The vegetation and ecological gradients of calcareous mires in the South Park valley, Colorado

Abstract

The vegetation, environment, and ecological gradients present on three calcareous mires in the South Park valley, Park County, Colorado, were investigated. Vegetation was classified into four habitat classes, nine subclasses, and twelve species associations using two-way species indicator analysis (TWINSPAN). Detrended correspondence analysis (DCA) was used to ordinate vegetation samples along two axes representing the three predominant ecological gradients: water table height, miremargin to expanse, and region. Canonical correspondence analysis (CCA) was used to directly relate local environmental conditions to vegetation. Water table depth, microtopographical development, soil and water pH and nutrient level, soil organic matter, and hydraulic head were significantly correlated with vegetation gradients. The mire soils consist of intermixed areas of organic and mineral soils. Mire soils and water are highly alkaline and nutrient-rich. Mean pore water calcium concentration on these mires is 115 mg/L, electrical conductivity averages 575 µS, and mean pH is 7.4. Owing to these conditions, the fen floras include a number of highly minerophilic species. Based on water chemistry and species criteria, each site was classified as rich to extremely rich fen, with the two fen types mixing in complex patterns according to local environmental conditions. The species Trichophorum pumilum, Salix candida, Salix myrtillifolia, Carex microglochin, Carex viridula, Carex scirpoidea, Eriophorum gracile, Triglochin maritimum, Triglochin palustris, Kobresia myosuroides, Kobresia simpliciuscula, Thalictrum alpinum, Scorpidium scorpioides, Scorpidium turgescens, and Calliergon trifarium were determined to be indicative of extremely rich fen conditions in the southern Rocky Mountains.Key words: Colorado, canonical correspondence analysis, detrended correspondence analysis, extremely rich fen, gradient analysis, mire.

Hydro-ecology of groundwater-dependent ecosystems: applying basic science to groundwater management

“…Plant species distributions in fens are a function of various physical gradients in groundwater depths and fluxes and chemistry (Bridgham et al 1996, Hajkova et al 2004, Wheeler et al 2004, and these gradients can be used to set thresholds to groundwater alteration based on hydroecological relationships. Numerous studies report that fen species respond to the maximum depth of the water (Amon et al 2002), calcareous mires in Colorado, USA (Johnson and Steingraeber 2003), spring fens in the Czech Republic (Hajkova et al 2004), peatlands in central Alberta, Canada (Karlin and Bliss 1984) and kettle hole fens in New York (Drexler et al 1999, Godwin et al 2002.…”

“…A fen whose water balance is dominated by a constant source of deeper groundwater is likely to have a highly stable hydroperiod (e.g. Johnson and Steingraeber 2003) compared to a fen receiving a combination of ground-and surface water and growing season precipitation (e.g. Waddington 2011, Duval et al 2012).…”

Water and nutrient discharge to a high‐value terrace–floodplain fen: resilience and risk

“…Although groundwater sources to these types of fens are assumed to be regional (Almendinger and Leete, 1998;Grootjans et al, 2006), irrigation is common on the agricultural terrace ( Figure 1) and water table levels in the permeable terrace deposits would be particularly susceptible to climate perturbations. Downgradient fens may be impacted by fluctuating water table conditions (Duval and Waddington, 2011), as water table dynamics control many physical and chemical conditions in fens (Mitsch and Gosselink, 2000;Johnson and Steingraeber, 2003;van Diggelen et al, 2006). Eutrophication of the fen from excessive nutrient loss from terrace agricultural activity may further impact fen biodiversity (Wassen and Olde Venterink, 2006;Lamers et al, 2014).…”

Influence of Bedrock Geology on Water Chemistry of Slope Wetlands and Headwater Streams in the Southern Rocky Mountains

“…Compared to the rich and extreme-rich peatlands that support rare plant species and calciphilic plant communities (Cooper 1996;Chapman et al 2003;Johnson and Steingraeber 2003), little is known about the water chemistry and plant communities of intermediate types (Johnson 2001, but see Cooper 1990Johnson 1996). To increase understanding of the biogeochemistry of Rocky Mountain slope wetlands, we compared wetland porewater and streamwater chemistry in basins underlain entirely by crystalline bedrock with water chemistry in basins containing a mixture of crystalline and sedimentary bedrock.…”