http://cfs.nrcan.gc.ca/authors/read/12747 Publications by W.C. Parker en-ca 2012-04-19 06:43:24 MST 2012-04-19 06:43:24 MST webmaster@nofc.cfs.nrcan.gc.ca http://cfs.nrcan.gc.ca/publications?id=33544 The influence of herbaceous and woody vegetation control applied over four conseCLItive growing seasons (GS) on microclimate. leaf gas exchange, water status, nutrient relations,and growth of planted eastern white pine (Pinus strobus L.) seedlings was examined in a central Ontario shelterwood. Treatment effects on pine seedling ecophysiology were closely associated with temporal changes in the structure and species composition of the developing understory plant communities. Vegetation control had minimal influence on air temperature, but herbaceous control. sometimes in combination with woody control, improved the soil thermal regime in every GS. Herbaceous vegetation control increased soil moisture availability in GS one and two, but only during mid-summer periods of little precipitation. Light availability showed a relatively large treatment response. with highest light levels created where both herbaceous and woody vegetation were suppressed. Herbaceous and woody vegetation control had additive or interactive effects on net carbon assimilation (An) and leaf conductance to water vapour (Gwv) in a given GS. while water use efficiency and midday leaf water potential (I/lm) were largely independent of treatment. The effects of vegetation control on An. Gwv• and I/Im were often correlated with treatment-induced changes in total vegetative cover. light. and soil moisture availability. Vector analysis of leaf nutrient(N. p. K. Ca. and Mg) relations suggested that herbaceous vegetation control relieved foliar N. P. and K deficiencies in 5-year-old white pine seedli ngs. woody vegetation control did not affect leaf nutrient relations. and total vegetation control provided non-limiting conditions. In GS four. white pine growth responses were highest where both herbaceous and woody vegetation control had been conducted. likely in response to improved microclimate. resource avai labi lity. leaf gas exchange. and foliar nutrition. Thu, 19 Apr 2012 http://cfs.nrcan.gc.ca/publications?id=33544 http://cfs.nrcan.gc.ca/publications?id=33070 We investigated the effects ofherbaceous and woody vegetation control onthesurvival and growth ofplanted and natural eastern white pine (Pinus strobus L.) seedlings through six growing seasons following auniform shelterwood regeneration harvest on two independent sites. Subsequent tochain scarification, white pine seedlings were planted at 2-m spacing, augmenting natural regeneration (full stocking and >3000 seedlings perha). Herbaceous vegetation control involved the suppression ofgrasses, forbs, ferns, and low shrubs, and was maintained for zero, two, orfour growing seasons after planting. Woodycontrol involved the removal of all tall shrubs and deciduous trees, and was conducted at the time of planting, atthe end ofthe second orfifth growing seasons, ornot at all. White pine seedling growth responded positively toincreased duration ofherbaceous vegetation control and negatively to delayed woody control. Maximum growth was not realized unless both types ofvegetation were suppressed. During the first six growing seasons, the height growth of planted pine was more than twice that ofnaturally regenerating pine, regardless oftending regime. The study suggests that successful white pine regeneration may be achieved by thinning from below to allow 50% to60% offull sunlight in the understory, followed by the proactive, early suppression ofwoody and herbaceous vegetation to maintain optimum light levels and reduce competitionfor soil moistureand nutrients. Mon, 16 Jan 2012 http://cfs.nrcan.gc.ca/publications?id=33070 http://cfs.nrcan.gc.ca/publications?id=31666 Wed, 05 May 2010 http://cfs.nrcan.gc.ca/publications?id=31666 http://cfs.nrcan.gc.ca/publications?id=31171 The influence of woody and herbaceous plant competition, either alone or in combination, on microclimate and growth of planted eastern white pine (Pinus strobus L.) seedlings was examined over four consecutive growing seasons in a central Ontario clearcut. Treatments that manipulated the comparative abundance of these two plant functional groups significantly affected light availability, soil moisture, and air and soil temperature regimes. These microclimate alterations, coupled with the relative competitiveness of herbaceous and woody vegetation, corresponded to temporal changes in vegetation cover and dominance. The more rapid colonization and growth of the herbaceous plant community, dominated by bracken fern (Pteridium aquilinum) and ericaceous shrubs (Kalmia sp., Vaccinium sp.), resulted in this form of vegetation being a comparatively important early competitor for soil moisture. As the woody plant community, dominated by naturally regenerated trembling aspen (Populus tremuloides Michx.), grew in height and leaf area, it became a comparatively strong competitor for both light and soil moisture. For all vegetation treatments combined, white pine seedling growth responses were strongly correlated with total cover of competing vegetation and its relative influence on above- and belowground microclimatic variables. Higher total cover of competing vegetation was generally associated with lower light and soil moisture availability and cooler soil temperatures. Multiple regression analyses indicated that pine seedling relative height growth increased with soil moisture content and growing season soil heat sum, while seedling relative diameter and relative volume growth increased with light availability. Thu, 21 Jan 2010 http://cfs.nrcan.gc.ca/publications?id=31171 http://cfs.nrcan.gc.ca/publications?id=29226 We investigated the effects of herbaceous and woody vegetation control on the survival and growth of planted eastern white pine (Pinus strobus L.) seedlings through six growing seasons. Herbaceous vegetation control involved the suppression of grasses, forbs, ferns, and low-shrubs, and was maintained for 0, 2, or 4 years after white pine seedlings were planted. Woody control involved the removal of all tall-shrub and deciduous trees, and was conducted at the time of planting, at the end of the second or fifth growing seasons, or not at all. Seedling height and basal diameter responded positively and proportionally to duration of herbaceous vegetation control. Gains associated with woody control were generally not significant unless some degree of herbaceous vegetation control was also conducted. Only herbaceous control increased pine crown closure and rate of crown closure. Herbaceous control and the presence of 5000–15,000 stems per ha of young overtopping aspen were associated with reduced weevil (Pissodes strobi Peck.) injury and increased pine height growth. The study suggests that white pine restoration strategies on clearcut sites should focus on the proactive, early management of understory vegetation and the gradual reduction of overtopping cover from woody vegetation to create a seedling light environment that supports acceptable growth with minimal weevil damage Thu, 29 Jan 2009 http://cfs.nrcan.gc.ca/publications?id=29226 http://cfs.nrcan.gc.ca/publications?id=18194 Climate change may profoundly influence Ontario's forest ecosystems and their management. Elevated atmospheric CO2 concentrations, increased temperature and altered precipitation regimes will affect forest vegetation through their influence on physiological (e.g., photosynthesis, respiration) and ecological processes (e.g., net primary production, decomposition), and may result in dramatic northward shifts in the natural range of forest types and species. More importantly, climate change is expected to increase the frequency of natural disturbances. Silvicultural intervention will increasingly be relied on to maintain forest health, manage declining stands, regenerate disturbed areas and cutovers with desired species and genotypes, maintain genetic diversity, and assist in species migration. Given the increasingly important role of Ontario's forests in national and provincial efforts to meet greenhouse gas emission reduction targets of the Kyoto Protocol, afforestation, conservation of existing forests, and increased forest management activities to accelerate the storage of carbon in Ontario's forests will be key aspects of forestry at the start of the third millennium. Thu, 31 May 2001 http://cfs.nrcan.gc.ca/publications?id=18194 http://cfs.nrcan.gc.ca/publications?id=9789 Fri, 21 Jul 2000 http://cfs.nrcan.gc.ca/publications?id=9789 http://cfs.nrcan.gc.ca/publications?id=9288 Fri, 21 Jul 2000 http://cfs.nrcan.gc.ca/publications?id=9288 http://cfs.nrcan.gc.ca/publications?id=9558 Fri, 21 Jul 2000 http://cfs.nrcan.gc.ca/publications?id=9558