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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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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
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Brigitte Rohner Harald Bugmann Christof Bigler 《European Journal of Forest Research》2013,132(5-6):751-764
Tree growth plays a key role in forest dynamics, yet little attention has been paid to quantifying tree age–diameter relationships. Predicting diameter growth of oaks is especially important due to their role in nature conservation and adaptive forest management under climate change. Thus, we (1) identified environmental variables that shape age–diameter relationships of oaks and (2) quantified the accuracy of predictions based on these variables. We determined the age–diameter relationship of 243 oaks (Quercus spp.) growing in Switzerland by using tree-ring samples. Nonlinear mixed-effects models based on a modified Chapman-Richards equation were fitted with environmental variables included as covariates. The fixed effects elevation, slope and water-holding capacity were most important in shaping the age–diameter relationships. Lower elevations, steeper slopes, north-facing aspects, higher water-holding capacities and moister summers resulted in larger maximum diameters. For 75 % of the oaks, age–diameter relationships predicted by the fixed effects matched fairly well the observations (root mean square error between predictions and observations <6 cm); the inclusion of random effects reduced root mean square errors for 86 % of the trees. These results suggest that water runoff plays a key role for the age–diameter relationships, accompanied by limiting temperature effects at higher elevations. The fixed effects covered variability in site quality, whereas the random effects included tree-specific deviations from expected age–diameter relationships, potentially due to neighbourhood effects such as stand density and competition. 相似文献
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Paul D. Henne Ché Elkin Daniele Colombaroli Stéphanie Samartin Harald Bugmann Oliver Heiri Willy Tinner 《Landscape Ecology》2013,28(5):819-833
Forests near the Mediterranean coast have been shaped by millennia of human disturbance. Consequently, ecological studies relying on modern observations or historical records may have difficulty assessing natural vegetation dynamics under current and future climate. We combined a sedimentary pollen record from Lago di Massacciucoli, Tuscany, Italy with simulations from the LandClim dynamic vegetation model to determine what vegetation preceded intense human disturbance, how past changes in vegetation relate to fire and browsing, and the potential of an extinct vegetation type under present climate. We simulated vegetation dynamics near Lago di Massaciucoli for the last 7,000 years using a local chironomid-inferred temperature reconstruction with combinations of three fire regimes (small infrequent, large infrequent, small frequent) and three browsing intensities (no browsing, light browsing, and moderate browsing), and compared model output to pollen data. Simulations with low disturbance support pollen-inferred evidence for a mixed forest dominated by Quercus ilex (a Mediterranean species) and Abies alba (a montane species). Whereas pollen data record the collapse of A. alba after 6000 cal yr bp, simulated populations expanded with declining summer temperatures during the late Holocene. Simulations with increased fire and browsing are consistent with evidence for expansion by deciduous species after A. alba collapsed. According to our combined paleo-environmental and modeling evidence, mixed Q. ilex and A. alba forests remain possible with current climate and limited disturbance, and provide a viable management objective for ecosystems near the Mediterranean coast and in regions that are expected to experience a mediterranean-type climate in the future. 相似文献
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