Hydrologic Response of a Montane Meadow from Conifer Removal and Upslope Forest Thinning

This study evaluates the hydrologic response of restoration of a montane meadow by removal of encroached Pinus contorta and thinning of the adjacent forest. It is now a follow-up with four years of post-restoration data, on a previous analysis of a hydrologic response of the same meadow one year following restoration. A hydrologic change was evaluated through a statistical comparison of soil moisture and depth to groundwater between the restored Marian Meadow and a Control Meadow. Meadow water budgets and durations of water table depths during the growing season were evaluated. The four years following restoration of Marian Meadow had an increase in volumetric soil moisture during the wet season, but decreased soil moisture during the dry season. An average decrease in depth to groundwater of 0.15 m was found, which is consistent with the first-year post-restoration. The water budget confirms the first-year results that the hydrologic change following removal of encroached conifers was primarily due to a reduction of vegetation interception capture. There was no measurable difference in depth to groundwater or soil moisture following the upslope forest thinning likely due to the low level of forest removal with 2.8 m2/hectare reduction of the forest basal area. The cost of restoration to water gained was $0.69 USD/1000 L ($2.62 USD/1000 gal.).

Hydrologic Response of Meadow Restoration the First Year Following Removal of Encroached Conifers

This study examines the hydrologic response of a montane meadow the first winter following restoration by removal of encroached conifers. Hydrologic change was evaluated through statistical comparison of soil moisture and water table depths between the restored meadow, Marian Meadow, and a Control Meadow before and after restoration. Meadow water budgets and durations of water table depths during the growing season were evaluated. Electrical resistivity tomography profiles were collected to improve the spatial interpretation of subsurface water beyond well measurements. The first year following restoration Marian Meadow had a statistically significant increase in volumetric soil moisture content of 4% with depth to the water table decreasing on average by 0.15 m. The water budget for the meadows demonstrated that the hydrologic change following removal of encroached conifers was primarily due to a reduction of vegetation interception capture. Soil evapotranspiration rates in both the Control and Marian Meadows were relatively stable ranging from 268–288 mm/yr with the exception of the year following conifer removal in Marian Meadow with 318 mm/yr. The increase in soil evapotranspiration in the first post restoration year is attributed to loss of vegetation cover and higher proportions of bare soil created from the harvest operations. The duration of post-restoration water table depths during the growing season at Marian Meadow were less than or equal to 0.7 m and 0.3 m for 85 days and 50 days, respectively, indicating hydrologic conditions conducive to meadow vegetation.

Plant dominance in a subalpine montane meadow: biotic vs. abiotic controls of subordinate diversity within and across sites

Background Understanding the underlying factors that determine the relative abundance of plant species is critical to predict both biodiversity and ecosystem function. Biotic and abiotic factors can shape the distribution and the relative abundance of species across natural communities, greatly influencing local biodiversity. Methods Using a combination of an observational study and a five-year plant removal experiment we: (1) documented how plant diversity and composition of montane meadow assemblages vary along a plant dominance gradient using an observational study; (2) tracked above- and belowground functional traits of co-dominant plant species Potentilla and Festuca along a plant dominance gradient in an observational study; (3) determined whether plant species diversity and composition was directly influenced by commonly occurring species Potentilla and Festuca with the use of a randomized plot design, 5-year plant removal experiment (no removal control, Potentilla removed, Festuca removed, n = 10). Results We found that subordinate species diversity and compositional dissimilarity were greatest in Potentilla and Festuca co-dominated sites, where neither Potentilla nor Festuca dominated, rather than at sites where either species became dominant. Further, while above- and belowground plant functional traits varied along a dominance gradient, they did so in a way that inconsistently predicted plant species relative abundance. Also, neither variation in plant functional traits of Festuca and Potentilla nor variation in resources and conditions (such as soil nitrogen and temperature) explained our subordinate diversity patterns. Finally, neither Potentilla nor Festuca influenced subordinate diversity or composition when we directly tested for their impacts in a plant removal experiment. Discussion Taken together, patterns of subordinate diversity and composition were likely driven by abiotic factors rather than biotic interactions. As a result, the role of abiotic factors influencing local-level species interactions can be just as important as biotic interactions themselves in structuring plant communities.