A topographic moisture index explains understory vegetation response to retention harvesting

Echiverri, Laureen F. I.; Macdonald, S. Ellen

doi:10.1016/j.foreco.2020.118358

Cited by 9 publications

(6 citation statements)

References 40 publications

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“…We found that understory species richness and diversity in the Monotheca forests varied significantly with canopy dominants, which is in agreement with various studies (Wang et al 2015;Kobal et al 2015;Echiverri & Macdonald 2020). Monotheca dominated forests with a maximum basal area of canopy species have high diversity in understory vegetation.…”

Section: Discussionsupporting

confidence: 92%

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Do environmental variables and overstory communities affect the spatial pattern of understory vegetation? Lessons from Monotheca buxifolia (Falc.) A. DC. forests in Pakistan

Ali

Khan

2022

Acta Bot. Bras.

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The importance of understory vegetation cannot be denied as an integral component of forest ecosystems, but there is a dearth of studies to explore the effects of environmental variables and canopy species on its diversity and composition. Here we investigated the effects of environmental variables and overstory stand structure on the understory vegetation in old-growth Monotheca buxifolia dominated forests with considerable co-dominance of other broadleaved by using ecologically standardized data collection methods across Pakistan. Multivariate analyses were used to examine the vegetation composition and different species assemblages with multiple influencing variables. We found a total of 58 understory species belonging to 55 genera and 30 families mostly representing pluriregional (33.89 %) chorological affinities with therophytic (17 species) life-form dominance and microphyll (34.48 %) leaf-size spectrum. Likewise, significant differences were observed in species richness and diversity indices between different understory community types. Attributes such as elevation, aspect, soil properties, and tree canopy structure were most strongly correlated with the Redundancy Analysis (RDA-ordination), indicating that several factors exert the strongest influence and explained the spatial pattern of understory vegetation. The findings of this research can assist forestry resources managers, forest biologists and ecologists in restoration and conservation plans for understory vegetation in the region.

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Section: Discussionsupporting

confidence: 92%

“…bulk density and soil slope potentially affect the understory vegetation composition (Echiverri & Macdonald 2020;Piazza et al 2016). In the northern areas of Pakistan, species richness was highly influenced by slope and altitude (Ali et al 2022b;Ullah et al 2020;Qureshi & Bhatti 2010).…”

Section: Fayaz Ali and Nasrullah Khanmentioning

confidence: 99%

Do environmental variables and overstory communities affect the spatial pattern of understory vegetation? Lessons from Monotheca buxifolia (Falc.) A. DC. forests in Pakistan

Ali

Khan

2022

Acta Bot. Bras.

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“…By 6-and 11-years post-harvest understory vascular plant cover was 1.5 to 2 times higher in lower (≤50%) retention levels than in 75% retention or the reference. This was the trend for all but the mixed (MX) forest type, for which there were never any effects of harvesting on understory cover; this supports previous evidence, that understory plant communities of mixed forests are less sensitive to the effects of harvesting (Echiverri & Ellen Macdonald, 2020;Macdonald & Fenniak, 2007). It is likely that the positive effects of harvesting (in terms of increased resource availability) on understory vascular plant cover and richness begin to manifest at 6 to 11 years post-harvest after an initial lag, especially as open-habitat species colonize and dominate available growing space and resources (Halpern et al, 2012;Roberts et al, 2016).…”

Section: Discussionsupporting

confidence: 87%

“…Stand development in the boreal forest can follow multiple pathways resulting in broadleaf‐, conifer‐ or mixed‐species dominance at any stage of stand development (Bergeron et al, 2014; Chen & Popadiouk, 2002). Previous studies have suggested that understory plant communities in conifer‐dominated boreal forests, along a moisture gradient within upland sites, may be more sensitive to harvesting than are mixedwoods (Echiverri & Ellen Macdonald, 2020; Macdonald & Fenniak, 2007). Given the strong influence of the overstory on understory plant communities (Bartemucci et al, 2006; Hart & Chen, 2006), it follows that understory responses will vary with forest type and harvesting intensity.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and recovery of forest understory biodiversity over 17 years following varying levels of retention harvesting

Bartels

Macdonald

2023

Journal of Applied Ecology

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Retention harvesting is advocated as an alternative to intensive timber harvesting, such as clear‐cutting, to better maintain or facilitate recovery of biodiversity and other ecological values in managed forests. However, it is not clear how long the benefits of retention harvests persist. We investigated responses of understory vascular plant cover, richness, diversity (inverse Simpson index) and composition to a gradient in dispersed retention (2% [clear‐ cut], 10%, 20%, 50% and 75% retention; unharvested reference [100% retention]) at 3, 6, 11, and 17 years after harvest, in four boreal mixedwood forest types (deciduous (broadleaf)‐dominated, deciduous‐dominated with conifer understory, mixed, and conifer‐dominated) in western Canada. Understory cover and richness tended to increase in the short‐term (3 years), peaked at 6–11 years with differences following the gradient of harvesting intensity, then plateaued or declined in the second decade (17 years), by which time there were minimal or no differences among harvesting levels, including the reference. Responses for diversity were minimal. In contrast, composition varied along the gradient of harvesting intensity and showed little recovery towards the unharvested condition over the 17‐year period. Generally, for plant community composition, clear‐cut and lower retention treatments (10%, 20%) were similar to one another but differed from the higher retention and unharvested reference treatments. Synthesis and applications: Retention harvests can moderate the negative impacts of harvesting and facilitate the recovery of biodiversity. Our results suggest that for the cover, richness and diversity of understory vascular plants, this moderating influence is weak and short‐lived. However, higher levels of retention can temper changes in understory composition relative to the unharvested forest, but full recovery is likely to be slow and will be complicated by post‐harvest regeneration dynamics.

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“…If wetter sites have higher biodiversity and productivity, managers face a challenge in achieving goals for maintaining biodiversity while extracting the greatest quantity of timber. However, this relationship is not always true among the three main forest types of western boreal forests (i.e., conifer, deciduous, mixedwood); in some cases the evidence suggests that targeting drier forest sites for retention would be better for conservation and recovery of biodiversity or forest regeneration after harvesting (Nijland et al, 2015a,b;Bartels et al, 2018aBartels et al, , 2019Echiverri and Macdonald, 2020).…”

Section: Introductionmentioning

confidence: 99%

Application of the Conservation Planning Tool Zonation to Inform Retention Planning in the Boreal Forest of Western Canada

et al. 2020

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Retention forestry is an approach in which live trees and other components of forest structure are retained within harvested areas. A primary objective of retention forestry is to maintain biodiversity and to hasten post-harvest recovery of forest structure and function. Retention is now a key element in sustainable forest management practices in many regions of the world. However, locating where retention should be placed to best achieve management objectives is a challenging problem, and evidence-based approaches to operational applications are rare. We suggest here that harvest planners could benefit from the use of systematic conservation planning principles and methods to inform retention design. Specifically, we used a conservation planning—or prioritization—tool, Zonation, to create spatially-explicit scenarios of retention harvesting in a boreal mixedwood forest in northwestern Alberta, Canada. Scenarios were informed by several environmental variables related to site productivity; in particular, we used a metric of wetness (depth-to-water from the Wet Areas Mapping algorithm) that is based on airborne lidar-derived terrain models previously shown to correlate with patterns in post-harvest forest regeneration and biodiversity. The nine retention scenarios examined here related to the placement of retention focused to drier, mesic, or wetter sites in combination with other prioritization constraints. Results were compared with an existing harvest plan to assess differences in the spatial pattern of retention (e.g., percent overlapping area, number of patches, size of the patches). We also tested for the homogeneity of forest attributes (e.g., tree species, deciduous density) between scenarios and the existing harvest plan using multivariate dispersion analysis. Our results showed limited commonalities among scenarios compared to the existing harvest plan; they were characterized as having limited spatial overlap, and more and smaller patches with the use of a timber-cost constraint further affecting retention patterns. While modeling results significantly differed from current retention practices, the approach presented here offers flexibility in testing different scenarios and assessing trade-offs between timber production and conservation goals using a standardized conservation planning toolkit.

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A topographic moisture index explains understory vegetation response to retention harvesting

Cited by 9 publications

References 40 publications

Do environmental variables and overstory communities affect the spatial pattern of understory vegetation? Lessons from Monotheca buxifolia (Falc.) A. DC. forests in Pakistan

Do environmental variables and overstory communities affect the spatial pattern of understory vegetation? Lessons from Monotheca buxifolia (Falc.) A. DC. forests in Pakistan

Dynamics and recovery of forest understory biodiversity over 17 years following varying levels of retention harvesting

Application of the Conservation Planning Tool Zonation to Inform Retention Planning in the Boreal Forest of Western Canada

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