Ten-year regeneration responses to varying levels of overstory retention in two productive southern British Columbia ecosystems

Newsome, Teresa A.; Heineman, Jean L.; Nemec, A.; Comeau, Philip G.; Arsenault, André; Waterhouse, M. J.

doi:10.1016/j.foreco.2010.04.012

Cited by 18 publications

(10 citation statements)

References 34 publications

(58 reference statements)

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“…These results contrast with reductions in stem density and biomass observed in P. tremuloides-dominated systems with 40% basal area retained [38]. However, our results align with findings that retention level (up to 50% basal area retained) had little effect on total or specifically aspen/birch sapling densities [22] and that stem density may be less impacted by retained overstory trees than growth rates [27]. Comparable eucalypt densities and growth rates between harvests with aggregated retention compared to clearcuts also suggests negative impacts on crop tree regeneration may be less of a concern in some systems [60].…”

Section: Discussionsupporting

confidence: 77%

Influence of Mature Overstory Trees on Adjacent 12-Year Regeneration and the Woody Understory: Aggregated Retention versus Intact Forest

Curzon

Baker

Kern

et al. 2017

Forests

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Abstract:Retention harvesting, an approach that intentionally retains legacy features such as mature overstory trees, provides options for achieving ecological objectives. At the same time, retained overstory trees may compete with the nearby recovering understory for resources, and much remains to be learned about potential trade-offs with regeneration objectives, particularly over extended time periods. We assessed the influence of aggregated retention (reserved mature overstory and understory patches) versus intact forest on structure and productivity (standing biomass) of the adjacent woody understory and regeneration 12 years after harvest in northern Minnesota, USA. Each site was dominated by Populus tremuloides Michx., a species that regenerates prolifically via root sprouts following disturbance. Overall, fewer differences than expected occurred between the effects of intact forest and aggregated retention on regeneration, despite the small size (0.1 ha) of aggregates. Instead, harvest status and distance from harvest edge had a greater influence on structure and standing woody biomass. Proximity to aggregates reduced large sapling biomass (all species, combined) relative to open conditions, but only up to 5 m into harvested areas. This suggests the trade-off for achieving productivity objectives might be minimal if managers use retention aggregates in this region to achieve ecological objectives and meet management guidelines.

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Section: Discussionsupporting

confidence: 77%

Influence of Mature Overstory Trees on Adjacent 12-Year Regeneration and the Woody Understory: Aggregated Retention versus Intact Forest

Curzon

Baker

Kern

et al. 2017

Forests

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“…1a). It is well known that understory light availability decreases as overstory density increases (Newsome et al 2010). In other words, light penetration through the canopy to the forest floor bounds upward based on the amount of canopy foliage, commonly defined as LAI (Unger et al iForest 10: 334-340 …”

Section: Leaf Area Index Light Transmission and Gapmentioning

confidence: 99%

Effects of altitudinal gradients on leaf area index, soil microbial biomass C and microbial activity in a temperate mixed forest ecosystem of Northwestern Turkey

Bolat¹,

Öztürk²

2017

iForest

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A high leaf area index (LAI) can provide indications of high fertility, such as optimal health and productivity in forest ecosystem. Yet, studying the microbial biomass and inherent activity in any forest ecosystem may enable better understanding of the role of microorganisms in soil quality and nutrient cycling. This study was carried out in the western Black Sea region of Turkey with the aim to determine the influence of elevation on LAI, microbial biomass and activity in a mixed forest ecosystem. Marked differences in the LAI, light transmission, soil temperature, Corg/Ntotal ratio, and microbial properties were found at sites sampled at different elevations along an altitudinal gradient (i.e., 1200, 1300 and 1400 m a.s.l.). The LAI was statistically (P < 0.05) higher at 1300 ( ) elevations compared to 1200 m (2.84 m 2 m -2 ) elevation, whereas the light transmission was statistically (P < 0.05) lower at 1300 and 1400 m elevations than that at 1200 m elevation. The amount of microbial biomass C at 1300 m (892.26 µg g -1 ) and 1400 m (725.99 µg g -1 ) elevations was significantly (P < 0.05) higher than that at 1200 m (650.84 µg g -1 ) elevation. Basal respiration did not vary significantly (P > 0.05) along the altitudinal gradient. An increase in respiration per unit biomass (i.e., increasing the metabolic quotient -qCO2) was also found in the sampling sites at 1200 m a.s.l. There was a positive relationship between the microbial biomass C and LAI (r = 0.612, P < 0.01) and negative relationship between the qCO2 and LAI (r = -0.592, P < 0.01). Our results showed that the elevation gradient has a significant influence on the LAI, microbial biomass C and microbial activity in the forest stand type analyzed. A subdivision of the forest stand types into different sub-types according to their productivity and development is advisable and recommended for forest management and administration purposes.

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“…5 E-mail: bpalik@fs.fed.us forest development, including supplying energy and nutrients to soil organisms, modifying microclimate, providing habitat for recolonizing organisms by structurally enriching the new stand, and improving connectivity in the landscape for some organisms (Franklin et al 2007, Baker et al 2013. A criticism of VRH systems, when advocated for use in commercial forests, is that ecological benefits may come at a cost of reduced growth of the regenerating cohort of trees, due to competition with residual trees (Rose and Muir 1997, Zenner et al 1998, Gradowski et al 2010, Newsome et al 2010, Scott et al 2013). This may be particularly true for species intolerant of low resource environments.…”

Section: Introductionmentioning

confidence: 99%

Biomass growth response to spatial pattern of variable‐retention harvesting in a northern Minnesota pine ecosystem

Palik

Montgomery

Boyden

2014

Ecological Applications

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Variable‐retention harvesting (VRH) is an approach for sustaining complex structure in managed forests. A criticism of VRH is that ecological benefits may come at a cost of reduced growth of regeneration, due to competition with residual trees. However, the spatial pattern of retention, i.e., dispersed or aggregated, in VRH systems can be manipulated to minimize suppression of regeneration, and resource limitation to regeneration might be mitigated by reduction of woody shrubs. Continued growth of the residual cohort will compensate for growth reduction of regeneration, although this may differ with retention pattern. We examined aboveground whole‐stand biomass growth of trees in a VRH experiment in Pinus resinosa forest in Minnesota, USA. Treatments included dispersed retention, aggregated retention, and an uncut control, as well as a shrub treatment (reduced density or ambient). We addressed the following hypotheses: (1) biomass growth of a cohort of planted pine seedlings will be highest with aggregated rather than dispersed retention, (2) biomass growth of the planted seedlings will increase with shrub reduction, and (3) biomass growth of the residual overstory will be higher with dispersed rather than aggregated retention. Aboveground biomass growth of the planted pines ranged from 0.4 kg·ha−1·yr−1 in the overstory‐control–ambient‐shrub treatment to 23 kg·ha−1·yr−1 in the aggregated‐retention–shrub‐reduction treatment. The difference between the control and the retention treatments was significant (P < 0.0001), but not between dispersed and aggregated retention (P = 0.97). Thus, our first hypothesis was not supported. In all treatments, biomass growth was significantly higher (>100% increase) with shrub reduction (P = 0.001), supporting our second hypothesis. Biomass growth of residual trees ranged from 2404 kg·ha−1·yr−1 in the uncut‐control–ambient‐shrub treatment to 1043 kg·ha−1·yr−1 in the aggregated‐retention–shrub‐reduction treatment. Differences were significant between the control and retention treatments (P = 0.003), and marginally higher with dispersed vs. aggregated retention (P = 0.09), lending support to our third hypothesis. Our results suggest that managers have flexibility in application of VRH and can expect similar stand‐level biomass growth of planted regeneration regardless of retention pattern, but somewhat higher stand‐level biomass growth of retained trees with dispersed retention.

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Ten-year regeneration responses to varying levels of overstory retention in two productive southern British Columbia ecosystems

Cited by 18 publications

References 34 publications

Influence of Mature Overstory Trees on Adjacent 12-Year Regeneration and the Woody Understory: Aggregated Retention versus Intact Forest

Influence of Mature Overstory Trees on Adjacent 12-Year Regeneration and the Woody Understory: Aggregated Retention versus Intact Forest

Effects of altitudinal gradients on leaf area index, soil microbial biomass C and microbial activity in a temperate mixed forest ecosystem of Northwestern Turkey

Biomass growth response to spatial pattern of variable‐retention harvesting in a northern Minnesota pine ecosystem

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