Linkages between silviculture and ecology: examination of several important conceptual models

Long, James N.; Dean, Thomas J.; Roberts, Scott D.

doi:10.1016/j.foreco.2004.07.005

Cited by 103 publications

(60 citation statements)

References 47 publications

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“…For some studies, the Bmeans^were calculated from regression lines. Studies that included standing stocks rather than growth were not included unless they were young plantations because standing stock is not necessarily correlated with productivity, particularly not at densities beyond canopy closure [121], and diversity-standing stock relationships can therefore be influenced by a different combination of factors compared with DPRs. The thick lines indicate the studies that accounted for factors that may have been confounded with species richness such as site characteristics, species pools, and stand density, either via the statistical analyses or because they were planted experiments.…”

Section: Introductionmentioning

confidence: 99%

A Review of Processes Behind Diversity—Productivity Relationships in Forests

2016

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Through complementarity interactions, mixedspecies forests can be more productive than monocultures, and this effect can increase with tree-species richness. However, this is not always the case. This review examines the processes and stand structural attributes that can influence diversity-productivity relationships (DPRs); how they influence resource availability, resource uptake, and resource-use efficiency; and also describes some important differences between tree-diversity versus grassland-diversity experiments. The size of the complementarity effects caused by these processes and stand structures varies along spatial and temporal gradients in resource availability and climate. These spatial and temporal dynamics have now been examined in many studies, and the general patterns are summarized using a simple framework; complementarity is predicted to increase as the availability of resource BX^declines (or climatic condition X becomes harsher) if the species interactions improve the availability, uptake, or use efficiency of resource X (or interactions improve climatic condition X). Importantly, this framework differs from the stress-gradient hypothesis to account for a wider range of inter-specific plant interactions (not only facilitation) by considering contrasting methods used to quantify species interactions while accounting for stand structure. In addition, complementarity (as opposed to facilitation) for a given species combination can increase as growing conditions improve in forests, contrary to predictions of the stressgradient hypothesis with regards to facilitation. This review indicates that while the effects of tree-species diversity on growth and other forest functions are now receiving a lot of attention, far less is known about the effects of structural diversity on growth or forest functioning. Direct measurements of the processes, as opposed to focusing mainly on growth responses, could greatly contribute to our understanding of structural diversity effects.

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Section: Introductionmentioning

confidence: 99%

A Review of Processes Behind Diversity—Productivity Relationships in Forests

2016

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“…The improvement in the agreement (cross-validated PRSME) between measured and modeled data obtained by including age-related variation in closure ( Figure 5) indicates that increment and biomass are strongly dependent on stand closure (c), as represented in the model. This conclusion is further supported by the result that mean estimated c follows the expected development over time, increasing as stands close after planting and decreasing in response to onset of thinnings and increased risk for disturbances at higher age ( Figure 7) [37]. It could be argued that the improvement in model performance obtained by including variable c could instead have been achieved by letting productivity (p) vary among age cohorts.…”

Section: Large Scale Modelmentioning

confidence: 66%

Large-Scale Forest Modeling: Deducing Stand Density from Inventory Data

Franklin

Moltchanova

Kraxner

et al. 2012

International Journal of Forestry Research

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While effects of thinning and natural disturbances on stand density play a central role for forest growth, their representation in large-scale studies is restricted by both model and data availability. Here a forest growth model was combined with a newly developed generic thinning model to estimate stand density and site productivity based on widely available inventory data (tree species, age class, volume, and increment). The combined model successfully coupled biomass, increment, and stand closure (=stand density/self-thinning limited stand density), as indicated by cross-validation against European-wide inventory data. The improvement in model performance attained by including variable stand closure among age cohorts compared to a fixed closure suggests that stand closure is an important parameter for accurate forest growth modeling also at large scales.

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“…In contrast, our use of c, the density compared to maximum density at the same mean tree biomass (b), provides an invariable basis for evaluating density effects measured over different time spans. This model implies that site conditions affect only the rate of change but not the path of relative density and biomass development of a stand, which has ample empirical support (Long et al, 2004).…”

Section: General Assumptionsmentioning

confidence: 98%

Un modèle générique des effets de l’éclaircie et de la densité des peuplements sur la croissance des forêts, la mortalité et l’accroissement net

2009

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Abstract• For assessing forest thinning effects at large (i.e. continental) scale, data scarcity and technical limitations prevent the application of localized or individual-based thinning models.• Here we present a simple general framework to analyze and predict the effects of thinning on growth and mortality, including the following stand density development. The effects are modeled in relative terms so that the model can be parameterized based on any thinning experiment that includes an unthinned control, regardless of site conditions and stand age.• The model was tested against observed thinning effects on growth and mortality from five temperate and boreal species (all species pooled r 2 = 0.51). It predicted a maximum increase in net stem biomass increment of 16% and a reduction in density-related mortality of 75% compared to unthinned conditions at stand densities of around 70% of the maximum (increment optimal density).• A sensitivity analysis revealed overlapping ranges of near optimal density (net increment within 95% of optimal) among all tested species, suggesting that one thinning scenario can be used for many species. The simple and general formulation of thinning effects based on only five parameters allows easy integration with a wide range of generic forest growth models. Mots-clés :bois mort / densité optimale / modèles de forêts / fermeture / foresterie Résumé -Un modèle générique des effets de l'éclaircie et de la densité des peuplements sur la croissance des forêts, la mortalité et l'accroissement net.• Pour évaluer les effets de l'éclaircie en forêt à une large échelle (c'est-à-dire continentale), la rareté des données et des limitations techniques empêchent l'application de modèles d'éclaircie localisés ou individuels.• Ici, nous présentons un simple cadre général pour analyser et prédire les effets de l'éclaircie sur la croissance et la mortalité, y compris le développement suivant de la densité du peuplement. Les effets sont modélisés en termes relatifs, de sorte que le modèle peut être paramétré sur la base de n'importe quelle expérience d'éclaircie qui inclut un témoin non éclairci, indépendamment des conditions du site et de l'âge du peuplement.• Le modèle a été testé contre les effets de l'éclaircie observés sur la croissance et la mortalité de cinq espèces tempérées et boréales (r 2 = 0,51) pour toutes les espèces mises en pool). Il a prédit une augmentation maximale de l'accroissement net de la biomasse des troncs de 16 % et une réduction de la mortalité liée à la densité de 75 % par rapport aux conditions de non éclaircie de densité de peuplement de l'ordre de 70 % du maximum (densité de l'accroissement optimal).• Une analyse de sensibilité a révélé des écarts de chevauchements près de la densité optimale (accroissement net dans 95 % de l'optimal) entre toutes les espèces testées, suggérant que un scénario d'éclaircie peut être utilisé pour de nombreuses espèces. La simple et générale formulation des effets de l'éclaircie basée sur seulement cinq paramètres permet une intégration ...

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Linkages between silviculture and ecology: examination of several important conceptual models

Cited by 103 publications

References 47 publications

A Review of Processes Behind Diversity—Productivity Relationships in Forests

A Review of Processes Behind Diversity—Productivity Relationships in Forests

Large-Scale Forest Modeling: Deducing Stand Density from Inventory Data

Un modèle générique des effets de l’éclaircie et de la densité des peuplements sur la croissance des forêts, la mortalité et l’accroissement net

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