Effects of multiaged silvicultural systems on reserve tree growth 19 years after establishment across multiple species in the Acadian forest in Maine, USA

Abstract

This study investigated the growth response of mature, isolated reserve trees (n = 528) in two multiaged silvicultural systems in the Acadian Forest Ecosystem Research Project (AFERP). Absolute and percent increases in basal area increment (BAI; cm2·year−1) were assessed for the five predominant reserve tree species in AFERP: Acer rubrum L., Picea rubens Sarg., Pinus strobus L., Thuja occidentalis L., and Tsuga canadensis (L.) Carrière. Absolute growth was significantly greater in the large-gap treatment (23.7 ± 1.1 cm2·year−1; mean ± SE) than in the small-gap treatment (16.3 ± 0.9 cm2·year−1). Percent growth increase was greater in the small-gap treatment (187.6% ± 15.8%) than in the large-gap treatment (143.4% ± 19.3%), and both treatments had greater percent increases than the unharvested control (9.6% ± 5.2%). Species differed in their response to treatment. Pinus strobus had the greatest absolute increase (large-gap, 52.5 cm2·year−1), while Tsuga canadensis (large-gap, 270% ± 71.6%) and Acer rubrum (small-gap, 262% ± 42.4%) had the greatest percent increases. Growth responses typically diminished with increasing tree size and pretreatment growth rate; however, reserve trees showed greater growth responses than their paired analogues in the control across all initial tree sizes and prior growth rates. The results suggest that these silivicultural systems accelerate the development of large trees.

Effect magnitudes of operational-scale partial harvesting on residual tree growth and mortality of ten major tree species in Maine USA

“…This indicates that higher light availability and lower post-harvest inter-tree competition resulted from high-intensity PH was crucial for improved diameter growth of all tree species. The positive effect of PH intensity on tree diameter growth has also been reported by other studies conducted in this region (Carter et al, 2017a;Prevost et al, 2010) as well as in other neighbouring regions (Bose et al, 2014a;Thorpe et al, 2007;Xing et al, 2018).…”

“…The knowledge gap is important considering the large-scale application of PH in this region and the lack of experiments that encompass the degree of complexities associated with operational-scale PH. Further, the existing knowledge on growth and mortality responses to PH is limited to just a few tree species even at the experimental level (e. g., Baral et al, 2016;Carter et al, 2017a;Forget et al, 2007;Jones and Thomas, 2004).…”

Mixedwood silviculture in North America: the science and art of managing for complex, multi-species temperate forests

“…As a refinement of this general recommendation, we propose that stand structure and composition must be managed at each entry to maintain vigorous trees of limiting species through time. Regardless of whether regeneration occurs periodically (i.e., in multi-aged systems) or at the end of a rotation (i.e., in even-aged systems), silvicultural systems for temperate mixedwoods should maintain limiting species as growing stock and seed sources (e.g., Boulfroy et al 2012;Carter et al 2017), provide an appropriate seedbed for germination (e.g., Larouche et al 2015), and moderate light and growing conditions to favor their development from seedling establishment through canopy ascension (e.g., Raymond and Bedard 2017;Raymond et al 2018). Abundance of the hardwood component and its relatively high regeneration potential and competitive ability usually provide ample opportunity for its persistence and dominance (e.g., Guyette and Dey 1997;Fei and Steiner 2007).…”

“…In all cases, seed trees of limiting species should be retained through the regeneration period or longer (e.g., Carter et al 2017). Where slow-growing and long-lived species such as eastern hemlock, red spruce, northern white-cedar, or eastern white pine are in mixture with short-lived hardwoods (e.g., paper birch or aspen) or softwoods (e.g., balsam fir), retaining some trees of limiting softwoods for more than a single rotation of shorter-lived species will provide insurance against regeneration failure and allow additional volume and value accrual (Boulfroy et al 2012).…”

“…In spruce -hardwoods, Raymond et al (2018) found that 100-250 m 2 gaps had higher densities of yellow birch than red spruce reproduction, though Dumais and Prévost (2014) observed favorable growth of red spruce in openings of that size. Regardless of opening size, carefully selected trees can be retained within gaps for seed, growing stock, or biodiversity conservation (Carter et al 2017;Kern et al 2017;Knapp et al 2019). Appropriate level of within-gap live-tree retention will vary depending on gap size and shade tolerance of desired reproduction (D'Amato et al 2015).…”