Browsing by Subject "jack pine"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Influence of logging, fire, and forest type on biodiversity and productivity in southern boreal forests
    (Ecological Society of America, 2001) Reich, Peter B; Bakken, Peter; Carlson, Daren; Frelich, Lee E; Friedman, Steve K; Grigal, David F
    The effects of logging on ecosystem sustainability are controversial. Surprisingly, existing data are inadequate to allow a comprehensive evaluation of logging effects on biodiversity, composition, and productivity since appropriate comparisons of stands of similar ages and differing disturbance histories are rare. We addressed this issue using a study of 2000 plots in 80 southern boreal forest stands in northern Minnesota, USA, wherein we contrasted naturally regenerated aspen (Populus tremuloides), jack pine (Pinus banksiana), and black spruce (Picea mariana) stands established following logging or the dominant natural disturbance, wildfire, for stands of two age classes (25-40 and 70-100 yr old). For young stands, those established postlogging had higher vascular plant diversity than those postwildfire. Otherwise, we found no evidence of differing species diversity (including canopy tree, shrub, herbaceous, and bryophyte species), composition, productivity, or nitrogen cycling, in forest stands of comparable age and forest type that originated after logging compared to after wildfire. These variables, however, differed significantly among forest types, with aboveground net primary productivity and plant species diversity generally higher in aspen than jack pine stands, even when growing on comparable soils, and lowest in black spruce. Although there is evidence that logging has increased the proportional landscape dominance by aspen, a forest type with higher diversity, nutrient cycling, and productivity than other types, our evidence refutes the idea that disturbance by logging has diminished stand-scale productivity or plant diversity in comparison to the common natural disturbance, wildfire.
  • Thumbnail Image
    Item
    Report on the Timberlands of the Northern and Cloquet Lumber Companies, St. Louis County, Minnesota
    (Bureau of Forestry, 1903-06) Chapman, C.S.
    The study of the timberlands of the Northern and Cloquet Lumber Companies, the results of which are presented in this report, was made primarily in order to determine whether future crops of merchantable timber may be harvested from lumbered lands within a reasonable time. The study undertook to devise practical modifications of present methods of logging which will hasten the production of a second crop on cut-over lands.
  • Thumbnail Image
    Item
    Spatial patterns and succession in a Minnesota southern-boreal forest
    (1995) Frelich, Lee E; Reich, Peter B
    Succession was studied in a cold-temperate forest in the Boundary Waters Canoe Area Wilderness (BWCAW) of northeastern Minnesota. The 13 X 18 km study area comprises a complex forest mixture of jack (Pinus banksiana) and other pines, quaking aspen (Populus tremuloides), paper birch (Betula papyrifera), black spruce (Picea mariana), balsam fir (Abies balsamea), and white cedar (Thuja occidentalis) on thin soils over the Canadian Shield bedrock. The main objectives of this study were to examine the relationships betweenspatial patchiness, spatial scale, and canopy succession in the southern-boreal forest of the BWCAW, and to evaluate under what conditions successional direction may remain stable, converge, or diverge. Knowledge of the successional direction of old forests in the BWCAW that are undergoing demographic transition from evenaged to uneven-aged is important because the landscape now has many old stands as a result of reduced fire frequency. Rotation periods for fires have changed from -50-100 yr in presettlement times to >1000 yr since 1910. Analyses were conducted at spatial scales ranging from the individual tree (0.01 ha) to the large stand (16 ha). Two permanent mapped plots (of area 0.53 and 0.56 ha) were established in stands of different age. Finescale age structure, successional change, transition from one species to another, and development of small patches (of area <0.25 ha) were studied by means of stand history reconstruction with increment cores, spatial autocorrelation, and analysis of replacement trees in canopy openings. Spatial processes at nested scales of 1, 4, and 16 ha were examined on 15 square 16-ha tracts of upland forest, which are distributed among forests ranging from 15 to 190 yr old. Canopy species composition and patch development over time on these 15 tracts were interpreted on air photos taken in 1934, 1961, and 1991. Thus, the study includes a chronosequence approach, with verification of chronosequence validity by checking patch development processes at more than one time point. This checking was done at small spatial scales by reconstruction of stand history on permanent mapped plots, and at larger spatial scales with sequential air photos of the same locations spanning a 57-year period. Results show that the reduced fire frequency in recent years has changed the dominant successional pathways. When fire frequency was high, jack pine or aspen stands usually burned while still in the even-aged stage of development, and the new trees after the burn were the same species as before. Currently, many stands are undergoing demographic transition from even-aged stands of catastrophic fire origin to uneven-aged stands. This transition parallels a change in canopy composition from jack pine (occasionally red pine (Pinus resinosa)) or aspen to an old-growth multi-aged mixture of black spruce, balsam fir, paper birch, and white cedar. The mechanism that moves this successional path forward is canopy openings, 10-30 m across on average, caused by wind, insect, and disease, that gradually chip away at the relatively uniform canopy of pines and aspen. Successional direction is individualistic in the sense that time and rate of transition from pine/aspen to other species depends on the action of heavy windstorms, insect infestation, and senescence of old pines that create canopy openings. Canopy openings are often filled with one of several species, but if more than one species invades an opening, monodominant patches of each species generally result. Understory-overstory interactions are very weak; the dominant species within each patch is apparently independent of the overstory species that died when the opening was created or the species dominating surrounding patches. During succession, the spatial structure of the stands at the 1-16 ha scales generally changes from a matrix heavily dominated by pine or aspen to a mosaic with relatively large mono-dominant patches that may be remnants of the extensive original matrix, and finally to a mixture with small patches (mean area 35 M2, maximum -0.1 ha) of black spruce, balsam fir, white cedar, and paper birch. Thus, at 1-16 ha spatial scales, succession leads to convergence on a mixture of species. At smaller spatial scales (e.g., 0.01-0.1 ha) successional pathways appear to diverge into four community types. The same successional pathways can be reconstructed from historical analysis of individual stands as from a chronosequence of stands; therefore, chronosequences in this area have been stable at least during the lifetime of the current generation of trees.