Long-term Ecosystem Research Articles

Terrestrial carbon sinks in China and around the world and their contribution to carbon neutrality

<p indent="0mm">Enhancing the terrestrial ecosystem carbon sink (referred to as terrestrial C sink) is an important way to slow down the continuous increase in atmospheric carbon dioxide (CO₂) concentration and to achieve carbon neutrality target. To better understand the characteristics of terrestrial C sinks and their contribution to carbon neutrality, this review summarizes major progress in terrestrial C budget researches during the past decades, clarifies spatial patterns and drivers of terrestrial C sources and sinks in China and around the world, and examines the role of terrestrial C sinks in achieving carbon neutrality target. According to recent studies, the global terrestrial C sink has been increasing from a source of (−0.2±0.9) Pg C yr⁻¹ (1 Pg=<sc>10¹⁵ g)</sc> in the 1960s to a sink of (1.9±1.1) Pg C yr⁻¹ in the 2010s. By synthesizing the published data, we estimate terrestrial C sink of 0.20–0.25 Pg C yr⁻¹ in China during the past decades, and predicted it to be 0.15–0.52 Pg C yr⁻¹ by 2060. The terrestrial C sinks are mainly located in the mid- and high latitudes of the Northern Hemisphere, while tropical regions act as a weak C sink or source. The C balance differs much among ecosystem types: forest is the major C sink; shrubland, wetland and farmland soil act as C sinks; and whether the grassland functions as C sink or source remains unclear. Desert might be a C sink, but the magnitude and the associated mechanisms are still controversial. Elevated atmospheric CO₂ concentration, nitrogen deposition, climate change, and land cover change are the main drivers of terrestrial C sinks, while other factors such as fires and aerosols would also affect ecosystem C balance. The driving factors of terrestrial C sink differ among regions. Elevated CO₂ concentration and climate change are major drivers of the C sinks in North America and Europe, while afforestation and ecological restoration are additionally important forcing factors of terrestrial C sinks in China. For future studies, we recommend the necessity for intensive and long-term ecosystem C monitoring over broad geographic scale to improve terrestrial biosphere models for accurately evaluating terrestrial C budget and its dynamics under various climate change and policy scenarios.

Toward integrated fire management to promote ecosystem resilience

•Management interventions for addressing invading annual grasses and encroaching conifers and their effects on fire dynamics in the sagebrush ecosystem are largely reactive.•Reactive management limits tools for promoting long-term ecosystem resilience on a fire-prone landscape.•We propose an integrated fire management approach in which all management activities before, during, and after wildfire are synergistic and improve long-term ecosystem response to fire.•Harney County Wildfire Collaborative is adapting the Potential Operational Delineations (PODs) framework to improve fire outcomes and promote values at risk in the Stinkingwater Mountains pilot project area.•The PODs framework serves to promote a broader geographic strategy for addressing the underlying causes of frequent and severe wildfires in the sagebrush ecosystem.

The Integrated Use of Dendrochronological Data and Paleoecological Records From Northwest European Peatlands and Lakes for Understanding Long-Term Ecological and Climatic Changes—A Review

Our overall understanding of long-term climate dynamics is largely based on proxy data generated from archives such as ice cores, ocean sediments, tree rings, speleothems, and corals, whereas reconstructions of long-term changes in vegetation and associated climate during the Holocene are largely based on paleoecological records from peat and lake sequences, primarily pollen and plant macrofossil data. However, since no proxy can provide a complete picture of the past, it is important to integrate different types of data, and to use methods that can support the paleoecological and paleoclimatic interpretations. Here we review how tree-ring data and dendrochronological approaches can be integrated with stratigraphic records to provide complementary paleoecological and paleoclimatic information. The review includes multiproxy studies in which dendrochronological data have been either compared or integrated with stratigraphic records, mainly pollen records, with the aim to contribute to a better understanding of long-term ecosystem and climate dynamics. We mainly focus on studies from northwest Europe in which tree-ring data and at least one type of paleoecological proxy record from the same site or area has been either compared or integrated. We find that integration of dendrochronological data and paleoecological records from peat and lake sequences is a powerful but underutilized approach to reconstruct long-term ecological and climatic changes. One likely reason for its limited use is the contrasting character of the two categories of data, including their different time resolution and occurrence, making them difficult to integrate. For example, subfossil wood providing annual dendrochronological data usually only occurs sporadically in peat and lake sediments, and the presence/absence of the trees are normally expected to be recorded in the pollen data with multi-decadal or coarser resolution. Therefore, we also discuss methods to compare and integrate dendrochronological and stratigraphic records, as well as the relevant paleoecological and paleoclimatic information provided by dendrochronology, pollen, and peat stratigraphy, with the aim to facilitate new multi-proxy initiatives that will contribute to a better understanding of long-term ecosystem and climate dynamics and thereby a firmer basis for future nature conservation initiatives.

Plant diversity and soil properties regulate the microbial community of monsoon evergreen broad-leaved forest under different intensities of woodland use

A key aspect of global forest management, woodland use intensity (WUI) greatly affects the composition and diversity of soil microbial communities, thereby affecting multiple ecosystem functions and services. However, the effects of WUI on soil microbial community composition and enzymatic activities remains unclear. The effects of anthropomorphic alterations to a natural monsoon evergreen broad-leaved forest in terms of the composition and diversity of soil fungal and bacterial communities, was investigated at a site in Yunnan Province, Southwest China. Soil microbial communities were assessed under four levels of disturbance with increasing levels of WUI: (i) none, undisturbed forest (control), (ii) light, naturally-regenerated Pinus kesiya Royle ex Gordon forest, (iii) intermediate, shrub and grassland communities formed through grazing, and (iv) severe, continuously managed coffee (Coffea arabica L.) plantations. With increasing WUI, the diversity of soil fungal and bacterial communities increased, while similarities in community composition decreased for fungi but increased for bacteria. Among fungal functional guilds, ectomycorrhizal fungi decreased significantly with increasing WUI, whereas saprotrophic fungi (undefined, wood, and soil saprotrophs) increased significantly. The species richness of woody plants remarkably affected fungal functional guilds. Ectomycorrhizal fungi interacted in a synergistic manner with the fungal network structure. Significantly affecting microorganismal network structure, WUI increases led to more homogeneous networks with less integration within modules within the microbial community. The WUI strongly altered hub identity and module composition in the microbial community. According to structural equation models, WUI had direct positive effects on soil fungal community composition via its effects on plant species richness. The diversity of bacterial and fungal communities and composition of bacterial communities were jointly regulated by the indirect effects of plant species richness and soil nutrients (including enzyme activity). Deterministic processes largely determined the composition of soil fungal and bacterial communities. This study highlights the importance of maintaining the diversity of soil fungal and bacterial communities despite changes in woodland use to sustain ecosystem functions. These results can be used to develop management practices in subtropical forests and help sustain plant and soil microbial diversity at levels sufficient to maintain long-term ecosystem function and services.

Functionally distinct tree species support long-term productivity in extreme environments.

Despite evidence of a positive effect of functional diversity on ecosystem productivity, the importance of functionally distinct species (i.e. species that display an original combination of traits) is poorly understood. To investigate how distinct species affect ecosystem productivity, we used a forest-gap model to simulate realistic temperate forest successions along an environmental gradient and measured ecosystem productivity at the end of the successional trajectories. We performed 10 560 simulations with different sets and numbers of species, bearing either distinct or indistinct functional traits, and compared them to random assemblages, to mimic the consequences of a regional loss of species. Long-term ecosystem productivity dropped when distinct species were lost first from the regional pool of species, under the harshest environmental conditions. On the contrary, productivity was more dependent on ordinary species in milder environments. Our findings show that species functional distinctiveness, integrating multiple trait dimensions, can capture species-specific effects on ecosystem productivity. In a context of an environmentally changing world, they highlight the need to investigate the role of distinct species in sustaining ecosystem processes, particularly in extreme environmental conditions.

Sources of terrestrial nitrogen and phosphorus mobilization in South and South East Asian coastal ecosystems

South and Southeast Asia (SSEA) is a socially, economically and ecologically diverse region, with a rapidly growing population and accelerating industrial development, agricultural intensification using manufactured fertilizers, terrestrial landscape change, expansion of water engineering, sewage production and land conversions. Nitrogen and phosphorus are major nutrients that play an essential role in the eutrophication of inland and coastal water bodies. Eutrophic areas, when combined with appropriate coastal ocean physical conditions, can develop into hypoxic zones that result in long-term ecosystem disruption. This study addressed changes in terrestrial nitrogen and phosphorus mobilization associated with land-use transitions, fertilizer use and sewage from 2002 to 2016 in the SSEA region, with a focus on the Mekong and Krishna-Godavari watersheds. Terrestrial mobilization results from the internal production or addition of reactive, soluble and/or plant available forms of nitrogen and phosphorus. To estimate terrestrial mobilization associated with land conversion, published data were mined for estimates of land cover change effects on soil carbon, nitrogen and phosphorus pools. Data on exogenous fertilizer and sewage effluents were also compiled from the literature. From the analysis, it showed that fertilizer input was the largest source of nitrogen and phosphorus in both case study watersheds. Sewage and land conversion were not a significant source of terrestrial phosphorus mobilization in either watershed. All land conversions resulted in declines in soil carbon, ranging from 11% to 38%. Nitrogen increased, on average by 15%, in conversions of agricultural to urban land, but decreased in all other conversions. Phosphorus increased by 89% in wetland to agriculture conversions, but decreased between 2% and 24% for other land conversions. Expansion of agriculture at the expense of forest was the dominant land conversion in the Mekong watershed. Urbanization, at the expense of agriculture and forest, was the dominant land conversion in the Krishna/Godavari watershed. These results suggest that management of nutrient pollution (N and P) in SSEA will need to focus on reducing the use and/or improving the efficiency of fertilizer use along with regular consolidated monitoring in both watersheds.

Building and sustaining emerging ecosystems through new focal ventures: Evidence from China's bike-sharing industry

• Two surviving and two failed emerging bike-sharing ecosystems in China are examined. • Three strategizing forms for developing emerging ecosystems are proposed. • Socio-spatial niche experimentation offers a holistic view on ecosystem boundaries. • Strategic versatility leads to positive interplay among ecosystem (non)focal actors. • Strategic suboptimality turns negative externalities into long-term ecosystem gains. Ecosystems research has theorized that overcoming economic and coopetitive challenges is crucial for ecosystem development, yet, they largely overlook the effects of sociopolitical challenges and interplays between economic, coopetitive, and sociopolitical challenges to the emergence and viability of ecosystems. By repositioning the sociopolitical challenges in the ecosystem development model, this study investigates how new focal ventures can develop ecosystem-specific strategies to recognize and overcome a combination of economic, coopetitive, and socio-political co-evolution challenges so as to ensure a viable ecosystem . Qualitative results from a multiple-case study of two surviving and two failed emerging bike-sharing ecosystems in China reveal three strategizing forms: (1) niche experimentation, which enables new focal ventures to obtain a more holistic understanding of the co-evolution challenges in economic and sociopolitical ecosystem environments; (2) strategic versatility , whereby ecosystem-specific strategies positively and simultaneously reinforce each other and collectively overcome the multiple co-evolution challenges in two ecosystem environments; and (3) strategic suboptimality , whereby new focal ventures sacrifice the short-term efficacy of specific strategies to reinforce the long-term effectiveness of related strategies to maintain ecosystem-level competitiveness. These findings indicate the nonlinear structural and intertemporal ecosystem dynamics that need to be considered in ecosystem development literature as well as by ecosystem practitioners.

Exploring the Impacts of an Intense Heatwave on Alaskan Marine Ecosystems

Between 2014 and 2016, the Gulf of Alaska experienced a prolonged and intense heatwave. The hot temperatures disrupted species interactions and stressed the Gulf of Alaska ecosystem past its tipping point. New research led by Dr Robert Suryan at the NOAA Alaska Fisheries Science Center suggests that this event may have left a long-standing mark on the Gulf of Alaska. Dr Suryan and his colleagues quantified the effects of the heatwave on all aspects of marine ecosystems. Their work highlights the importance of long-term ecosystem monitoring in tracking, predicting, and preparing for a changing climate.

Resting Subtropical Grasslands from Grazing in the Wet Season Boosts Biocrust Hotspots to Improve Soil Health

Effective grazing management in Australia’s semi-arid rangelands requires monitoring landscape conditions and identifying sustainable and productive practice through understanding the interactions of environmental factors and management of soil health. Challenges include extreme rainfall variability, intensifying drought, and inherently nutrient-poor soils. We investigated the impacts of grazing strategies on landscape function—specifically soil health—as the foundation for productive pastures, integrating the heterogenous nature of grass tussocks and the interspaces that naturally exist in between them. At Wambiana—a long-term research site in north-eastern Australia—we studied two soil types, two stocking rates (high, moderate), and resting land from grazing during wet seasons (rotational spelling). Rotational spelling had the highest biocrust (living soil cover), in interspaces and under grass tussocks. Biocrusts were dominated by cyanobacteria that binds soil particles, reduces erosion, sequesters carbon, fixes nitrogen, and improves soil fertility. Rotational spelling with a moderate stocking rate emerged as best practice at these sites, with adjustment of stocking rates in line with rainfall and soil type recommended. In drought-prone environments, monitoring the presence and integrity of biocrusts connects landscape function and soil health. Biocrusts that protect and enrich the soil will support long-term ecosystem integrity and economic profitability of cattle production in rangelands.

Carbon and Nitrogen Dynamics in Mexican Management Forest: Simulation of Biomass Harvesting and C and N Amendments

AbstractSustainable silvicultural management requires the maintenance of long-term ecosystem processes. We used the CENTURY model to simulate the impact of wood extraction and organic amendments on aboveground biomass, carbon (C) storage, and the availability of nitrogen (N) in the two dominant silvicultural methods in Mexico: the silvicultural development method (SDM) and irregular forest management (IFM). The values of the mean absolute percentage error for the SDM and IFM were 2.1% and 3.3% for C in aboveground biomass, 5.7% and 5.0% for soil organic carbon (SOC), and 14.9% and 21.6% for N, respectively. Simulation for the SDM (1967–2068) suggested a reduction of ~7% in C in soil, microbial biomass, and litter, 9% in aboveground biomass C, and ~20% in the mineral N available. For IFM, the simulation (2009–2019) suggested a reduction of 14% in the accumulation of aboveground biomass and 13% in the mineral N available. Simulation of the adoption of management practices suggested that N mineral availability would increase by 2%–3% without drastically reducing the SOC, improving aboveground biomass production by ~7%, in each management system.Study ImplicationsIn Mexico, current silvicultural management is causing alterations in the biological and chemical processes of the soil, but the future impacts on the production of forest wood and loss of fertility cannot be estimated by direct measurements. We simulated two silvicultural management alternatives with two rotation cycles and measured the response in terms of SOC, nitrogen availability, and aboveground biomass. The model shows that improving forest residue management by adding organic amendments to the soil would counteract changes in soil microbial activity, nitrogen availability, SOC, and aboveground biomass in the future. Managers should consider this information to reorient current crop residue management to achieve the objectives and the sustainability of forest management in Mexican temperate forests.

Finding Liebig's law of the minimum.

Liebig’s law of the minimum (LLM) is often used to interpret empirical biological growth data and model multiple substrates co‐limited growth. However, its mechanistic foundation is rarely discussed, even though its validity has been questioned since its introduction in the 1820s. Here we first show that LLM is a crude approximation of the law of mass action, the state of art theory of biochemical reactions, and the LLM model is less accurate than two other approximations of the law of mass action: the synthesizing unit model and the additive model. We corroborate this conclusion using empirical data sets of algae and plants grown under two co‐limiting substrates. Based on our analysis, we show that when growth is modeled directly as a function of substrate uptake, the LLM model improperly restricts the organism to be of fixed elemental stoichiometry, making it incapable of consistently resolving biological adaptation, ecological evolution, and community assembly. When growth is modeled as a function of the cellular nutrient quota, the LLM model may obtain good results at the risk of incorrect model parameters as compared to those inferred from the more accurate synthesizing unit model. However, biogeochemical models that implement these three formulations are needed to evaluate which formulation is acceptably accurate and their impacts on predicted long‐term ecosystem dynamics. In particular, studies are needed that explore the extent to which parameter calibration can rescue model performance when the mechanistic representation of a biogeochemical process is known to be deficient.

Birds diversity and faunogenetic structure of avifauna in forests parks of two megalopolises (Ukraine)

Background. In the 21st century, landscape transformation processes are underway in large cities, which affects the stability of wildlife habitats. Habitat transformations often reduce species richness due to a decrease in the population sizes of some species, and therefore, small in number and rare species are eliminated from bird communities. Rare species can have unique consortive relationships, which makes them particularly important for the long-term ecosystem functioning. A study of the avifauna of forest parks makes it possible to develop an algorithm for the coexistence of human and birds. Methods. The number and distribution of birds were determined by route counting. The total length of the fixed route was 5.7 km in Kyiv and 3.5 km in Kharkiv. On each route, observations were carried out annually with three repetitions during the nesting period when the birds are most attached to their habitats (end of April–May–June). The average data for the total study period (2013–2017) were calculated for each city. For the average number, the standard deviation was calculated. An analysis of the faunogenetic structure of avifauna was carried out according to the method developed by V.P. Belik. A faunogenetic complex is a group of animal species associated by a common origin with ecosystems of a certain landscape-geographical zone. We also classified bird species into ecological groups according to the patterns of microhabitat choice. To compare the α-diversity of bird in the forest-park zones of cities, a number of commonly accepted indices that express the correlation between the number and density of species were calculated: 1) Berger–Parker dominance index: DBP = Nimax / N; 2) Shannon diversity index: H´ = -∑(Pi × LnPi); 3) Pielou evenness index: E = H´ / LnS; where: Nі– the number of each species; Nimax – the maximum value of Nі; N = ∑Ni – the total number of all species (pairs/km); Pi = Ni / N – the ratio of each species; S – total number of the species. Results. The study presents a comparative analysis of diversity and faunogenetic structure of avifauna in the forest park zones of Kyiv and Kharkiv, inhabited by 71 breeding species of birds that belong to 10 orders. In the eastern region, the proportion of birds of the boreal and the European forest-steppe complex decreases, but the share of the desert-mountain complex increases. The fauna of the European nemoral complex dominates (32.8 % in Kyiv and 40.4 % in Kharkiv). The basis of the communities are dendrophils: 83.6 % (n = 67) in Kyiv and 82.7 % (n = 52) in Kharkiv. The dominant species in all forest parks are the great tit (Parus major) and chaffinch (Fringilla coelebs). Conclusions. The differences in the faunogenetic structure of bird communities are due to the proximity of model forest parks on the territory of Kyiv to the forest natural geographical zone, and on the territory of Kharkiv to the steppe, which leads in the eastern region to a decrease in the proportion of birds of the boreal and the European forest-steppe complex while the proportion of desert-mountain complex increases. Dendrophils predominate significantly, and the share of sclerophils and limnophils in total is less than 20 % of the bird community in the forest parks of each city. As a consequence of the fragmentation of the Kiev forest park zone, the diversity of nesting birds communities in the forest-park zone of Kyiv is slightly lower than of Kharkiv, and the pressure of the dominant species is more significant.

Research Infrastructure Contact Zones: A method to visualise and align the activities of major biodiversity informatics initiatives

In an effort to characterise the various dimensions of activity within the biodiversity informatics landscape, we developed a framework to survey these dimensions for ten major organisations*1 relative to both their current activities and long-term strategic ambitions. This survey assessed the contact between these infrastructure organisations by capturing the breadth of activities for each infrastructure across five categories (data, standards, software, hardware and policy), for nine types of data (specimens, collection descriptions, opportunistic observations, systematic observations, taxonomies, traits, geological data, molecular data, and literature), and for seven phases of activity (creation, aggregation, access, annotation, interlinkage, analysis, and synthesis). This generated a dataset of 6,300 verified observations, which have been scored and validated by leading members of each infrastructure organisation. In this analysis of the resulting data, we address a set of high-level questions about the overall biodiversity informatics landscape, looking at the greatest gaps, overlap and possible rate-limiting steps. Across the infrastructure organisations, we also explore how far each is in relation to achieving its ambitions and the extent of its niche relative to other organisations. Our results show that when viewed by scope, most infrastructures occupy a relatively narrow niche in the overall landscape of activity, with the notable exception of the Global Biodiversity Information Facility (GBIF) and possibly LifeWatch. Niches associated with molecular data and biological taxonomy are very well filled, suggesting there is still considerable room for growth in other areas, with the Distributed System of Scientific Collections (DiSSCo) and the Integrated European Long-Term Ecosystem Research Infrastructure (eLTER RI) showing the highest levels of difference between their current activities and stated ambitions, potentially reflecting the relative youth of these organisations. iNaturalist, the Biodiversity Heritage Library and Catalogue of Life all occupy narrow and tightly circumscribed niches. These organisations are also amongst the closest to achieving their stated ambitions within their respective areas of activity. The largest gaps in infrastructure activity relate to the development of hardware and standards, with many gaps set to be addressed if the stated ambitions of those surveyed come to fruition. Nevertheless, some gaps persist, outlining a potential role for this survey as a planning tool to help coordinate and align investment in future biodiversity informatics activities. GBIF and LifeWatch are the two infrastructures where there is the most similarity in ambition with DiSSCo, with the greatest overlap concentrated on activities related to data/content, specimen data and their shared ambition to interlink information. While overlap appears intense, the analysis is limited by the resolution of the survey framework and ignores existing collaborations between infrastructures. In addition to presenting the results of this survey, we outline our plans to publish this work and a proposal to develop the methodology as an interactive web-based tool. This would allow other projects and infrastructures to self-score their activities and visualise their niche within the current landscape, encouraging better global alignment of activities. For example, our results should make it easier for initiatives to strengthen collaboration and differentiate work when their activities overlap. Likewise, this approach would be useful for funding agencies when targeting gaps in the informatics landscape or increasing the technical maturity of certain critical activities, e.g., to improve immature data standards. While no framework is perfect, we hope to encourage a dialogue on the potential for taking an algorithmic approach to community alignment and see this as a means of strengthening community cooperation when addressing problems that require global cooperation.

Integrating Multi-Sensors Data for Species Distribution Mapping Using Deep Learning and Envelope Models

The integration of ecological and atmospheric characteristics for biodiversity management is fundamental for long-term ecosystem conservation and drafting forest management strategies, especially in the current era of climate change. The explicit modelling of regional ecological responses and their impact on individual species is a significant prerequisite for any adaptation strategy. The present study focuses on predicting the regional distribution of Rhododendron arboreum, a medicinal plant species found in the Himalayan region. Advanced Species Distribution Models (SDM) based on the principle of predefined hypothesis, namely BIOCLIM, was used to model the potential distribution of Rhododendron arboreum. This hypothesis tends to vary with the change in locations, and thus, robust models are required to establish nonlinear complex relations between the input parameters. To address this nonlinear relation, a class of deep neural networks, Convolutional Neural Network (CNN) architecture is proposed, designed, and tested, which eventually gave much better accuracy than the BIOCLIM model. Both of the models were given 16 input parameters, including ecological and atmospheric variables, which were statistically resampled and were then utilized in establishing the linear and nonlinear relationship to better fit the occurrence scenarios of the species. The input parameters were mostly acquired from the recent satellite missions, including MODIS, Sentinel-2, Sentinel-5p, the Shuttle Radar Topography Mission (SRTM), and ECOSTRESS. The performance across all the thresholds was evaluated using the value of the Area Under Curve (AUC) evaluation metrics. The AUC value was found to be 0.917 with CNN, whereas it was 0.68 with BIOCLIM, respectively. The performance evaluation metrics indicate the superiority of CNN for species distribution over BIOCLIM.

Tracing the Long-Term Evolution of Land Cover in an Alpine Valley 1820–2015 in the Light of Climate, Glacier and Land Use Changes

Alpine glacial environments and their fluvial systems are among those landscapes most comprehensively affected by climate change. Typically, studies on the consequences of climate change in such environments, e.g., glacier retreat, cover a maximum of 70 years, reflecting the availability of orthophotos or satellite images. This study addresses the long-term transformation processes in a glaciated catchment and highlights the role of human agency in a changing Alpine environment. In order to identify land cover changes between 1820 and 2015 in the Long-Term Ecosystem Research (LTER) site “Jamtal” (Tyrol, Austria) we apply a “regressive-iterative GIS reconstruction method” combining both historical maps and optical remote sensing data. Below 2,100 m a.s.l. the Jamtal experienced a massive 62% decline of unvegetated debris areas and bedrock outcrops (so-called “wasteland”) that was mainly transformed to grassland and sparsely wooded areas. Forests increased by an outstanding 323% and grassland was replaced by sparsely or densely wooded areas. This primarily reflects the abandonment of agricultural uses at unfavourable remote sites. In the higher (formerly) glaciated subbasin, ice-covered areas declined by 55%, which was associated with a major (82%) growth of exposed wasteland. Concurrently, Alpine grassland expanded by 196% and krumholz even by 304%. Approximately half of the new fluvial system that evolved in deglaciated areas between 1870 and 1921 still existed in 2015. Unconsolidated debris buried almost one fifth of the new channels, and almost one third was colonized by vegetation. Recent data show that the deglaciation process is much faster than the colonization process by Alpine vegetation. Accordingly, the extent of wasteland has expanded and potentially amplifies the sediment supply to the fluvial system. Alterations in high Alpine hydrological and sediment/debris regimes significantly affect human use in lower, more favourable areas of the Alpine region. The long-term investigation of the Alpine landscape reveals that the transformation processes have accelerated in recent decades.

Coupling Between the Responses of Plants, Soil, and Microorganisms Following Grazing Exclusion in an Overgrazed Grassland.

Grazing exclusion is an effective management practice to restore grassland ecosystem functioning. However, little is known about the role of soil microbial communities in regulating grassland ecosystem functioning during long-term ecosystem restorations. We evaluated the recovery of a degraded semiarid grassland ecosystem in northern China by investigating plant and soil characteristics and the role of soil microbial communities in ecosystem functioning after 22 years of grazing exclusion. Grazing exclusion significantly increased the alpha diversity and changed the community structure of bacteria, but did not significantly affect the alpha diversity or community structure of fungi. The higher abundance of copiotrophic Proteobacteria and Bacteroidetes with grazing exclusion was due to the higher carbon and nutrient concentrations in the soil, whereas the high abundance of Acidobacteria in overgrazed soils was likely an adaptation to the poor environmental conditions. Bacteria of the Sphingomonadaceae family were associated with C cycling under grazing exclusion. Bacteria of the Nitrospiraceae family, and especially of the Nitrospira genus, played an important role in changes to the N cycle under long-term exclusion of grazing. Quantitative PCR further revealed that grazing exclusion significantly increased the abundance of nitrogen fixing bacteria (nifH), ammonia oxidizers (AOA and AOB), and denitrifying bacteria (nirK and nosZ1). Denitrifying enzyme activity (DEA) was positively correlated with abundance of denitrifying bacteria. The increase in DEA under grazing exclusion suggests that the dependence of DEA on the availability of NO3– produced is due to the combined activity of ammonia oxidizers and denitrifiers. Our findings indicate that decades-long grazing exclusion can trigger changes in the soil bacterial diversity and composition, thus modulating the restoration of grassland ecosystem functions, carbon sequestration and soil fertility.

The opportunity cost of delaying climate action: Peatland restoration and resilience to climate change

Ecosystem restoration and, in particular, peatland restoration, are considered a promising greenhouse gas (GHG) mitigation strategy to move towards net zero emissions. To remain within acceptable limits for projected warming scenarios, inaction with respect to GHG mitigation in the short term implies a need for even larger removals of GHGs in the longer term, which can be conceptualized as a ‘mitigation debt’. This paper explores the economic implications of delaying GHG mitigation through ecosystem restoration using data of a large survey (N = 1377) that included a choice experiment to elicit the public’s willingness to pay (WTP) for peatland restoration in Scotland, UK. The valuation specifically considers the interaction between the timing of restoration action and long-term ecosystem resilience. We find that respondents have a substantial WTP for peatland restoration. Importantly, we find considerable benefits for early restoration action (up to £191 million annually in our case study), which is linked to an increased resilience of peatlands under future climate change. This demonstrates that delaying restoration and thus accumulating a mitigation debt has an important opportunity cost that substantially decreases the related economic benefits. Attitudes towards climate change and climate change beliefs are found to explain variation in the public’s WTP. Our research strengthens the economic argument for not delaying climate change mitigation through ecosystem restoration, demonstrating that the mitigation debt also translates into a welfare loss. To fully realise the potential benefits associated with immediate mitigation using peatland restoration, however, more needs to be understood about the mechanisms that facilitate large-scale implementation in practice.

A quantitative synthesis of Holocene vegetation change in Nigeria (Western Africa)

Understanding long-term (centennial–millennial scale) ecosystem stability and dynamics are key to sustainable management and conservation of ecosystem processes under the currently changing climate. Fossil pollen records offer the possibility to investigate long-term changes in vegetation composition and diversity on regional and continental scales. Such studies have been conducted in temperate systems, but are underrepresented in the tropics, especially in Africa. This study attempts to synthesize pollen records from Nigeria (tropical western Africa) and nearby regions to quantitatively assess Holocene regional vegetation changes (turnover) and stability under different climatic regimes for the first time. We use the squared chord distance metric (SCD) to assess centennial-scale vegetation turnover in pollen records. Results suggest vegetation in most parts of Nigeria experienced low turnover under a wetter climatic regime (African Humid Period), especially between ~8000 and 5000 cal year BP. In contrast, vegetation turnover increased significantly under the drier climatic regime of the late-Holocene (between ~5000 cal year BP and present), reflecting the imp role of moisture changes in tropical west African vegetation dynamics during the Holocene. Our results are consistent with records of vegetation and climatic changes in other parts of Africa, suggesting the Holocene pattern of vegetation change in Nigeria is a reflection of continental-scale climatic changes.

Lianas Significantly Reduce Aboveground and Belowground Carbon Storage: A Virtual Removal Experiment

Lianas are structural parasites of trees that cause a reduction in tree growth and an increase in tree mortality. Thereby, lianas negatively impact forest carbon storage as evidenced by liana removal experiments. In this proof-of-concept study, we calibrated the Ecosystem Demography model (ED2) using 3 years of observations of net aboveground biomass (AGB) changes in control and removal plots of a liana removal experiment on Gigante Peninsula, Panama. After calibration, the model could accurately reproduce the observations of net biomass changes, the discrepancies between treatments, as well as the observed components of those changes (mortality, productivity, and growth). Simulations revealed that the long-term total (i.e., above- and belowground) carbon storage was enhanced in liana removal plots (+1.2 kgC m–2 after 3 years, +1.8 kgC m–2 after 10 years, as compared to the control plots). This difference was driven by a sharp increase in biomass of early successional trees and the slow decomposition of liana woody tissues in the removal plots. Moreover, liana removal significantly reduced the simulated heterotrophic respiration (−24%), which resulted in an average increase in net ecosystem productivity (NEP) from 0.009 to 0.075 kgC m–2 yr–1 for 10 years after liana removal. Based on the ED2 model outputs, lianas reduced gross and net primary productivity of trees by 40% and 53%, respectively, mainly through competition for light. Finally, model simulations suggested a profound impact of the liana removal on the soil carbon dynamics: the simulated metabolic litter carbon pool was systematically larger in control plots (+51% on average) as a result of higher mortality rates and faster leaf and root turnover rates. By overcoming the challenge of including lianas and depicting their effect on forest ecosystems, the calibrated version of the liana plant functional type (PFT) as incorporated in ED2 can predict the impact of liana removal at large-scale and its potential effect on long-term ecosystem carbon storage.

Building the GLENCOE Platform -Grasslands LENding eConomic and ecOsystems sErvices

To feed the rising population whilst also preserving ecosystem functions, creative solutions are needed for the ecological intensification of natural grassland-based livestock systems. In Uruguay, natural grasslands are the main nutritional resource for livestock production. In these ecosystems, cattle and sheep graze together all the year round, and grasslands are frequently heavily grazed. Considerable research has been generated concerning grassland management, but there is still no knowledge about the impact of decision rules that supports management actions on long-term ecosystem functioning, at the system level. To meet this deficit, a participatory working group of farmers, researchers, and consultants have developed the GLENCOE platform. This platform is a large-scale facility, supported by INIA-Uruguay, designed to answer the following question: How to intensify the grazing management to improve the sustainability of livestock systems based on natural grasslands? To build the platform three steps were followed: (I) definition of the research problem using a problem tree analysis; (ii) conceptualization of the platform and the design of the grazing systems to be evaluated; and, (iii) spatial allocation of the grazing systems according to the variability of soil, slopes, and seasonal dynamic of vegetation indexes. These criteria were considered across farmlets that were equivalent in the initial stage, allowing causal inferences for the systems trajectories on productive and environmental traits. The platform is composed of three independent farmlets of 50 ha each, where multiparous Hereford cows and Merinos wethers co-graze under three grazing management systems. Each farmlet is managed according to different spatio-temporal decisions of the specific management of vegetation communities, grazing methods, and the stockpile of forage that is allowed by the number of the existing paddocks. Farmlet-1; comprises less decisions (2 paddocks), Farmlet-2; intermediate (8 paddocks), and Farmlet-3; high level of decisions (32 paddocks). This innovative platform will be used as a participatory and interdisciplinary space for research and co-learning of management on processes that can only be observed in long-term evaluations, and at farmlet scale. We expect that this new approach will contribute to the developement and implemention of sustainable grazing management systems in Uruguay.