conditions such as altitude, slope, precipitation and temperature.

Climate instability in the Eemian Interglacial is gaining more and more evidence. One of such oscillations in the Beckentin record is indicated by the disappearance of the Cladocera and changes in macroremains at the beginning of E4a (Corylus phase). They confirm the shallowing of the reservoir, probably caused by climate changes, but not reflected in the palynological record. However, a significant oscillation observed in the first half of the E5 (Carpinus phase), ~5860 years after the boreal forests subsided and ~6290 years after the onset of interglacial forestation, suggests that, although not being an analogue of the OHO (Older Holsteinian Oscillations) in MIS 11c and the 8.2 ka cold event in the Holocene, it is very similar to these oscillations. The Eemian oscillation was noted also in the Bispingen profile in northern Germany, ~6500 years after the interglacial forestation. However, the course of vegetation changes there differs from that in Beckentin. The analysis of macroremains and Cladocera confirms the disappearance of rush and water vegetation in the water reservoir at that time in Beckentin. These results confirm that numerous climatic oscillations could have occurred in the Eemian Interglacial.

To investigate the Lateglacial and early Holocene climatic and environmental dynamics in the Eastern Baltic we analysed chironomid and pollen data from Lieporiai palaeolake, North Lithuania. The first quantitative mean July air temperature reconstruction from Lithuania based on fossil chironomid assemblages was performed using expanded Fennoscandian calibration model. Our study suggests that sedimentation started at about 14 600 cal yrs BP and lasted until the early Holocene. The mean July air temperature for Lateglacial and early Holocene from studied site ranged between 13 °C−16 °C which was ~ 2–4 °C lower than the present. Rapidly after the deglaciation during Bolling (GI-1e) interstadial reconstructed July air temperature reached ~ 15 °C. The marked temperature decrease to 13.2 °C was recorded during the Older Dryas (GS-1d). Temperature reached its highest values (up to 16 °C) during the Allerod (GI-1a). The Younger Dryas (GS-1) was relatively cold with the mean July air temperature ~ 14 °C and this was 3.9 °C colder than the present. The pattern of the Lateglacial temperature changes from Lieporiai Lake shows both similarities and some differences from the other chironomid based regional and European reconstructions. Chironomid inferred palaeoenvironmental changes are in positive correlation with changes in the development of vegetation.

The assimilation of carbon by terrestrial vegetation via photosynthesis, or gross primary productivity (GPP), is a vital part of the carbon cycle. This process may be hampered locally by drought stress on vegetation. In a warming climate with droughts occurring more frequently, quantifying the associated deficit in carbon uptake, as attempted in this study, becomes crucial for refined regional greenhouse gas budgets. These are needed, for example, in assessing CO2 mitigation strategies involving forestation or avoidance of land-use change. In summer 2018, a drought paired with temperatures above average prevailed on the British Iles and most other parts of transalpine Europe. Using satellite images of solar-induced chlorophyll fluorescence (SIF) from the Global Ozone Monitoring Experiment-2 (GOME-2) and GOSIF data, which is based on satellite images from the Orbiting Carbon Observatory 2 (OCO-2), a GPP deficit of −98 ± 19 gC m−2 between June and September 2018 and −139 ± 25 gC m−2 for the whole year 2018 was retrieved for the British Iles. The latter corresponds to ~44 TgC, or 44% of the mass of carbon released by anthropogenic CO2 emissions 2018 in the United Kingdom.

The floristic life-form spectrum of any area unveils the prevailing phytoclimatic conditions, helps in understanding the species-environment relationship and can be applied to compare the vegetation pattern of one eco-zone to another. We scrutinized the pattern of species richness (SR) and floristic spectrum along the elevation gradient in a biodiversity-rich eco-zone of western Himalaya (western Ramganga valley, Uttarakhand, India) between 1200 m (river bank) to 3100 m a.s.l. (summit). The elevation range was classified into six elevation bands (i.e. 2700 m), to prepare the presence (1)/ absence (0) species data matrix using local distribution (elevation range) of each species to estimate the SR of various growth-forms and life-forms for the particular elevational band. The findings suggest that the correlation of SR with elevation is not linear as the species richness peaks at the middle elevation (humped-back shape relationship). The forest cover is large and continues up to the summit; thus, the correlation of tree and shrub SR with elevation is not clear; though, a partly positive correlation was observed between elevation and herb SR while negative correlation between climber SR and elevation. The percentage of phanerophytes and therophytes in total life-forms decreased significantly with increase in elevation while inverse trend was shown by hemicryptophytes and cryptophytes. The pattern of phytoclimate in the area varied from phanero-therophytic at the lower elevation to phanero-hemicryptophytic at the middle and hemicrypto-phanerophytic at the upper elevation. The present contribution is an attempt to fill the knowledge gap in pattern of growth-form, life-form and phytoclimate within the forest-covered montane zone of western Himalaya. It will be helpful in understanding the vegetation dynamics in mountain ecosystems and serve as a ready reference to planners in any future conservation strategy for the area.

The complete or partial collapse of the forests of Amazonia is consistently named as one of the top ten possible tipping points of Planet Earth in a changing climate. However, apart from a few observational studies that showed increased mortality after the severe droughts of 2005 and 2010, the evidence for such collapse depends primarily on modelling. Such studies are notoriously deficient at predicting the rainfall in the Amazon basin and how the vegetation interacts with the rainfall is poorly represented. Here, we use long-term surface-based observations of the air temperature and rainfall in Amazonia to provide a constraint on the modelled sensitivity of temperature to changes in precipitation. This emergent constraint also allows us to significantly constrain the likelihood of a forest collapse or dieback. We conclude that Amazon dieback under IPCC scenario RCP8.5 (crossing the tipping point) is not likely to occur in the twenty-first century.

Satellite remote sensing is a popular approach for identifying vegetation change in northern environments; however, disentangling ecological processes causing variability in spectral indices remains a challenge. Here, we aim to determine how shrub characteristics differ between low and rapidly greening areas near Nain, Nunatsiavut, Canada. Using a cross-scale approach, we combined remotely sensed spectral greening trends (Normalized Difference Vegetation Index; Landsat Collection 1, 1985–2018) with shrub dynamics derived from ring-widths of green alder (Alnus alnobetula (Ehrh.) K. Koch) and dwarf birch (Betula glandulosa Michx.). Differentiation of spectral greening classes appears to be driven by the distribution of shrub species. Alder were taller, grew faster, had more recent stem initiation than dwarf birch, and were dominant in rapid greening subplots. In low greening subplots, alder were co-dominant with dwarf birch, whose dominant stems initiated more gradually, were shorter, and had lower rates of vertical growth. The radial growth of both shrub species was favoured by warm winter temperatures and precipitation, whereas rapid greening alder was also favoured by warm summer temperatures. Further shrub growth will likely be enhanced under continued climate warming if moisture does not become limiting. This research demonstrates the importance of species identity in determining rates of spectral greening in northern environments.

Cyperus esculentus (yellow nutsedge) is an alien species that started to spread in arable fields in Slovenia and has already become a noxious weed. In this study we present the spatio-temporal pattern of this invasion in Slovenia. Species was first recorded in 1980 and currently two hotspots are evident (Ljubljana Basin and Posočje). Habitat preferences of Cyperus esculentus and the floristic compostion of invaded plant communities were studied. These communites were compared to similar communities in Slovenia and to so far described vegetation types with dominating Cyperus esculentus in Europe. Based on these analyses we described new weed association, namely Digitario sanguinalis-Cyperetum esculenti.

This paper aims to determine and classify the land cover and assess the impact of agriculture expansion on the land surface temperature (LST) and normalized difference vegetation index (NDVI) in El-Beheira Governorate, Egypt. To achieve these objectives, the multi-temporal Landsat 5 and 8 satellites images for nine different dates were obtained every five years during 1985–2020. Four land cover categorize of agriculture, urban, desert and water lands were distinguished and mapped using the supervised maximum likelihood classification technique in ArcGIS Desktop 10.6. The created land cover maps illustrate a significant expansion in agriculture from 4212 to 7523 km2 (nearly 473 km2 every five years). The desert area decreased from 5417 to 1817 km2 (about 514 km2 every five years) during 1985–2020. The latitudinal variation for LST and NDVI demonstrated that they have a strong negative correlation (R 91%) across all selected dates. The highest positive values for NDVI corresponded to the lowest values for LST over agricultural lands and reversed over desert areas. Where, the relative impacts of agriculture, desert, urban and water on LST (45.1, 50, 4.8 and 0.1% respectively) reveals that the vegetation and desert represents the most significant land cover categorize that determinantes the spatial and temporal distributions of NDVI and LST.

Brazil’s leadership in soybean and maize production depends on predictable rainfall in the Amazon-Cerrado agricultural frontier. Here we assess whether agricultural expansion and intensification in the region are approaching a climatic limit to rainfed production. We show that yields decline in years with unusually low rainfall or high aridity during the early stages of crop development—a pattern observed in rainfed and irrigated areas alike. Although agricultural expansion and intensification have increased over time, dry–hot weather during drought events has slowed their rate of growth. Recent regional warming and drying already have pushed 28% of current agricultural lands out of their optimum climate space. We project that 51% of the region’s agriculture will move out of that climate space by 2030 and 74% by 2060. Although agronomic adaptation strategies may relieve some of these impacts, maintaining native vegetation is a critical part of the solution for stabilizing the regional climate. Soybean and maize yields in the Amazon-Cerrado region of Brazil are dependent on water from rain. Warming and drying will make the climate less suitable for agricultural production; changes have already moved 28% of croplands out of their optimum climate space.

Methane (CH4) emissions from the boreal and arctic region are globally significant and highly sensitive to climate change. There is currently a wide range in estimates of high-latitude annual CH4 fluxes, where estimates based on land cover inventories and empirical CH4 flux data or process models (bottom-up approaches) generally are greater than atmospheric inversions (top-down approaches). A limitation of bottom-up approaches has been the lack of harmonization between inventories of site-level CH4 flux data and the land cover classes present in high-latitude spatial datasets. Here we present a comprehensive dataset of small-scale, surface CH4 flux data from 540 terrestrial sites (wetland and non-wetland) and 1247 aquatic sites (lakes and ponds), compiled from 189 studies. The Boreal–Arctic Wetland and Lake Methane Dataset (BAWLD-CH4) was constructed in parallel with a compatible land cover dataset, sharing the same land cover classes to enable refined bottom-up assessments. BAWLD-CH4 includes information on site-level CH4 fluxes but also on study design (measurement method, timing, and frequency) and site characteristics (vegetation, climate, hydrology, soil, and sediment types, permafrost conditions, lake size and depth, and our determination of land cover class). The different land cover classes had distinct CH4 fluxes, resulting from definitions that were either based on or co-varied with key environmental controls. Fluxes of CH4 from terrestrial ecosystems were primarily influenced by water table position, soil temperature, and vegetation composition, while CH4 fluxes from aquatic ecosystems were primarily influenced by water temperature, lake size, and lake genesis. Models could explain more of the between-site variability in CH4 fluxes for terrestrial than aquatic ecosystems, likely due to both less precise assessments of lake CH4 fluxes and fewer consistently reported lake site characteristics. Analysis of BAWLD-CH4 identified both land cover classes and regions within the boreal and arctic domain, where future studies should be focused, alongside methodological approaches. Overall, BAWLD-CH4 provides a comprehensive dataset of CH4 emissions from high-latitude ecosystems that are useful for identifying research opportunities, for comparison against new field data, and model parameterization or validation. BAWLD-CH4 can be downloaded from https://doi.org/10.18739/A2DN3ZX1R (Kuhn et al., 2021).

Within the subfamily Scelidotheriinae, Valgipes bucklandi represents one of the least known taxa due to its scarce records and material found so far. This Pleistocene ground sloth had been registered only in Brazil, within the Brazilian Intertropical Region (BIR) in the states of Bahia, Minas Gerais, Piaui, Rio Grande do Norte and, more recently, outside the BIR, in Mato Grosso do Sul. A particular feature of this sloth is the proximal and distal fusion of the tibia and fibula in adults. Here, we report a tibia-fibula assigned to V. bucklandi found in Arroyo del Vizcaino (Canelones, Uruguay), a fossiliferous site that harbors a large amount of megamammal remains at an approximate age of 30 ka (29696–32009 cal yr B.P.). We performed stable isotopes analyses and ecological niche models (ENM) to study V. bucklandi distribution and climatic and dietary preferences, as well as to better understand its presence ~2000 km southward of its previous recorded occurrences. δ13C values were consistent with those of the BIR, indicating a similar preference for C3 plants, while the results of δ18O values could be related to colder and more humid environments, clearly different from those obtained from BIR specimens. Furthermore, the ENM results also showed colder and more humid environments for the AdV record, with the occurrence being in the margins of the predicted potential distribution of the taxa. This discovery expands the distribution of this taxa to southern colder climates, indicating a greater climatic tolerance. Moreover, our results support the existence of mixed faunas composed of Southern and Northern taxa coexisting in Southern Uruguay at the onset of the Last Glacial Maximum, and provide evidence of the existence of an open mosaic habitat with patches of mixed vegetation in the region.

The aim of this work was to carry out a paleoenvironmental study of Holocene sedimentary deposits in the southern sector of Pernambuco's coast (northeastern Brazil). This work addresses an important aspect of Quaternary research that has implications for current climate debates, for instance, how does vegetation react to changing climate and rising sea levels. Thus, we provide a combined approach using sedimentological, palynological, geochemical analyses (stable isotopes i.e., δ13C, δ15N and C:N), in addition to AMS 14C dating from two surficial sediment cores i.e. T4 (up to 150 cm depth) and T5 (up to 136 cm depth) collected from the Formoso River estuarine system. Climatic oscillations show variation in precipitation and atmosphere humidity, marked by areas of expansion and/or retraction of herbaceous plain and forest vegetation. Variations in vegetation composition over the last 7168–7260 cal yr BP in the Formoso River estuary reflects the strong influence of sea-level variations, which were responsible for changes in coastal paleogeography and paleogeomorphology. Changes in vegetation composition indicate its close relationship with transgressive and regressive marine events and corresponding variation of the depositional environment like lakes to coastal lagoons, tidal channels, sandy strand-plain, and the modern estuary of the Formoso River.

Resprouting is an efficient life history strategy by which woody savanna species can recover their aboveground biomass after fire. However, resprouting dynamics after fire and the time it takes to start producing flowers and fruits are still poorly understood, especially for the Brazilian savanna (Cerrado biome), where fire is an important driver of vegetation structure and ecosystem functioning. We investigated the resprouting dynamics and production of flowers and fruits of 26 woody species (20 tree and 6 shrub species for a total of 485 individuals) that were burned and the production of flowers and fruits for a subset of 12 species (139 individuals) in an unburned area in a Brazilian savanna. We classified the species’ resprouting strategies as hypogeal (at the soil level, with main stem death), epigeal (on the main stem or crown), and hypogeal + epigeal. We used generalized linear mixed-effect models to identify the post-fire recovery patterns for five years. Individuals with basal resprouts (hypogeal and hypogeal + epigeal resprouting) produced an average of 6 basal resprouts, but only 33% of resprouts survived after five years. Individuals in burned areas produced fewer flowers and fruits than individuals in unburned areas. At least a subset of individuals in all the resprouting strategies started to produce flowers and fruits in the first-year post-fire. About 68% of the species with hypogeal resprouts produced flowers and fruits in the first-year post-fire, but the intensity of flowering and fruiting was lower compared to individuals with other resprouting strategies over time. Although woody species have invested in post-fire growth and sexual reproduction in all resprouting strategies, the long time needed to recover these processes can make these species more vulnerable to frequent fires.

It is hypothesized that in the Holocene dune fynbos-thicket mosaics of the Cape, decades-long absence of fire results in closed-canopy thicket replacing more open fynbos shrublands. We tested this hypothesis by analyzing repeat photographs from 16 sites at Cape St Francis in the south-eastern Cape Floristic Region. The period of monitoring ranged from 55 to 17 year and most sites had been last burnt between 30 and 50 years ago. We divided the sites into coastal (salt wind-exposed) and inland zones and computed, for each pair of photographs, the rate of change of four plant types, namely thicket shrubs, fynbos woody, fynbos herbaceous and grass. Coastal zone sites showed a significant increase in thicket shrub cover and a significant decline in both grass and fynbos herbaceous cover. Fynbos woody cover declined in the face of thicket invasion, but increased in grassy sites, most likely due to a decline in herbivory intensity. No significant changes in plant types were observed in the inland sites, although thicket shrub cover did increase marginally at the expense of fynbos woody plants. However, thicket invasion was restricted to swales and lower dune slopes; the dune fynbos of the upper slopes and crests remains uninvaded by thicket and surprisingly vigorous after 30–50 year without fire. This is consistent with the notion that fynbos species occupy drier sites than thicket in these dune landscapes and regular fire is not a prerequisite for its persistence. Overall, we showed a large increase in woody plant cover throughout the study area. While this pattern is consistent with predictions for vegetation change in response to atmospheric [CO2] pollution, it can also be explained by land use changes experienced in the study area, starting in the early 1960s, involving a shift from subsistence agriculture to holiday resort development and tourism.

The vegetation history and climate in southeastern Brazil, as well as the oceanic dynamics of the tropical Atlantic Ocean offshore, were reconstructed for the last 7.4 cal ka BP. This reconstruction was based on pollen, fern spores and dinoflagellate cysts identified in a marine core (CF10–04B). It was possible to verify the presence of an ombrophilous forest from 7.4 cal ka BP. Near the base of the PI zone low concentrations of pollen and fern spores are recorded, along with low frequencies of forest taxa and fern spores and an increase in pollen types of open vegetation, suggesting less humid climatic conditions than currently observed in the coastal regions of Southeastern Brazil. The assemblages of dinoflagellate cysts suggest a neritic zone with warm upper column temperature, high salinity and oligotrophic environment (evidenced by the presence of O. centrocarpum, Spiniferites spp. and L. machaerophorum). An increase in Tropical Waters (TW) and the approximation of the Brazilian Current (BC) in the middle shelf of southeastern Brazil in the mid-Holocene probably influenced the low accumulation of cysts, pollen grains, fern spores, and their associations. It is still possible to verify that at approximately 4.6 cal ka BP, an increase in the rainfall in the southeastern Brazilian region was probably the fundamental factor for the expansion of vegetation, mainly based on the considerable increases in hygrophytic and aquatic plants. The marked increase in the accumulation of dinoflagellate cysts, with the dominance of autotroph taxa (mainly O. centrocarpum, followed by Spiniferites spp), evidences the warmer waters of the BC and more intense surface upwelling of the South Atlantic Central Water (SACW).

Fire is an essential component of tropical savannas, driving key ecological feedbacks and functions. Indigenous manipulation of fire has been practiced for tens of millennia in Australian savannas, and there is a renewed interest in understanding the effects of anthropogenic burning on savanna systems. However, separating the impacts of natural and human fire regimes on millennial timescales remains difficult. Here we show using palynological and isotope geochemical proxy records from a rare permanent water body in Northern Australia that vegetation, climate, and fire dynamics were intimately linked over the early to mid-Holocene. As the El Niño/Southern Oscillation (ENSO) intensified during the late Holocene, a decoupling occurred between fire intensity and frequency, landscape vegetation, and the source of vegetation burnt. We infer from this decoupling, that indigenous fire management began or intensified at around 3 cal kyr BP, possibly as a response to ENSO related climate variability. Indigenous fire management reduced fire intensity and targeted understory tropical grasses, enabling woody thickening to continue in a drying climate.

We present a high resolution multi-proxy study about environmental changes that occurred during the Holocene sea-level transgression and successive highstand (7–5.5 Kyr) in the central zone of Bahia Samborombon (∼35.6° S), Argentina. This study, one of the first in the area that integrates geomorphological and paleontological proxy data (pollen, non-pollen palynomorphs, foraminifera and mollusk shells), and focusing on a short time interval, offers the advantage of recognizing environmental and vegetation changes in a more comprehensive way. The aim of this work is to reconstruct the salt marsh vegetation history and paleoenvironmental changes; and to develop a model of the geomorphological evolution during the mid-Holocene sea-level transgressive phase. Between 6700 cal yr BP and 6500 cal yr BP, several rapid environmental changes took place. Those changes affected vegetation and microfauna, as well as the geomorphological features. During this period, middle to high salt marsh vegetation developed in an extensive and open tidal plain, where wide and long paleo tidal channels were flowing. Between 6500 and 6220 cal yr BP, the salt marsh transitioned into low salt marsh one as a response to a continued rise in sea level, resulting in the landward transgression of the coastline. The relative sea level reached the highstand between 6220 and 5500 cal yr BP and, consequently, extensive inundation of the coastal plain took place, except for the elevated areas such lunettes and ridges. After 5500 cal yr BP, seaward prograding beach and sand ridges formed in response to the onset of a regressive phase. Since then, the ancient tidal plain, extending ∼10 km from the present coastline, has been subjected to aeolian and pedogenetic processes.

Cities are designed for humans but are also highly dynamic ecosystems that provide habitats for wild animals. These habitats depend on a city's green infrastructure which is increasingly threatened by urban densification. A commonly studied model taxon for wild animals in cities are birds, and the importance of large green spaces for the diversity of birds in cities has been shown. However, how small-scale green spaces affect bird communities, which local characteristics are important, and whether there are seasonal differences remains unclear. We asked how and to what extent the characteristics of city squares in Munich affect the diversity and abundance of birds and if there are differences between bird communities in spring, autumn, and winter. We monitored birds on 103 city squares in Munich using a search-route method. Sampled squares spanned a spatial gradient from the center to the periphery of the city and differed in sealed surface proportion and vegetation structures, such as trees, shrubs, and lawns. The diversity and abundance of birds increased with a higher proportion of green characteristics on the square. Especially the proportion of grass cover and the density of trees had strong positive effects. Old trees had additional effects on birds beyond the effects of trees in general, while the mean number of people on a square negatively influenced bird abundance and diversity. Despite seasonal changes in bird composition, square characteristics showed consistent effects on bird abundance and diversity over seasons. These results underline that the green characteristics of city squares, and therefore of small-scale green spaces, affect their suitability as habitat for wildlife in cities. Integrating this knowledge into city planning can help to maintain or even increase urban biodiversity in the future.

Northern aapa mire complexes are characterized by patterned fens with flarks (wet fen surfaces) and bog zone margins with Sphagnum moss cover. Evidence exists of a recent increase in Sphagnum over fens that can alter ecosystem functions. Contrast between flarks and Sphagnum moss cover may enable remote sensing of these changes with satellite proxies. We explored recent changes in hydro-morphological patterns and vegetation in a south-boreal aapa mire in Finland and tested the performance of Landsat bands and indices in detecting Sphagnum increase in aapa mires. We combined aerial image analysis and vegetation survey, repeated after 60 years, to support Landsat satellite image analysis. Aerial image analysis revealed a decrease in flark area by 46% between 1947 and 2019. Repeated survey showed increase in Sphagnum mosses (S. pulchrum, S. papillosum) and deep-rooted vascular plants (Menyanthes trifoliata, Carex rostrata). A supervised classification of high-resolution UAV image recognized the legacy of infilled flarks in the patterning of Sphagnum carpets. Among Landsat variables, all separate spectral bands, the Green Difference Vegetation Index (GDVI), and the Automated Water Extraction Index (AWEI) correlated with the flark area. Between 1985 and 2020, near-infrared (NIR) and GDVI increased in the central flark area, and AWEI decreased throughout the mire area. In aapa mire complexes, flark fen and Sphagnum bog zones have contrasting Landsat NIR reflectance, and NIR band is suggested for monitoring changes in flarks. The observed increase in Sphagnum mosses supports the interpretation of ongoing fen–bog transitions in Northern European aapa mires, indicating significant ecosystem-scale changes.

In 2018 and 2019, central Europe was affected by two consecutive extreme dry and hot summers (DH18 and DH19). The DH18 event had severe impacts on ecosystems and likely affected vegetation activity in the subsequent year, for example through depletion of carbon reserves or damage from drought. Such legacies from drought and heat stress can further increase vegetation susceptibility to additional hazards. Temporally compound extremes such as DH18 and DH19 can, therefore, result in an amplification of impacts due to preconditioning effects of past disturbance legacies. Here, we evaluate how these two consecutive extreme summers impacted ecosystems in central Europe and how the vegetation responses to the first compound event (DH18) modulated the impacts of the second (DH19). To quantify changes in vegetation vulnerability to each compound event, we first train a set of statistical models for the period 2001–2017, which are then used to predict the impacts of DH18 and DH19 on enhanced vegetation index (EVI) anomalies from MODIS. These estimates correspond to expected EVI anomalies in DH18 and DH19 based on past sensitivity to climate. Large departures from the predicted values can indicate changes in vulnerability to dry and hot conditions and be used to identify modulating effects by vegetation activity and composition or other environmental factors on observed impacts. We find two regions in which the impacts of the two compound dry and hot (DH) events were significantly stronger than those expected based on previous climate–vegetation relationships. One region, largely dominated by grasslands and crops, showed much stronger impacts than expected in both DH events due to an amplification of their sensitivity to heat and drought, possibly linked to changing background CO2 and temperature conditions. A second region, dominated by forests and grasslands, showed browning from DH18 to DH19, even though dry and hot conditions were partly alleviated in 2019. This browning trajectory was mainly explained by the preconditioning role of DH18 on the impacts of DH19 due to interannual legacy effects and possibly by increased susceptibility to biotic disturbances, which are also promoted by warm conditions. Dry and hot summers are expected to become more frequent in the coming decades, posing a major threat to the stability of European forests. We show that state-of-the-art process-based models could not represent the decline in response to DH19 because they missed the interannual legacy effects from DH18 impacts. These gaps may result in an overestimation of the resilience and stability of temperate ecosystems in future model projections.

Assimilation of mercury (Hg) by vegetation represents one of the largest global environmental Hg mass fluxes. We estimate Hg assimilation by vegetation globally via a bottom-up scaling approach using tissue Hg concentrations synthesized from a comprehensive database multiplied by respective annual biomass production (NPP). As global annual NPP is close to annual vegetation die-off, Hg mass associated with global NPP approximates the transfer of Hg from plants to soils, which represents an estimate of vegetation-mediated atmospheric deposition. Annual vegetation assimilation of Hg from combined atmospheric and soil uptake is estimated at 3062 ± 607 Mg yr-1, which is composed of 2491 ± 551 Mg yr-1 from aboveground tissue uptake and 571 ± 253 Mg yr-1 from root uptake. Assimilation of atmospheric Hg amounts to 2422 ± 483 Mg yr-1 when considering aboveground tissues only. Atmospheric assimilation increases to 2705 ± 504 Mg yr-1 when considering that root Hg may be partially derived from prior foliar uptake and transported internally to roots. Estimated atmospheric Hg assimilation by vegetation is 54-137% larger than the current model and litterfall estimates, largely because of the inclusion of lichens, mosses, and woody tissues in deposition and all global biomes. Belowground, about 50% of root Hg was taken up from soils with currently unknown ecological and biogeochemical consequences.

Core Ideas • Smartphones allow a rapid and repeatable measurement of vegetation cover. • The interpretation of results depends on weather conditions, the camera, and canopy height. • Measurements can classify vegetation density but cannot be compared across devices. Smartphone-based visual assessment of vegetation cover is a promising, fast, and repeatable approach that allows land managers to compare measurements on their farm with other farms. This study determined the influence of the smartphone device on green cover measurements on several crops. The hypothesis was that different smartphones would provide similar green cover (reflectance) for management purposes (i.e.

Nowadays, there are many dryness indices based on vegetation indices (VIs)-land surface temperature (Ts) feature space. Which dryness index should we use in dryness monitoring? The differences and capabilities for dryness monitoring among seven indices were evaluated in this study. These dryness indices were based on VIs-Ts or Albedo feature space. For instance, Temperature Vegetation Dryness Index (TVDI) from a triangle NDVI (Normalized Difference Vegetation Index)-Ts feature space (TVDIt), TVDI from bi-parabolic NDVI-Ts feature space (TVDIc), TFDI from FPAR (Fraction of Absorbed Photosynthetically Active Radiation)-Ts feature space, TVDI from LAI (Leaf Area Index)-Ts feature space (TLDI), TVDI from EVI (Enhanced Vegetation Index)-Ts feature space (TEDI), TVDI from SAVI (Soil Adjusted Vegetation Index)-Ts feature space (TSDI) and Vegetation Condition Albedo Dryness Index (VCADI) from NDVI-Albedo feature space. In this study, the assimilated 5/10 cm depth soil moisture, field measured 10 cm depth soil moisture, precipitation, and the assimilated land surface temperature data were selected as the indicators to test the performance of each dryness index in two periods of 2013/2015 and three periods of 2018. The results showed that the spatial distributions of dryness from TVDIc, TVDIt, TFDI, TLDI, TEDI, and TSDI were similar, except for VCADI. The ability of TSDI and TVDIt in dryness monitoring was not as good as TVDIc and TEDI, however, the robustness of them was stable and can be an alternative dryness index. TFDI can be applied to evaluate dryness conditions, but its robustness was not stable and its monitoring performance was not as good as other indices in Shaanxi province, China. Although TLDI can detect dryness conditions when NDVI reached saturation, its robustness was worse than TEDI. When NDVI did not reach saturation, TVDIc had the best ability in dryness monitoring. TEDI was the optimal dryness index when NDVI was approaching or reaching saturation. This study determined that NDVI reached saturation (LAI = 3) when its average value was >0.5368.

The phytosociological researches which intent for studying the performance of weeds and the structure of weed assemblages associated with different crops derives their importance mainly from the adverse effect of weeds on crop productivity. Consequently, it is worth questioning about the ecological preferences of the weed growth in response to three main drivers for weed community structure associated with agronomic, and horticultural crops: crop diversification, crop seasonality, and soil type. A study area was selected comprising farmland of Nile Delta and its adjoining east and west territories, Egypt. A total of 555 species were recorded in 30 agroecosystems monitored and depending on species frequency/abundance values, 150 species were designated as the most influential weeds in weed community structure associated with agronomic and horticultural crops. The ecological preference of species for crop seasonality was evident through the results of Agglomerative hierarchical clustering. Three weed assemblage groups (WAG) identified: WAG A associated with winter agronomic crops, WAG B associated with summer agronomic crops, and WAG C associated with perennial agronomic crops and horticultural crops (orchards). Their diversity evaluated at different levels. The growth preference of the 150 species which were assigned as most influential weeds was gauged in response to the three environmental variables. 61 species were faithful to WAG A, 45 to WAG B, and 44 to WAG C. Concerning crop diversification, 34-species were significantly affected and scored coefficient of variation ≥ 100%. As for soil type, indicator species analysis revealed that 66-species show growth preference in fine grained soil while 84-species prefer coarse grained soil. In the three vegetation units (WAG A – C), 12 within-group associations (alliances) were specified of less-common (differential) species. The record of these alliances match to a specific environmental condition (ecological niche) and in them 29 strong indicators are identified. Redundancy analysis was used to extract and summarize the variation in species records in the response matrix (species vs. sites) that can be explained by the three different types of growth preference (explanatory variables), and the partial linear effect of them was evaluated by variation partitioning.

The Kettara abandoned mine, Morocco, is a highly acid drainage-generating site with negative impacts. In order to impede the water–oxygen migration within tailings of Kettara mine, a store-and-release (SR) cover made with phosphate mine wastes (PMW) layers was implemented on the tailings of Kettara mine in five experimental cells. The characterization of vegetation is an important aspect of the monitoring strategy for the SR cover. In this optic, the objective of this study was to follow the local flora dynamic on the SR cover. Furthermore, this research highlighted the potential of this flora for the development of other appropriate phytomanagement plans of mining wastes. The monitoring surveys were carried out over five years (March 2015–April 2019). Six permanent transects were placed on five-constructed cells. The method of Line Intercept Transect was used to evaluate the vegetation cover and to determinate the floristic composition and relative frequency of the species. Plant diversity was quantified by Shannon diversity (H′) and Pielou evenness (J') indices. Four functional groups of plants were identified; therophytes and chamaephytes were the most abundant. Among 19 recorded families on SR cover, the most widely represented were Compositae (26.83%), Leguminosae and Poaceae with 9.76%, Apiaceae and Brassicaceae with 7.32% of the total taxa for each one of them. Of the 39 identified vascular species on SR cover, the most abundant were Anacyclus valentinus L., Calendula arvensis M.Bieb., Emex spinosa (L.) Campd., Hirschfeldia incana (L.) Lagr.-Foss., Spergularia rubra (L.) J.Presl & C.Presl, Stipa capensisthunb, and Herniaria cinerea L. Significant differences in Shannon diversity index (H′) were observed between the sampling areas (p > 0.05), it ranged from 0.739 to 3.857 bits/ind. on SR cover. The Pielou evenness index was not significantly different through transects; it varied from 0.578 to 0.978. These values indicated an equitable distribution of individuals within species on the investigated transects. The study revealed 29 vascular plant species that represent a great potential to be promoted for the phytomanagement of mine wastes in the context of arid and semi-arid environments.

Coastal wetlands reclamation is facing the problem of salinization. Along with the alternation of ecosystem status, studying the following effect on soil properties becomes emergency. Here we reported the pH, salinity and elemental content (mainly metals) variation affected by the vegetation situations, water sources and geographic positions. The results showed that vegetation could lead the pH and salinity of seawater zones closer to that of freshwater zones in both spatial and time scales. Spartina alterniflora (SA) was the most efficient species among the investigated plants, causing decreases of 0.15–0.69 in pH and 2.250–3.821 in salinity. This result might be caused by the absorption of Ca and K from salt marshes by SA and Suaeda salsa (SS), due to the fact that the component content of calcium (all reduced to approximate one-third) and potassium (reduced in some samples) both decreased. Meanwhile, vegetation could improve soil in seawater zones in Fe content with no extra negative influences in elemental analysis. Thus, ecological engineered vegetation indicated great potential in alternating coastal salt marshes to favorable wetlands or farmlands with almost primitive ecosystem. The results might be significant for ecological engineering and agricultural management in future.

The stability of a dike is influenced strongly by its water content, by way of changes in effective stress and weight. While flow through porous media is relatively well understood, water flux in and out of a dike through a vegetated surface is not as well understood. This paper presents a numerical study of the soil–vegetation–atmosphere interaction and discusses how it influences the stability of dikes covered with grass. A crop model was used to simulate vegetation growth and infiltration in response to meteorological forcing. The PLAXIS finite-element method model was used to simulate the impact of this infiltration on hydromechanical behaviour and dike stability. Results from a 4-year analysis indicated a strong correlation between root zone water content (WC rz) and factor of safety, although the relationship is not unique. The leaf area index (LAI) was also found to have a strong, lagged correlation with the water flux into the dike. This suggests that monitoring LAI could be a useful tool to identify vulnerable locations along dikes. It is therefore proposed that vegetation and root zone water content could be used as an indication to detect vulnerable dikes in the early stage.

In low latitude regions, due to impact of abrupt climate change/human interference, significant changes in vegetation, particularly the destruction of the highly fragile mangrove ecosystem has been noticed in different tropical areas of the world. In this study, a sediment core collected from the Kali Estuary has been used to determine the vegetation distribution of the Western Ghats since the late Holocene. Pollen and magnetic susceptibility data have been used as proxies to achieve objectives of the study. There has been a dramatic decrease in mangroves, evergreen (tree taxa) and deciduous forest pollens and the abundance of herbaceous/savanna type grassland pollen over the past 3.5 ka. This is supported by the significant decrease of the low-frequency magnetic susceptibility (χlf) of the core reflecting the decrease in the summer monsoon rainfall. Therefore, the post-3.5 ka time period marks the beginning of the recolonization of vegetation. Rarefied diversity pattern plots were used to evaluate abundance and evenness in the pollen data as a result of the late-Holocene climate change. A significant increase in the diversity of herbaceous/savanna grassland taxa in the post-3.5 ka sequence of the core indicates the regional expansion of the agriculture in the Kali River basin. In contrast, the reduction in the taxonomic diversity of mangroves and arboreal taxa implies less-conducive environmental conditions for their growth, with further reduction due to anthropogenic interference. The magnetic susceptibility of the core measured at one cm interval indicates the general decrease in the intensity of the summer monsoon rainfall.

Severe soil erosion occurs on the Loess Plateau in China, which makes the Yellow River the most sediment-laden river in the world. Construction of about 60,000 sediment check dams has remarkably controlled soil erosion on the Loess Plateau and reduced the sediment load of the middle and lower Yellow River. Nonetheless, little is known about the mechanism of erosion control and vegetation development of sediment check dams. The function of a single check dam mainly is trapping sediment, while the function of a train of check dams comprising dozens of or over hundreds of check dams in a gully encompasses controlling bed incision and reducing erosion energy. A formula was proposed to calculate the potential energy of bank failure and slope failure in a gully, which essentially constitutes the erosion energy. The erosion energy increases when gully incision occurs, which is induced by the incision of the Yellow River and its tributaries on the Loess Plateau. Sediment deposition in many gullies due to construction of check dams reduces the erosion energy to almost zero, which in turn greatly reduces soil erosion and sediment yield. Construction of check dams promotes vegetation development. The vegetation-erosion dynamics model was used to study the effect of check dams on vegetation development. Simulation results show that reforestation without check dam construction might result in an increase of vegetation cover in the first ten years and then a drop of vegetation cover to less than 10% in the later years. The check dams provide a foundation for vegetation development.

Although there are still some conflicts, previous studies based on lacustrine or aeolian deposits provide an overall understanding of the Holocene environment in the Qinghai Lake Basin. Compared to lacustrine deposits, aeolian sediments have received less attention, and the loess on the south coast and the Hudong Sandy Land on the east coast has received the most attention. The Ganzihe Sandy Land, the second largest sandy land in the Qinghai Lake Basin, is far from lakeshore areas and shows an obvious degradation trend. Very few reports have been published on the Ganzihe Sandy Land, especially regarding the Holocene environment. Here, we report a new and well-reserved aeolian sand-paleosol profile found in the Ganzihe Sandy Land. We used 7 optically stimulated luminescence (OSL) and accelerator mass spectrometry (AMS) 14C dating to establish the chronological framework and measured the magnetic susceptibility (MS), grain size, color parameters and total organic carbon (TOC) in the profile. Combined with lithologic changes and chronological data from published aeolian profiles, the results indicate that the aeolian activity in the Ganzihe Sandy Land during the Holocene was mainly affected by climate change in marginal monsoon areas by at least ~10 ka; the climate then improved, and vegetation began to develop from ~10 ka-~8 ka; from ~8 ka-~4 ka, the climate was warm/wet and stable, dunes were fixed and the sandy land entered the “Holocene climatic optimum”; since ~4 ka, the regional climate has gradually become drier and cooler, and aeolian sand has again accumulated on a large scale, particularly in the past thousand years. To prevent further environmental deterioration in the Ganzihe Sandy Land, we believe that straw-breaks should be established and increasing efforts should be made to artificially enclose the mobile dune region inside the sandy land, control the amount of animal husbandry and emphasize water conservation in the marginal areas. Further, sand control stations should be set up to carry out land monitoring and forecasting, and local residents should be educated about scientific and legal issues.

Riparian vegetation provides a wide range of ecosystem services including water quality regulation, flooding avoidance, and the natural control of stream temperatures. Changes in land use and the increase of anthropogenic activities in the proximity of rivers affect the growth and development of riparian buffers. The aim of the work was to assess the effects of riparian vegetation on the evapotranspiration processes and the water quality of small plain streams using remote sensing resources and in-situ monitoring. The area of study considered two neighboring basins of small plain streams (Glavacioc and Ilfov) from Romania. The data obtained from in-situ monitoring performed in 2019 was used in the Penman-Monteith algorithm to calculate the potential evapotranspiration (PET) based on a series of specific parameters. The Green Normalized Difference Vegetation Index (GNDVI), computed from LANDSAT 8 images, has been used to assess the vegetation status at the basin scale. The GNDVI fluctuations were linked to the variations in precipitation regimes and land use modifications. Remote sensing data have shown changes in GNDVI between June and September 2019 in both riparian areas resulting in an intense spread of cattail (Typha spp.). Surface waters arriving at the entrance control sections had a basic pH and were loaded with nitrates and ammonium ion (NH4+), which had decreased at the downstream section after passing the cattail phytosociological associations and the riparian patches, thus acting as buffer areas. The current anthropogenic pressures on the riparian areas might have degenerative effects on the integrity of the vegetation structure. Thus, for effective and sustainable management, it is essential to identify the main stressors and to assess to what extent they affect the riparian ecosystem as a whole.

Accurately mapping, modeling, and managing the diversity of wetlands present in estuaries often relies on habitat classification systems that consistently identify differences in biotic structure or other ecosystem characteristics between classes. We used field data from four Oregon estuaries to test for differences in vegetation structure and edaphic characteristics among three tidal emergent marsh classes derived from National Wetlands Inventory (NWI) data: low estuarine marsh, high estuarine marsh, and tidal palustrine marsh. Independently of NWI class, we also evaluated the number and types of plant assemblages present and how edaphic variables, non-native plant cover, and plant species richness varied among them. Pore water salinity varied most strongly across marsh classes, with sediment carbon and nitrogen content, grain size and marsh surface elevation showing smaller differences. Cover of common vascular plant species differed between marsh classes and overall vegetation composition was somewhat distinct among marsh types. High estuarine marsh had the largest species pools. However, plot-level plant diversity was similar among marsh classes. Non-native species cover was highest in tidal palustrine and high estuarine marshes. The marshes in the study contained a large number of plant assemblages with most occurring across more than one marsh class. The more common assemblages occurred along a continuum of tidal elevation, soil salinity, and edaphic characteristics, with varying plant richness and non-native cover. Our data suggest that NWI classes are useful for differentiating several general features of Oregon tidal marsh structure, but that more detailed information on plant assemblages found within those wetland classes would allow more precise characterization of additional wetland features such as edaphic conditions and plant diversity.

Record-breaking fire seasons in many regions across the globe raise important questions about plant community responses to shifting fire regimes (i.e., changing fire frequency, severity, and seasonality). Here, we examine the impacts of climate-driven shifts in fire regimes on vegetation communities, and likely responses to fire coinciding with severe drought, heatwaves and/or insect outbreaks. We present scenario-based conceptual models on how overlapping disturbance events and shifting fire regimes interact differently to limit post-fire resprouting and recruitment capacity. We demonstrate that, although many communities will remain resilient to changing fire regimes in the short-term, longer-term changes to vegetation structure, demography and species composition are likely, with a range of subsequent effects on ecosystem function. Resprouting species are likely to be most resilient to changing fire regimes. However, even these species are susceptible if exposed to repeated short-interval fire in combination with other stressors. Post-fire recruitment is highly vulnerable to increased fire frequency, particularly as climatic limitations on propagule availability intensify. Prediction of community responses to fire under climate change will be greatly improved by addressing knowledge gaps on how overlapping disturbances and climate change-induced shifts in fire regime affect post-fire resprouting, recruitment, growth rates, and species-level adaptation capacity. This article is protected by copyright. All rights reserved.