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Drainage-induced shifts in physicochemical peat properties are irreversible on a decadal time span. We investigated whether carbon emissions from fen peat can be estimated using two proxies: current water levels and peat properties (as affected by drainage history, i.e. degradation legacy). We collected bare peat monoliths from a long-term drained and an undrained fen. In a crossed design, half of the monoliths was kept wet and the other half was drained. Highest carbon dioxide (CO2) emissions came from the originally undrained peat under low water levels (607 mmol m-2 d-1). Overall, CO2 emissions were primarily determined by drainage history, with 141 % higher emissions from the originally undrained peat. In addition, low current water levels correlated with 42 % higher emissions. Highest methane (CH4) emissions were measured in the originally undrained peat under high water levels (123 mmol m-2 d-1). Overall, CH4 emissions were primarily determined by current water levels, with 430 % higher emissions under high water levels. In addition, the originally undrained peat had 180 % higher emissions. The lower C efflux from originally drained peat correlated with lower concentrations of methanogens and of easily-degradable carbon substrate (cellulose). We conclude that substrate limitation in long-term drained fens ensures low baseline carbon emissions, which provides opportunities for renewed carbon sequestration by rewetting. [ABSTRACT FROM AUTHOR]

In tropical regions the extent of agricultural land is increasing rapidly at the expense of natural forest, with associated losses of biodiversity and ecosystem services. Agroforestry has long been proposed as a more sustainable agricultural system, conserving biodiversity while providing significant local livelihoods. In this context, camera traps were deployed to compare communities of large mammals between natural forest (22,272 hours across 24 deployments) and extensively managed coffee forest (19,059 hours, 23 deployments) for the first time in the south-west Ethiopian highlands. Mammal communities in the two forest types were similar in species richness and Shannon diversity but differed in community composition. Significant indicator species of coffee forest were the crested porcupine Hystrix cristata and the Ethiopian hare Lepus fagani, whereas leopards Panthera pardus and civets Civettictis civetta had a preference for natural forest. The number of detections of mammals was higher in coffee forest, where activity patterns were predominantly crepuscular and nocturnal, which may be a direct adaptation to frequent human disturbance. In natural forest, mammal activity peaked during daytime. Despite the high mammal diversity in extensively managed coffee forest, it cannot fully replace natural forest as a habitat for large mammals. We suggest that a balanced landscape mosaic of coffee and natural forest may be a valuable combination for both conservation and coffee cultivation. [ABSTRACT FROM AUTHOR]

Despite the importance of water purification to society, it is one of the more difficult wetland ecosystem services to quantify. It remains an issue in ecosystem service assessments where rapid estimates are needed, and poor-quality indicators are overused. We attempted to quantify the water purification service of South African palmiet wetlands (valley-bottom peatlands highly threatened by agriculture). First, we used an instantaneous catchment-scale mass balance sampling approach, which compared the fate of various water quality parameters over degraded and pristine sections of palmiet wetlands. We found that pristine palmiet wetlands acted as a sink for water, major cations, anions, dissolved silicon and nutrients, though there was relatively high variation in these trends. There are important limitations to this catchment-scale approach, including the fact that at this large scale there are multiple mechanisms (internal wetland processes as well as external inputs) at work that are impossible to untangle with limited data. Therefore, secondly, we performed a small field-scale field survey of a wetland fragment to corroborate the catchment-scale results. There was a reasonable level of agreement between the results of the two techniques. We conclude that it appears possible to estimate the water purification function of these valley-bottom wetlands using this catchment-scale approach. [ABSTRACT FROM AUTHOR]

Patches are of central interest to many areas of environmental science because they provide a lower limit of structural detail in synoptic studies, and an upper limit of contextual structure for point measurement-based studies. Identification and delineation of macrophyte patches however, is often arbitrary and case-specific. In this paper we propose a widely-applicable set of guidelines for delineating a “patch” and “patch matrix” – the latter implying a collection of interacting patches – which could standardise future research. To support this proposal, we examine examples from eco-hydrological studies, focusing on interactions between plants, water flow, sediment, and invertebrates. We discuss three aspects that are key to the delineation of a patch: (1) constitution (variable(s) whose values define the patch), (2) spatial properties (patch boundaries), and (3) distinction (of isolated single patches from multiple separate-but-interacting patches). The discussion of these aspects results in guidelines for identifying and delineating a patch which is applicable to any aquatic habitat, and covers a broad range of disciplines such as plant and animal ecology, biogeochemistry, hydraulics, and sedimentology. [ABSTRACT FROM AUTHOR]

Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen’s sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration. [ABSTRACT FROM AUTHOR]

Global land-use intensification and drainage has altered the biogeochemical properties of many peatlands, and concomitant eutrophication has led to a loss of low-competitive fen species. We investigated the hypothesis that removal of a degraded and eutrophied top peat layer, thereby exposing an underlying peat layer, can improve conditions for rich fen restoration. We studied the long-term (3–18 years) effects of past topsoil removal in six rich fens in Western Europe by comparing topsoil removal plots with (untouched) control plots. Overall, topsoil removal plots were characterized by lower bulk densities and soil nutrient pools of P and KCl-extractable NH 4 + , while organic matter contents and soil C:N ratios were higher. Pore water concentrations of NO 3 − and NH 4 + also decreased in the topsoil removal plots, while concentrations of base cations (Ca 2+ , Mg 2+ , Na + , K + ) and HCO 3 − increased. Furthermore, lower nutrient levels appeared to restrict herb biomass production in the topsoil removal plots, so that optimized light conditions led to the establishment of light-demanding target species and a significant increase in bryophyte cover. Multivariate analysis revealed that most variation in vegetation assembly was due to higher groundwater levels in the topsoil removal plots, closely followed by a higher relative light intensity (RLI) at surface level, lower pore water nutrient (NH 4 + ) concentrations, and higher concentrations of base cations. We conclude that topsoil removal can be an effective mechanism to “reset” a degraded peatland to its initial state of nutrient limitation, base saturation and high availability of light, thereby improving the conservation prospects of endangered rich fen communities. [ABSTRACT FROM AUTHOR]

Foraging activity in animals reflects a compromise between acquiring food and avoiding predation. The risk allocation hypothesis predicts that prey animals optimize this balance by concentrating their foraging activity at times of relatively low predation risk, as much as their energy status permits, but empirical evidence is scarce. We used a unique combination of automated telemetry, manual radiotelemetry and camera trapping to test whether activity at high risk times declined with food availability as predicted in a Neotropical forest rodent, the Central American agouti, Dasyprocta punctata. We found that the relative risk of predation by the main predator, the ocelot, Leopardus pardalis, estimated as the ratio of ocelot to agouti activity on camera trap photographs, was up to four orders of magnitude higher between sunset and sunrise than during the rest of the day. Kills of radiotracked agoutis by ocelots during this high-risk period far exceeded expectations given agouti activity. Both telemetric monitoring of radiotagged agoutis and camera monitoring of burrow entrances indicated that agoutis exited their burrows later at dawn, entered their burrows earlier at dusk and had lower overall activity levels when they lived in areas with higher food abundance. Thus, agoutis avoided activity during the high-risk period more strongly when access to food was higher. Our study provides quantitative empirical evidence of prey animals concentrating their activity at times of relatively low predation risk. [ABSTRACT FROM AUTHOR]

Soil inoculation from plant species-rich into species-poor grasslands may enable the establishment of self-facilitating networks between microbes and vegetation, thereby steering ecosystem development. We conducted a three-year experiment that covered a wide range of post-agricultural grasslands to determine how succession is affected by the interactive effects of edaphic properties, grass layer removal and hay or soil fragment transfer from a late-successional donor grassland. Soil inoculation generally impacted community assembly of vegetation and fungi, but not of prokaryotes. Effects were strongest when preceded by removal of the grass layer, indicating the importance of priority effects and dispersal limitation. Inoculation enabled the establishment of putative rhizosphere-associated fungal taxa, particularly from the families Helotiaceae, Glomeraceae and Archaeorhizomycetaceae. Nonetheless, effect sizes were mostly small, as was overall resemblance of the receptor grasslands to the donor. Fungal communities were primarily shaped by environmental filters and only reached a high resemblance to the donor in nutrient-poor sites. Shifts in the vegetation were strongest in those grasslands where the mycobiome more closely resembled that of the donor. Soil inoculation generally facilitates colonization by target plant and fungal communities, where establishment success of the former can be predicted by the latter, but the final outcome of succession is environmentally determined. • Soil inoculation impacts community assembly of vegetation and fungi in grasslands. • Inoculation enables the establishment of putative rhizosphere-associated fungal taxa. • Local environmental filters determine the final outcome of succession. [ABSTRACT FROM AUTHOR]

Many peatlands have been affected by water table drawdown and carbon loss. Rewetting may push a drained peatland back towards its pre-degradation state and may result in renewed carbon accumulation, but there is little consensus on its effectiveness. Moreover, rewetting typically leads to a spike in methane emissions. Whether rewetting suffices to restore drained peatlands hinges to a large extent on whether microbial communities, and the functions they perform, are able to recover. We studied prokaryote communities in fens across temperate Europe using high-throughput amplicon sequencing of 16S rRNA, within the framework of RePeat (REstoration and prognosis of PEAT formation in fens - linking diversity in plant functional traits to soil biological and biogeochemical processes 2016-2019; BiodiVErSA). We included undrained, drained and rewetted fens to evaluate the effects of fen rewetting on microbial recovery. Prokaryote communities were highly stratified with depth, and there was a clear division between communities of drained and undrained fens. Prokaryote communities in rewetted fens were largely similar to those of undrained fens, but only where soil organic matter contents and bulk densities were respectively still high and low. Our results suggest that altered physio-chemical peat properties following drainage may hamper complete prokaryote recovery after rewetting, at least in the short term. [ABSTRACT FROM AUTHOR]

The formation of soil aggregates is related to the stability of soil organic carbon, which distinguishes the living conditions of microbial communities in different micro-niches. Here, we investigated fungal and bacterial community structure, networks, biomass and respiration in individual micro-niches between and within soil aggregates using seven different chronosequences (both primary and secondary successions from pioneer stages to well-developed ecosystems) on a European-scale gradient from a maritime climate in Belgium to a more continental climate in Hungary. We showed that geographical location was the most important factor (74% for bacterial community, 53% for fungal community) affecting microbial community composition, while soil aggregates (5% for bacterial community and 12% for fungal community) were the second most important factor followed by age of succession and vegetation. Moreover, aggregates (52%) were the most important factor influencing the biomass of major microbial groups, followed by location (37%) and age of succession (6%). Interestingly, macro-aggregates had less interconnected microbial networks and low microbial respiration rates compared to other aggregate sizes. We therefore hypothesize that the embedding of organic particles in the mineral matrix of macro-aggregates is a crucial point in microbial community organization, as evidenced by microbial community connectivity and microbial respiration. Our results demonstrate the importance of soil aggregates for microbial community organization and soil carbon stabilization. • Soil aggregates were an important determinant of microbial community structure and biomass. • Microbial community networks were less interconnected in macro-aggregates over wide areas. • Macro-aggregates had lower microbial respiration rates compared to the other aggregates. • Microbial community network degrees were correlated with microbial respiration. [ABSTRACT FROM AUTHOR]