Patterns and gradients of diversity in South Patagonian ombrotrophic peat bogs

Many north‐hemispherical mires seemingly untouched by drainage and cultivation are influenced by a diffuse sum of man‐made environmental changes, such as atmospherical nitrogen deposition that mask general patterns in species richness and functional group responses along resource gradients. To obtain insights into natural diversity‐environment relationships, we studied the vegetation and the peat chemistry of pristine bog ecosystems in southern Patagonia along a west–east transect across the Andes. The studied bog ecosystems covered a floristic gradient from hyperoceanic blanket bogs dominated by cushion building vascular plants via a transitional mixed type to Sphagnum‐dominated raised bogs east of the mountain range. To test the influence of resource availability on diversity patterns, species richness and functional groups were related to environmental variables by calculating general regression models and generalized additive models. Species richness showed strong linear correlations to peat chemical features and the general regression model resulted in three major environmental variables (water level, total nitrogen, NH₄Cl soluble calcium), altogether explaining 76% of variance. Functional group response illustrated a clear separation along environmental gradients. Mosses dominated at the low end of a nitrogen gradient, whereas cushion plants had their optimum at intermediate levels, and graminoids dominated at high nitrogen contents. Further shifts were related to NH₄Cl soluble calcium and water level. The models documented partly non‐linear relationships between functional group response and trophical peat properties. Within the three bog types, the calculated models differed remarkably illustrating the scale‐dependency of the explanatory factors. Our findings confirmed several general patterns of species richness and functional shifts along resource gradients in a surprisingly clear way and underpin the significance of undisturbed peatlands as reference systems for testing of ecological theory and for conservation and ecological restoration in landscapes with strong human impact.     

Comparative analysis of the phytoplankton communities of a peat bog from Tierra del Fuego (Argentina)

The phytoplankton communities of five water hollows and a river from the Rancho Hambre peat bog (Tierra del Fuego, Argentina) are compared as to species composition and densities, as well as morphological, chemical and physical data.A total of 212 taxa is reported, the river having the highest species richness (105) and algal density (6374 ind. ml^–1). Water hollows showed remarkable differences in the structure of their phytoplankton communities.A cluster analysis, based on species presence-absence, clearly distinguishes the river from the water hollows. The hollows fall into groups. One contains the shallow ones the other, the smallest, deepest ones.Correlation analyses between biotic and abiotic variates shows strong correlations between the relative frequencies of some major groups (Chrysophyceae, Euglenophyceae, Tribophyceae) and the values of abiotic variables (alkalinity, pH, conductivity and dissolved phosphate).     

Interspecific and geographical differences of plant tissue nutrient concentrations along an environmental gradient in Southern Patagonia, Chile

Foliar nutrient concentrations of South Patagonian ombrotrophic peatland species were analyzed along a gradient of increasing continentality. We paid particular attention to nutrient demands of Sphagnum magellanicum, the dominant constituent of continental raised bogs, and to those of cushion-forming vascular plants such as Astelia pumila, dominating in western hyperoceanic blanket bogs. With exception of one graminoid species, nutrient concentrations in leaf tissues were generally low, but showed considerable variation. Extremely low concentrations were measured in S. magellanicum reflecting the unpolluted, pristine character of the investigated bog ecosystems. Nutrient concentrations in cushion plants showed remarkable variation. While nutrient concentrations in Donatia fascicularis were almost as low as in S. magellanicum, they were significantly higher in A. pumila. Variation in foliar nutrient concentrations was predominantly due to differences between species. Nevertheless, there was a significant shift within species along the considered west-to-east continental gradient. The stronger minerotrophic character of the western cushion bogs was reflected by higher Ca contents. N concentrations increased and P concentrations decreased westward in most species. Consequently, the most noticeable shift was an increasing N:P ratio indicating a higher degree of P limitation towards western cushion dominated blanket bogs.     

Feral horse impacts on threatened plants and animals in sub‐alpine and montane environments in Victoria,Australia

Feral herbivores are a major driver of biodiversity loss globally and can alter the structure, composition and functioning of ecosystems. The direct impacts of feral herbivores on plant communities are well studied, but the direct and indirect effect they have on wildlife is not well understood. In Victoria (south‐eastern Australia), a large feral Horse (Equus caballus) population coincides with highly sensitive and nationally endangered Alpine Sphagnum Bogs and Associated Fens communities, and several threatened animal species. We assessed the impact of feral horses on this ecological community and the Alpine Water Skink (Eulamprus kosciuskoi) and the Broad‐toothed Rat (Mastacomys fuscus) at 20 sites with varying levels of horse disturbance. We used scat counts to determine an index of feral horse abundance and quantified impacts associated with their presence in the landscape. Active searches were used for Alpine Water Skink and scat and runway surveys for Broad‐toothed Rat. We also measured the vegetation structure and the abundance of different vegetation types (life forms). Our results suggest that feral horses are associated with vegetation types and characteristics that negatively influence the presence or abundance of Alpine Water Skink and Broad‐toothed Rat. Sites with high horse activity had more low‐growing forbs, and the abundance of Alpine Water Skink was negatively related to this vegetation type. Grasses, sedges, rushes and shrubs were also less dense and lower in height in high horse activity sites, and Broad‐toothed Rat was less likely to be present in areas with these habitat attributes. We recommend that feral horses are controlled to protect these threatened vertebrate species and their Sphagnum bog habitat.     

Natural peat bog remnants promote distinct spider assemblages and habitat specific traits

Peat bogs are very sensitive and highly endangered ecosystems. They were once typical landscape elements in northern Germany, but today only a few remnants exist. On-going habitat degradation has alarming adverse effects on biodiversity, and, from a conservation viewpoint, it is imperative to evaluate the current ecological quality of the remaining peat bog remnants to assess the intensity of degradation and to suggest reasonable management strategies. In 2007, spiders were sampled in 23 study sites representing typical peat bog habitat types in the northern parts of Westphalia (NW Germany). In all, 214 species from 18,413 adult individuals have been collected. Multivariate analyses showed that different peat bog successional stages harbour distinct spider assemblages with succession being the main driver for species separation. Pardosa sphagnicola, Pirata piscatorius and P. uliginosus can be considered as flagship species for near-natural or natural peat bogs. Trait analyses showed that habitat specialisation for high moisture is negatively affected by succession. Peat bogs are now only small remnants, but, nevertheless, they have a high conservation value as they still harbour a distinct species assemblage and specialised species.     

Classification of peatland vegetation in Atlantic Canada

Abstract. The peatlands of Atlantic Canada are classified in four plant alliances, consisting of 10 plant associations. The four plant alliances comprise the dry bog communities (Kalmio-Cladonion Wells 1981), wet bog communities (Scirpo-Sphagnion Wells 1981), hummock and ridge communities of slope and string fens (Betulo-Sphagnion Wells all. nov.), and poor, intermediate and rich fen plant communities (Scirpo-Myricion Wells 1981). Distribution maps are presented for relevés in each of the 10 associations. Based on species distributions, floristic regions are defined for peatlands in Atlantic Canada. Nutritional characteristics are also described for each plant association. pH and total soil concentrations of calcium, nitrogen and iron proved reliable in separating bog from fen. A boundary between ombrotrophic peatlands and minerotrophic peatlands is suggested, based on a soil pH of 4.0, total soil concentrations of 3.0 mg g^?1 Ca, 4.0 mg g^?1 Fe, 13.0 mg g^?1 N and a Ca/Mg ratio of 2.5. Comparisons between the syntaxa for peatlands in Atlantic Canada and those in Europe are discussed for higher taxa. The possibility of establishing a new order (Chamaedaphno-Scirpetalia Wells ord. nov.) for peatlands in Atlantic Canada is also discussed.     

Deep peat warming increases surface methane and carbon dioxide emissions in a black spruce‐dominated ombrotrophic bog

Boreal peatlands contain approximately 500 Pg carbon (C) in the soil, emit globally significant quantities of methane (CH₄), and are highly sensitive to climate change. Warming associated with global climate change is likely to increase the rate of the temperature‐sensitive processes that decompose stored organic carbon and release carbon dioxide (CO₂) and CH₄. Variation in the temperature sensitivity of CO₂ and CH₄ production and increased peat aerobicity due to enhanced growing‐season evapotranspiration may alter the nature of peatland trace gas emission. As CH₄ is a powerful greenhouse gas with 34 times the warming potential of CO₂, it is critical to understand how factors associated with global change will influence surface CO₂ and CH₄ fluxes. Here, we leverage the Spruce and Peatland Responses Under Changing Environments (SPRUCE) climate change manipulation experiment to understand the impact of a 0–9°C gradient in deep belowground warming (“Deep Peat Heat”, DPH) on peat surface CO₂ and CH₄ fluxes. We find that DPH treatments increased both CO₂ and CH₄ emission. Methane production was more sensitive to warming than CO₂ production, decreasing the C‐CO₂:C‐CH₄ of the respired carbon. Methane production is dominated by hydrogenotrophic methanogenesis but deep peat warming increased the δ¹³C of CH₄ suggesting an increasing contribution of acetoclastic methanogenesis to total CH₄ production with warming. Although the total quantity of C emitted from the SPRUCE Bog as CH₄ is <2%, CH₄ represents >50% of seasonal C emissions in the highest‐warming treatments when adjusted for CO₂ equivalents on a 100‐year timescale. These results suggest that warming in boreal regions may increase CH₄ emissions from peatlands and result in a positive feedback to ongoing warming.     

Global Peatland Restoration after 30 years: where are we in this mossy world?

As part of the Society of Ecological Restoration World Conference in 2015, we held a Global Peatland Restoration symposium, where we gave experts from around the world the mandate to provide an updated picture of peatland restoration in their part of the world and scan the horizon to identify challenges and opportunities to come. This special section was put together to make these valuable contributions available to all.     

Polytrichum Strictum as a Solution to Frost Heaving in Disturbed Ecosystems: A Case Study with Milled Peatlands

Substrate instability is a common problem in many disturbed ecosystems. In the case of milled harvested peatlands, the pioneer moss Polytrichum strictum is commonly found; it is well adapted to tolerate the harsh microclimatic conditions and peat instability of these sites. A field experiment was used to determine the effectiveness of P. strictum against frost heaving, a major type of disturbance on bare peat. Wooden dowels and fir trees (Abies balsamea) placed in a P. strictum carpet experienced almost no frost heaving, whereas heaving was severe on bare peat. Reintroduced P. strictum fragments thinly spread on bare peat reduced but did not eliminate frost heaving. Straw mulch (a protective cover often required in peatland restoration) effectively reduced heaving in the fall, but was less effective in the spring because it had partially decomposed. The P. strictum carpet, P. strictum fragments, and straw mulch reduced frost heaving by reducing the number of freeze–thaw cycles, by slowing the rate of ground thaw in the spring, and by reducing the unfrozen water content of the peat during the spring thaw. Different species of Polytrichum mosses should be considered for the restoration or regeneration of disturbed ecosystems where soil stability is problematic.     

Diatom flora of a kettle-hole bog in relation to hydrarch succession zones

Diatom assemblages were compared to the vegetational seres and to physical and chemical parameters of a kettle-hole bog which had distinct hydrarch successional zones and was in turn surrounded by a cattail marsh and a willow swamp. Multivariate analysis of variance showed the water parameters (temperature, pH, conductivity, color, free calcium) among the zones were significantly different (p < 0.0001). Diatoms were enumerated using the first 500 valves counting method and results showed each zone had a distinct flora. Cluster analysis of the diatom data by both species and zones grouped the bog successional zones into one major group and the marsh/swamp zones into the second major group. The occurrence of well defined seral stages of vegetation and diatoms suggests microorganisms are undergoing ecological succession in kettle-hole bogs.