Short-interval severe fire erodes the resilience of subalpine lodgepole pine forests

Subalpine forests in the northern Rocky Mountains have been resilient to stand-replacing fires that historically burned at 100- to 300-year intervals. Fire intervals are projected to decline drastically as climate warms, and forests that reburn before recovering from previous fire may lose their ability to rebound. We studied recent fires in Greater Yellowstone (Wyoming, United States) and asked whether short-interval (<30 years) stand-replacing fires can erode lodgepole pine (Pinus contortavar.latifolia) forest resilience via increased burn severity, reduced early postfire tree regeneration, reduced carbon stocks, and slower carbon recovery. During 2016, fires reburned young lodgepole pine forests that regenerated after wildfires in 1988 and 2000. During 2017, we sampled 0.25-ha plots in stand-replacing reburns (n= 18) and nearby young forests that did not reburn (n= 9). We also simulated stand development with and without reburns to assess carbon recovery trajectories. Nearly all prefire biomass was combusted (“crown fire plus”) in some reburns in which prefire trees were dense and small (≤4-cm basal diameter). Postfire tree seedling density was reduced sixfold relative to the previous (long-interval) fire, and high-density stands (>40,000 stems ha−1) were converted to sparse stands (<1,000 stems ha−1). In reburns, coarse wood biomass and aboveground carbon stocks were reduced by 65 and 62%, respectively, relative to areas that did not reburn. Increased carbon loss plus sparse tree regeneration delayed simulated carbon recovery by >150 years. Forests did not transition to nonforest, but extreme burn severity and reduced tree recovery foreshadow an erosion of forest resilience.

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Effects of Soil Abiotic and Biotic Factors on Tree Seedling Regeneration Following a Boreal Forest Wildfire

Ecosystems ◽

10.1007/s10021-021-00666-0 ◽

2021 ◽

Author(s):

Theresa S. Ibáñez ◽

David A. Wardle ◽

Michael J. Gundale ◽

Marie-Charlotte Nilsson

Keyword(s):

Boreal Forest ◽

Betula Pendula ◽

Fire Severity ◽

Tree Regeneration ◽

Soil Biota ◽

Fire Disturbance ◽

Burn Severity ◽

Soil Conditions ◽

Tree Seedling ◽

Seedling Regeneration

AbstractWildfire disturbance is important for tree regeneration in boreal ecosystems. A considerable amount of literature has been published on how wildfires affect boreal forest regeneration. However, we lack understanding about how soil-mediated effects of fire disturbance on seedlings occur via soil abiotic properties versus soil biota. We collected soil from stands with three different severities of burning (high, low and unburned) and conducted two greenhouse experiments to explore how seedlings of tree species (Betula pendula, Pinus sylvestris and Picea abies) performed in live soils and in sterilized soil inoculated by live soil from each of the three burning severities. Seedlings grown in live soil grew best in unburned soil. When sterilized soils were reinoculated with live soil, seedlings of P. abies and P. sylvestris grew better in soil from low burn severity stands than soil from either high severity or unburned stands, demonstrating that fire disturbance may favor post-fire regeneration of conifers in part due to the presence of soil biota that persists when fire severity is low or recovers quickly post-fire. Betula pendula did not respond to soil biota and was instead driven by changes in abiotic soil properties following fire. Our study provides strong evidence that high fire severity creates soil conditions that are adverse for seedling regeneration, but that low burn severity promotes soil biota that stimulates growth and potential regeneration of conifers. It also shows that species-specific responses to abiotic and biotic soil characteristics are altered by variation in fire severity. This has important implications for tree regeneration because it points to the role of plant–soil–microbial feedbacks in promoting successful establishment, and potentially successional trajectories and species dominance in boreal forests in the future as fire regimes become increasingly severe through climate change.

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Tree regeneration and soil responses to management alternatives in beetle-infested lodgepole pine forests

Forest Ecology and Management ◽

10.1016/j.foreco.2020.118182 ◽

2020 ◽

Vol 468 ◽

pp. 118182 ◽

Cited By ~ 2

Author(s):

Charles C. Rhoades ◽

Robert M. Hubbard ◽

Kelly Elder ◽

Paula J. Fornwalt ◽

Elizabeth Schnackenberg ◽

...

Keyword(s):

Lodgepole Pine ◽

Tree Regeneration ◽

Pine Forests ◽

Management Alternatives ◽

Soil Responses

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Landscape variation in tree regeneration and snag fall drive fuel loads in 24-year old post-fire lodgepole pine forests

Ecological Applications ◽

10.1002/eap.1412 ◽

2016 ◽

Vol 26 (8) ◽

pp. 2424-2438 ◽

Cited By ~ 14

Author(s):

Kellen N. Nelson ◽

Monica G. Turner ◽

William H. Romme ◽

Daniel B. Tinker

Keyword(s):

Lodgepole Pine ◽

Tree Regeneration ◽

Pine Forests ◽

Fuel Loads ◽

Landscape Variation

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Short-interval disturbance in lodgepole pine forests, British Columbia, Canada: Understory and overstory response to mountain pine beetle and fire

Forest Ecology and Management ◽

10.1016/j.foreco.2014.11.011 ◽

2015 ◽

Vol 338 ◽

pp. 163-175 ◽

Cited By ~ 15

Author(s):

Marc Edwards ◽

Meg A. Krawchuk ◽

Philip J. Burton

Keyword(s):

British Columbia ◽

Mountain Pine Beetle ◽

Lodgepole Pine ◽

Short Interval ◽

Pine Forests ◽

Mountain Pine ◽

Pine Beetle

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Baumartenwechsel in den Walliser Waldföhrenwäldern verstärkt nach grossen Störungen

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2018.0260 ◽

2018 ◽

Vol 169 (5) ◽

pp. 260-268 ◽

Cited By ~ 2

Author(s):

Thomas Wohlgemuth ◽

Violette Doublet ◽

Cynthia Nussbaumer ◽

Linda Feichtinger ◽

Andreas Rigling

Keyword(s):

Scots Pine ◽

Forest Fire ◽

Tree Regeneration ◽

Fire Disturbance ◽

Pine Forests ◽

The Past ◽

Vegetation Shift ◽

Tree Demography ◽

Scots Pine Forests ◽

High Share

Vegetation shift in Scots pine forests in the Valais accelerated by large disturbances In the past dozen years, several studies have concluded a vegetation shift from Scots pine to oak (pubescent and sessile) forests in the low elevated zones of the Valais. It is, however, not fully clear in which way such a vegetation shift actually occurs and on which processes such a shift would be based. Two studies, one on the tree demography in the intact Pfynwald and the other on the tree regeneration on the large Leuk forest fire patch, serve to discuss different aspects of the shift from Scots pine to oak. The forest stands of Pfynwald consist of 67% Scots pines and 14% oaks. Regenerating trees are 2–3.5 times more frequent in small gaps than under canopy. In gaps of the Upper Pfynwald, seedlings and saplings of Scots pine are three times more abundant than oaks, while both species regenerate in similar quantities under canopy. In the Lower Pfynwald, young oaks – especially seedlings – are more frequent than Scots pines. A different process is going on at the lower part in the Leuk forest fire patch where Scots pines prevailed before the burn of 2003. While Scots pines regenerate exclusively close to the edge of the intact forest, oaks not only resprout from trunk but also profit from unlimited spreading of their seeds by the Eurasian jay. Regeneration from seeds are hence observed in the whole studied area, independent of the proximity of seed trees. After the large fire disturbance, a mixed forests with a high share of oaks is establishing, which translates to a rapid vegetation shift. The two trajectories are discussed in the light of climate change.

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Stand-level biomass models for predicting C stock for the main Spanish pine species

Forest Ecosystems ◽

10.1186/s40663-021-00308-w ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Ana Aguirre ◽

Miren del Río ◽

Ricardo Ruiz-Peinado ◽

Sonia Condés

Keyword(s):

Form Factor ◽

Pinus Halepensis ◽

Dry Weight ◽

Pinus Nigra ◽

Carbon Stocks ◽

Tree Size ◽

Pine Forests ◽

Stand Volume ◽

Biomass Models ◽

Pine Species

Abstract Background National and international institutions periodically demand information on forest indicators that are used for global reporting. Among other aspects, the carbon accumulated in the biomass of forest species must be reported. For this purpose, one of the main sources of data is the National Forest Inventory (NFI), which together with statistical empirical approaches and updating procedures can even allow annual estimates of the requested indicators. Methods Stand level biomass models, relating the dry weight of the biomass with the stand volume were developed for the five main pine species in the Iberian Peninsula (Pinus sylvestris, Pinus pinea, Pinus halepensis, Pinus nigra and Pinus pinaster). The dependence of the model on aridity and/or mean tree size was explored, as well as the importance of including the stand form factor to correct model bias. Furthermore, the capability of the models to estimate forest carbon stocks, updated for a given year, was also analysed. Results The strong relationship between stand dry weight biomass and stand volume was modulated by the mean tree size, although the effect varied among the five pine species. Site humidity, measured using the Martonne aridity index, increased the biomass for a given volume in the cases of Pinus sylvestris, Pinus halepensis and Pinus nigra. Models that consider both mean tree size and stand form factor were more accurate and less biased than those that do not. The models developed allow carbon stocks in the main Iberian Peninsula pine forests to be estimated at stand level with biases of less than 0.2 Mg∙ha− 1. Conclusions The results of this study reveal the importance of considering variables related with environmental conditions and stand structure when developing stand dry weight biomass models. The described methodology together with the models developed provide a precise tool that can be used for quantifying biomass and carbon stored in the Spanish pine forests in specific years when no field data are available.

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