Sedges

Ecoregions are increasingly being used as a framework for conservation planning. The Mid-Boreal Uplands Ecoregion stretches across Canada from Manitoba to British Columbia. From the perspective of conservation and to understand the dynamics of plant diversity and community composition in a common wetland type, we examined the plant communities and environmental variables in 80 wooded moderate-rich fens within this ecoregion. Regional diversity totalled 273 species, with 86 bryophytes and 187 vascular plants. Total diversity was greatest in Manitoba and decreased in a longitudinal trend west through Saskatchewan and Alberta. This may be related, in part, to orographic precipitation at Manitoba sites and a gradient of growing degree days. Richness of locally rare vascular plants exhibited a clear west to east gradient. Ten species of provincially rare vascular plants were observed across the ecoregion, but without pattern. Ordinations and other analyses revealed distinct plant communities for all three locations, with vascular plant assemblages more discrete than bryophyte assemblages. Bryophyte diversity increased with latitude and longitude, whereas vascular plant diversity decreased. Additionally, elevation, precipitation, surface water alkalinity, water temperature, percent overstory density, and peat organic C played a role in determining species richness and community composition. Overall, species composition and diversity in a single wetland type exhibited continuous change across multiple political jurisdictions at the ecoregion scale. Conservation plans for wetlands at the ecodistrict scale may be preferable.

The evolution of C4 photosynthesis was a signal shift in the history of life on Earth, including at least 50 independent origins in 19 families of higher plants (1). Today, C4 plants account for a quarter of the primary productivity on the planet despite representing a small fraction (∼3%) of the estimated 250,000 land plant species (2). Most C4 plants are grasses (family Poaceae, 4,500 species), followed by sedges (family Cyperaceae, 1,500 species) and dicots (1,200 species). A few C4 plant species contribute significantly to the human diet, either directly as domesticated cereals (e.g., maize, sorghum, millet) and additives (e.g., cane sugar, corn syrup) or indirectly via animals raised on C4 crops and pastures. As a result, human tissues can have high δ13C values because C4 plants and their consumers are enriched in 13C (3). In recent years, this telltale signature of a C4-based diet has also been found in a wide range of hominin species (4), a finding that has both informed and fueled debate. Now, paleoanthropologists must contend with a unique and surprising finding.

Highlights • In the boreal region, knowledge of plant species diversity (richness and rarity) is low compared with other taxa such as birds and mammals. This is particularly true of peatlands, which have a higher proportion of characteristic species compared to upland ecosystems in the same region. • Peatlands influence biodiversity far beyond their borders by maintaining hydrological and microclimate features of adjacent areas and providing temporary habitats or refuges for upland species. • Although not yet commonly logged in western Canada, wooded moderate-rich fens and black spruce swamps may have stands of marketable timber. Research has shown that, compared to other peatland types, these types have significantly higher plant diversity. • Knowledge of plant diversity in peatlands can improve the development of effective forest management plans. What is currently known about plant diversity in peatlands could be integrated into forest management plans at the ecosite and ecoeleme...