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Phillips ML, Lauria C, Spector T, Bradford JB, Gehring C, Osborne BB, Howell A, Grote EE, Rondeau RJ, Trimber GM, Robinson B, Reed SC. Trajectories and tipping points of piñon-juniper woodlands after fire and thinning. GLOBAL CHANGE BIOLOGY 2024; 30:e17149. [PMID: 38342970 DOI: 10.1111/gcb.17149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/29/2023] [Accepted: 12/04/2023] [Indexed: 02/13/2024]
Abstract
Piñon-juniper (PJ) woodlands are a dominant community type across the Intermountain West, comprising over a million acres and experiencing critical effects from increasing wildfire. Large PJ mortality and regeneration failure after catastrophic wildfire have elevated concerns about the long-term viability of PJ woodlands. Thinning is increasingly used to safeguard forests from fire and in an attempt to increase climate resilience. We have only a limited understanding of how fire and thinning will affect the structure and function of PJ ecosystems. Here, we examined vegetation structure, microclimate conditions, and PJ regeneration dynamics following ~20 years post-fire and thinning treatments. We found that burned areas had undergone a state shift that did not show signs of returning to their previous state. This shift was characterized by (1) distinct plant community composition dominated by grasses; (2) a lack of PJ recruitment; (3) a decrease in the sizes of interspaces in between plants; (4) lower abundance of late successional biological soil crusts; (5) lower mean and minimum daily soil moisture values; (6) lower minimum daily vapor pressure deficit; and (7) higher photosynthetically active radiation. Thinning created distinct plant communities and served as an intermediate between intact and burned communities. More intensive thinning decreased PJ recruitment and late successional biocrust cover. Our results indicate that fire has the potential to create drier and more stressful microsite conditions, and that, in the absence of active management following fire, there may be shifts to persistent ecological states dominated by grasses. Additionally, more intensive thinning had a larger impact on community structure and recruitment than less intensive thinning, suggesting that careful consideration of goals could help avoid unintended consequences. While our results indicate the vulnerability of PJ ecosystems to fire, they also highlight management actions that could be adapted to create conditions that promote PJ re-establishment.
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Affiliation(s)
- Michala L Phillips
- U.S. Geological Survey, Pacific Island Ecosystems Research Center, Hawai'i Volcanoes National Park, Hawai'i, USA
| | - Cara Lauria
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
| | - Tova Spector
- U.S. Forest Service, Intermountain Region 4, Ogden, Utah, USA
| | - John B Bradford
- U.S. Geological Survey, Southwest Biological Science Center, Flagstaff, Arizona, USA
| | - Catherine Gehring
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Brooke B Osborne
- Department of Environment and Society, Utah State University, Moab, Utah, USA
| | - Armin Howell
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
| | - Edmund E Grote
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
| | - Renee J Rondeau
- Colorado State University, Colorado Natural Heritage Program, Hesperus, Colorado, USA
| | - Gillian M Trimber
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | | | - Sasha C Reed
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, USA
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Vasey GL, Urza AK, Chambers JC, Pringle EG, Weisberg PJ. Clinal variations in seedling traits and responses to water availability correspond to seed-source environmental gradients in a foundational dryland tree species. ANNALS OF BOTANY 2023; 132:203-216. [PMID: 36905361 PMCID: PMC10583205 DOI: 10.1093/aob/mcad041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND AND AIMS In dryland ecosystems, conifer species are threatened by more frequent and severe droughts, which can push species beyond their physiological limits. Adequate seedling establishment will be critical for future resilience to global change. We used a common garden glasshouse experiment to determine how seedling functional trait expression and plasticity varied among seed sources in response to a gradient of water availability, focusing on a foundational dryland tree species of the western USA, Pinus monophylla. We hypothesized that the expression of growth-related seedling traits would show patterns consistent with local adaptation, given clinal variation among seed source environments. METHODS We collected P. monophylla seeds from 23 sites distributed across rangewide gradients of aridity and seasonal moisture availability. A total of 3320 seedlings were propagated with four watering treatments representing progressively decreasing water availability. Above- and below-ground growth-related traits of first-year seedlings were measured. Trait values and trait plasticity, here representing the degree of variation among watering treatments, were modelled as a function of watering treatment and environmental conditions at the seed source locations (i.e. water availability, precipitation seasonality). KEY RESULTS We found that, under all treatments, seedlings from more arid climates had larger above- and below-ground biomass compared to seedlings from sites experiencing lower growing-season water limitation, even after accounting for differences in seed size. Additionally, trait plasticity in response to watering treatments was greatest for seedlings from summer-wet sites that experience periodic monsoonal rain events. CONCLUSIONS Our results show that P. monophylla seedlings respond to drought through plasticity in multiple traits, but variation in trait responses suggests that different populations are likely to respond uniquely to changes in local climate. Such trait diversity will probably influence the potential for future seedling recruitment in woodlands that are projected to experience extensive drought-related tree mortality.
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Affiliation(s)
- Georgia L Vasey
- Department of Natural Resources and Environmental Science, University of Nevada Reno, 1664 N. Virginia Street, Mail Stop 186, Reno, NV 89557, USA
| | - Alexandra K Urza
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Road, Reno, NV 89512, USA
| | - Jeanne C Chambers
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Road, Reno, NV 89512, USA
| | - Elizabeth G Pringle
- Department of Biology, Program in Ecology, Evolution and Conservation Biology, University of Nevada Reno, 1664 N. Virginia Street, Mail Stop 0314, Reno, NV 89557, USA
| | - Peter J Weisberg
- Department of Natural Resources and Environmental Science, University of Nevada Reno, 1664 N. Virginia Street, Mail Stop 186, Reno, NV 89557, USA
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Noel AR, Shriver RK, Crausbay SD, Bradford JB. Where can managers effectively resist climate-driven ecological transformation in pinyon-juniper woodlands of the US Southwest? GLOBAL CHANGE BIOLOGY 2023; 29:4327-4341. [PMID: 37246831 DOI: 10.1111/gcb.16756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/30/2023]
Abstract
Pinyon-juniper (PJ) woodlands are an important component of dryland ecosystems across the US West and are potentially susceptible to ecological transformation. However, predicting woodland futures is complicated by species-specific strategies for persisting and reproducing under drought conditions, uncertainty in future climate, and limitations to inferring demographic rates from forest inventory data. Here, we leverage new demographic models to quantify how climate change is expected to alter population demographics in five PJ tree species in the US West and place our results in the context of a climate adaptation framework to resist, accept, or direct ecological transformation. Two of five study species, Pinus edulis and Juniperus monosperma, are projected to experience population declines, driven by both rising mortality and decreasing recruitment rates. These declines are reasonably consistent across various climate futures, and the magnitude of uncertainty in population growth due to future climate is less than uncertainty due to how demographic rates will respond to changing climate. We assess the effectiveness of management to reduce tree density and mitigate competition, and use the results to classify southwest woodlands into areas where transformation is (a) unlikely and can be passively resisted, (b) likely but may be resisted by active management, and (c) likely unavoidable, requiring managers to accept or direct the trajectory. Population declines are projected to promote ecological transformation in the warmer and drier PJ communities of the southwest, encompassing 37.1%-81.1% of our sites, depending on future climate scenarios. Less than 20% of sites expected to transform away from PJ have potential to retain existing tree composition by density reduction. Our results inform where this adaptation strategy could successfully resist ecological transformation in coming decades and allow for a portfolio design approach across the geographic range of PJ woodlands.
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Affiliation(s)
- Adam R Noel
- US Geological Survey, Southwest Biological Science Center, Flagstaff, Arizona, USA
- Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, Arizona, USA
| | - Robert K Shriver
- Department of Natural Resources and Environmental Sciences, University of Nevada-Reno, Reno, Nevada, USA
| | | | - John B Bradford
- US Geological Survey, Southwest Biological Science Center, Flagstaff, Arizona, USA
- Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, Arizona, USA
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Loehman RA, Heyerdahl EK, Pederson GT, McWethy D. Climate and Landscape Controls on Old-Growth Western Juniper Demography in the Northern Great Basin, USA. Ecosystems 2022. [DOI: 10.1007/s10021-022-00762-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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McNellis BE, Smith AMS, Hudak AT, Strand EK. Tree mortality in western U.S. forests forecasted using forest inventory and Random Forest classification. Ecosphere 2021. [DOI: 10.1002/ecs2.3419] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Brandon E. McNellis
- Department of Forest, Rangeland, and Fire Sciences University of Idaho Moscow Idaho83844USA
| | - Alistair M. S. Smith
- Department of Forest, Rangeland, and Fire Sciences University of Idaho Moscow Idaho83844USA
| | - Andrew T. Hudak
- USDA Forest Service Rocky Mountain Research Station Forestry Sciences Laboratory Moscow Idaho83843USA
| | - Eva K. Strand
- Department of Forest, Rangeland, and Fire Sciences University of Idaho Moscow Idaho83844USA
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Urza AK, Weisberg PJ, Dilts T. Evidence of widespread topoclimatic limitation for lower treelines of the Intermountain West, United States. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02158. [PMID: 32365241 DOI: 10.1002/eap.2158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/24/2020] [Accepted: 04/03/2020] [Indexed: 06/11/2023]
Abstract
Many forests in dry mountain regions are characterized by a lower elevational treeline. Understanding the controls on the position of lower treeline is important for predicting future forest distributional shifts in response to global environmental change. Lower treelines currently at their climate limit are expected to be more sensitive to changing climate, whereas lower treelines constrained by non-climatic factors are less likely to respond directly to climate change but may be sensitive to other global change agents. In this study, we used existing vegetation classifications to map lower treelines for our 1.7 million km2 study region in the U. S. Intermountain West. We modeled topoclimatic drivers of lower treeline position for each of three dominant forest types to identify topoclimatically limited treelines. We then used spatial data of edaphic properties, recent fire, and land use to identify lower treelines potentially constrained above their ecophysiological limits by non-climatic processes. We found that the lower treeline ecotone of pinyon-juniper woodlands is largely limited by topoclimate and is likely to be sensitive to increasing temperatures and associated droughts, though these effects may be heterogeneously distributed across the landscape. In contrast, dry mixed-conifer lower treelines in the northern portion of the study area rarely reached their modeled topoclimatic limit, suggesting that non-climatic processes, including fire and land use, constrain the lower treeline above its ecophysiological limits in this forest type. Our results suggest that much of the lower treeline in the Intermountain West is currently climate limited and will thus be sensitive to ongoing climate changes. Lower treelines in other arid or semi-arid mountainous regions around the globe may also be strongly sensitive to climate, though treeline response to climate change will be mediated at the local scale by soil properties, biotic interactions, and natural or anthropogenic disturbances. Our regional study of lower treeline provides a framework for identifying the drivers of lower treeline formation and allows for more robust projections of future treeline dynamics, which are needed to anticipate shifting global distributions of the forest biome.
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Affiliation(s)
- Alexandra K Urza
- USDA Forest Service, Rocky Mountain Research Station, 920 Valley Road, Reno, Nevada, 89512, USA
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
| | - Peter J Weisberg
- Program in Ecology, Evolution and Conservation Biology, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
- Department of Natural Resources and Environmental Science, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
| | - Thomas Dilts
- Department of Natural Resources and Environmental Science, University of Nevada-Reno, 1664 North Virginia Street, Reno, Nevada, 89557, USA
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Teshome DT, Zharare GE, Naidoo S. The Threat of the Combined Effect of Biotic and Abiotic Stress Factors in Forestry Under a Changing Climate. FRONTIERS IN PLANT SCIENCE 2020; 11:601009. [PMID: 33329666 PMCID: PMC7733969 DOI: 10.3389/fpls.2020.601009] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/05/2020] [Indexed: 05/11/2023]
Abstract
Plants encounter several biotic and abiotic stresses, usually in combination. This results in major economic losses in agriculture and forestry every year. Climate change aggravates the adverse effects of combined stresses and increases such losses. Trees suffer even more from the recurrence of biotic and abiotic stress combinations owing to their long lifecycle. Despite the effort to study the damage from individual stress factors, less attention has been given to the effect of the complex interactions between multiple biotic and abiotic stresses. In this review, we assess the importance, impact, and mitigation strategies of climate change driven interactions between biotic and abiotic stresses in forestry. The ecological and economic importance of biotic and abiotic stresses under different combinations is highlighted by their contribution to the decline of the global forest area through their direct and indirect roles in forest loss and to the decline of biodiversity resulting from local extinction of endangered species of trees, emission of biogenic volatile organic compounds, and reduction in the productivity and quality of forest products and services. The abiotic stress factors such as high temperature and drought increase forest disease and insect pest outbreaks, decrease the growth of trees, and cause tree mortality. Reports of massive tree mortality events caused by "hotter droughts" are increasing all over the world, affecting several genera of trees including some of the most important genera in plantation forests, such as Pine, Poplar, and Eucalyptus. While the biotic stress factors such as insect pests, pathogens, and parasitic plants have been reported to be associated with many of these mortality events, a considerable number of the reports have not taken into account the contribution of such biotic factors. The available mitigation strategies also tend to undermine the interactive effect under combined stresses. Thus, this discussion centers on mitigation strategies based on research and innovation, which build on models previously used to curb individual stresses.
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Affiliation(s)
- Demissew Tesfaye Teshome
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | | | - Sanushka Naidoo
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
- *Correspondence: Sanushka Naidoo,
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