Restoration of plant communities to red-burned soils

Fire, natural or anthropogenic, is a common occurrence in the open forests and grasslands of Western North America. The effects of fire on soil and vegetation depend largely on the soil temperatures and the residence time of the burn. Generally, the more severe the fire, the more significant the changes are to soil and vegetation. The relationship between the most severe fires, or where the soil has been oxidized to a red colour, and invasive species is unknown. Resource availability may increase on these soils, leading to favourable conditions for invasive species, or the disturbance may be so severe that nothing is able to grow indefinitely. I performed two studies to investigate the relationship between invasive species and red-burned soil. To reduce the threat of interface fires near Kamloops, BC, excess timber was harvested, piled and burned on site (pile burning), created multiple burn scars denuded of vegetation and large areas of red soil. In the first study, I investigated soil nutrient flux differences between red-burned and unburned soil using ion-exchange resin technology. I also investigated three restoration methods to control invasive species: the addition of agronomic or native seed, the addition of arbuscular mycorrhizal fungi (AMF) inoculum, and the addition of soil cover. Non-native species cover was high on red soil 2 years post-burn, which may be linked to measured increased nutrients. Only the addition of agronomic seed was successful at suppressing non-native species cover. The second study compared the growth of native, agronomic and invasive species on unburned and red-burned soil in a greenhouse study. Soil was collected in the field and transferred to a greenhouse. Treatments were soil burning, AMF, and watering. Burning increased aboveground biomass for the native species. AMF addition increased invasive species aboveground biomass for the invasive species, but decreased biomass for agronomic and native species. Watering increased aboveground biomass for the agronomic and invasive species. The findings here suggest that pile burning creates areas that are susceptible to colonization of non-native species. Restoration efforts should be directed at these sites as soon as possible to ameliorate the effects of invasive species colonization.Science, Faculty ofBotany, Department ofGraduat

Restoration of slash pile burn scars to prevent establishment and propagation of non-native plants

Logging and burning of the resultant woody debris is a management tool to reduce fire risk. Burning of the debris as piles affects the underlying soil biota and soil physical/chemical properties. The resulting disturbance created by the burns may create opportunities for the establishment and spread of non-native plant species. Here, we test three restoration treatments on recent, approximately one-year-old, pile burn scars, including an arbuscular mycorrhizal fungal (AMF) inoculant (present or absent), a ground cover (straw or no straw added), and seeding (native seed mix, agronomic seed mix, no seed). The most effective treatment in reducing undesired non-native species cover was the seeding of agronomic species; here “native and “non-native” groups exclude sown agronomic species. Undesired non-native cover was 15.1% in plots with no seed, 9.1% with native seed added, and 3.5% with agronomic seed added. Total vegetation cover, mostly through the increase of agronomic species, was increased by seeding and by the application of straw cover. Commercial AMF inoculum was an ineffective treatment, suggesting that a better understanding of host specificity is warranted. Restoration efforts should be directed at burn scar sites after burning to ameliorate the effects of invasive species colonization, and the use of agronomic species may prevent non-native invasive plants from establishing.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Understory Plant Community Responses to Fuel-Reduction Treatments and Seeding in an Upland Piñon-Juniper Woodland

Woody plant expansion and infilling into nonwooded rangeland ecosystems have been observed worldwide. Such expansion may lead to declines in herbaceous understory plant communities and increased fuel loads in rangelands. Under the US National Fire Plan, fuel-reduction treatments have been implemented over vast expanses of western forest types to reduce the risk of catastrophic wildfire and restore historical ecosystem structure, function, and diversity. The benefits of fuel-reduction may, however, also carry inherent ecological risk such as promoting non-native species colonization. Here, we compare understory plant community responses to three commonly used fuel-reduction treatments with seeding applications in an upland piñon (Pinus edulis Engelm.)- juniper (Juniperus osteosperma [Torr.] Little) woodland on the Colorado Plateau: 1) mechanical mastication, 2) lop and slash piled then burned (pile burn), and 3) lop and scatter followed by a broadcast burn (broadcast burn). Data were collected pretreatment (2009) and one (2010), two (2011), and six (2015) growing seasons post treatment. We found while understory perennial herbaceous plant cover remained low 1 and 2 yr post treatment, it increased by > 700% in all fuel-reduction treatment plots six growing seasons post treatment. Furthermore, while we observed minor increases in invasive annual grass, Bromus tectorum L. (cheatgrass), colonization in 2010 and 2011, there were substantial increases in B. tectorum cover by 2015. B. tectorum cover varied among treatments with the greatest cover in the unseeded mastication plot at nearly 30%. Seeding applications did not increase overall seed mix species cover but enhanced seed mix species richness and, thus, may have increased resistance to B. tectorum invasion in seeded treatment plots. Our findings offer valuable insights to the ecological consequences of fuel-reduction activities in piñon-juniper woodlands through comparison of common fuel-reduction treatments and seeding applications and highlight differences in understory plant community responses to treatments across short to longer time scales. © 2017 The Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Using revegetation to suppress invasive plants in grasslands and forests

1. Following the removal of invasive plant species, most land managers rely on natural succession to re-establish native plant communities. However, insufficient native propagule pressure combined with legacy effects of invasive plant species means that passive approaches to restoration are often inadequate to establish native communities and prevent reinvasion. 2. In this paper, we review literature evaluating the ability of active revegetation to suppress re-establishment of invaders in grasslands and woodlands. 3. We find that existing literature consistently demonstrates reduced performance of invasive plant species in revegetated grasslands, but that the magnitude of impact on invasive plants is highly variable. In contrast, the efficacy of revegetation in woodlands has rarely been reported, but the small number of such studies are consistent with results from grasslands. 4. Synthesis and applications. Our review highlights the mechanisms that lead to revegetation suppressing invasive plants in grasslands and identifies knowledge gaps associated with revegetation using woody species or targeting woody invaders. We recommend concerted efforts be made to evaluate the viability of woody plant revegetation and the efficacy of revegetation in woodlands. Furthermore, we suggest that land managers may need to embrace novel species assemblages in order to prevent reinvasion

Sustaining forest soil quality and productivity

Soil sustainability is key to maintaining forest growth and ecosystem services around the world. Determining how to maintain soil functions and knowing when soils are degraded can be difficult. Complicating our understanding of the relationship between soil functions and soil sustainability is the inherent heterogeneity of forest soils. However, maintaining or improving soil organic matter (OM) contents is essential to soil health, quality, and sustainability, and both OM quantity and quality have key roles in soil porosity, water infiltration, gas exchange, nutrient cycling, aggregate stability, trafficability, and flood control. Forest management practices, such as harvesting and site preparation, have a major impact on soil properties, which can vary widely across different soil types and climatic regimes. We also examine how compaction, fertilization, and herbicide use can influence forest sustainability. This chapter is structured to give an overview of management-related changes on soil properties, and how these practices may be refined to sustain or improve forest soil quality and productivity. In addition, a synthesis of soil monitoring practices is provided to show the importance of this information for adaptive management