Juvenile growth of hybrid poplars on acidic boreal soil determined by environmental effects of soil preparation, vegetation control, and fertilization

Abstract

a b s t r a c tThe silviculture of hybrid poplars and other fast-growing tree species is a promising solution to reduce the pressure on natural forests while maintaining wood supplies to industries. However, hybrid poplars are very sensitive to competing vegetation and to inadequate soil conditions and fertility. Possible management tools include mechanical site preparation (MSP), vegetation control (VC), and fertilization. Experimental plantations of hybrid poplars (one clone, Populus balsamea × Populus maximowiczii) were established at eight formerly forested sites on acidic soil in the southern boreal forest of Quebec, Canada. The objective was to test the response of hybrid poplars to the interaction of several silvicultural tools, which has been rarely done. Four MSP treatments (in decreasing order of intensity: mounding, harrowing, heavy disk trenching, light disk trenching) and a control (unprepared) were all combined with four different frequencies of plant competition control by brushing (from never up to once a year). Fertilization with N or N + P was also tested in three selected MSP treatments. After five years, hybrid poplar tree growth among MSP treatments increased in the following order: unprepared < light disk trenching < heavy disk trenching < harrowing < mounding. MSP was also essential in favouring early tree survival, as illustrated by mortality rates of over 20% in unprepared plots and below 5% in all other MSP treatments. The effect of competition control on hybrid poplar growth was greatest in the less intensive MSP treatments, where competing vegetation was the most abundant. On the contrary, fertilization effect was significant only in the most intensive MSP (mounding). Moreover, neither fertilization nor VC could compensate for inadequate soil preparation. Of all the silvicultural treatments tested, mounding provided the best tree growth despite a nitrogen and carbon impoverished surface soil.

Managing tree plantations as novel socioecological systems: Australian and North American perspectives

“…(i) To ensure that fast-growing trees can achieve their full potential without using herbicides, which are banned in Quebec in forestry operations, through employing site-preparation techniques such as trenching and mounding (Bilodeau-Gauthier et al 2011;Buitrago et al 2015). These techniques create a heterogeneous microtopography that could provide habitat for vascular understory plant species (Haeussler et al 1999;Ramovs and Roberts 2003), as well as hatching habitat for amphibians (Semlitsch et al 2009).…”

Effects of Weed Control and Fertilization on Wood and Chemi-mechanical Pulp Properties of a Populus deltoides Clone

“…Bilodeau-Gauthier et al (2011) claimed that the use of weed control treatments for Populus typically led to an increase in the growth rate of the trees and consequently to possible modifications of wood quality. In Argentina, Monteoliva and Senisterra (2008) analysed 12 poplar clones (10-year-old Delta Gold) grown in the same location of this study; the authors found positive correlations between growth parameters and density.…”

“…The application of nitrogen (N) fertilizers and the control of herbaceous vegetation have received considerable attention as two different approaches that can enhance the growth rate and the productivity of forest plantations (Little et al 2003;Bilodeau-Gauthier et al 2011).…”

Effects of Direct Application of Fertilizers and Hydrogel on the Establishment of Poplar Cuttings

“…Van den Driessche (1999) demonstrated that the application of fertilizers about 20 cm from the poplar cuttings enhanced growth compared to untreated cuttings and was about twice as effective as banding of fertilizers [12]. Similarly, Bilodeau-Gauthier (2011) found that the application of fertilizers applied to the base of a planted tree positively influenced its growth [13]. Since poplars are sensitive to competing vegetation [9,14,15] and fertilizing whole areas increases the growth of competing vegetation [16], the application of fertilizers directly to the transplant could be an alternative strategy for addition of extra nutrients at the time of planting.…”