The light interception index: a potential tool for assisting in vegetation management decisions

DeLong, S. Craig

doi:10.1139/x91-142

Cited by 35 publications

(23 citation statements)

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“…Our data suggest that competitors nearest the seedlings had a disproportionate influence on growth. This follows closely with many competition-modeling approaches that use distance to modify competitive effects [1,8,23]. At both sites in this study a larger treatment area was required to maximize DBH growth compared to height growth.…”

Section: Response To Area Of Weed Controlsupporting

confidence: 58%

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Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control

Rose

Rosner

2005

Ann. For. Sci.

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-Coastal Douglas-fir growth response to eight experimental weed control treatments has been followed for eight years since planting at two western Oregon sites. Treatments included six areas of weed control around individual trees -0.0m 2 , 0.375 m 2 , 1.49 m 2 , 3.35 m 2 , 5.95 m 2 , and 9.63 m 2 (total vegetation control [TVC]) -control of herbaceous competition only or control of woody competition only. Herbaceous vegetation control treatments were maintained for the first two years after planting, while woody vegetation control treatments were maintained for three years. The greatest gain in Douglas-fir growth from increasing the area of control was observed between the 0.0 m 2 and the 0.375 m 2 treatments. Growth continued to increase, however, with increasing area of control out to complete weed control. The 5.95 m 2 and 9.63 m 2 treatments increased eighth-year individual-tree volume relative to the check treatment by 260% (20.9 dm 3 ) and 307% (24.7 dm 3 ), respectively. While herbaceous control increased growth at both sites, woody control affected growth only at the site having the hardwood component with greater height growth potential. Growth differences among treatments eight years after planting are discussed in terms of distance to competition and shifting dominance from herbaceous to woody vegetation over time.vegetation management / herbaceous competition / woody competition / area of weed control / herbicides Résumé -Impact de la surface désherbée et d'un contrôle de la végétation herbacée ou de la végétation ligneuse sur la croissance de jeunes sapins de Douglas âgés de huit ans. La réponse en termes de croissance de plants de Douglas verts huit ans après plusieurs modalités de contrôle de la végétation adventice a été étudiée dans deux sites de l'ouest de l'Oregon. Les traitements comprennent 6 surfaces de contrôle des mauvaises herbes autour d'arbres individuels -0,0 m 2 , 0,375 m 2 , 1,49 m 2 , 3,35 m 2 , 5,95 m 2 et 9,63 m 2 (contrôle total de la végétation (TVC)) -contrôle de la compétition herbacée seulement ou contrôle de la végétation ligneuse. Les traitements de contrôle de la végétation herbacée ont été maintenus les 2 premières années après plantation tandis que les traitements de contrôle de la végétation ligneuse ont été maintenus 3 ans. Le plus grand gain de croissance du Douglas avec l'augmentation de la surface de contrôle a été observé entre le traitement 0,0 m 2 et 3,75 m 2 . Toutefois la croissance continue à augmenter avec l'accroissement de la surface de contrôle en dehors d'un contrôle total des mauvaises herbes. Les traitements 5,95 m 2 et 9,63 m 2 présentent après 8 années un accroissement relatif de volume individuel d'un arbre de 260 % (20,9 dm 2 ) et 307 % (24,7 dm 2 ). Alors que le contrôle de la végétation herbacée augmente la croissance dans les deux sites d'étude, le contrôle de la végétation ligneuse influence la croissance uniquement dans le site qui a une composante d'espèces de feuillus ayant un fort potentiel de croissance en hauteur. Les différence...

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Section: Response To Area Of Weed Controlsupporting

confidence: 58%

“…Competition models typically use distance modifiers or a fixed-radius zone of influence to modify competitive effects [1,3,7,8,23,29,30]. Zone size varies depending on the model and species and typically ranges from 1 to 20 m 2 .…”

Section: Introductionmentioning

confidence: 99%

Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control

Rose

Rosner

2005

Ann. For. Sci.

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“…If light had remained at the level measured in 1998 over the entire period since planting, and thus comparable among the three plantations (Table 1), the observed differences in growth could have been attributed to the species-specific competition for underground resources (DeLong 1991, Burton 1993. However, comparisons on RCI revealed no significant differences Table 1.…”

Section: Discussionmentioning

confidence: 93%

“…Previous studies on the growth of planted conifer seedlings under vegetation competition were almost exclusively concerned with plantations established after timber harvesting (e.g., DeLong 1991, Wagner and Radosevich 1991, Comeau et al 1993, Jobidon 1994, Puettmann and Reich 1995, Wang et al 2000. Although most spruce plantations on mixedwood sites have been established after timber harvesting, spruce plantations have also been established after fire disturbances in southeastern Manitoba.…”

Section: Introductionmentioning

confidence: 99%

Growth of black spruce seedlings planted in burned, logged, and undisturbed boreal mixedwood stands of southeastern Manitoba

Wang¹,

Su²

2002

The Forestry Chronicle

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Growth of black spruce seedling planted in burned, harvested, and undisturbed boreal mixedwood stands was studied in southeastern Manitoba. Although seedlings on each site were subjected to similar light competition (measured by % of full sunlight received at the middle crown of each crop seedling in 1998), mean annual growth of height, root collar diameter and aboveground biomass was different among the three sites, with burned > logged > undisturbed. During each of last seven years (1992 to 1998 except 1997), the burned site had greater annual height growth than the logged and undisturbed sites. Similarly, the logged site had greater height growth than the undisturbed site except 1997 and 1998. Relative competition intensity (calculated based on annual height growth from 1992 to 1998) fluctuated between 0.70 to 0.76 on the undisturbed site, increased from 0.48 to 0.73 on the logged site, and increased from 0.23 to 0.74 on the burned site. Relative competition intensity remained similar in the most recent three years (1996-1998) despite larger differences found in earlier years (1992)(1993)(1994)(1995) between sites. A significant relationship was found between the relative competition intensity and % full sunlight on each site. Results from this case study suggested that, by affecting the development of competing vegetation, the type/intensity of past disturbances created different competition dynamics for black spruce seedlings planted on the burned, logged and undisturbed sites.Keywords: interspecific competition, vegetation management, competition dynamics, plantation La croissance de semis d'épinette noire plantés dans des peuplements mélangés boréaux brûlés, récoltés et non perturbés, a été étudiée dans le sud-est du Manitoba. Même si les semis de chaque site ont été soumis à une compétition semblable pour la lumière (mesurée en % de l'ensoleillement total reçu sur le milieu de la cime de chaque semis d'arbre à être récolté en 1998), la croissance annuelle moyenne de la hauteur, du diamètre au collet et de la biomasse au-dessus du sol était différente sur les trois sites, soit brûlés > récoltés > non perturbés. Au cours de chacune des sept dernières années (de 1992 à 1998, à l'exception de 1997) le site brûlé montrait une croissance annuelle en hauteur plus importante que les sites récoltés et non perturbés. De même le site récolté démontrait une croissance en hauteur plus importante que le site non perturbés sauf en 1997 et en 1998. L'intensité relative de la compétition (calculée selon la croissance annuelle en hauteur de 1992 à 1998) a varié entre 0,70 et 0,76 sur le site non perturbé, a augmenté de 0,48 à 0,73 sur le site récolté, et a augmenté de 0,23 à 0,74 sur le site brûlé. L'intensité relative de la compétition est demeurée semblable au cours des dernières années (1996-1998) malgré les plus grandes différences retrouvées au cours des années antérieures (1992)(1993)(1994)(1995) entre les sites. Une relation significative a été trouvée entre l'intensité relative de la compétition et le % d'ensoleil...

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“…Moreover Mitchell (2003) and Newsome et al (2010) reported that diameter is an excellent response variable for competition studies because interspecific competition affects diameter growth more than it affects height growth. In many investigations (DeLong 1991;Simard et al 2001;Newsome et al 2008) it was reported that diameter responds more quickly than height to external sources whereas height responses tend not to be expressed until conifers are experiencing extreme stress and low vigour. The most appropriate functional forms between the response variables and each competition index were identified according to .…”

Section: Statistical Analysesmentioning

confidence: 99%

Birch (Betula papyrifera) × white spruce (Picea glauca) interactions in mixedwood stands: implications for management

Hawkins¹,

Dhar²

2013

J. For. Sci.

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Current British Columbia forest regulations drive the regeneration management towards pure conifer stands rather than remaining in a mixed-species condition. This approach may result in unnecessary vegetation control. The main objective of this investigation was to study the impact of variable paper birch densities on white spruce growth in 15-20 years old stands for management implications. Regression analysis was used to examine the effect of birch density and two competition indices to predict spruce growth. A mixed model ANOVA showed that spruce mean annual DBH and basal area increment differed significantly among sites and density. From the regression analysis it appears that birch density up to 4,000 stems·ha -1 had no significant influence on spruce growth which is much higher than the current BC reforestation guideline (1,000 stems·ha -1 broadleaves). Similarly, birch relative density index (RDI) had to exceed 3 to affect spruce DBH growth significantly on all sites except one. On most sites, spruce had a larger DBH than birch. Our results also suggest that rather than following the current broadcast approach to vegetation management, a targeted approach could enhance forest productivity and stand diversity.

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The light interception index: a potential tool for assisting in vegetation management decisions

Cited by 35 publications

References 0 publications

Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control

Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control

Growth of black spruce seedlings planted in burned, logged, and undisturbed boreal mixedwood stands of southeastern Manitoba

Birch (Betula papyrifera) × white spruce (Picea glauca) interactions in mixedwood stands: implications for management

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