Predicting and managing light in the understory of boreal forests

Lieffers, V.J.; Messier, Christian; Stadt, K.J.; Gendron, F.; Comeau, P.G.

doi:10.1139/cjfr-29-6-796

Cited by 96 publications

(117 citation statements)

References 69 publications

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“…4). This is a common observation with seedling regeneration of many species (Helms and Standiford 1985;Lieffers et al 1999;Stancioiu and O'Hara 2006) including understory redwood in multiaged stands (Berrill and O'Hara 2007), and confirms previous results from this study site with redwood stump sprouts (O'Hara et al 2007). 2.…”

Section: Discussionsupporting

confidence: 90%

Dynamics of coast redwood sprout clump development in variable light environments

O’Hara

Berrill

2010

Journal of Forest Research

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Post-thinning stump sprout response was assessed in a coast redwood [Sequoia sempervirens (D. Don) Endl.] stand from 5 to 9 years after five treatments were initiated. Nine years after treatment, leaf area index (LAI) ranged from 5.9 to 14.1 and the percent above canopy light (PACL) ranged from 0.8 to 3.9. Sprout responses included rapid self-thinning in all treatments with complete sprout mortality at low light regimes. Selfthinning of clumps increased with greater overstory LAI and poorer light regimes. Leaf area of individual sprout clumps also declined in low light regimes. The probability of sprout survival declined rapidly below 10 PACL and coincided with declining leaf area in sprout clumps. A conceptual model is presented that shows the sensitivity of redwood sprouts to light regime. Results have implications for management of multiaged stands and indicate these redwood coppice systems require relatively severe overstory treatments to provide sufficient light for sprout vigor and growth.

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Section: Discussionsupporting

confidence: 90%

Dynamics of coast redwood sprout clump development in variable light environments

O’Hara

Berrill

2010

Journal of Forest Research

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“…While light conditions alone clearly do not determine regeneration response following harvesting, they remain a key factor (e.g., Lapointe et al, 2006), and a factor that can be manipulated through silvicultural interventions (Lieffers et al, 1999). Because of inter-specific differences in response to light, managing light intensities through variations in the intensity and patterns of tree removal can create conditions that will favour the recruitment, growth and survival of some species more than others .…”

Section: Management Implicationsmentioning

confidence: 99%

“…Adequately managing post-harvest light conditions is essential to obtaining the desired species composition of tree species regeneration, and is therefore an important component of successful partial harvesting interventions (Lieffers et al, 1999). At the individual tree level, light is a major determinant of growth and survival.…”

Section: Introductionmentioning

confidence: 99%

“…At the individual tree level, light is a major determinant of growth and survival. At the community level -due to inter-specific differences in response to light -variations in light conditions can affect important processes such as regeneration establishment, competition dynamics and species succession (Lieffers et al, 1999). Maintaining a pattern of variability in light conditions similar to that found in natural forests is also expected to play an important role in preserving understory species diversity (Bartemucci et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Numerous light models have been developed over the years (reviewed in Lieffers et al, 1999). Among these models, spatially explicit, individual-tree models are particularly appropriate in a context where exploring the impact of partial harvesting is of interest, especially in structurally complex and species-diverse forests (Brunner, 1998;Canham et al, 1999;Stadt and Lieffers, 2000).…”

Section: Introductionmentioning

confidence: 99%

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Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

Beaudet

Harvey

Messier

et al. 2011

Forest Ecology and Management

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a b s t r a c tIn the context of partial harvesting, adequately managing post-harvest light conditions are essential to obtain a desired composition of tree species regeneration. The objective of this study was to determine how varying the intensity and spatial pattern of harvest would affect understory light conditions in boreal mixedwood stands of northwestern Quebec using the spatially explicit SORTIE-ND light model. The model was evaluated based on comparisons of observed and predicted light levels in both mapped and un-mapped plots. In mapped plots, reasonably accurate predictions of the overall variation in light levels were obtained, but predictions tended to lack spatial precision. In un-mapped plots, SORTIE-ND accurately predicted stand-level mean GLI (Gap Light Index) under a range of harvest intensities. The model was then used to simulate nine silvicultural treatments based on combinations of three intensities of overstory removal (30%, 45% and 60% of basal area) and three harvest patterns (uniform, narrow strips, large gaps). Simulations showed that increasing overstory removal had less impact on light conditions with uniform harvests, and a more marked effect with more aggregated harvest patterns. Whatever the harvest intensity, uniform cuts almost never created high light conditions (GLI > 50%). Gap cuts, on the other hand, resulted in up to 40% of microsites receiving GLI > 50%. Our results suggest that either a 30% strip or gap cut or a 45-60% uniform partial harvest could be used to accelerate the transition from an aspen dominated composition to a mixedwood stand because both types of cut generate the greatest proportion of moderately low light levels (e.g., 15-40% GLI). These light levels tend to favour an accelerated growth response among shade-tolerant conifers, while preventing excessive recruitment of shade-intolerant species. A better understanding of how spatial patterns of harvest interact with tree removal intensity to affect understory light conditions can provide opportunities for designing silvicultural prescriptions that are tailored to species' traits and better suited to meet a variety of management objectives.

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Effects of Habitat Light Intensity on Mammalian Eye Shape

Veilleux

Lewis

2011

The Anatomical Record

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Many aspects of mammalian visual anatomy vary with activity pattern, reflecting the divergent selective pressures imposed by low light and high light visual environments. However, ambient light intensity can also differ substantially between and within habitats due to differences in foliage density. We explored the effects of interhabitat and intrahabitat variation in light intensity on mammalian visual anatomy. Data on relative cornea size, activity pattern, and habitat type were collected from the literature for 209 terrestrial mammal species. In general, mammalian relative cornea size significantly varied by habitat type. In within-order and across-mammal analyses, diurnal and cathemeral mammals from forested habitats exhibited relatively larger corneas than species from more open habitats, reflecting an adaptation to increase visual sensitivity in forest species. However, in all analyses, we found no habitat-type effect in nocturnal species, suggesting that nocturnal mammals may experience selection to maximize visual sensitivity across all habitats. We also examined whether vertical strata usage affected relative cornea size in anthropoid primates. In most analyses, species occupying lower levels of forests and woodlands did not exhibit relatively larger corneas than species utilizing higher levels. Thus, unlike differences in intensity between habitat types, differences in light intensity between vertical forest strata do not appear to exert a strong selective pressure on visual morphology. These results suggest that terrestrial mammal visual systems reflect specializations for habitat variation in light intensity, and that habitat type as well as activity pattern have influenced mammalian visual evolution. Anat Rec, 294:905-914, 2011. V V C 2011 Wiley-Liss, Inc.

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Predicting and managing light in the understory of boreal forests

Cited by 96 publications

References 69 publications

Dynamics of coast redwood sprout clump development in variable light environments

Dynamics of coast redwood sprout clump development in variable light environments

Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

Effects of Habitat Light Intensity on Mammalian Eye Shape

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