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Rohal CB, Duncan B, Follstad Shah J, Veblen KE, Kettenring KM. Targeted grazing reduces a widespread wetland plant invader with minimal nutrient impacts, yet native community recovery is limited. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 362:121168. [PMID: 38823302 DOI: 10.1016/j.jenvman.2024.121168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 05/06/2024] [Accepted: 05/10/2024] [Indexed: 06/03/2024]
Abstract
Targeted grazing to control undesirable plant species is increasingly of interest across a diversity of ecosystems, particularly as an alternative or complement to widely used herbicides. However, there are limited comprehensive evaluations of targeted grazing that evaluate both invasive species management effectiveness and potential negative effects on the ecosystem. Phragmites australis, a tall-statured, dense perennial invasive grass from Eurasia, is a pervasive problem in wetlands across the North American continent. As with many invasive species where management has historically relied on herbicides and resistance is a growing concern, land managers seek viable alternatives that have minimal negative ecosystem impacts. Grazing has been used for millennia to manage native Phragmites in Europe. Similarly, in its invasive range within North America, small-scale studies suggest Phragmites may be suppressed by grazers. Yet, the effectiveness of grazing at large scales and its effects on broader ecosystem properties remain largely unknown. We evaluated the influence of targeted grazing on vegetation, soil nutrients, and water nutrients over two years in large plots (∼300x the size of previous studies). We also tested the effects of mowing, a treatment that can be used to facilitate grazer access to large, dense Phragmites stands. In line with our predictions, we found that cattle grazing effectively suppressed invasive Phragmites over two years. Mowing reduced litter, and moderately reduced standing dead Phragmites, both of which suppress native plant germination in this system. However, these reductions in Phragmites were not accompanied by indications of native plant community recovery, as we had optimistically predicted. Despite the potential for grazing to reduce nutrient sequestration by plants and fertilize soils, we were surprised to find no clear negative effects of grazing on nutrient mobilization to groundwater or floodwater. Taken together, our findings indicate that targeted grazing, when implemented at broad scales over short time frames, is effective at achieving invasive plant management goals without sizable nutrient impacts. However, additional steps will be needed to achieve the restoration of diverse, robust native plant communities.
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Affiliation(s)
- Christine B Rohal
- Department of Environmental Horticulture and Soil, Water, and Ecosystem Sciences Department, University of Florida, Gainesville, FL, 32611, USA; Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT, 84322, USA.
| | - Brittany Duncan
- Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT, 84322, USA; Utah Department of Agriculture and Food, Taylorsville, UT, 84129, USA
| | - Jennifer Follstad Shah
- School of the Environment, Society & Sustainability, University of Utah, Salt Lake City, UT, 84112, USA
| | - Kari E Veblen
- Department of Wildland Resources and Ecology Center, Utah State University, Logan, UT, 84322, USA
| | - Karin M Kettenring
- Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT, 84322, USA
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Langhammer PF, Bull JW, Bicknell JE, Oakley JL, Brown MH, Bruford MW, Butchart SHM, Carr JA, Church D, Cooney R, Cutajar S, Foden W, Foster MN, Gascon C, Geldmann J, Genovesi P, Hoffmann M, Howard-McCombe J, Lewis T, Macfarlane NBW, Melvin ZE, Merizalde RS, Morehouse MG, Pagad S, Polidoro B, Sechrest W, Segelbacher G, Smith KG, Steadman J, Strongin K, Williams J, Woodley S, Brooks TM. The positive impact of conservation action. Science 2024; 384:453-458. [PMID: 38662833 DOI: 10.1126/science.adj6598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 03/14/2024] [Indexed: 05/03/2024]
Abstract
Governments recently adopted new global targets to halt and reverse the loss of biodiversity. It is therefore crucial to understand the outcomes of conservation actions. We conducted a global meta-analysis of 186 studies (including 665 trials) that measured biodiversity over time and compared outcomes under conservation action with a suitable counterfactual of no action. We find that in two-thirds of cases, conservation either improved the state of biodiversity or at least slowed declines. Specifically, we find that interventions targeted at species and ecosystems, such as invasive species control, habitat loss reduction and restoration, protected areas, and sustainable management, are highly effective and have large effect sizes. This provides the strongest evidence to date that conservation actions are successful but require transformational scaling up to meet global targets.
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Affiliation(s)
- Penny F Langhammer
- Re:wild, PO Box 129, Austin, TX 78767, USA
- Arizona State University, School of Life Sciences, PO Box 874501, Tempe, AZ 85287, USA
| | - Joseph W Bull
- Department of Biology, University of Oxford, 11a Mansfield Rd, Oxford OX1 3SZ, UK
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, UK
- Wild Business Ltd, London, UK
| | - Jake E Bicknell
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, UK
| | | | | | - Michael W Bruford
- School of Biosciences and Sustainable Places Research Institute, Cathays Park, Cardiff CF10 3AX, UK
- IUCN SSC Conservation Genetics Specialist Group, 28 rue Mauverney, 1196 Gland, Switzerland
| | - Stuart H M Butchart
- BirdLife International, David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK
- Department of Zoology, University of Cambridge, Downing St., Cambridge CB2 3EJ, UK
| | - Jamie A Carr
- Leverhulme Centre for Anthropocene Biodiversity, University of York, York YO10 15DD, UK
- Department of Environment and Geography, University of York, York YO10 5DD, UK
- IUCN SSC Climate Change Specialist Group, 28 rue Mauverney, 1196 Gland, Switzerland
| | - Don Church
- Re:wild, PO Box 129, Austin, TX 78767, USA
| | - Rosie Cooney
- CEESP/SSC IUCN Sustainable Use and Livelihoods Specialist Group, 28 rue Mauverney, 1196 Gland, Switzerland
- Fenner School of Environment and Society, Australian National University, ACT 2601, Australia
| | | | - Wendy Foden
- IUCN SSC Climate Change Specialist Group, 28 rue Mauverney, 1196 Gland, Switzerland
- South African National Parks, Cape Research Centre, Tokai, Cape Town, 7966, South Africa
- FitzPatrick Institute of African Ornithology, Rondebosch, Cape Town, 7701, South Africa
- Global Change Biology Group, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
| | | | - Claude Gascon
- The Global Environment Facility, 1818 H Street NW, Washington, DC 20433, USA
| | - Jonas Geldmann
- Department of Zoology, University of Cambridge, Downing St., Cambridge CB2 3EJ, UK
- Center for Macroecology, Evolution and Climate, GLOBE Institute, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen E, Denmark
| | - Piero Genovesi
- Institute for Environmental Protection and Research, Via Vitaliano Brancati 48, 00144 Rome, Italy
- IUCN SSC Invasive Species Specialist Group, 00144 Rome, Italy
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - Michael Hoffmann
- IUCN Species Survival Commission, 28 rue Mauverney, 1196 Gland, Switzerland
- Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Jo Howard-McCombe
- School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
- RZSS WildGenes, Conservation Department, Royal Zoological Society of Scotland, Edinburgh EH12 6TS, UK
| | - Tiffany Lewis
- Arizona State University, 427 E. Tyler Mall, Tempe, AZ 85281, USA
| | | | - Zoe E Melvin
- School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
- Bangor University, School of Natural Sciences, Deiniol Road, Bangor, Gwynedd, Wales LL57 2UW, UK
| | | | - Meredith G Morehouse
- LLaves: Keys to Bilingual Conservation, LLC, 346 Mayberry Hill Road, Casco, Maine 04015, USA
| | - Shyama Pagad
- University of Auckland, Auckland 1072, New Zealand
| | - Beth Polidoro
- IUCN Species Survival Commission, 28 rue Mauverney, 1196 Gland, Switzerland
- Arizona State University, 4701 W. Thunderbird Rd, Glendale, AZ 85382, USA
| | | | - Gernot Segelbacher
- IUCN SSC Conservation Genetics Specialist Group, 28 rue Mauverney, 1196 Gland, Switzerland
- University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany
| | - Kevin G Smith
- IUCN, The David Attenborough Building, Pembroke St, Cambridge CB2 3QZ, UK
| | - Janna Steadman
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, UK
| | - Kyle Strongin
- Arizona State University, 800 S. Cady Mall, Tempe, AZ 85281, USA
| | - Jake Williams
- Imperial College London, Silwood Park, Ascot SL5 7PY, UK
| | - Stephen Woodley
- IUCN World Commission on Protected Areas, 64 Juniper Road, Chelsea, Quebec J9B 1T3, Canada
| | - Thomas M Brooks
- IUCN, 28 rue Mauverney, 1196 Gland, Switzerland
- World Agroforestry Center, University of The Philippines Los Baños, Laguna, Philippines
- Institute for Marine & Antarctic Studies, University of Tasmania, Hobart, Australia
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Tarsa EE, Holdaway BM, Kettenring KM. Tipping the balance: The role of seed density, abiotic filters, and priority effects in seed-based wetland restoration. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2706. [PMID: 35808932 DOI: 10.1002/eap.2706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Sowing native seeds is a common approach to reintroduce native plants to degraded systems. However, this method is often overlooked in wetland restoration despite the immense global loss of diverse native wetland vegetation. Developing guiding principles for seed-based wetland restoration is critical to maximize native plant recovery, particularly in previously invaded wetlands. Doing so requires a comprehensive understanding of how restoration manipulations, and their interactions, influence wetland plant community assembly. With a focus on the invader Phragmites australis, we established a series of mesocosm experiments to assess how native sowing density, invader propagule pressure, abiotic filters (water and nutrients), and native sowing timing (i.e., priority effects) interact to influence plant community cover and biomass in wetland habitats. Increasing the density of native seeds yielded higher native cover and biomass, but P. australis suppression with increasing sowing densities was minimal. Rather, community outcomes were largely driven by invader propagule pressure: P. australis densities of ≤500 seeds/m2 maintained high native cover and biomass. Low-water conditions increased the susceptibility of P. australis to dominance by native competitors. Early sowing of native seeds showed a large and significant benefit to native cover and biomass, regardless of native sowing density, suggesting that priority effects can be an effective restoration manipulation to enhance native plant establishment. Given the urgent wetland restoration need combined with the limited studies on seed-based wetland restoration, these findings provide guidance on restoration manipulations that are grounded in ecological theory to improve seed-based wetland restoration outcomes.
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Affiliation(s)
- Emily E Tarsa
- Ecology Center and Department of Watershed Sciences, Utah State University, Logan, Utah, USA
| | - Bailey M Holdaway
- Ecology Center and Department of Watershed Sciences, Utah State University, Logan, Utah, USA
| | - Karin M Kettenring
- Ecology Center and Department of Watershed Sciences, Utah State University, Logan, Utah, USA
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