Environmental controls of raised-bog vegetation in the Baltic boreo-nemoral zone

Raised peat bogs harbor unique vegetation types in specific hydrological conditions. Environmental controls of peat bog vegetation are relatively well known for the boreal zone, while in the European boreo-nemoral zone healthy raised bogs are nowadays very rare. By contrast, Latvia, located in the transition zone between the nemoral and the boreal biomes, still has a large number of active raised bogs. The aim of the present study was to characterize the environmental controls on raised bog vegetation structure, species composition and ecology in Latvia. The study includes 17 raised bogs, where vascular plants, bryophytes and lichens were recorded in 480 sample plots and related to environmental variables (microtopography, litter cover, electric conductivity, pH, and macroelements Na, K, Ca, Mg and P in bog surface waters). The factor best explaining total species richness and composition was microtopography, which also affected most other explanatory factors. Thereby total species richness and cover were highest on hummocks. However, the importance and direction of the effects of microtopography and the other factors differed between vegetation groups. When disregarding microtopography, species composition was most strongly correlated with alkaline ions and litter cover and for bryophytes also with vascular plant cover. The present study is the first wide-scale study in Latvia relating raised bog vegetation to environmental conditions.     

Seasonal Influences on the Ecology of Testate Amoebae (Protozoa) in a Small <Emphasis Type="Italic">Sphagnum</Emphasis> peatland in Southern Ontario,Canada

Testate amoebae (Protozoa) were studied in spring, summer, and fall from the same microhabitats in a small Sphagnum-dominated peatland in southern Ontario, Canada. A total of 32 sampling stations were established in two wetland plant communities, 19 in an open Ericaceae low-shrub community and 13 in a closed Picea mariana and Larix laricina swamp community. Sphagnum was collected in each station for analysis of testate amoebae and measurement of soil water content parameters and water table depth in May, August, and October 2001. pH and dissolved oxygen of the groundwater under the Sphagnum were measured also. A total of 52 taxa including the rotifer, Habrotrocha angusticollis, were identified. Soil water content and water table variables emerged as the primary factors separating testate amoebae between the open bog/fen community and swamp community. Testate amoebae in the open bog/fen community showed a clear separation between the May sampling period and the August and October sampling periods. Sampling stations in May had much higher water table and were wetter than those in August and October. Conversely, testate amoebae in the swamp community did not show a clear difference between sampling periods. Soil moisture and water tables appear to be more constant in the swamp communities. Biological factors or other microscale environmental factors may need to be considered to explain seasonal changes in testate amoebae. A greater understanding of relationships between testate amoebae and microenvironmental factors is necessary to track seasonality in testate amoebae distributions.     

Methane Biogeochemistry and Methanogen Communities in Two Northern Peatland Ecosystems,New York State

Rates of methane (CH₄) production vary considerably among northern peat-forming wetlands, and it is not clear whether variability is caused by environmental factors affecting CH₄ production or differences in methanogen communities. We investigated CH₄ production and emission dynamics concomitantly with 16S rRNA gene sequence-based community analysis of Archaea in two contrasting peat-forming northern wetlands, an ombrotrophic bog and a minerotrophic conifer swamp. Individual measurements of CH₄ emissions to the atmosphere followed a lognormal distribution pattern in both sites, and mean rates were 30× greater in the bog site. Rates of CH₄ production measured in vitro were initially 3× greater in the bog than in the conifer swamp; although, after 30 days of incubation, production rates were similar suggesting that in situ environmental conditions limited production in the conifer swamp. Amplified ribosomal DNA restriction analysis (ARDRA) and rarefaction techniques indicated that both sites had similar levels of archaeal richness, with 27 unique taxa in the bog and 23 taxa in the conifer swamp. However, the bog had more pronounced dominance of a few taxa, whereas the conifer swamp had more even distribution among taxa. A 16S rRNA gene sequence-based phylogenetic analysis indicated high levels of diversity with similarity to known methanogenic families Methanosarcinaceae, Methanosaetaceae, Methanobacteriaceae, and likely Methanomicrobiaceae as well as two additional lineages previously characterized as groups of yet uncultivated Euryarchaeota commonly occurring in flooded rice soils. Therefore, sites with low and high rates of CH₄ production supported very diverse methanogenic communities.     

A synthesis of methane emissions from 71 northern,temperate, and subtropical wetlands

Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30‐day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30‐day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release.     

苔草草丘恢复湿地的景观格局变化——以哈尔滨太阳岛为例

湿地景观变化是湿地生态学领域研究的重要内容。湿地景观要素在不同时间和空间的变化过程研究是揭示湿地演变规律,开展生态恢复实践的重要科学基础。以哈尔滨太阳岛苔草草丘恢复湿地为例,采用野外调查与3S技术相结合的方法,选取草丘面积、斑块形状特征、草丘数量及形态特征等指标,探究草丘湿地恢复过程中的景观变化,为开展湿地恢复提供了重要的科学依据。结果表明:经过8年的恢复,苔草草丘景观变化明显。草丘数量增多,丘墩高度、直径、植株高度、冠幅显著增加(P0.05);湿地恢复后,苔草群落向外扩展722 m~2,苔草草丘总面积达2222 m~2,扩展率为48.13%;在湿地微地貌和水文条件等因素的综合作用下,草丘群落扩展方向具有一定规律性,斑块边界和质心分别向西南方向扩展了29.91 m和迁移了5.9 m,扩展度和曲线边界比重不断增加,斑块形状和边界趋于复杂,景观空间异质性增强;利用根茎克隆繁殖结合水位调控可实现苔草草丘的快速恢复。     

Peatland establishment on mineral soils: Effects of water level, amendments, and species after two growing seasons

Recent surveys of peatland initiation that occurred over the past 10,000 years in northeastern Alberta have revealed that most peatlands initiated by paludification, or swamping of upland soils. Peatland ecologists have long known the importance of the paludification process, but it has not been transferred to peatland restoration methodologies. We initiated this study to determine if wetland structure and function could be re-established on two well sites established with mineral fill within a peatland complex. At two well sites near Peace River, AB, the mineral material was lowered to near the water level of the surrounding peatland. We placed 288 plots of 2 m × 2 m in size using a series of fertilizer, water level, cultivation, and amendment treatments and then introduced a suite of wetland plants. Four questions are addressed: - (1) Will locally available peatland vascular plant species establish on these wet, compacted, mineral soils? If so: (2) are species responses affected by these treatments? (3) are plants that we did not introduce in the planting regime (weeds) a concern? and (4) will the surrounding bog water chemistry have an effect on water in contact with mineral soils? Results after two growing seasons are - (1) Carex aquatilis and Salix lutea have all successfully established at both well sites; (2) C. aquatilis plants (ramets) have increased to an average of 58.5 per plot, up from the 16 original genets planted; (3) the plant responses to amendments are not significantly different from the control plots; (4) weed abundance is significantly different among some amendment types; and (5) pad ditch water chemistry is affected by the surrounding bog waters.     

Microtopography enhances nitrogen cycling and removal in created mitigation wetlands

Natural wetlands often have a heterogeneous soil surface topography, or microtopography (MT), that creates microsites of variable hydrology, vegetation, and soil biogeochemistry. Created mitigation wetlands are designed to mimic natural wetlands in structure and function, and recent mitigation projects have incorporated MT as one way to attain this goal. Microtopography may influence nitrogen (N) cycling in wetlands by providing adjacent areas of aerobic and anaerobic conditions and by increasing carbon storage, which together facilitate N cycling and removal. This study investigated three created wetlands in the Virginia Piedmont that incorporated disking-induced MT during construction. One site had paired disked and undisked plots, allowing an evaluation of the effects of this design feature on N flux rates. Microtopography was measured using conventional survey equipment along a 1-m circular transect and was described using two indices: tortuosity (T), describing soil surface roughness and relief, and limiting elevation difference (LD), describing soil surface relief. Ammonification, nitrification, and net N mineralization were determined with in situ incubation of modified ion-exchange resin cores and denitrification potential was determined using denitrification enzyme assay (DEA). Results demonstrated that disked plots had significantly greater LD than undisked plots one year after construction. Autogenic sources of MT (e.g. tussock-forming vegetation) in concert with variable hydrology and sedimentation maintained and in some cases enhanced MT in study wetlands. Tortuosity and LD values remained the same in one wetland when compared over a two-year period, suggesting a dynamic equilibrium of MT-forming and -eroding processes at play. Microtopography values also increased when comparing the original induced MT of a one-year old wetland with MT of older created wetlands (five and eight years old) with disking-induced MT, indicating that MT can increase by natural processes over time. When examined along a hydrologic gradient, LD increased with proximity to an overflow point as a result of differential sediment deposition and erosion during flood events. Nitrification increased with T and denitrification potential increased with LD, indicating that microtopographic heterogeneity enhances coupled N fluxes. The resulting N flux patterns may be explained by the increase in oxygen availability elicited by greater T (enhancing nitrification) and by the adjacent zones of aerobic and anaerobic conditions elicited by greater LD (enhancing coupled nitrification and denitrification potential). Findings of this study support the incorporation of MT into the design and regulatory evaluation of created wetlands in order to enhance N cycling and removal.     

Reading the landscape: temporal and spatial changes in a patterned peatland

The Everglades of south Florida is a patterned peatland that has undergone major hydrologic modification over the last century, including both drainage and impoundment. The Everglades ridge and slough patterns were originally characterized by regularly spaced elevated ridges and tree islands oriented parallel to water flow through interconnected sloughs. Many areas of the remaining Everglades have lost this patterning over time. Historical aerial photography for the years 1940, 1953, 1972, 1984, and 2004 provides source data to measure these changes over six decades. Maps were created by digitizing the ridges, tree islands, and sloughs in fifteen 24 km² study plots located in the remaining Everglades, and metrics were developed to quantify the extent and types of changes in the patterns. Pattern metrics of length/width ratios, number of ridges, and perimeter/area ratios were used to define the details and trajectories of pattern changes in the study plots from 1940 through 2004. These metrics characterized elongation, smoothness, and abundance of ridges and tree islands. Hierarchical agglomerative cluster analysis was used to categorize these 75 maps (15 plots by 5 years) into five categories based on a suite of metrics of pattern quality. Nonmetric multidimensional scaling, an ordination technique, confirmed that these categories were distinct with the primary axis distinguished primarily by the abundance of elongated ridges in each study plot. Strong patterns like those described historically were characterized by numerous, long ridges while degraded patterns contained few large, irregularly shaped patches. Pattern degradation usually occurred with ridges fusing into fewer, less linear patches of emergent vegetation. Patterning improved in some plots, probably through wetter conditions facilitating expression of the underlying microtopography. Trajectories showing responses of individual study plots over the six decades indicated that ridge and slough patterns can degrade or improve over time scales of a decade or less. Changes in ridge and slough patterns indicate that (1) patterns can be lost quickly following severe peat dryout, yet (2) patterns appear resilient at least over multi-decadal time periods; (3) patterns can be maintained and possibly strengthened with deeper water depths, and (4) the sub-decadal response time of pattern changes visible in aerial imagery is highly useful for change detection within the landscape. This analysis suggests that restoration of some aspects of these unique peatland patterns may be possible within relatively short planning time frames. Use of aerial photography in future Everglades restoration efforts can facilitate restoration and adaptive management by documenting sub-decadal pattern changes in response to altered hydrology and water management.     

滇西北高原纳帕海湿地土壤氮矿化特征

采用树脂芯原位培育法,研究了纳帕海沼泽、沼泽化草甸和草甸土壤氮的矿化特征。结果表明,铵态氮（NH₄⁺-N）为沼泽、沼泽化草甸土壤中无机氮的主要存在形式,分别占无机氮含量的96.76%和75.24%,而硝态氮（NO₃^--N）为草甸土壤中无机氮的主要存在形式,占无机氮含量的58.77%。植物生长期内,纳帕海湿地土壤的净氮矿化速率表现为沼泽化草甸 > 草甸 > 沼泽,表明干湿交替的土壤环境更利于土壤氮矿化作用的进行,土壤中氮素有效性和维持植物可利用氮素的能力更强。整个生长季,沼泽和草甸土壤氮矿化为硝化作用,而沼泽化草甸土壤氮矿化为氨化作用。土壤硝态氮含量、有机质含量、碳氮比和含水量均对纳帕海沼泽、沼泽化草甸和草甸土壤的氮矿化产生显著影响。     

Short-term changes in soil nutrients during wetland creation

This study examined changes in pH and extractable nutrients in soilsfollowing wetland creation. Sample plots were established in two areas: (1) an old-field with parts that were flooded during wetland creation, and (2) a native wetland in a floodplain of the Ohio River called Green Bottom Swamp. Soils were sampled before inundation and eight months afterwards. Compared to old-field soils in the pre-inundation period, swamp soils exhibited: (1) higher acidity, (2) lower NO3 and higher NH4 concentrations, (3) higher extractable P, Fe, and Mn, and (4) lower Ca, Mg, and Zn concentrations. Eight months after inundation, the old-field soil redox decreased from +210 mV in the old field –290 mV, and extractable NO3 and Ca decreased and extractable NH4 and Fe increased, but pH and extractable P, Mn, Mg, and Zn changed either slightly or not at all. These results suggest that eight months is an insufficient period of time for a complete change. Other results suggest that the response of nitrogen during the wetland creation processes may be extremely rapid.     

Short-term changes in soil nutrients during wetland creation

This study examined changes in pH and extractable nutrients in soilsfollowing wetland creation. Sample plots were established in two areas: (1) an old-field with parts that were flooded during wetland creation, and (2) a native wetland in a floodplain of the Ohio River called Green Bottom Swamp. Soils were sampled before inundation and eight months afterwards. Compared to old-field soils in the pre-inundation period, swamp soils exhibited: (1) higher acidity, (2) lower NO3 and higher NH4 concentrations, (3) higher extractable P, Fe, and Mn, and (4) lower Ca, Mg, and Zn concentrations. Eight months after inundation, the old-field soil redox decreased from +210 mV in the old field ?290 mV, and extractable NO3 and Ca decreased and extractable NH4 and Fe increased, but pH and extractable P, Mn, Mg, and Zn changed either slightly or not at all. These results suggest that eight months is an insufficient period of time for a complete change. Other results suggest that the response of nitrogen during the wetland creation processes may be extremely rapid.

     

受损湿地植被的恢复与重建研究进展

 自20世纪90年代以来,有关受损湿地植被恢复与重建的研究大量涌现。在大量文献调研的基础上,对湿地植被恢复的目的、优先原则、策略和途径、理论、技术、长期监测及评价作了回顾,对贫营养沼泽和富营养沼泽的恢复技术作了详细总结。湿地恢复的策略主要有修复和重建,指导理论主要有次生演替、自设计和入侵理论等。泥炭地植被受损后的恢复技术主要有播种法、泥炭藓片段散布法、营养体移植法、草皮移植法等。种子(繁殖体)库在植被恢复中的作用也不可忽视。恢复初期的抚育和管理必不可少。最后指出了湿地恢复研究中亟待解决的问题。     

围栏禁牧对滇西北高寒湿地土壤活性有机碳的影响

过度放牧导致滇西北高寒湿地碳汇功能逐渐丧失,围栏禁牧作为一种有效的湿地恢复方式,其对滇西北高寒湿地土壤碳库的影响尚缺乏研究。为探明围栏禁牧对滇西北高寒湿地土壤活性有机碳的影响,以纳帕海湿地不同禁牧年限(未禁牧、禁牧3年、禁牧8年、禁牧10年)的草甸和沼泽化草甸作为研究对象,对比分析不同禁牧年限草甸和沼泽化草甸土壤总有机碳(TOC)、颗粒有机碳(POC)、溶解性有机碳(DOC)、易氧化有机碳(EOC)和微生物生物量碳(MBC)含量特征。研究结果表明,随着禁牧年限的增加(<10 a),草甸和沼泽化草甸土壤TOC、DOC、EOC、MBC含量显著增加(P<0.05);随着土壤深度的增加,草甸和沼泽化草甸土壤TOC、EOC和MBC含量逐渐下降,而POC和DOC含量逐渐增加。土壤理化性质显著影响土壤活性有机碳各组分含量,其中总氮(TN)是影响草甸和沼泽化草甸土壤活性有机碳各组分含量的主导因素。围栏禁牧有利于滇西北高寒湿地土壤质量和固碳能力的恢复,且随着禁牧年限的增加,恢复效果越明显。相同恢复年限,纳帕海沼泽化草甸土壤恢复效果比草甸土壤显著。研究可以为放牧湿地恢复研究提供理论基础。     

Species richness in boreal swamp forests of SE Norway: The role of surface microtopography

Question: What is the relative importance of environmental gradients and surface microtopography (variation in vertical level within sampling units) for fine‐scale plant species richness in Picea abies swamp forests? Location: 11 swamp forests in SE Norway. Methods: We recorded species richness (number of species of vascular plants, mosses, Sphagnum and hepatics), depth to water table, soil base status and vertical range (microtopographic relief) in 2400 microplots, (each 1/16 m²), in 150 1‐m² plots in the 11 swamp forests. Relationships between species richness and environmental predictors were modelled by GLMM. Results: Moss and hepatic species richness increased with increasing microtopographic relief, most strongly for wet acid sites, in which similar trends were also found for Sphagnum. Relief was a poor predictor of vascular plant species richness. Conclusions: Microtopographic relief is a good predictor of local species richness in Picea abies swamp forests, partly because larger vertical variability means higher within‐plot habitat diversity with respect to the wet‐dry gradient, and partly because qualitatively new microhabitats associated with steep slopes are added in drier sites. The relationship between species richness and microtopographic relief is context dependent, differing in complex ways among species groups and among sites with different environmental conditions.     

Seasonal changes in the chemical quality and biodegradability of dissolved organic matter exported from soils to streams in coastal temperate rainforest watersheds

The composition and biodegradability of streamwater dissolved organic matter (DOM) varies with source material and degree of transformation. We combined PARAFAC modeling of fluorescence excitation–emission spectroscopy and biodegradable dissolved organic carbon (BDOC) incubations to investigate seasonal changes in the lability of DOM along a soil-stream continuum in three soil types: bog, forested wetland and upland forest. The percent BDOC ranged from 7 to 38% across all sites, and was significantly greater in soil compared to streamwater in the bog and forested wetland, but not in the upland forest. The percent BDOC also varied significantly over the entire sampling period in soil and streamwater for the bog and forested wetland, as BDOC peaked during the spring runoff and was lowest during the summer months. Moreover, the chemical quality of DOM in wetland soil and streamwater was similar during the spring runoff and fall wet season, as demonstrated by the similar contribution of protein-like fluorescence (sum of tyrosine and tryptophan fluorescence) in soil water and in streams. These findings suggest that the tight coupling between terrestrial and aquatic ecosystems is responsible for the delivery of labile DOM from wetland soils to streams. The contribution of protein-like fluorescence was significantly correlated with BDOC (p < 0.001) over the entire sampling period indicating DOM is an important source of C and N for heterotrophic microbes. Taken together, our findings suggest that the production of protein-rich, labile DOM and subsequent loss in stream runoff might be an important loss of labile C and N from coastal temperate watersheds.     

三江平原建三江地区30年湿地景观退化评价

因高强度农业开发,1975～2004年的30a间,三江平原自然湿地景观发生了剧变.评估该湿地景观面临的各种压力、分析其所处状态、揭示其演变规律,对于三江平原的湿地保护和恢复至关重要.选取1975年、1989年和2004年的三期Landsat TM遥感影像,基于压力-状态-响应的生态评价框架,对黑龙江省建三江地区景观演变进行分析.结果表明,(1)从1975年到2004年,建三江地区自然湿地大幅减少,农田大幅增加,景观多样性和破碎度显著提高;农业开发是自然湿地面临的主要压力,其中草甸和沼泽湿地是主要的开发对象.(2) 1975～1989年的农业开发强度高于1989～2004年.1975～1989年,农田、沟渠面积大幅增加,湿地面积大量减少;通过沟渠排水将湿地开发为旱田,导致该区生态环境质量下降,洪涝灾害频繁;1989～2004年,人们意识到湿地保护的重要性,自然湿地开垦减少,沟渠面积略有增加,并把部分旱田转为水田来达到"以稻治涝"的目的;同时,建立了多个湿地自然保护区并制定了相应的湿地保护条例,使得该区的湿地景观得到了一定的保护.(3) 当前三江平原湿地景观面临的问题依然严峻,尤其是排水沟渠的大量存在和旱田转化为水田后导致的水资源短缺和地下水位下降等问题,还将继续威胁现有湿地的存续,基于沟渠系统的综合性水资源管理势在必行.     

Soil amendments promote denitrification in restored wetlands

Wetlands perform important ecosystem functions, including improvement of water quality through the process of denitrification. To offset the negative environmental impact of replacing wetlands with agriculture and development, the United States has a policy requiring that losses in wetland area are compensated for through wetland restoration elsewhere. However, these restored wetlands may require decades to achieve functional equivalency to natural wetlands. We evaluated the efficacy of using carbon amendments during restoration to promote denitrification potential in four restored wetlands in central New York State, United States. The amendments were straw, topsoil, and biochar, chosen to range along a gradient of carbon lability. Soil samples collected 6 years after restoration were analyzed for denitrification potential and associated soil properties, including soil carbon and nitrogen, pH, microbial biomass carbon and nitrogen, carbon lability, and potential net nitrogen mineralization and nitrification. Compared to unamended control plots, denitrification potential was approximately 3 times higher in straw‐amended plots, 8 times higher in topsoil‐amended plots, and 11 times higher in biochar‐amended plots. Denitrification potential positively correlated with both soil organic carbon and microbial biomass nitrogen, suggesting that the use of soil amendments in restorations can help stimulate the development of denitrification potential by facilitating the suite of carbon and nitrogen cycling processes that underlie this function. However, denitrification potential in a nearby natural reference wetland was at least 50 times higher than it was in the restored wetland plots, highlighting the limitations of using wetland restoration to compensate for the loss of natural wetlands.     

Comparison of mosquito (Diptera: Culicidae) populations by wetland type and year in the lower river Dal?lven region, Central Sweden

We studied adult mosquito assemblages in six wetlands, representing three types (wet meadow, alder swamp, and bog), in the lower part of the River Dal?lven in Central Sweden during three consecutive years (2000-2002) and evaluated the influence of wetland type and year. Mosquito abundance differed significantly between years but not between wetland types. Mosquito species richness showed no significant variation between years or wetland types. Cluster analysis based on percentage of similarity resulted in three clusters, with high similarity between all wetlands in 2000. Ordination analysis showed that mosquito assemblages were mainly correlated with wetland type and water level increase in the previous month. Hydrological conditions varied between the years and between the wetland types, and our collections also included a year (2000) with extreme flood situations. The floodwater mosquito species Ochlerotatus sticticus was the predominant species with a strong influence on the whole study due to its long-range dispersal ability. The entire region suffered from enormous numbers of Oc. sticticus in 2000. The data from this study provided the basis for the initiation of a mosquito control project in the region.     

If we build – they mostly come: partial functional recovery but persistent compositional differences in wetland beetle community restoration

There is growing evidence of restoration success for wetland plant communities. However, little research has been done on the associated invertebrate community. We test whether restoring plant communities after peat extraction is sufficient for restoring the taxonomic and functional composition of beetle communities. We monitored taxonomic and trait‐based community metrics for beetle assemblages on restoration islands that were up to 13 years old and compared these with the adjacent “target” undisturbed peat bog. Recovery of beetle abundance, species richness, and trophic structure on the islands was remarkably rapid (i.e. within a decade) and converged on that of the undisturbed peat bog within 13 years after restoration commenced. In contrast, small, native, and poor‐dispersing taxa were persistently less abundant on the islands than in the undisturbed peat bog, causing persistent differences in species composition, even on the oldest islands. These poor‐dispersers probably need assistance to reach the islands and possibly ongoing intervention to allow them to survive there. Our findings emphasize the potential for functional trait analysis to reveal barriers to full restoration of insect community composition.     

Responses of Pioneer and Later‐Successional Plant Assemblages to Created Microtopographic Variation and Soil Treatments in Riparian Forest Restoration

Riparian forest restoration generally involves introduction of later‐successional tree species, but poor species suitability to severely altered or degraded site conditions results in high mortality and poor community development. Additionally, while microtopographic heterogeneity plays a crucial role in the development of natural riparian forests, little is known regarding effects of restored or created microtopography on the development of introduced plant communities. The objective of this study was to determine the influence of created microtopography and soil treatments on early development of introduced pioneer and later‐successional plant communities in riparian forest restoration. Ridges, flats, and a mound‐and‐pool complex were created, and pioneer and later‐successional tree assemblages were planted within plots in each of these three microtopographic positions. Straw‐based erosion control mats were placed on half the plots as a source of mulch. After two growing seasons, growth and survival of the pioneer assemblage were equal among microtopographic positions, but survival of the later‐successional assemblage was significantly higher on ridges (59%) than on mounds and pools (22%) and flats (26%). A suitability index indicated that performance of the later‐successional assemblage on ridges was higher than that of the pioneer assemblage for all microtopographic positions. Flood duration explained much of the variation in plant assemblage survival, and erosion control mats had little influence on seedling survival. Restoring microtopographic features has the potential to enhance species survival and promote community development. Microtopographic restoration may be as important in riparian forest restoration as proper species selection and hydrologic reestablishment, especially at severely disturbed sites.