Scott A. Weyenberg, Lee E. Frelich, Peter B. Reich. (2004). Logging versus fire: how does disturbance type influence the abundance of Pinus strobus regeneration? Silva Fennica vol. 38 no. 2 article id 427. https://doi.org/10.14214/sf.427

Keywords: disturbance refugia; interspecific competition; Minnesota; seedling dispersion; seed source; white pine

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Eastern white pine (Pinus strobus) has decreased in abundance over the past century throughout the Great Lakes Region of North America, but the relative constraints placed on recruitment under contrasting disturbance regimes are not well understood. The objectives of this study were to determine the extent to which white pine could invade areas recently disturbed by fire or logging (within 10–28 years), and assess the relative limitations placed on recruitment by seed supply, microsite habitat, and competition. We compared white pine regeneration on 61 sites disturbed by fire or logging that were adjacent to intact mature stands that provided a seed source. White pine seedling and sapling densities declined with increasing distance from a seed source, and the rate of decrease was determined by the interaction between seed supply and variation in number and quality of safe sites. For a given combination of seed source and site, white pine seedlings were three times more abundant on burned than logged sites. White pine seedlings grew into the sapling size class more often on burned than logged sites due to lower shrub cover on burned sites. At 25 years after disturbance, regeneration densities of white pine sufficient to achieve eventual future dominance occurred up to 80 m and 20 m from the edge of mature white pine stands after fire and logging, respectively. To attain a similar level of white pine stocking after disturbance, three to four times as many patches of mature white pine need to be left after logging than after fire.

Weyenberg, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: saw@nn.us
Frelich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: freli001@umn.edu
Reich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: pbr@nn.us

article id 691, category Research article

Jacek Oleksyn, Mark G. Tjoelker, Peter B. Reich. (1998). Adaptation to changing environment in Scots pine populations across a latitudinal gradient. Silva Fennica vol. 32 no. 2 article id 691. https://doi.org/10.14214/sf.691

Keywords: Pinus sylvestris; climate change; provenance; growth; temperature; photoperiod

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In several growth chamber and field experiments we examined the growth response of Scots pine (Pinus sylvestris L.) populations from a wide latitudinal range to temperature and photoperiod. The duration of the shoot elongation period of one-year-old seedlings was affected by temperature and photoperiod. In contrasting temperatures, 23/20 °C, 20/17 °C, and 17/14 °C (day/night), shoot elongation period for all populations was shortest in the high and longest in the low temperature treatments. The northern populations from 61–57°N ceased height growth earlier than the other populations in the southern 50°N photoperiod. The order of growth cessation among populations at 50°N in the chamber experiment and at 52°N in the field experiment was similar and related to observed population differences in terminal leader growth and total tree height. Since the length of growing season is under strong environmentally-mediated genetic control in Scots pine, potential climatic changes such as increasing temperature will probably alter the length and timing of growth in aboveground tree parts, but likely in the opposite direction (a shorter growing season) than has been often hypothesized (a longer growing season). Tree-ring analyses of a provenance experiment established in 1912 indicate that the main climatic factors that limited ring-width growth in Scots pine were air temperatures in the winter months of December through March. Low winter temperatures were followed by the formation of narrow rings over the next summer. Based on responses to temperature, Scots pine populations from the continuous European range can be divided in several geographic groups along a latitudinal gradient. Our results suggest that in developing new models to predict the response of Scots pine to changing environmental conditions, it is necessary to include intraspecific differentiation in acclimation and adaptation to environmental factors.

Oleksyn, Polish Academy of Sciences, Institute of Dendrology, Parkowa 5, PL-62-035 Kórnik, Poland; University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: oleks001@gold.tc.umn.edu
Tjoelker, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: mgt@nn.us
Reich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: pbr@nn.us

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