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1.
Petrovska R. Bugmann H. Hobi M. L. Ghosh S. Brang P. 《European Journal of Forest Research》2022,141(1):43-58
European Journal of Forest Research - Low mortality rates and slow growth differentiate shade-tolerant from shade-intolerant species and define the survival strategy of juvenile trees growing in... 相似文献
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Kathrin Priewasser Peter Brang Hansheinrich Bachofen Harald Bugmann Thomas Wohlgemuth 《European Journal of Forest Research》2013,132(2):231-240
Downed and standing deadwood (DW) is a key resource for maintaining forest biodiversity. Although extreme events such as windthrow and fires produce large quantities of DW, this substrate is often drastically reduced by logging activities. To elucidate the respecting consequences of salvage-logging, we assessed both quantity and quality of storm-derived DW (storms Vivian 1990 and Lothar 1999) in Swiss forests using a sample of 90 windthrow sites with ≥3 ha complete windthrow and at elevations ranging from 350 to 1,800 m a.s.l. The majority had been salvage-logged (SL) a few years after the windthrow. On each site, we recorded DW amount and quality on six circular sample plots 20 or 50 m2 in size. DW volume on SL sites was surprisingly high, with 76.4 m3 ha?1 on average 20 years after Vivian and 73.8 m3 ha?1 10 years after Lothar. In comparison, DW volumes on unsalvaged sites, that is, with no post-windthrow intervention (NI), amounted to 270 m3 ha?1. A wide variety of wood decay stages and diameter classes (10 to ≥70 cm) was found on both NI and SL sites, suggesting considerable habitat diversity for DW-associated species irrespective of the treatment. The considerable amounts of DW left after salvage-logging distinctly exceed the minimum DW volumes in forest stands proposed by Müller and Bütler (Eur J For Res 129: 981–992, 2010) in a conservation context, which demonstrates the importance of wind disturbance for biodiversity. Further studies should quantify DW of individual tree species, since habitat requirements are species-specific. 相似文献
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Andrea?D.?KupferschmidEmail author Peter?Brang Walter?Sch?nenberger Harald?Bugmann 《European Journal of Forest Research》2006,125(2):163-179
A bark beetle (Ips typographus) infestation caused the death of almost all Norway spruce (Picea abies) trees in a mountain forest in the Swiss Alps. We developed a tree regeneration model, ‘RegSnag’ (=REGeneration in a SNAG stand), to project the future amount and height of tree regeneration in these snag stands. The model combines a height-class structured tree module with a microsite-based module of snag decay and ground-vegetation succession. Microsite-specific rates of germination, mortality and height growth were modelled for four tree species (Picea abies, Sorbus aucuparia, Acer pseudoplatanus and Betula pendula) in eight height classes (from seedlings to saplings 5 m tall) and on 26 microsite types (e.g. moss, grass). Model tests with independent field data from 8 years after the Picea die-back demonstrated that microsites had a considerable effect on the development of tree regeneration on both the montane and the subalpine level. With microsite-specific parameters, the height and frequency of Picea in each microsite could be simulated more accurately than without considering microsite effects (e.g. bias of 8 vs. 119 saplings ha−1 on the montane level). Results of simulations 40 years into the future suggest that about 330–930 Picea saplings per ha out of those that germinated in 1994 and 1996 will reach a height of 5 m within 30–35 years after Picea die-back. This is due to differences in seed inflow and browsing intensities. Picea and not Betula or Sorbus trees will replace the current herbaceous vegetation in these snag stands. 相似文献
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Many mountain forests in the Swiss Alps are dense and overmature. The resulting lack of tree regeneration threatens their future ability to provide products and services for humans, e.g., protecting settlements and infrastructure against avalanches. To promote natural regeneration, slit-shaped gaps have been cut since the 1980s in many of Switzerland's Alpine forests dominated by Norway spruce (Picea abies). However, little is known about the success of this silvicultural technique. We sampled 38 gaps in 2001 and 2006 and analysed the density and vitality of P. abies seedlings in these gaps, and monitored the growth and survival of selected seedlings between the two inventories. The gaps analysed were located in upper montane and subalpine P. abies dominated forests in the Vorderrhein valley in the Grisons. The density and vitality of large (10–129 cm tall) and small (<10 cm tall) P. abies seedlings were assessed in three parallel transects running perpendicular to the longitudinal axis of each gap. The mean density of large seedlings increased significantly between 2001 and 2006 from 0.1 to 0.3 seedlings/m2, whereas that of small seedlings stayed constant at 0.7 seedlings/m2, even though it shifted locally between inventories. Significantly higher regeneration densities were found for gaps with NE–SW orientation (afternoon sun) and for those located at lower altitudes. While in gaps on North-facing slopes large P. abies seedlings were more frequent on the middle transect, in gaps on South-facing slopes they were denser near the lower gap edge which is usually less exposed to direct radiation. As expected regeneration density was significantly higher within the gaps than just outside underneath the adjacent stands for all P. abies seedlings. Damage caused by browsing did not turn out to be problematic in this study site. From the selected 280 small seedlings monitored in 2001, 53% died until 2006, 33% became large seedlings and 14% remained small (<10 cm). Our results suggest that creating slit-shaped gaps is a successful procedure to promote P. abies regeneration in the upper montane and subalpine belt of the northern intermediate Alps and helps to preserve protection forests and their goods and services for the coming generations. 相似文献
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Temperli Christian Stadelmann Golo Th&#;rig Esther Brang Peter 《European Journal of Forest Research》2017,136(4):711-725
Timber use in central Europe is expected to increase in the future, in line with forest policy goals to strengthen local wood supply for CO2-neutral energy production, construction and other uses. Growing stocks in low-elevation forests in Switzerland are currently high as exemplified by the Swiss canton of Aargau, for which an average volume of 346 ± 16 m3 ha−1 was measured in the 3rd Swiss National forest inventory (NFI) in 2004–2006. While this may justify a reduction of growing stocks through increased timber harvesting, we asked whether such a strategy may conflict with the sustainability of timber production and conservation goals. We evaluated a range of operationally relevant forest management scenarios that varied with respect to rotation length, growing stock targets and the promotion of conifers in the regeneration. The scenarios aimed at increased production of softwood, energy wood, the retention of potential habitat trees (PHTs) and the conversion to a continuous cover management system. They were used to drive the inventory-based forest simulator MASSIMO for 100 years starting in 2007 using the NFI sampling plots in Aargau. We analyzed model outputs with respect to projected future growing stock, growth, timber and energy yield and harvesting costs. We found growing stock to drop to 192 m3 ha−1 in 2106 if business-as-usual (BAU as observed between the 2nd and 3rd NFI) timber volumes were set as harvesting targets for the whole simulation period. The promotion of conifers and a reduction of rotation lengths in a softwood scenario yielded 25% more timber over the whole simulation period than BAU. An energy wood scenario that reduced growing stock to 200 m3 ha−1 by 2056 and promoted the natural broadleaved regeneration yielded 9% more timber than BAU before 2056 and 30% less thereafter due to decreasing increments. The softwood scenario resulted in higher energy yield than the energy wood scenario despite the lower energy content of softwood. Retaining PHT resulted in a reduction of timber harvest (0.055 m3 ha−1 yr−1 per habitat tree) and higher harvesting costs. Continuous cover management yielded moderate timber amounts throughout the simulation period, yet sustainably. Considering climate change, we discuss the risks associated with favoring drought- and disturbance-susceptible conifers at low elevations and emphasize that continuous cover management must allow for the regeneration of drought-adapted tree species. In conclusion, our simulations show potential for short-term increases in timber mobilization but also that such increases need to be carefully balanced with future forest productivity and other forest ecosystem services.
相似文献7.
A. Wehrli P. J. Weisberg W. Schönenberger P. Brang H. Bugmann 《European Journal of Forest Research》2007,126(1):131-145
Simulation models such as forest patch models can be used to forecast the development of forest structural attributes over
time. However, predictions of such models with respect to the impact of forest dynamics on the long-term protective effect
of mountain forests may be of limited accuracy where tree regeneration is simulated with little detail. For this reason, we
improved the establishment submodel of the ForClim forest patch model by implementing a more detailed representation of tree
regeneration. Our refined submodel included canopy shading and ungulate browsing, two important constraints to sapling growth
in mountain forests. To compare the old and the new establishment submodel of ForClim, we simulated the successional dynamics
of the Stotzigwald protection forest in the Swiss Alps over a 60-year period. This forest provides protection for an important
traffic route, but currently contains an alarmingly low density of tree regeneration. The comparison yielded a significantly
longer regeneration period for the new model version, bringing the simulations into closer agreement with the known slow stand
dynamics of mountain forests. In addition, the new model version was applied to forecast the future ability of the Stotzigwald
forest to buffer the valley below from rockfall disturbance. Two scenarios were simulated: (1) canopy shading but no browsing
impact, and (2) canopy shading and high browsing impact. The simulated stand structures were then compared to stand structure
targets for rockfall protection, in order to assess their long-term protective effects. Under both scenarios, the initial
sparse level of tree regeneration affected the long-term protective effect of the forest, which considerably declined during
the first 40 years. In the complete absence of browsing, the density of small trees increased slightly after 60 years, raising
hope for an eventual recovery of the protective effect. In the scenario that included browsing, however, the density of small
trees remained at very low levels. With our improved establishment submodel, we provide an enhanced tool for studying the
impacts of structural dynamics on the long-term protective effect of mountain forests. For certain purposes, it is important
that predictive models of forest dynamics adequately represent critical processes for tree regeneration, such as sapling responses
to low light levels and high browsing pressure. 相似文献
8.
Christian Temperli Golo Stadelmann Esther Thürig Peter Brang 《European Journal of Forest Research》2017,136(3):493-509
The demand for wood as construction material, renewable source for energy and feedstock for chemicals is expected to increase. However, timber increments are currently only partly harvested in many European mountain regions, which may lead to supply shortages for local timber industries, decreases in forest resistance to disturbances and functioning as protection from gravitational hazards. Using an inventory-based forest simulator, we evaluated scenarios to increase wood mobilization in the 7105-km2 Swiss canton of Grisons for the period 2007–2106. Scenarios varied with respect to landscape-scale harvesting amounts and silvicultural strategies (low vs. high stand-scale treatment intensity) and accounted for regulations and incentives for protection forest management. With 50 and 100% increases of harvests, the current average growing stock of 319 m3 ha?1 was simulated to be reduced by 12 and 33%, respectively, until 2106 in protection forests of Northern Grisons, where management is prioritized due to subsidies. Outside protection forests and in Southern Grisons, growing stock was simulated to continually increase, which led to divergent developments in forest structure in- and outside protection forests and in the Northern and Southern Grisons. The effect of silvicultural strategies on simulated forest structure was small compared to the effect of future harvesting levels. We discuss opportunities and threats of decreasing management activities outside protection forests and advocate for incentives to promote natural regeneration also outside protection forests to safeguard long-term forest stability. 相似文献
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Thomas Wohlgemuth Raphael Schwitter Peter Bebi Flurin Sutter Peter Brang 《European Journal of Forest Research》2017,136(5-6):1029-1040
The two storms Vivian (1990) and Lothar (1999) left an area of roughly 9000 ha of fully damaged protection forests in Swiss mountain regions. Given this huge dimension, questions arose on how to manage these areas to keep the protection gap, i.e. the time period with reduced overall protection against natural hazards, short. Quantifications are presented for the stability of lying logs left in place, the frequency of post-disturbance mass movements, and the tree regeneration in windthrow areas. The average height above ground of unsalvaged lying logs decreased from 2.1 m shortly after disturbance to 0.8 m 20 years later. In the period 1990–2014, the number of avalanches in windthrow areas was markedly small, and annual rates of shallow landslides and debris flows in windthrow areas did not differ from rates in comparable undamaged forested areas. Regeneration density rarely exceeded 4000 stems ha?1 20 years post-windthrow at elevations above 1200–1500 m a.s.l. Mean height of tallest trees reached 5.6 m in areas that were cleared and 6.5 m in those left unsalvaged. Trees planted post-windthrow were 1.0–2.4 m taller than naturally regenerated ones. Practitioners rated the protective effect to be acceptable 24 years post-disturbance in only 5 out from 16 observed windthrow areas (31%), with planting trees as the main cause of success. We conclude that in protection forests the regeneration speed after disturbance rarely meets practitioner’s expectations in terms of both stem density and stand structure. However, leaving woody debris from wind disturbance in place proved to replace protective effects for an astonishingly long time. An intensive management with salvage logging, planting and even technical constructions seems therefore only inevitable on windthrown areas where risks seem too high based on hazard, damage potential and possible spread of bark beetles to nearby protection forests. A management alternative applicable to many other cases of windthrown protection forests is to plant trees between lying stems. 相似文献