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Janda P, Trotsiuk V, Mikoláš M, Bače R, Nagel TA, Seidl R, Seedre M, Morrissey RC, Kucbel S, Jaloviar P, Jasík M, Vysoký J, Šamonil P, Čada V, Mrhalová H, Lábusová J, Nováková MH, Rydval M, Matějů L, Svoboda M. The historical disturbance regime of mountain Norway spruce forests in the Western Carpathians and its influence on current forest structure and composition. FOREST ECOLOGY AND MANAGEMENT 2017; 388:67-78. [PMID: 28860676 PMCID: PMC5572639 DOI: 10.1016/j.foreco.2016.08.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In order to gauge ongoing and future changes to disturbance regimes, it is necessary to establish a solid baseline of historic disturbance patterns against which to evaluate these changes. Further, understanding how forest structure and composition respond to variation in past disturbances may provide insight into future resilience to climate-driven alterations of disturbance regimes. We established 184 plots (mostly 1000 m2) in 14 primary mountain Norway spruce forests in the Western Carpathians. On each plot we surveyed live and dead trees and regeneration, and cored around 25 canopy trees. Disturbance history was reconstructed by examining individual tree growth trends. The study plots were further aggregated into five groups based on disturbance history (severity and timing) to evaluate and explain its influence on forest structure. These ecosystems are characterized by a mixed severity disturbance regime with high spatiotemporal variability in severity and frequency. However, periods of synchrony in disturbance activity were also found. Specifically, a peak of canopy disturbance was found for the mid-19th century across the region (about 60% of trees established), with the most important periods of disturbance in the 1820s and from the 1840s to the 1870s. Current stand size and age structure were strongly influenced by past disturbance activity. In contrast, past disturbances did not have a significant effect on current tree density, the amount of coarse woody debris, and regeneration. High mean densities of regeneration with height >50 cm (about 1400 individuals per ha) were observed. Extensive high severity disturbances have recently affected Central European forests, spurring a discussion about the causes and consequences. We found some evidence that forests in the Western Carpathians were predisposed to recent severe disturbance events as a result of synchronized past disturbance activity, which partly homogenized size and age structure and made recent stands more vulnerable to bark beetle outbreak. Our data suggest that these events are still part of the range of natural variability. The finding that regeneration density and volume of coarse woody debris were not influenced by past disturbance illustrates that vastly different past disturbance histories are not likely to change the future trajectories of these forests. These ecosystems currently have high ecological resilience to disturbance. In conclusion, we suggest that management should recognize disturbances as a natural part of ecosystem dynamics in the mountain forests of Central Europe, account for their stochastic occurrence in management planning, and mimic their patterns to foster biodiversity in forest landscapes.
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Affiliation(s)
- Pavel Janda
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
- Corresponding author. (P. Janda)
| | - Volodymyr Trotsiuk
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Martin Mikoláš
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
- PRALES, o. z., Odtrnovie 563, SK-013 22 Rosina, Slovakia
| | - Radek Bače
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Thomas A. Nagel
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
- Department of Forestry and Renewable Forest Resources, University of Ljubljana, Slovenia
| | - Rupert Seidl
- Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU) Vienna, Austria
| | - Meelis Seedre
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Robert C. Morrissey
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | | | - Peter Jaloviar
- Faculty of Forestry, Technical University of Zvolen, Slovakia
| | - Marián Jasík
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
- PRALES, o. z., Odtrnovie 563, SK-013 22 Rosina, Slovakia
| | - Juraj Vysoký
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
- PRALES, o. z., Odtrnovie 563, SK-013 22 Rosina, Slovakia
| | - Pavel Šamonil
- Department of Forest Ecology, The Silva Tarouca Research Institute for Landscape and Ornamental Gardening, Brno, Czech Republic
| | - Vojtěch Čada
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Hana Mrhalová
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Jana Lábusová
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Markéta H. Nováková
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Miloš Rydval
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Lenka Matějů
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
| | - Miroslav Svoboda
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Czech Republic
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Seidl R, Vigl F, Rössler G, Neumann M, Rammer W. Assessing the resilience of Norway spruce forests through a model-based reanalysis of thinning trials. FOREST ECOLOGY AND MANAGEMENT 2017; 388:3-12. [PMID: 28860674 PMCID: PMC5572630 DOI: 10.1016/j.foreco.2016.11.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
As a result of a rapidly changing climate the resilience of forests is an increasingly important property for ecosystem management. Recent efforts have improved the theoretical understanding of resilience, yet its operational quantification remains challenging. Furthermore, there is growing awareness that resilience is not only a means to addressing the consequences of climate change but is also affected by it, necessitating a better understanding of the climate sensitivity of resilience. Quantifying current and future resilience is thus an important step towards mainstreaming resilience thinking into ecosystem management. Here, we present a novel approach for quantifying forest resilience from thinning trials, and assess the climate sensitivity of resilience using process-based ecosystem modeling. We reinterpret the wide range of removal intensities and frequencies in thinning trials as an experimental gradient of perturbation, and estimate resilience as the recovery rate after perturbation. Our specific objectives were (i) to determine how resilience varies with stand and site conditions, (ii) to assess the climate sensitivity of resilience across a range of potential future climate scenarios, and (iii) to evaluate the robustness of resilience estimates to different focal indicators and assessment methodologies. We analyzed three long-term thinning trials in Norway spruce (Picea abies (L.) Karst.) forests across an elevation gradient in Austria, evaluating and applying the individual-based process model iLand. The resilience of Norway spruce was highest at the montane site, and decreased at lower elevations. Resilience also decreased with increasing stand age and basal area. The effects of climate change were strongly context-dependent: At the montane site, where precipitation levels were ample even under climate change, warming increased resilience in all scenarios. At lower elevations, however, rising temperatures decreased resilience, particularly at precipitation levels below 750-800 mm. Our results were largely robust to different focal variables and resilience definitions. Based on our findings management can improve the capacity to recover from partial disturbances by avoiding overmature and overstocked conditions. At increasingly water limited sites a strongly decreasing resilience of Norway spruce will require a shift towards tree species better adapted to the expected future conditions.
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Affiliation(s)
- Rupert Seidl
- Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
- Corresponding author. (R. Seidl)
| | - Friedrich Vigl
- Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Günter Rössler
- Department of Forest Growth and Silviculture, Austrian Research Center for Forests (BFW), Vienna, Austria
| | - Markus Neumann
- Department of Forest Growth and Silviculture, Austrian Research Center for Forests (BFW), Vienna, Austria
| | - Werner Rammer
- Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
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Bebi P, Seidl R, Motta R, Fuhr M, Firm D, Krumm F, Conedera M, Ginzler C, Wohlgemuth T, Kulakowski D. Changes of forest cover and disturbance regimes in the mountain forests of the Alps. FOREST ECOLOGY AND MANAGEMENT 2017; 388:43-56. [PMID: 28860675 PMCID: PMC5572777 DOI: 10.1016/j.foreco.2016.10.028] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Natural disturbances, such as avalanches, snow breakage, insect outbreaks, windthrow or fires shape mountain forests globally. However, in many regions over the past centuries human activities have strongly influenced forest dynamics, especially following natural disturbances, thus limiting our understanding of natural ecological processes, particularly in densely-settled regions. In this contribution we briefly review the current understanding of changes in forest cover, forest structure, and disturbance regimes in the mountain forests across the European Alps over the past millennia. We also quantify changes in forest cover across the entire Alps based on inventory data over the past century. Finally, using the Swiss Alps as an example, we analyze in-depth changes in forest cover and forest structure and their effect on patterns of fire and wind disturbances, based on digital historic maps from 1880, modern forest cover maps, inventory data on current forest structure, topographical data, and spatially explicit data on disturbances. This multifaceted approach presents a long-term and detailed picture of the dynamics of mountain forest ecosystems in the Alps. During pre-industrial times, natural disturbances were reduced by fire suppression and land-use, which included extraction of large amounts of biomass that decreased total forest cover. More recently, forest cover has increased again across the entire Alps (on average +4% per decade over the past 25-115 years). Live tree volume (+10% per decade) and dead tree volume (mean +59% per decade) have increased over the last 15-40 years in all regions for which data were available. In the Swiss Alps secondary forests that established after 1880 constitute approximately 43% of the forest cover. Compared to forests established previously, post-1880 forests are situated primarily on steep slopes (>30°), have lower biomass, a more aggregated forest structure (primarily stem-exclusion stage), and have been more strongly affected by fires, but less affected by wind disturbance in the 20th century. More broadly, an increase in growing stock and expanding forest areas since the mid-19th century have - along with climatic changes - contributed to an increasing frequency and size of disturbances in the Alps. Although many areas remain intensively managed, the extent, structure, and dynamics of the forests of the Alps reflect natural drivers more strongly today than at any time in the past millennium.
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Affiliation(s)
- P. Bebi
- WSL-Institute for Snow and Avalanche Research SLF, Davos, Switzerland
- Corresponding author. (P. Bebi)
| | - R. Seidl
- University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - R. Motta
- Università degli Studi di Torino, DISAFA, Largo Braccini 2, 10095 Grugliasco (TO), Italy
| | - M. Fuhr
- Univ. Grenoble Alpes, Irstea, F-38402 St-Martin-d’Hères, France
| | - D. Firm
- Department of Forestry and Renewable Forest Resources, Biotechnical Faculty, University of Ljubljana, Slovenia
| | - F. Krumm
- European Forest Institute, Freiburg, Germany
| | - M. Conedera
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Switzerland
| | - C. Ginzler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Switzerland
| | - T. Wohlgemuth
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Switzerland
| | - D. Kulakowski
- WSL-Institute for Snow and Avalanche Research SLF, Davos, Switzerland
- Graduate School of Geography, Clark University, Worcester, MA, USA
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