Key Ecological Functions Research Articles

Ecotoxicological tools in support of the aims of the European Water Framework Directive: A step towards a more holistic ecosystem-based approach

The Water Framework Directive (WFD) aims to attain ‘good quality’ status for all European water bodies through the achievement of good ecological status. To this purpose, the WFD advocates the creation of cost-effective monitoring tools to deliver appropriate data that help to create links between chemical and ecological indicators, as those from ecotoxicological research. Here, it was evaluated whether the integration of ecotoxicological tools, as bioassays and biomarkers, did (or did not) strengthen the robustness of the assessment of the ecological status obtained through well stablished biotic indices in two Atlantic estuaries. For that, a battery of in-situ bioassays, including five macroinvertebrate species (the crab Carcinus maenas, the amphipod Echinogammarus marinus, the isopod Cyathura carinata, the snail Peringia ulvae and the polychaete Hediste diversicolor, each one providing complementary information regarding key ecological functions) and a set of biomarkers, was used. In addition, the concentrations of heavy metals in sediments, and in macroalgae (Fucus), were determined, along with sediment granulometric, water physicochemical and nutrients characterization. We show that by interpreting the values of all indicators together, along with environmental components, it is possible to perform a more holistic description of the quality status of a waterbody – and, to begin to allude to factors limiting that quality. Ecotoxicological tools (in situ bioassays and biomarkers) appear to provide an added value of useful information for monitoring programmes regarding the true state - within which, both known and unknown contaminants are potentially present at concentrations sufficient to cause biological effects. Our results support the use of in situ bioassays and biomarkers within protocols aimed at fulfilling the goals of the WFD. In doing so, more complete and informative assessments of the ecological quality status of water bodies can take place.

ЕКОСИСТЕМНІ ПЛАТЕЖІ ЯК ІНСТРУМЕНТ РЕАЛІЗАЦІЇ ЕКОСИСТЕМНОГО ПІДХОДУ В УПРАВЛІННІ ПРИРОДОКОРИСТУВАННЯМ

Зростання екологічних загроз і виснаження природних ресурсів мотивують до перегляду наукових концепцій взаємодії суспільства з природою. Одночасно в економіку природокористування поступово впроваджується екосистемний підхід, теоретико-методологічні засади якого в Україні ще належним чином не сформовано. З огляду на це, обґрунтовано особливості трансформації сучасного механізму природокористування шляхом упровадження екосистемного підходу з використанням основного його економічного інструменту – екосистемних платежів. Екосистемний підхід до природокористування – напрям в управлінні, який забезпечує врахування при плануванні й здійсненні будь-яких заходів природокористування складних біологічних відносин усередині екосистеми, природні ресурси якої експлуатуються; усвідомлення цінності цих відносин завдяки їх спроможності позитивно впливати на стан, продуктивність екосистеми і виконання нею важливих екологічних функцій. Ієрархічну структуру процесу впровадження екосистемного підходу в практику управління природокористуванням відображають керівні принципи Конвенції про біологічне різноманіття, які з науково-практичної точки зору доцільно розділяти на організаційно-економічні та еколого-економічні. Екосистемні платежі – це платежі за використання, невикористання ресурсів або послуг екосистеми, відшкодування її забруднення чи деградації; усі платежі, що здійснюються в межах екосистемного підходу і мають на меті захист, збереження екосистем, раціональне використання їх ресурсів та підвищення ефективності функцій. Вони включають обов’язкові платежі за використання ресурсів екосистем, їх забруднення, виснаження або деградацію; компенсаційні платежі, які держава сплачує громадянам за використання їх екосистем або фермерам за невикористання ними екосистем чи використання на умовах упровадження нових технологій; платежі за екосистемні послуги; еквівалентні платежі. Критеріями визначення типу платежів є їх добровільність; належність бюджету, за рахунок якого вони сплачуються; переважання екосистемної цінності над ринковими інтересами; сутність платежу; можливість регулювання за допомогою цивільних договорів, відтермінування платежу і зміни його розміру; залежність платежу від результатів господарської діяльності; обопільність вигоди.

A strategic model of a host-microbe-microbe system reveals the importance of a joint host-microbe immune response to combat stress-induced gut dysbiosis.

Microbiomes provide key ecological functions to their host; however, most host-associated microbiomes are too complicated to allow a model of essential host–microbe–microbe interactions. The intestinal microbiota of salmonids may offer a solution since few dominating species often characterize it. Healthy fish coexist with a mutualistic Mycoplasma sp. species, while stress allows the spread of pathogenic strains, such as Aliivibrio sp. Even after a skin infection, the Mycoplasma does not recover; Aliivibrio sp. often remains the dominant species, or Mycoplasma–Aliivibrio coexistence was occasionally observed. We devised a model involving interactions among the host immune system, Mycoplasma sp. plus a toxin-producing pathogen. Our model embraces a complete microbiota community and is in harmony with experimental results that host–Mycoplasma mutualism prevents the spread of pathogens. Contrary, stress suppresses the host immune system allowing dominance of pathogens, and Mycoplasma does not recover after stress disappears.

Functional diversity and trait filtering of insectivorous bats on forest islands created by an Amazonian mega dam

Abstract Mega dams in lowland tropical forests often create large archipelagos, leading to biodiversity decay and disruption of ecosystem functioning in remnant habitat islands. We investigated the functional diversity and functional trait filtering of aerial insectivorous bats in both insular forest patches created by a vast ~30‐year‐old hydropower reservoir and the adjacent mainland continuous forest in Central Amazonia. Bats were surveyed using passive bat recorders across 34 forest sites. Based on a set of morphological traits derived for each species recorded, we estimated both the bat functional richness, functional evenness and functional dispersion at each surveyed site. We further assessed the effects of local vegetation, patch and landscape features on patterns of functional diversity. The interaction between functional traits, environmental characteristics, and species distribution was investigated using a combination of RLQ and fourth‐corner analyses. We found that mainland sites retained higher functional richness and lower functional evenness compared to forest islands, indicating a more complete functional assemblage in the mainland. Additionally, species composition was affected by local vegetation structure and forest area, with small isolated islands exhibiting pervasive loss of functional traits. RLQ and fourth‐corner analyses showed that larger understorey foraging species with greater dispersal capacity, constant frequency–frequency modulated calls, and higher frequency of maximum energy were associated with more isolated small islands. Conversely, forest subcanopy species, exhibiting quasi‐constant frequency calls and presenting low dispersal capacity were associated with continuous forests and islands with greater forest area, and were therefore more sensitive to habitat insularization. Our study calls attention to the pervasive impacts induced by large dams on the functional diversity of tropical insectivorous bats. We recommend that future assessments of the effects of habitat fragmentation on mammals should include traits linked to ecosystem services. In designing and licensing new dams, we suggest the creation of extensive protected areas surrounding mainland forests to minimize the detrimental impacts of small isolated islands and safeguard the full complement of key ecological functions provided by insectivorous bats. Read the free Plain Language Summary for this article on the Journal blog.

Seascape context matters more than habitat condition for fish assemblages in coastal ecosystems

Ecosystems are increasingly degraded, fragmented and lost because of human activities globally. These impacts cause changes in the distribution of biodiversity and key ecological functions, modifications to food webs and reductions in ecosystem condition and seascape connectivity. Understanding whether, and how, the spatial context (i.e. extent, position) and condition (i.e. structure and condition of patches, including habitat forming species) of ecosystems coalesce to support their function as animal habitats is critical for effective and cost efficient coastal management. These potential combined, or interactive, effects of spatial context and habitat condition on fish assemblages are, however, rarely quantified. We sampled fish assemblages from six different ecosystems (mangrove, seagrass, saltmarsh, log snag, rocky outcrop and unvegetated sediment) across 13 estuaries in eastern Australia and quantified the relative importance of spatial context and habitat condition variables for fish assemblage composition. Spatial context variables were consistently more important than habitat condition in structuring fish abundance and diversity. Sites that were closer to smaller vegetated habitats (i.e. mangrove and seagrass) and key seascape features (i.e. estuary mouth and intertidal flats) typically supported diverse fish assemblages in high abundance. While the composition of fish assemblages was primarily linked to spatial context variables, habitat condition variables that index food availability were also important for fish in mangroves, seagrass and rocky outcrops. Our results show that fish abundance and diversity are intimately linked to seascape connectivity and heterogeneity, and have important implications for conservation planning and fisheries management decisions in coastal ecosystems. We highlight the importance of quantifying the influence of the combined effects of habitat condition and spatial context for biodiversity across multiple ecosystems, and expect the outcomes to lead to more efficient and effective management planning.

Un-biodegradable and biodegradable plastic sheets modify the soil properties after six months since their applications

Nowadays, microplastics represent emergent pollutants in terrestrial ecosystems that exert impacts on soil properties, affecting key soil ecological functions. In agroecosystems, plastic mulching is one of the main sources of plastic residues in soils. The present research aimed to evaluate the effects of two types of plastic sheets (un-biodegradable and biodegradable) on soil abiotic (pH, water content, concentrations of organic and total carbon, and total nitrogen) and biotic (respiration, and activities of hydrolase, dehydrogenase, β-glucosidase and urease) properties, and on phytotoxicity (germination index of Sorghum saccharatum L. and Lepidium sativum L.). Results revealed that soil properties were mostly affected by exposure time to plastics rather than the kind (un-biodegradable and biodegradable) of plastics. After six months since mesocosm setting up, the presence of un-biodegradable plastic sheets significantly decreased soil pH, respiration and dehydrogenase activity and increased total and organic carbon concentrations, and toxicity highlighted by S. saccharatum L. Instead, the presence of biodegradable plastic sheets significantly decreased dehydrogenase activity and increased organic carbon concentrations. An overall temporal improvement of the investigated properties in soils covered by biodegradable plastic sheets occurred.

Microplastics cause neurotoxicity and decline of enzymatic activities in important bioturbator Hediste diversicolor

Microplastics (MPs) tend to accumulate in marine sediments thus benthic fauna is particularly vulnerable to microplastic pollution. Hediste diversicolor is a widespread species in coastal marine sediments. It plays key ecological functions mostly related to bioturbation process which means sediment reworking due to the worm burrowing activity and building a network of galleries. Herein, we show that commercial plastic microspheres of two sizes (63–75 and 300–355 μm) have the potential to cause neurotoxicity in H. diversicolor. The whole-body acetylcholinesterase (AChE) activity – a common indicator of neurotoxic effect - was on average 60% lower in polychaetes exposed for 28 days to MPs served at environmentally relevant concentrations (0.08% sediment d. wt.), than in unexposed ones. Significantly reduced activities of antioxidant enzymes (SOD, CAT, GST) indicated suppression of the cellular antioxidative system in worms exposed to MPs. No changes were, however, observed in tGSH, lipid or protein oxidation measures (CBO, MDA), and in the energetic value of these polychaetes. The response was generally similar with no regard to MPs size. Only very few microspheres were found in polychaetes exposed to MPs spiked sediment.The potential role of MPs-associated pollutants as a factor responsible for observed biochemical effects, is discussed.

Incorporating Ecosystem Service Multifunctionality and Its Response to Urbanization to Identify Coordinated Economic, Societal, and Environmental Relationships in China

Urbanization poses a threat to ecosystems and contributes to the degradation of the environment. It is of great importance to identify coordinated economic, societal, and environmental relationships with key ecological functions and services to achieve regional sustainability. Based on a case study in China, this study seeks to fill this gap by estimating the spatial distribution of ecosystem service multifunctionality (ESM) and its spatially heterogeneous response to urbanization. First, the biophysical values of five typical ecosystem services (ESs) (carbon storage, habitat quality, net primary production, soil conservation, and water yield) were assessed based on several simulation models. The biophysical values of these ESs were then standardized and summed to obtain the spatial distribution of ESM. Afterward, the urbanization level was evaluated, and finally, the spatial interaction between urbanization and ESM was exhibited based on the bivariate Moran’s I and Getis-Ord Gi* statistic. The results showed that: (1) the ESM showed obvious spatial heterogeneity in southeastern and northwestern China, with a gradual decline from the coast to the interior; (2) ESM and urbanization had different spatial distribution patterns and produced significant local aggregation effects; and (3) harmonious relationships between ESM and urbanization were observed in southeastern coastal China and the surrounding areas of the North China Plain, which were related to the capacity of local coastal ecosystems, mangrove forests, and aquatic ecosystems to provide multiple services and goods simultaneously. Our results suggest that multifunctional ecosystems can realize a ‘win–win’ situation for ecological conservation and socioeconomic development. The results of this study can advance our understanding of the ecological effects of urbanization on ecosystems and provide valuable implications for the coordinated development of humans and nature in the rapid urbanization process.

Meta-analysis of the impact of freeze–thaw cycles on soil microbial diversity and C and N dynamics

Reduction in snow cover is a prominent aspect of global change. Freeze–thaw cycles (FTCs) of different amplitudes and durations in soil due to insufficient thermal insulation may alter microbial diversity and key ecological functions mediated by microorganisms. These changes could then further alter the cycling of material and energy in the ecosystem. Yet despite many assessments, the impact of FTCs upon microbial diversity remains poorly understood. Here, 546 observations from 61 published studies were collected for a global meta-analysis with the objective to explore how soil microbial diversity and C and N dynamics it drives respond to FTCs. The results showed that: in general, FTCs did not lead to a reduction of microbial α-diversity, but they did reduce levels of soil microbial biomass carbon, microbial biomass nitrogen, and phospholipid fatty acid by 7%, 12%, and 11%, respectively; they also significantly changed the microbial community structure. FTCs did not significantly affect the α-diversity of bacteria and fungi, but community structures of both were changed significantly, with that of the bacteria more sensitive to FTCs. FTCs were responsible for a 6% decrease in functions related to C, N cycling, which could be explained by the changes found in microbial biomass and community structure. FTCs could also indirectly impact microbial biomass via changed pH and soil water content (SWC). The response of microbial community to FTCs was related to the FTC frequency, freezing temperature and sampling time. FTCs had a large effect on the C and N pool components and fluxes in soil. It is particularly noteworthy that FTCs drove a 137% increase in N2O emission. Further, the changes in pH and SWC directly affected the C and N pool components and fluxes. The results of current meta-analysis deepen the comprehensive understanding of the effects of FTCs on the soil microbial community and C and N dynamics it mediated, and provide a reference for subsequent research in terms of experimental scheme and scientific issues requiring close attention.

Epipelic diatom diversity as a bioindicator in River Aturukuku, Eastern Uganda

ABSTRACT Background Despite their key ecological functions and application in biomonitoring, little is known about the algal flora in Uganda, especially those of lotic systems. Aim This study related the community composition of the epipelic diatoms to environmental variables to establish the influence of rural and urban activities on water quality and on the biota on spatial and seasonal scales along River Aturukuku in Eastern Uganda. Methods Epipelic diatoms and selected environmental variables were compared among sites: two urban, a reference site upstream, and a site downstream from the urban area, spanning the dry and wet seasons from February to October, 2018. Results Total phosphorus and nitrogen concentrations were above the natural threshold in the river. The diatom species such as Gyrosigma attenuatum and Placoneis gastrum, tolerant of pollution, dominated in the river. Total phosphorus, pH, temperature, and bottom substrates were most related to the composition of the diatom communities. The abundances of P. gastrum and Sellaphora nyassensis correlated with increased pH at the urban sewage effluent, suggesting that they are potential indicators of this kind of polluted environment. Conclusions: The study provides baseline information on diatom community, and is relevant for biomonitoring and biodiversity conservation in Uganda and other tropical countries.

Habitat wise distribution of ants with special reference to their host plants in Kholahat Reserve Forest, Assam, India

Ants play a major role in the terrestrial ecosystem by conducting many key ecological functions. The present study was undertaken to investigate the habitatwise distribution of ants in Kholahat Reserve Forest, Assam. The ants were collected from forest habitat, grassland habitat and human habitat from September 2017 to August 2020. A total of 30 ant species belonging to 22 genera and 6 Subfamilies were recorded. The Shannon diversity indices indicated that the diversity was highest in forest habitat (3.32), followed by grassland habitat (3.29) and lowest in human habitat (3.04). The Sorenson’s similarity index was highest between forest and grassland habitat while lowest between forest and human habitat. Six ant species were observed in teak and sal trees, while nine ant species were observed exclusively foraging on the soil during the daytime.

Evaluating Communities’ Willingness to Participate in Ecosystem Conservation in Southeast Tibetan Nature Reserves, China

Southeast Tibet is significant in maintaining key ecological functions and providing irreplaceable ecosystem services but is also extremely vulnerable and susceptible to the impacts of human activities. Understanding the attitudes of local residents toward ecosystem conservation is considered essential for nature resource management. We therefore aimed to conduct an evaluation framework under hypothetical scenarios to measure communities’ willingness to participate in ecosystem conservation using the contingent valuation method (CVM). Second, this study determined the underlying factors that might affect local’s willingness to participate and then compared the willingness to pay (WTP) and willingness to work (WTW) for different types of nature reserves. We found that income, education, community attachment, and acceptance of a payment scheme are significant factors determining the average amount that residents are willing to pay for ecosystem conservation, while their income, acceptance of a work scheme, and education are significant factors influencing the average service time that residents are willing to devote to work. Our results revealed that community residents have considerable willingness to participate in ecosystem conservation, which points not only to the great value attached to the ecosystem service function of Southeast Tibet nature but also suggests that people’s willingness to participate is influenced by a conglomeration of socio-economic characteristics and their previous experience. The information herein can be used to implement conservation planning that involves community co-management and policymaking for sustainable development and will be beneficial to the dynamic conservation and adaptive management of Tibetan nature reserves.

A conservation planning framework for China’s national key ecological function area based on ecological risk assessment

National Key Ecological Functions Areas (NKEFAs) in China perform critical ecological functions and play a key role in ensuring the ecological safety of a large region or the whole country. Conservation planning in NKEFAs needs to scientifically locate conservation areas and development sites to support the "globally conserved, locally developed" strategy. However, popular conservation planning approaches often underestimate the impacts of natural and anthropogenic stressors and thus fail to handle the conflicts between conservation and development goals. This article proposes a conservation planning framework (CP-NKEFA) to overcome the limitations of popular conservation planning approaches and fulfill the conservation planning requirements of China's NKEFAs. Conservation planning is converted to an ecological risk assessment problem to integrate natural and anthropogenic stressors analysis with ecosystem service (ES) evaluation. The framework clarifies stressor types and quantifies stressor risks and ES importance to set conservation, development, and buffer zones. As a case study, the framework was implemented in Changyang County, China, an NKEFA for water and soil retention in the Three Gorges Reservoir Region. The framework is more useful than typical ecological redline zoning for instructing conservation and development spatial arrangement with a multi-category zoning scheme. The zoning results protect the areas vulnerable to natural and anthropogenic stressors or significant for ES provisions. Furthermore, the buffer zone prevents direct impacts of human activities on conservation areas and permits trade-offs between conservation and development goals. Except for NKEFAs, the framework also applies to conservation planning in other areas where conservation and development goals must be handled.

草地生态系统植被变化的自然与人为因素定量区分方法

定量区分导致草地生态系统植被变化的自然和人为因素，是生态系统科学管理和保育的关键。因此，综述当前应用较为广泛的定量区分方法，包括主成分分析法、层次分析法、残差趋势法和模型差值法等，比较不同方法的计算原理、优势及误差来源，进而结合典型区域或典型生态系统，对不同方法进行对比和分析。总体而言，每种方法各有其优势和缺点，当前采用同一方法在不同区域或生态系统类型应用的研究较多，但针对方法本身改进或优化的研究较少。此外，针对同一区域开展的不同区分方法间的结果也存在差异。定量区分的结果除受方法本身算法的局限外，也受数据源的时空连续性及分辨率的影响。未来定量区分方法将强调：（1）在指标的选取上，要兼顾全面、多角度、不冗余等原则；（2）进行多源数据与多时空尺度融合，在更高时空分辨率定量区分自然与人为因素，从单一因子的贡献率区分到更多综合性指标的贡献率区分；（3）对定量区分方法本身的改进，这是当前的重点与难点。以期为生态系统适应性管理与关键生态功能的针对性保育提供科学依据和政策导向。;Quantitative assessment the impact of natural factors and anthropogenic factors on grassland ecosystem changes is vital to grassland scientific protection and restoration. Therefore, this paper reviewed and summarized the quantitative assessment methods which are widely used at present, including principal component analysis (PCA), analytic hierarchy process (AHP), residual trend (RESTREND) method and ecosystem model method (difference between remote sensing model and process-based ecosystem model or climate-productivity model). We focused on comparing the algorithm, advantages and drawbacks of different methods. Furthermore, these methods were summarized and analyzed in combination with the typical region or typical ecosystems. In general, each method had its own advantages and disadvantages in data acquisition, temporal and spatial resolution. At present, many studies focused on the application of the same method in different regions or grassland types, but few studies focused on the improvement or optimization of the method itself. In addition, even in the same region and the same grassland type, the results of quantitative assessment of natural and anthropogenic factors on vegetation changes of grassland ecosystem varied in different methods. Besides the limitations of their own calculation methods, the results of quantitative assessment of natural and anthropogenic factors were also affected by the spatial and temporal resolution and continuity of the natural and anthropogenic data sources. In the future, we proposed that studies should focus on these aspects:(1) indicator selection was the first step of quantitative assessment, and it is particularly important to select indicators that can represent the changes of grassland ecosystem in different spatial and temporal scale from different perspectives. As for the selection of natural and anthropogenic factors indicators, we should also pay attention to the non-redundancy and non-correlation between indicators; (2) the data sources of natural and anthropogenic indicators were varied in different scales, it is vital to integrate multi-source of quantitative and qualitative data with different temporal and spatial scale to distinguish the contribution of single factor and the interaction between natural and anthropogenic factors in higher spatial and temporal resolution; (3) the improvement of quantitative assessment method itself, breaking through the limitations of existing methods, and developing new ideas and methods of quantitative assessment of natural and anthropogenic factors on vegetation changes of grassland ecosystem, which is also the key point and difficult point of the future research. For the purpose of providing scientific basis and policy guidance for adaptive management of ecosystem and targeted conservation of key ecological functions of ecosystems.

Farming intensity indirectly reduces crop yield through negative effects on agrobiodiversity and key ecological functions

Farming intensity and landscape heterogeneity influence agrobiodiversity and associated ecological functions. The relative contributions of these agroecosystem components to agricultural production remain unclear because of inter-relations and weather-dependant variations. Using a structural equation modelling approach, we estimated direct and indirect contributions of farming intensity (soil management, pesticide use and fertilisation) and landscape heterogeneity (of semi-natural covers and crop mosaic) to cereal crop production, in 54 fields (mostly wheat), in two years (24 and 30 fields). Indirect effects were evaluated through agrobiodiversity (carabid and plant communities) and ecological functions (pollination and pest control). In 2016, farming intensity had the largest direct positive effect on cereal crop yield, followed by agrobiodiversity (74% of the farming intensity impact) and ecological functions. However, the direct benefits of farming intensity were halved due to negative indirect effects, as farming intensity negatively affected within-field biodiversity and ecological functions. Overall, agrobiodiversity and farming intensity had equal net contributions to cereal crop yields, while heterogeneity of the crop mosaic enhanced biodiversity. In 2017, neither higher farming intensity nor agrobiodiversity and ecological functions could lift cereal production, which suffered from unfavourable meteorological conditions. Semi-natural habitats supported agrobiodiversity. Our study suggests that a reduction of farming intensity combined with higher heterogeneity of crop mosaic can enhance the benefits of ecological functions towards crop production. Semi-natural covers seem to play an essential role in the face of climatic events, by supporting agrobiodiversity and the potential resilience of the agroecosystem functioning.

Direct and indirect disturbance impacts on forest biodiversity

AbstractUnderstanding the responses of biodiversity to forest disturbance is critical for maintaining ecosystem integrity and key ecological functions. Ecological research in forests after major disturbance typically focuses on the direct responses of individual species or communities, often with only limited consideration of the interactions between forest structure and biodiversity. Despite this, these interactions can mediate indirect disturbance impacts throughout forest ecosystems. Using data from a decade of extensive, empirical research, we employ structural equation modeling to quantify the direct and indirect impacts of multiple stand‐replacing disturbances on elements of forest structure (basal area (BA) of dominant plant lifeforms and number of hollow‐bearing trees) and on biodiversity (plant diversity, arboreal marsupials, and avifauna) in the southeastern Australian montane‐ash forests. The number of stand‐replacing disturbances resulted in a lower species richness and lower functional dispersion of avifauna and had a strong negative influence on the number of hollow‐bearing trees. In contrast, the number of stand‐replacing disturbances increased plant species richness in the understory, after controlling for the influence of stand age. In this ecosystem, we also found evidence of ecological interactions that mediated indirect impacts. For instance, disturbance‐induced declines in the number of hollow‐bearing trees had negative impacts on the richness of arboreal marsupials. Moreover, disturbance‐induced increases in the richness of understory plants had positive impacts on avian richness, partially mitigating direct disturbance impacts. Our novel integrative study provides new insights into the mechanisms that underpin disturbance impacts in forests at the ecosystem level. This has enabled the development of a new conceptual model on forest responses to the number of stand‐replacing disturbances. By exploring interactions between elements of biodiversity, forest structure, and disturbance, our model demonstrates how disturbance‐induced changes in one measure can have cascading effects on another. This understanding will provide for an integrative approach to management and planning.

Land use effects on termite assemblages in Kenya

Termites perform key ecological functions and they also cause crop damage. Land use change resulting from agricultural intensification can result in changes in termite species diversity and abundance. Termite species occurring in natural vegetation, maize monocrop and maize-beans intercrop macrohabitats were investigated in Embu and Machakos Counties, Kenya. Influence of soil properties and seasons was also evaluated. Across the two Counties, seven termite species were recorded with Machakos County having the highest number. Additive diversity partitioning of species richness and Simpson diversity showed that, α component contributed to 98.3% and 99.1% of the total diversity, respectively. Population densities of three termite species significantly varied between land use types in Machakos County but there were no differences in termite species abundance in Embu County. In addition, there were no significant differences in species richness between macrohabitats within each County. In Embu, season significantly influenced the abundance of Macrotermes subhyalinus, M. herus, and Coptotermes formosanus which occurred in greater numbers during the wet season. There was a significant influence of land use on Trinervitermes gratiosus and C. formosanus in Machakos with both species occurring in higher numbers in natural vegetation. Trinervitermes gratiosus was negatively associated with Mn and positively correlated to pH and sand. Macrotermes subhyalinus and M. herus showed a positive association with P and silt while C. formosanus was positively correlated to Ca and Mg. These findings provide an insight into the effects of land use change from natural vegetation to maize agro-ecosystems on termite diversity. It also provides a baseline for further studies on termite diversity in Kenya and their ecological significance.

Indigenous impacts on north Australian savanna fire regimes over the Holocene

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.

Contrasting altitudinal patterns and co-occurrence networks of soil bacterial and fungal communities along soil depths in the cold-temperate montane forests of China

Soil bacterial and fungal communities with different key ecological functions play important roles in boreal forest ecosystems. Although several studies have reported on the altitudinal distribution patterns of microbes, our understanding of the characteristics of the microbial community and the core composition of the microbiome in cold-temperate montane forests is still limited. In this study, Illumina MiSeq sequencing was used to investigate the changes in soil bacterial and fungal communities in surface and subsurface soils along an altitudinal gradient (from 830 m to 1300 m) on Oakley Mountain. The diversity of the bacterial and fungal communities showed a monotonic decrease and a monotonic increase with altitude, respectively. The influence of altitude on the bacterial and fungal community composition was stronger than that of soil depth. The variations in pH and dissolved organic nitrogen content at different altitudes were the main factors influencing the bacterial and fungal community structures, respectively. There was no obvious difference between the network structures of the surface and subsurface soil fungal communities, while the network of the subsurface soil bacterial community was more complex and intricate than that of the surface soil bacterial community. The network nodes mainly belonging to Proteobacteria and Actinobacteria were the key bacterial taxa in the two soil layers. Although the main drivers of microbial community structure are consistent for whole and sub-nerwork communities, the subnetwork community analysis revealed other important drivers (i.e. soil temperature and nitrate nitrogen) that do not capture by whole community analysis. Thus, the more comprehensive picture of the important factors shaping microbial community structure can be achieved by combining whole and subnetwork community analyses. Our results demonstrated that altitude had a stronger influence on soil bacterial and fungal communities than soil depth and that bacterial and fungal communities showed divergent patterns with altitude and soil depth.

Disturbance alters the forest soil microbiome.

Billions of microorganisms perform critical below-ground functions in all terrestrial ecosystems. While largely invisible to the naked eye, they support all higher lifeforms, form symbiotic relationships with ~90% of terrestrial plant species, stabilize soils, and facilitate biogeochemical cycles. Global increases in the frequency of disturbances are driving major changes in the structure and function of forests. However, despite their functional significance, the disturbance responses of forest microbial communities are poorly understood. Here, we explore the influence of disturbance on the soil microbiome (archaea, fungi and bacteria) of some of the world's tallest and most carbon-dense forests, the Mountain Ash forests of south-eastern Australia. From 80sites, we identified 23,277 and 19,056microbial operational taxonomic units from the 0-10cm and 20-30cm depths of soil respectively. From this extensive data set, we found the diversity and composition of these often cryptic communities has been altered by human and natural disturbance events. For instance, the diversity of ectomycorrhizal fungi declined with clearcut logging, the diversity of archaea declined with salvage logging, and bacterial diversity and overall microbial diversity declined with the number of fires. Moreover, we identified key associations between edaphic (soil properties), environmental (slope, elevation) and spatial variables and the composition of all microbial communities. Specifically, we found that soil pH, manganese, magnesium, phosphorus, iron and nitrate were associated with the composition of all microbial communities. In a period of widespread degradation of global forest ecosystems, our findings provide an important and timely insight into the disturbance responses of soil microbial communities, which may influence key ecological functions.