Persistence of high elevation fens in the Southern Rocky Mountains,on Grand Mesa,Colorado, U.S.A.

Small headwater fens at high elevations exist in the dry climatic regime of western Colorado, despite increasing demands for water development since the 1800’s. Fens on Grand Mesa have accumulated plant material as peat for thousands of years due to cold temperatures and consistently saturated soils. The peatlands maintain unique plant communities, wildlife habitat, biodiversity, and carbon storage. We located and differentiated 88 fens from 15 wet meadows and 2 marshes on Grand Mesa. Field work included determining vegetation, soils, moisture regimes, and impacts from human activities. All fens were groundwater-supported systems that occurred in depressions and slopes within sedimentary landslide and volcanic glacial till landscapes. Fens occupied 400 ha or less than 1 % of the 46,845 ha research area and ranged in size from 1 to 46 ha. Peat water pH in undisturbed sites ranged from 4.3 to 7.1. Most fens had plant communities dominated by sedges (Carex) with an understory of brown mosses. Variation in vegetation was controlled by stand wetness, water table level, organic C, conductivity (EC), and temperature °C. Fen soils ranged from 13.6 to 44.1 % organic C with a mean of 30.3 %. Species diversity in fens was restricted by cold short growing seasons, stressful anaerobic conditions, and disturbance. Multivariate analysis was used to analyze relationships between vegetation, environmental, and impact variables. Stand wetness, water table level, OC, electrical conductivity (EC), and temperature were used to analyze vegetation variance in undisturbed fens, wet meadows, and marshes. Vegetation composition in impacted fens was influenced by flooding, sedimentation, stand wetness, water table level, OC, EC, and temperature. Hydrologically modified fens supported 58 plant species compared to 101 species in undisturbed fens. Analysis of historical 1936–2007 aerial photographs and condition scalars helped quantify impacts of human activities in fens as well as vegetation changes. Fourteen fens had evidence of peat subsidence, from organic soil collapse, blocks of peat in the margins, soil instability, and differences in surface peat height between the fen soil surface and the annually flooded soil surface. Of 374 ha of fens in the Grand Mesa study area, 294 ha (79 %) have been impacted by human activities such as ditching, drainage, flooding, or vehicular rutting. Many fens had little restoration potential due to severe hydrological and peat mass impacts, water rights, or the cost of restoration.     

Divergent Pathways of Successional Recovery for In Situ Oil Sands Exploration Drilling Pads on Wooded Moderate‐Rich Fens in Alberta,Canada

Peatlands in northern Alberta, Canada, are being rapidly impacted by oil sands activities, with potentially long‐term consequences for their recovery. In situ oil sands extraction requires exploration of oil resources on a dense network of drilling pads across the landscape. This study examined the recovery of wooded moderate‐rich (WMR) fens 10 years after abandonment of these sites with minimal restorative measures. Bryophyte and vascular plant diversity, site microtopography, and water chemistry were assessed on drilling pads and in adjacent areas of undisturbed reference habitat. WMR fens affected by drilling activities were divided a priori into two groups based on strongly divergent trends in their successional development. One group represented the majority of WMR fens observed on the land base; at these sites hummock‐forming mosses including minerotrophic Sphagnum species were infrequent and tree recruitment was almost absent. The other group was dominated by Sphagnum species, had Picea mariana and Larix laricina recruitment, and appeared to recover more quickly. Both groups had high abundance of wetland sedges, notably Carex aquatilis. Further, drilling pads belonging to the first group had a high water table, limited elevated microsites, and had surface flooding over a portion of the growing season, in contrast to Sphagnum‐dominated sites. Development of the aquatic, bryophyte‐poor wetland type is comparable to early stages of wetland succession and these systems will recover relatively slowly, likely from decades to more than a century. Restoring part of the vertical distribution of microhabitats before abandonment of these pads could stimulate the successional recovery of vegetation.     

Roadside revegetation with native plants: Experimental seeding and transplanting of stem cuttings

Questions: Can we use local native plants for roadside revegetation? What cultural methods help enhance the process? Location: Trans Canada Highway, Terra Nova National Park, Newfoundland. Objectives: To (1) test stratification requirements for seed ger‐mination, (2) determine if germination, survival and growth of seedlings and stem cuttings of selected plants can be increased by mulching treatments and (3) identify native plants and cultural treatments useful for revegetation. Methods: We tested seed germination of Kalmia angustifoliaIris versicolorJuncus effususEriophorum vaginatum, Clintonia borealis and Cornus canadensis in a greenhouse experiment. We conducted field experiments of roadside revegetation using seeds of K. angustifolia, I. versicolorJ. effusus and E. vaginatum, as well as seedlings of I. versicolor and rooted stem cuttings of Emptrum nigrum and Juniperus communis after hay‐mat mulch and organic matter mulch application. Results: Stratified seeds of K. angustifoliaI. versicolor, J. effusus and E. vaginatum germinated successfully in the greenhouse, whereas C. borealis and C. canadensis seeds did not. Along roadsides, only I. versicolor seeds germinated. Iris versicolor cover increased significantly in organic matter mulch compared to hay‐mat mulch and control. Transplanted I. versicolor seedlings had high survival in all treatments but growth was reduced in organic matter mulch. Survival and growth of stem cuttings of E. nigrum and J. communis were significantly increased on hay‐mat mulch. Application: Rooted stem cuttings of E. nigrum and J. communis planted on hay‐mat mulch can be used as a practical method of roadside revegetation. These shrubs have low structure, are evergreen, and exhibit stress‐tolerance properties, which make them ideal species for roadside revegetation. They are also non‐palatable to wildlife. Roadside ditches can be revegetated by seeds or seedlings of I. versicolor. Robust roots and rhizomes of this plant may provide soil stability and dark green leaves and attractive flowers create aesthetically pleasing vegetation cover.     

Use of soil transfer for reforestation on abandoned mined lands in Alaska

Soil transfers from an intermediate successional site and a mature forest site were applied to Populus balsamifera L. cuttings and Alnus crispa (Ait.) Pursh seedlings placed on an abandoned mined site in south central Alaska to improve plant establishment. Mycorrhizal fungi in the soil transfers from the two successional stages were hypothesized to have different effects on plant species that colonize disturbed sites at different times or on different substrates. The site consisted of coarse, dry, low-nutrient spoils and was naturally colonized by scattered P. balsamifera but not A. crispa, although seed sources for both were adjacent to the site. Physical dimensions of the transplanted seedlings and cuttings were measured at the beginning and end of each growing season. Selected plants were harvested at the end of the 2-year study and examined for mycorrhizal formation, current growth, and leaf tissue nutrient concentrations. Both plant species were taller when treated with the soil transfers from the mature forest than with soils from the intermediate site although the increase for A. crispa was greater. Physical dimensions, current growth, and nutrient concentrations were greater when A. crispa was treated with the mature soil transfer compared with the intermediate soil transfer. Mycorrhizae which infected Alnus were predominantly a brown woody type, while other types accounted for greater relative mycorrhizal infection percentage on Populus. Insufficient quantities of mycorrhizal inoculum of suitable species, as well as low moisture and low nutrient conditions, may be factors limiting A. crispa colonization on primary disturbed sites in south central Alaska.     

Revegetation of Roadcut Slopes in Mesa Verde National Park, U.S.A.

The geology of Mesa Verde National Park (MVNP) poses unique problems to road construction and maintenance. Major geologic formations of the Park consist of an overlying resistant sandstone cap underlain by highly erodable shales. Once this sandstone cap is removed, the shales are easily eroded away, creating the notable mesas of the region. In many places, road construction has removed the sandstone layer and vegetation resulting in unaesthetic barren slopes that require continual maintenance and have proven difficult to revegetate. An experiment was conducted to evaluate the effectiveness of several cultural techniques combined with seeding and transplanting indigenous plants for revegetation of these roadcut slopes. Techniques evaluated were fertilization, mulching, soil pitting, and polyacrylamide amendments. Replicated test plots were established at three roadcut sites in MVNP to evaluate these techniques by measuring percent plant cover by species over a 4‐year period. A combination of seeding grasses and transplanting forbs and shrubs appeared to be the optimal way to maintain species diversity and structure on the roadcuts while accomplishing the goal of revegetating these difficult sites. The perennial forb Aster glaucodes and the shrub Artemisia ludoviciana showed high survival when transplanted in the experimental roadcut sites. These species, as well as the perennial grass Pascopyrum smithii, also established well from seed. The addition of an organic fertilizer, in combination with mulch, proved to be the most effective method of improving vegetation cover for these and other transplanted species.     

Transplanting Sedges (Carex spp.) in Southwestern Riparian Meadows

Abstract The success of revegetation efforts in southwestern U.S. riparian meadows has been limited because natural recolonization is often poor and little is known about establishment of transplanted native meadow species such as sedges. To evaluate their potential use in riparian restoration, the survival and growth of transplanted wildlings of three sedge species, Carex lanuginosa (woolly sedge), C. nebrascensis (Nebraska sedge), and C. rostrata (beaked sedge), were assessed. Transplanting occurred during two seasons (summer and fall) using two transplant sizes (295 and 680 cm³) at seven montane meadow sites in Arizona. Survival was similar among species, but shoot numbers were greater for C. lanuginosa (12.7 shoots/wildling) compared with C. nebrascensis (5.5 shoots/wildling) and C. rostrata (7.9 shoots/wildling). Survival was significantly greater for the summer transplant season (55.1%) versus fall (24.1%). Survival and growth were greater for the larger transplant size (46.1% large vs. 33.0% small; 8.1 shoots/wildling large vs. 6.4 small). Wildling survival was related to depth to groundwater for each species. Survival was highest for C. lanuginosa (78.6%), C. nebrascensis (88.2%), and C. rostrata (64.3%) where the groundwater depth was ?48 to ?60, ?28 to ?47, and ?8 to ?27 cm, respectively. These results suggest that restoration will be most successful if transplanting occurs in summer, using large wildling transplants when under stressful conditions such as waterlogged or dry soils, and when species are planted at appropriate groundwater depths.     

Revegetation of harvested peat surfaces in relation to substrate quality

Abstract. The relationship between substrate quality and pattern of revegetation of harvested peat surfaces was studied by means of a survey and a field experiment examining influences of modest NPK-fertilization on plant colonization of an initially bare peat surface. The harvested peat surfaces varied a great deal in their chemical and physical characteristics and the sites differed in revegetation pattern. Early successional vegetation was dominated by perennial species native to nutrient-poor habitats on all sites. Soluble phosphorus and ash content, mean particle size of surface peat, and thickness of peat layer had the strongest influence in a CCA-ordination of species. The species composition depended on the amount and form of soluble nitrogen in the surface peat. Sites with a high content of phosphorus and ammonium nitrogen, and with a thick peat layer were usually densely revegetated by Eriophorum vaginatum alone, while sites characterized by thin peat layers associated with a high ash content, large particle size and a high content of nitrate nitrogen were mainly dominated by different grass and weed species. Deschampsia cespitosa clearly favoured sites with a high potassium content and small particle sizes of the peat. The importance of nutrient availability for the rate and pattern of colonization was also demonstrated by the field experiment. Application of 20 g/m² of NPK-fertilizer resulted in a significant increase in the number of established plant individuals and marked differences in species composition compared to unfertilized plots.     

Livestock exclusion alters plant species composition in fen meadows

Questions

Our study evaluated how species composition and plant traits that indicate functioning condition in fens responded to grazing cessation over time in an arid ecosystem of the western US. The specific questions addressed were: (i) how does livestock exclusion influence species composition in fens; (ii) is grazing cessation associated with shifts in species functional traits that indicate fen condition; and (iii) what is the pattern of response to livestock exclusion over time?

Location

Plumas National Forest, California, US.

Methods

We studied paired fenced and unfenced study sites in two fens to examine the effects of livestock exclusion. Parallel transects were established at each site, and plant species and ground cover were repeatedly surveyed, once prior to and multiple times following treatment, using 0.01 m² frequency frames. We used NMDS to analyse species composition, RLQ and fourth‐corner analysis to evaluate species functional traits and environmental variables, and linear mixed effects models to examine differences in responses between fenced and unfenced study sites over time.

Results

After fencing, we observed unexpected shifts in species composition and plant functional traits. Grazed sites were associated with peat‐forming obligate wetland, moss and sedge species, while fenced sites were characterized by non‐peat‐forming facultative upland, and upland forb, grass and early seral species. Species composition also varied between sites and sample years.

Conclusions

We found that livestock exclusion strongly affects plant species composition in fens, including promoting species with functional traits that indicate a loss of functioning condition, such as ruderal and upland species. Possible explanations for these observed shifts include: (1) biomass accumulation in the absence of herbivory, (2) competitive exclusion in fenced sites, (3) succession, (4) the abiotic conditions of our study sites, particularly hydrology and nutrient status, and (5) interactions among these factors. We conclude that degradation of fen wetlands caused by livestock grazing in the arid western US may not be reversed by excluding livestock alone.     

Short-Term Vegetation Dynamics of Alnus Dominated Peatlands: a High Resolution Palaeoecological Case Study from Western Pomerania (NE Germany)

Actual ecological research postulates for alder carrs a cyclic alternation of Alnus tree vegetation with open fen or Salix dominated vegetation. Such cycles are also indicated in palaeo-ecological studies, but normally the temporal resolution of these studies is insufficient to resolve the duration of short-term cycles in vegetation development. This paper presents a high resolution palaeoecological study (including pollen, macrofossils and non-pollen palynomorphs) of a Late Holocene wood peat section from the small, long-term Alnus dominated peatland ‘Heger Soll’ in the ‘Rodder Forst’ in Western Pomerania (NE Germany) to reconstruct short-term vegetation changes. During a time-span of ca. 800 years, sedge-dominated fen vegetation types alternated with two phases of Alnus carr and one phase of Salix shrubland. The alder carr decline coincided with the beginning of intensified human activity in the surroundings of the mire and was probably connected to increased water discharge resulting from large-scale deforestation, after which willow scrub and sedge fen became established. Growth of Alnus trees was associated with prolonged phases of reduced human impact and probably less water supply. This study shows that human impact on the uplands surrounding the mire and on the alder carr itself may explain the observed “cyclic” vegetation development of alder carrs, willow scrubs and sedge fens in Central Europe.     

Shrubby today but not tomorrow? Structure,composition and regeneration dynamics of direct seeded revegetation

Summary The establishment of direct seeded revegetation is well researched. However, there is little understanding of whether revegetation simplifies with age and loses many of the short‐lived understorey shrub species that provide critical resources for birds and other fauna, or regenerates sufficiently to be self‐sustaining. We sought to address this by investigating the change in structure and composition of 33 direct seeded sites established by Greening Australia between 1990 and 1996 in the Southern Tablelands of NSW. Transects were used to collect data describing the abundance and richness of woody plants in 1998 and 2008, and the abundance of woody plant regeneration in 2008. Our analysis showed the predicted number of live stems per metre declined exponentially from 5.8 stems/m (～17 000 stems/ha) at age 1.5 years to 1.5 stems/m (～4500 stems/ha) at age 17.5 years. Predicted woody plant species richness also declined with age, with a linear relationship. The number of species in the seed mix affected predicted woody plant species richness. However, large increases in seed mix richness produced relatively small increases in predicted species richness. Regeneration (new stems) was present at high levels (>100 stems/ha); however, 82% of regeneration appeared to originate from delayed germination of sown seed rather than seed from established plants (recruitment). The predicted abundance of new stems (delayed germination and recruitment) declined with age, and for a given age increased with row width. Young stands (11.5 years), seeded with wide rows (4 m), had approximately six times the new stems of similar aged stands seeded with narrow rows (2 m). Our results indicate direct seeded stands simplify with age, becoming less dense and containing fewer species. Maintaining a diversity of shrub species in direct seeded sites may therefore require ongoing disturbances (scarifying, scalping, fire, thinning) of established sites and changes to establishment techniques for new sites. We suggest further research to establish the status of soil seed banks in direct seeded sites, testing different forms of disturbances to trigger regeneration in older revegetation sites and establishing new sites using wide rather than narrow rows and seed mixes enriched with species from genera other than Eucalyptus or Acacia.     

Field Simulation of Global Change: Transplanting Northern Bog Mesocosms Southward

A large proportion of northern peatlands consists of Sphagnum-dominated ombrotrophic bogs. In these bogs, peat mosses (Sphagnum) and vascular plants occur in an apparent stable equilibrium, thereby sustaining the carbon sink function of the bog ecosystem. How global warming and increased nitrogen (N) deposition will affect the species composition in bog vegetation is still unclear. We performed a transplantation experiment in which mesocosms with intact vegetation were transplanted southward from north Sweden to north-east Germany along a transect of four bog sites, in which both temperature and N deposition increased. In addition, we monitored undisturbed vegetation in control plots at the four sites of the latitudinal gradient. Four growing seasons after transplantation, ericaceous dwarf shrubs had become much more abundant when transplanted to the warmest site which also had highest N deposition. As a result ericoid aboveground biomass in the transplanted mesocosms increased most at the southernmost site, this site also had highest ericoid biomass in the undisturbed vegetation. The two dominant Sphagnum species showed opposing responses when transplanted southward; Sphagnum balticum height increment decreased, whereas S. fuscum height increment increased when transplanted southward. Sphagnum production did not differ significantly among the transplanted mesocosms, but was lowest in the southernmost control plots. The dwarf shrub expansion and increased N concentrations in plant tissues we observed, point in the direction of a positive feedback toward vascular plant-dominance suppressing peat-forming Sphagnum in the long term. However, our data also indicate that precipitation and phosphorus availability influence the competitive balance between Sphagnum, dwarf shrubs and graminoids.     

Ecophysiological mechanisms characterising fen and bog species: focus on variations in nitrogen uptake traits under different soil–water pH

Although the productivity and nitrogen (N)-use traits of mire plants differ dramatically between fens and bogs, soil N richness does not necessarily differ, whereas the soil–water pH is distinctly lower in bogs than in fens. The ecophysiological mechanisms underlying these relations are unclear. To assess the relative availability of N forms in relation to soil–water pH, we focused on the net N uptake rate per unit root weight (NNUR), glutamine synthetase activity and nitrate reductase activity, and performed reciprocal transplant experiments with the seedlings of fen (Carex lyngbyei) and bog (C. middendorffii) sedge species in intact habitat sites. The soil–water pH was clearly lower at the bog site, but the NH₄ ⁺, NO₃ ⁻ or dissolved organic-N concentrations did not differ between the fen and bog sites. The activity of both enzymes for inorganic-N assimilation did not differ among the sites and species. However, the fen species grown at bog sites showed a drastic decrease in the NNUR, suggesting a suppression of organic-N uptake. The bog species showed no NNUR difference between the sites. These results indicate that inorganic-N availability does not differ between the two habitats, but organic-N availability is lowered in a low-pH bog, particularly in the case of fen species. Therefore, the relative availability of N forms shows species-specific variations that depend on the differences in the soil–water pH of root zone, even at similar N richness, which would play a key role in plant distribution strategies in relation to the fen-bog gradient.     

Spontaneous revegetation of mined peatlands: An useful restoration tool?

The recent development of peatlandrestoration activities indicates thatmodern peat mining techniques seriouslyhamper the natural capacity of bogecosystems to regenerate after adisturbance. However, some plants have theability to colonize dry peat deposits, andseem to help stabilize the soil surface andfacilitate the establishment of other plantspecies. In this paper, we review studiesregarding the spontaneous regeneration ofombrotrophic peatlands. There are numerousexamples throughout North America andEurope showing that spontaneousrevegetation of mined peatlands by typicalbog plants, and particularly by Sphagnum species, is possible. However,this phenomenon is much more common inblock-cut peatlands than in vacuum-minedsites. The slow recovery of vacuum-minedpeatlands compared to block-cut sites isprobably related to intense drainagenecessary for the use of tractor-drawnvacuum machines. There are some cases,however, where the spontaneous revegetationof vacuum-mined sites is successful,particularly for vascular plants. Thesesites are mainly dominated by cotton-grass(Eriophorum vaginatum L.). Itseems that the microclimatic conditionscreated by cotton-grass tussocks improveestablishment conditions for other vascularand non-vascular plants. Restorationactivities should be minimal in minedpeatlands already invaded by cotton-grass,and spontaneous revegetation processescould and should be integrated intopeatland restoration programs.     

The Regeneration of a Highly Disturbed Ecosystem: A Mined Peatland in Southern Québec

We studied the natural regeneration of an ombrotrophic peatland (Cacouna bog) located in southern Québec that was disturbed by peat mining and other anthropogenic activities over a 200-year period. Using an extensive collection of historical documents, as well as dendrochronological data, we reconstructed the history of the peatland. We also sampled vegetation and environmental variables, and integrated the data in a geographic information system. More than 60% of the total area of the bog was mined between 1942 and 1975, and 98 km of ditches were dug to drain the site. The peatland lost 34% of its initial peat volume between 1946 and 1998. Although the bog was severely disturbed, the spontaneous revegetation of the site by vascular plants was successful (90%–100% cover). However, only 10% of the total mined area has been recolonized by Sphagnum species, mainly because drainage ditches are still operational and contribute to drying out the bog. Water table level, peat deposit thickness, and pH are abiotic factors strongly influencing the vegetation composition in the bog. Spatial and historical factors are also important components in this study since they explain, either alone or in interaction with abiotic factors, 44% of the variation of the species data. The intensity of mining activities and the pattern of abandonment of mined sectors strongly influenced abiotic factors, which in turn affected the revegetation process. Even if the Sphagnum cover of the bog is low, the rapid “recovery” of the vegetation cover in the peatland indicates that after the reestablishment of an appropriate hydrological regime, a highly disturbed peatland has a considerable potential for regeneration. Received 24 April 2001; accepted 30 October 2001.     

Conservation of bog plant species assemblages: Assessing the role of natural remnants in mined sites

Abstract. Bogs, economically valuable wetlands, are subjected to exploitation in southern Canada. We addressed plant conservation within bogs mined for peat, in which small undisturbed remnants are left, mostly at the margins of the mined areas. The main goal of the study was to test whether these remnants act as refuges for plants which could recolonize areas that are planned for restoration after mining is completed. Mosses, lichens and vascular plants were sampled in remnants of 24 mined bogs in southeastern Canada during the summer of 1997. The vegetation was also sampled at the margins and centres of 24 nearby natural bogs in plots similar in size to these remnants. Using similarity analysis and ordination techniques, we found that plant species assemblages in remnants of mined bogs differ from those near the margins of natural bogs, and that certain species are associated with the centre of natural bogs, due to the presence of pools. We also showed that water conditions of remnants are affected by drainage due to peat mining. Sphagnum moss showed itself to be a key indicator of mining effects on vegetation. Implications for peat resource management and bog conservation are discussed.     

Topographic position and water chemistry of fens in a Dutch river plain

Abstract. On the Vecht river plain (western Netherlands), small fens, remnants of a large mesotrophic wetland bordering a moraine, of 1 to 5 ha are found in a man-made matrix of lakes and pastures. The regional position of the fens, local position of sampling sites, composition of the vegetation and local hydrological variables were measured. Polders in the river plain produce a complex hydrology obscuring the regional zonation between moraine and river. Water supply and species composition are determined more by a site's regional than local position. High-productivity reedlands are abundant close to the river. Carex paniculata reedlands receive large amounts of river water, which gives their fen water a high K⁺ concentration. Low-productivity C. diandra fens and litter fens have their optimum closer to the moraine. C. diandra fens are fed mainly by inflowing nutrient-poor ground- or surface water; litter fens receive primarily rainwater. Nutrients in fen water and in peat are lowest in C. diandra and C. lasiocarpa fens, but do not differ significantly between the communities. In both, iron seems to be more important than calcium in reducing phosphate solubility. Iron richness in the C. diandra fens is caused by present inflows of ground- or surface water, while in C. lasiocarpa fens, which succeed the former, iron richness is the result of historical inflows.     

Establishment of Carex stricta Lam. seedlings in experimental wetlands with implications for restoration

The loss of Carex dominated meadows due to agricultural drainage in the previously glaciated midcontinent of North America has been extensive. The lack of natural Carex recruitment in wetland restorations and the failures of revegetation attempts underscore the need for information on the establishment requirements of wetland sedges. In this study, seedlings of Carex stricta Lam. were planted in three experimental wetlands in east-central Minnesota, USA to investigate the biotic and abiotic environmental limitations to establishment. Seedlings were planted along an elevational water depth gradient to assess the effects of water depth and water level fluctuation on seedling survival and growth. A different water level fluctuation regime was assigned to each of the experimental wetlands to assess seedling tolerance for seasonal water level changes. The effects of seedling planting density and the presence or absence of non-sedge colonizers on seedling survival and growth were also studied. The experiment was followed for three growing seasons. The results of this study indicate that C. stricta seedlings were sensitive to the timing and duration of inundation during the first growing season. Once established, plants tolerated a broad range of seasonal drying and flooding conditions. Seedling and juvenile growth was slowed by non-sedge colonizers during the first two growing seasons, but by the third growing season, C. stricta was able to out-grow all annual and perennial weeds, except the aggressive perennial, Phalaris arundinacea L. The rapid growth of C. stricta plants, once established, indicates that the use of seedlings is a successful method for (re) introducing this tussock sedge into wetland restorations under a variety of environmental conditions. Comparison with other studies performed under similar conditions suggests that planting of seedlings is a more appropriate method of establishing this species than the use of transplanted rhizomes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Taming the Beast: Managing Hydrology to Control Carolina Willow (Salix caroliniana) Seedlings and Cuttings

Historically, wetlands along the St. Johns River, Florida, were dominated by herbaceous marshes. However, in the last 50 years many areas transformed to shrub‐dominated wetlands, at the same time a system of levees and canals was constructed to control flooding. We tested the role of water management in controlling Carolina willow (Salix caroliniana), a native shrub that accounts for most of this shift. We assessed survival and growth of seedlings and cuttings on four artificial islands. We planted willow seedlings and cuttings at the spring waterline and at three higher levels (+17.5, +35, and +50 cm) and evaluated their responses to natural hydrologic fluctuations. Overall, seedlings had lower survival than cuttings. Highest mortality occurred during summer floods and willows greater than 50 cm above marsh surface had the highest survivorship. Surviving seedlings attained similar height and biomass among elevations, but the cuttings had greater stem diameter, stem height, and biomass at higher elevations. In the second experiment, we planted seedlings and short (25 cm) and tall (50 cm) cuttings at the waterline and at three higher levels (+25, +35, and +50 cm) in artificial ponds with controlled water levels. Before flooding, seedlings at the highest elevation suffered some mortality due to desiccation, but after flooding, they had the highest survival. Elevation did not affect cutting survival, but those at the lowest elevation had the greatest height and biomass. Hydrologic manipulation can be a powerful tool to control willow establishment. However, its success depends on timely and prolonged inundation or water drawdown .     

Methane dynamics of recolonized cutover minerotrophic peatland: Implications for restoration

In North America, mulching of vacuum-harvested sites combined with blocking of the drainage system is widely used for peatland restoration to accelerate Sphagnum establishment. However, peat extraction in fen peatlands or exposure of deeper minerotrophic peat layers results in soil chemistry that is less suitable for re-establishment of Sphagnum moss. In this situation, restoration of plant species characteristic of minerotrophic peatlands is desirable to return the site to a carbon accumulating system. In these cases, it may be worthwhile to maintain spontaneously revegetating species as part of restoration if they provide desirable ecosystem functions. We studied the role of six spontaneously recolonizing vegetation communities for methane (CH₄) emissions and pore water CH₄ concentration for two growing seasons (2008 and 2009) at an abandoned minerotrophic peatland in southeastern Quebec. We then compared the results with bare peat and adjacent natural fen vegetation. Communities dominated by Eriophorum vaginatum, Carex aquatilis and Typha latifolia had CH₄ flux an order of magnitude greater than other cutover vegetation types and natural sites. In contrast, Scirpus atrocinctus and Equisetum arvense had CH₄ emission rates lower than natural hollow vegetation. We found seasonal average water table and vegetation volume had significant correlation with CH₄ flux. Water table and soil temperature were significantly correlated with CH₄ flux at plots where the water table was near or above the surface. Pore water CH₄ concentration suggests that CH₄ is being produced at the cutover peatland and that low measured fluxes likely result from substantial oxidation of CH₄ in the unsaturated zone. Understanding ecosystem functions of spontaneously recolonizing species on cutover fens can be used to help make decisions about the inclusion of these communities for future restoration measures.     

Use of Plant Strategy Ordination,DCA and ANOVA to elucidate relationships among habitats of Salix planifolia and Salix monticola

Abstract. Detrended Correspondence Analysis (DCA) was used on a data set of 112 species from 14 stands dominated by Salix planifolia and/or S. monticola. Environmental variables were determined which might be important to explain differences in stand vegetation composition, and willow stature (height), in willow carrs in the Rocky Mountain National Park. Correlation of environmental variables with DCA stand scores indicate that peat depth and soil redox potential are highly related to the primary DCA axis. Soils in stands of S. planifolia are more reduced in the early summer and have greater peat depths, than soils in stands of S. monticola. The second DCA axis is related to a water chemistry gradient of hydrogen ion, sulphate, and ammonium concentration. Four environmental variables selected by correlation analysis were regressed on stand scores from the first two DCA axes. Regression coefficients of August soil redox potential and soil water pH were significantly non-zero on the primary DCA axis. In addition to overall vegetation relationships elucidated by DCA, the relationships between willow stature and environmental variables were tested by simultaneous ANOVAs. ANOVA results and DCA ordinations indicate that S. planifolia and S. monticola plants achieve the greatest stature in the least reduced soils, and in shallow peat. Competitive, stress tolerant, and ruderal plant strategy theory applied to the vegetation data produced an arrangement of stands highly correlated to the DCA Axis 1 stand arrangement. These correlations indicate that the primary axis of vegetation structure can be extracted either by species composition, or species morphology/physiology relationships. Concurrent use of DCA and plant strategy theory is suggested as a tool for the prediction of community composition.