Eco‐evolutionary dynamics in restored communities and ecosystems

Recent ecological studies have revealed that rapid evolution within populations can have significant impacts on the ecological dynamics of communities and ecosystems. These eco‐evolutionary dynamics (EED) are likely to have substantial and quantifiable effects in restored habitats over timescales that are relevant for the conservation and restoration of small populations and threatened communities. Restored habitats may serve as “hotspots” for EED due to mismatches between transplanted genotypes and the restored environment, and novel interactions among lineages that do not share a coevolutionary history, both of which can generate strong selection for rapid evolutionary change that has immediate demographic consequences. Rapid evolution that influences population dynamics and community processes is likely to have particularly large effects during the establishment phase of restoration efforts. Finally, restoration activities and their associated long‐term monitoring programs provide outstanding opportunities for using eco‐evolutionary experimental approaches. Results from such studies will address questions about the effects of rapid evolutionary change on the ecological dynamics of populations and interacting species, while simultaneously providing critical, but currently overlooked, information for conservation practices.     

Carbon budgets of wetland ecosystems in China

Wetlands contain a large proportion of carbon (C) in the biosphere and partly affect climate by regulating C cycles of terrestrial ecosystems. China contains Asia's largest wetlands, accounting for about 10% of the global wetland area. Although previous studies attempted to estimate C budget in China's wetlands, uncertainties remain. We conducted a synthesis to estimate C uptake and emission of wetland ecosystems in China using a dataset compiled from published literature. The dataset comprised 193 studies, including 370 sites representing coastal, river, lake and marsh wetlands across China. In addition, C stocks of different wetlands in China were estimated using unbiased data from the China Second Wetlands Survey. The results showed that China's wetlands sequestered 16.87 Pg C (315.76 Mg C/ha), accounting for about 3.8% of C stocks in global wetlands. Net ecosystem productivity, jointly determined by gross primary productivity and ecosystem respiration, exhibited annual C sequestration of 120.23 Tg C. China's wetlands had a total gaseous C loss of 173.20 Tg C per year from soils, including 154.26 Tg CO₂‐C and 18.94 Tg CH₄‐C emissions. Moreover, C stocks, uptakes and gaseous losses varied with wetland types, and were affected by geographic location and climatic factors (precipitation and temperature). Our results provide better estimation of the C budget in China's wetlands and improve understanding of their contribution to the global C cycle in the context of global climate change.     

Climatic change and hydrophyte-dominated communities in inland wetland ecosystems

Thoughts about the potential effects of climatic change due to greenhouse warming on hydrophytes and hydrophyte communities in inland still waters of Europe are presented. A distinction is made between permanent and temporary shallow aquatic ecosystems and between freshwater and brackish systems. Potential effects of greenhouse warming on the hydrology and salinity of isolated brackish waters are illustrated with a computer model, simulating several scenario's of climatic change and differently shaped waters.In permanent waters, greenhouse warming may result in an earlier onset of growth of those hydrophytes in which the germination of propagules and the resumption of growth is primarily controlled by temperature. This may occur at the cost of macrophytes that have dormancy mechanisms regulated by environmental cues other than temperature (e.g. photoperiod). In addition, it seems plausible that because of milder winters, some thermophilous aquatic plants spread to the north. Furthermore, in culturally eutrophicated waters, in which the sediment compartment is heavily loaded with organic matter and/or nutrients, a rise in temperature may accelerate nutrient turn-over for several years, resulting in algal blooms and shifts in quality and quantity of macrophyte vegetation.Effects of greenhouse warming on temporary shallow waters will be more complex. Changes in temperature, precipitation and evaporation may lead to larger seasonal fluctuations in the water table and a more frequent or more prolonged period of desiccation. Some hydrophytes can cope with these circumstances, while others withstand desiccation only for a short period. Macrophyte communities may also be affected in an indirect way by periodic desiccation of their habitats. In emerged bottoms the rate of mineralization is probably higher than when overlying water is present. When water returns, a pulse of mineral nutrients may temporarily result in algal blooms and a high turbidity of the water, thus hampering hydrophyte growth. In addition, in isolated brackish waters an increased evaporation may result in larger fluctuations in salinity. In such a harsh environment species diversity of aquatic macrophytes will most probably decline.     

湿地微生物介导的甲烷排放机制

湿地生态系统是陆地上巨大的有机碳库,同时也是大气中甲烷(CH_4)的主要排放源。由于CH_4对全球的增温潜能是CO2的34倍,因此关于湿地CH_4排放在全球气候变化中有关碳汇、碳源的研究具有极其重要的意义。全球80%–90%的CH_4排放离不开微生物活动,湿地生态系统中产CH_4菌和CH_4氧化菌的种类组成、数量及功能与CH_4通量密切相关,但基于湿地生态系统中介导CH_4循环的功能微生物对甲烷排放通量的影响及作用机制研究相对比较分散。为更好地认识微生物介导的CH_4排放过程的微生物调控机制,本文综述了湿地生态系统中参与CH_4循环的功能微生物,对介导CH_4循环相关微生物活性的影响因子进行了回顾,重点总结了湿地生态系统微生物介导的CH_4排放机制,并对未来的相关研究方向进行了展望。由于湿地微生物介导的碳循环过程也可能决定了湿地生态系统对全球气候变暖的反馈,因此本文也能为全球气候变化研究提供微生物方面的参考。     

Soil microbial communities in restored and unrestored coastal dune ecosystems in California

Most restoration projects involving invasive plant eradication tend to focus on plant removal with little consideration given to how these invasives change soil microbial communities. However, soil microorganisms can determine invasibility of habitats and, in turn, be altered by invasives once established, potentially inhibiting native plant establishment. We studied soil microbial communities in coastal dunes with varying invasion intensity and different restoration approaches (herbicide, mechanical excavation) at Point Reyes National Seashore. Overall, we found evidence of a strong link between bacterial and fungal soil communities and the presence of invasives and restoration approach. Heavily invaded sites were characterized by a lower abundance of putatively identified nitrifiers, fermentative bacteria, fungal parasites, and fungal dung saprotrophs and a higher abundance of cellulolytic bacteria and a class of arbuscular mycorrhizal fungi (Archaeosporomycetes). Changes in soil microbiota did not fully dissipate following removal of invasives using herbicide, with exception of reductions in cellulolytic bacteria and Archaeosporomycetes abundance. Mechanical restoration effectively removed both invasives and soil legacy effects by inverting or “flipping” rhizome‐contaminated surface soils with soils from below and may have inadvertently induced other adverse effects on soils that impeded reestablishment of native dune plants. Land managers should consider additional measures to counteract lingering legacy effects and/or focus restoration efforts in areas where legacy effects are less pronounced.     

Predicting biodiversity loss in island and countryside ecosystems through the lens of taxonomic and functional biogeography

We investigate how variation in patch area and forest cover quantified for three different spatial scales (buffer size of 500, 1500 and 3000 m radius) affects species richness and functional diversity of bat assemblages in two ecosystems differing in fragment–matrix contrast: a landbridge island system in Panama and a countryside ecosystem in the Brazilian Amazon. Bats were sampled on 11 islands and the adjacent mainland in Panama, and in eight forest fragments and nearby continuous forest in Brazil. Species–area relationships (SAR) were assessed based on Chao1 species richness estimates, and functional diversity–area relationships (FAR) were quantified using Chao1 functional diversity estimates measured as the total branch length of a trait dendrogram. FARs were calculated using three trait sets: considering five species functional traits (FAR_ALL), and trait subsets reflecting ‘diet breadth’ (FAR_DIET) and ‘dispersal ability’ (FAR_DISPERSAL). We found that in both study systems, FAR_ALL was less sensitive to habitat loss than SAR, in the sense that an equal reduction in habitat loss led to a disproportionately smaller loss of functional diversity compared to species richness. However, the inhospitable and static aquatic matrix in the island ecosystem resulted in more pronounced species loss with increasing loss of habitat compared to the countryside ecosystem. Moreover, while we found a significant FAR_DISPERSAL for the island ecosystem in relation to forest cover within 500 m landscape buffers, FAR_DIET and FAR_DISPERSAL were not significant for the countryside ecosystem. Our findings highlight that species richness and functional diversity in island and countryside ecosystems scale fundamentally differently with habitat loss, and suggest that key bat ecological functions, such as pollination, seed dispersal and arthropod suppression, may be maintained in fragments despite a reduction in species richness. Our study reinforces the importance of increasing habitat availability for decreasing the chances of losing species richness in smaller fragments.     

Microbially mediated climate feedbacks from wetland ecosystems

Wetlands are crucial nodes in the carbon cycle, emitting approximately 20% of global CH₄ while also sequestering 20%–30% of all soil carbon. Both greenhouse gas fluxes and carbon storage are driven by microbial communities in wetland soils. However, these key players are often overlooked or overly simplified in current global climate models. Here, we first integrate microbial metabolisms with biological, chemical, and physical processes occurring at scales from individual microbial cells to ecosystems. This conceptual scale-bridging framework guides the development of feedback loops describing how wetland-specific climate impacts (i.e., sea level rise in estuarine wetlands, droughts and floods in inland wetlands) will affect future climate trajectories. These feedback loops highlight knowledge gaps that need to be addressed to develop predictive models of future climates capturing microbial contributions. We propose a roadmap connecting environmental scientific disciplines to address these knowledge gaps and improve the representation of microbial processes in climate models. Together, this paves the way to understand how microbially mediated climate feedbacks from wetlands will impact future climate change.     

Linking soil process and microbial ecology in freshwater wetland ecosystems

Soil microorganisms mediate many processes such as nitrification, denitrification, and methanogenesis that regulate ecosystem functioning and also feed back to influence atmospheric chemistry. These processes are of particular interest in freshwater wetland ecosystems where nutrient cycling is highly responsive to fluctuating hydrology and nutrients and soil gas releases may be sensitive to climate warming. In this review we briefly summarize research from process and taxonomic approaches to the study of wetland biogeochemistry and microbial ecology, and highlight areas where further research is needed to increase our mechanistic understanding of wetland system functioning. Research in wetland biogeochemistry has most often been focused on processes (e.g., methanogenesis), and less often on microbial communities or on populations of specific microorganisms of interest. Research on process has focused on controls over, and rates of, denitrification, methanogenesis, and methanotrophy. There has been some work on sulfate and iron transformations and wetland enzyme activities. Work to date indicates an important process level role for hydrology and soil nutrient status. The impact of plant species composition on processes is potentially critical, but is as yet poorly understood. Research on microbial communities in wetland soils has primarily focused on bacteria responsible for methanogenesis, denitrification, and sulfate reduction. There has been less work on taxonomic groups such as those responsible for nitrogen fixation, or aerobic processes such as nitrification. Work on general community composition and on wetland mycorrhizal fungi is particularly sparse. The general goal of microbial research has been to understand how microbial groups respond to the environment. There has been relatively little work done on the interactions among environmental controls over process rates, environmental constraints on microbial activities and community composition, and changes in processes at the ecosystem level. Finding ways to link process-based and biochemical or gene-based assays is becoming increasingly important as we seek a mechanistic understanding of the response of wetland ecosystems to current and future anthropogenic perturbations. We discuss the potential of new approaches, and highlight areas for further research.     

不同干扰方式下松江湿地土壤微生物群落结构和功能特征

以松江湿地为研究对象,采用磷脂脂肪酸(PLFA)和BIOLOG微平板法,系统分析4种干扰方式(农业、工业、旅游和保护)对湿地土壤微生物群落结构和功能的影响。结果表明,微生物对碳源利用能力由强到弱依次为:滨江湿地(保护)金河湾湿地(旅游)白鱼泡湿地(旅游)太阳岛湿地(旅游)呼兰河口湿地(农业)阿什河湿地(工业)。松江湿地土壤微生物对羧酸类、糖类和氨基酸类碳源利用率较高,而对多聚物类、酚类和胺类的利用率较低,其中羧酸类和糖类是影响微生物群落代谢功能的敏感碳源。松江湿地土壤微生物以细菌为主,占总PLFA的69.72%—80.97%,真菌次之(9. 20%—23. 51%),放线菌最少(6.77%—9.82%); Shannon多样性指数以滨江湿地最高(2.994),阿什河湿地最低(2.881)。RDA分析表明,受工业、农业干扰的阿什河湿地和呼兰河口湿地微生物群落结构与TN、NO_3~--N和NH_4~+-N呈显著正相关(P0.05);受旅游干扰的太阳岛湿地微生物群落结构与pH呈显著正相关;而同样受旅游干扰的白鱼泡和金河湾湿地微生物群落结构与p H呈显著负相关;受保护的滨江湿地微生物群落结构主要受TC/TN影响。     

Nitrogen mineralization,nitrification and denitrification in upland and wetland ecosystems

Summary Nitrogen mineralization, nitrification, denitrification, and microbial biomass were evaluated in four representative ecosystems in east-central Minnesota. The study ecosystems included: old field, swamp forest, savanna, and upland pin oak forest. Due to a high regional water table and permeable soils, the upland and wetland ecosystems were separated by relatively short distances (2 to 5 m). Two randomly selected sites within each ecosystem were sampled for an entire growing season. Soil samples were collected at 5-week intervals to determine rates of N cycling processes and changes in microbial biomass. Mean daily N mineralization rates during five-week in situ soil incubations were significantly different among sampling dates and ecosystems. The highest annual rates were measured in the upland pin oak ecosystem (8.6 g N m^–2 yr^–1), and the lowest rates in the swamp forest (1.5 g N m^–2 yr^–1); nitrification followed an identical pattern. Denitrification was relatively high in the swamp forest during early spring (8040 g N₂O–N m^–2 d^–1) and late autumn (2525 g N₂O–N m^–2 d^–1); nitrification occurred at rates sufficient to sustain these losses. In the well-drained uplands, rates of denitrification were generally lower and equivalent to rates of atmospheric N inputs. Microbial C and N were consistently higher in the swamp forest than in the other ecosystems; both were positively correlated with average daily rates of N mineralization. In the subtle landscape of east-central Minnesota, rates of N cycling can differ by an order of magnitude across relatively short distances.     

Clonal plants and plant species diversity in wetland ecosystems in China

Abstract. Clonal plants play important roles in maintaining wetland ecosystems in China. By analysing 108 wetland quadrats distributed throughout China, we evaluated (1) the importance of clonal growth forms in different Chinese wetlands, (2) how the abundance of clonal plants is related to climatic and geographical conditions, and (3) how plant species diversity is related to the abundance of clonal plants. Significant differences in clonal plant importance values were found between different regions of China. Clonal plants were more important in wetland ecosystems located towards the West and North and at higher elevations and, accordingly, experiencing a colder and drier climate. Plant species diversity showed a significant inverse correlation with the importance value of ‘guerilla’‐type plants in most of the wetland regions. However, we found no significant correlation between plant species diversity and importance values of ‘phalanx’‐type plants. In most Chinese wetlands, plant species diversity decreased with increasing importance of guerilla plants and also with an increase of the entire guild of clonal plants. In wetlands with low species richness, however, plant species diversity increased with increasing importance of guerilla plants and of all clonal plants together, suggesting that in these disturbed habitats clonal growth may facilitate the establishment of other, non‐clonal wetland plants.     

Area reduction and trace element pollution in Nile Delta wetland ecosystems

The three main Nile Delta wetland ecosystems, Manzala, Burullus and Edku lagoons, are among the most ecologically important and productive habitats in Egypt. We studied the area degradation and the human health risks associated with trace metal accumulation in Tilapia zillii harvested from these lakes. The area of Manzala lagoon has shrunken from about 3035 km² in 1800 to about 288 km² in 2015, the area of Edku has shrunken from about 336 km² in 1824 to about 18 km² in 2014, and the area of Burullus has shrunken from about 1116 km² in 1949 to about 546 km² in 2014. This area degradation is attributed to drying for housing, land reclamation and fish farming. As a result, the concentration of pollutants and nutrients has subsequently increased, and large parts of the lakes have been overgrown with aquatic vegetation, which increased the rate of degradation and land transformation. Metal pollution was detected in water, sediment and edible fish harvested from the lakes. The hazard index, an indicator of human health risks associated with fish consumption, showed adverse health effects of zinc and lead metals for habitual fish consumers. The impact of the high dam on the lakes was discussed.     

农果复合系统营养物质的盈亏平衡特征

采用盈亏平衡分析方法,对黄土高原南部3个村农果复合型生态农业的营养物质平衡进行了研究.结果表明,施肥是农果复合生态系统营养物质的主要输入途径.输入的营养物质中,化石能所占比重较大,而有机肥投入相对不足.农果复合生态系统内用于循环的N、P、K仍远低于营养物质N、P、K的输出量.3村营养物质的产投比虽有差异,但总体水平仍很低.     

Hydrological and biogeochemical processes in wetland ecosystems in relation to biodiversity restoration

Wetlands Ecology and Management -     

Plant community establishment in a restored wetland: Effects of soil removal

Question: This study investigated the establishment of wetland plant assemblages following soil removal and restored hydrology in a former agricultural field. The following questions were posed. Does plant community composition differ as a result of soil removal? Does soil removal reduce the frequency of non-wetland plants? Does soil removal reduce the frequency of non-native invasive plants? Location: The Panzner Wetland Wildlife Reserve (PWWR) in Summit County, northeastern Ohio, USA. Methods: During 2000–2001, restoration was conducted on two adjoining fields (3.9 ha total) by excavating the upper 40–50 cm of soil layer and establishing 12 10 m × 10 m undisturbed control plots. Preliminary data included seed bank composition and soil organic matter, estimated from three different soil depths on the control plots. In spring 2004, a 10 m × 10 m soil-removed plot was established adjacent to each control plot. Plant percent cover of all species was estimated within the center 5 m × 5 m of every plot. Above-ground biomass of all species from three 0.25-m² quadrats was collected. Environmental water measurements included water depth, temperature, dissolved oxygen, pH, and conductivity. Results: The top 10 cm of soil contained the most seeds, the highest species diversity, the greatest proportion of annual to perennial plants, and the lowest organic content. Obligate and facultative wetland plants were found in soil-removed plots while facultative upland and upland plants were found in control plots. The only plots with arable weeds were the control plots. However, plant communities on soil-removed plots in the North field, which had a higher elevation (ca. 15–20 cm), had a different species composition than soil-removed plots in the South field. Conclusions: The results of a controlled, replicated large-scale study on the effects of soil removal showed that soil removal altered both the biotic and abiotic environment, but that the proximity to the water table was the primary controlling factor in the assembly of plant communities.     

Effects of fathead minnows and restoration on prairie wetland ecosystems

SUMMARY 1. Research has shown that fish influence the structure and processes of aquatic ecosystems, but replicated studies at the ecosystem level are rare as are those involving wetlands. Some wetlands of the Prairie Pothole Region (PPR) of North America support fish communities dominated by fathead minnows ( Pimephales promelas ) while others are fishless, providing an opportunity to assess the influence of these fish on wetland ecosystems. Additionally, many wetlands have previously been drained and subsequently restored, but the success of these efforts is poorly known and restoration may be impeded by the presence of fish.
2. We assessed the effects of fathead minnows and drainage by studying 20 semipermanent, prairie wetlands in Minnesota from 1996 to 1999. We used a 2 × 2 factorial design to examine the effects of presence and absence of minnows and drainage history (restored/never drained) on the abundance of aquatic invertebrates and amphibians, as well as on the concentrations of chlorophyll a , total phosphorus, total nitrogen and turbidity in the water column.
3. Results showed that fathead minnows are an important determinant of many biotic and abiotic characteristics of wetlands in the eastern PPR. Wetlands with fathead minnows had fewer aquatic insects, large- and small-bodied cladocerans, calanoid copepods, ostracods and larval tiger salamanders, as well as a higher abundance of corixids and greater turbidity and chlorophyll a . A higher concentration of phosphorus in restored basins was the only consistent effect of past management.
4. Fathead minnows usually dominate fish communities in eastern PPR wetlands where fish are present, and can have several strong ecosystem effects. While abiotic variables are important determinants of ecosystem structure in prairie wetlands, they can be strongly influenced by biotic factors.     

Tracking wetland loss to improve evidence-based wetland policy learning and decision making

At the core of any evidence-based policy analysis are accurate data and the policy analytic capacity of government agencies to use these data to develop and measure metrics of policy success. This study evaluated the government’s policy capacity to manage wetlands in Alberta, Canada, by measuring and evaluating three policy metrics: (1) no net change of wetland area; (2) permitted versus unpermitted wetland loss; and (3) an information tracking system that provides credible regulatory oversight. Using a climate-corrected wetland loss inventory, we detected the loss of 242 wetlands, totaling 71 ha, in the Beaverhill subwatershed between 1999 and 2009. The majority of the losses occurred on land that were classified as ‘developed’ (urban and industrial) or ‘agriculture’. When wetland loss was compared to government-issued wetland permit data, we found that over 80 % of the wetland area was lost without a government permit. The wetland permit data also revealed serious problems with information tracking by both government and non-government agencies responsible for policy and regulatory oversight. In order to resolve these common policy failures, governments need to commit more resources towards acquiring, effectively managing, and freely sharing information that can be used to evaluate policy outcomes to ‘open up’ wetland management and decision making to include active participation from informal institutions, local governments, and the general public as a means to drive improved regulatory oversight.     

Effects of vegetation and hydrologic load on sedimentation patterns in experimental wetland ecosystems

Vegetation and water velocity effects on patterns of sediment deposition were tested by monitoring sedimentation rates in dense cattail, open water, and transitional vegetation zones at distances of 5, 10, and 20 m from the inflows of two experimental wetland basins at the Des Plaines River Wetlands Demonstration Project, northeastern Illinois, USA. One basin received a high hydrologic load (up to 50 cm/wk) and one basin received a low load (up to 6 cm/wk). Sediment deposition rates within 20 m of the inflows reached 3300 g dry wt m⁻² day⁻¹ in the high-load basin and 700 g dry wt m⁻² day⁻¹ in the low-load basin. Vegetation patterns did not have a significant effect (P > 0.05) on sediment deposition rates in the high-load basin, whereas water velocity effects on rates of sedimentation were significant (P < 0.01) in three of four periods of monitoring. In the low-load basin, vegetation effects were significant (P < 0.01) during the entire period of investigation. Experimental research at this scale aids in the assessment of design criteria for constructed wetlands.