Density-dependent mortality versus spatial segregation in early life stages of Abies densa and Rhododendron hodgsonii in Central Bhutan

Gratzer, Georg; Bahadur, P.

doi:10.1016/j.foreco.2003.12.020

Cited by 27 publications

(23 citation statements)

References 71 publications

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“…Some detailed studies on Abies densa regeneration and its controlling factors near alpine treelines in Bhutan showed intense recruitment (Gratzer et al, 2002;Gratzer and Rai, 2004). Expanding treeline populations of Smith fir (Abies georgei var.…”

Section: Seed-based Regenerationmentioning

confidence: 99%

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

et al. 2015

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Abstract. Climate warming is expected to induce treelines to advance to higher elevations. Empirical studies in diverse mountain ranges, however, give evidence of both advancing alpine treelines and rather insignificant responses. The inconsistency of findings suggests distinct differences in the sensitivity of global treelines to recent climate change. It is still unclear where Himalayan treeline ecotones are located along the response gradient from rapid dynamics to apparently complete inertia. This paper reviews the current state of knowledge regarding sensitivity and response of Himalayan treelines to climate warming, based on extensive field observations, published results in the widely scattered literature, and novel data from ongoing research of the present authors.Several sensitivity indicators such as treeline type, treeline form, seed-based regeneration, and growth patterns are evaluated. Since most Himalayan treelines are anthropogenically depressed, observed advances are largely the result of land use change. Near-natural treelines are usually krummholz treelines, which are relatively unresponsive to climate change. Nevertheless, intense recruitment of treeline trees suggests a great potential for future treeline advance. Competitive abilities of seedlings within krummholz thickets and dwarf scrub heaths will be a major source of variation in treeline dynamics. Tree growth-climate relationships show mature treeline trees to be responsive to temperature change, in particular in winter and pre-monsoon seasons. High pre-monsoon temperature trends will most likely drive tree growth performance in the western and central Himalaya. Ecological niche modelling suggests that bioclimatic conditions for a range expansion of treeline trees will be created during coming decades.

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Section: Seed-based Regenerationmentioning

confidence: 99%

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

et al. 2015

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“…Neighborhood processes can influence survival, recruitment, and growth of plant species positively through facilitation (Wills et al, 1997) or negatively by competition (Getzin et al, 2006;Gratzer and Rai, 2004), and indirectly by specialist herbivores and pathogens (Dobbertin et al, 2001;Gunton and Kunin, 2007;Hyatt et al, 2003;Janzen, 1970;Peters, 2003). These processes together to regulate species coexistence (Pacala, 1989;Peters, 2003;Volkov et al, 2005;Wills et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Few studies have investigated competition of trees of different growth forms. This is important because the extent and spatial scale of the density-dependent effect may also change with growth forms (Gratzer and Rai, 2004). Knowledge of the relative importance of density dependence in different growth forms can help understand plant population dynamics and species coexistence.…”

Section: Introductionmentioning

confidence: 99%

Density dependence on tree survival in an old-growth temperate forest in northeastern China

Zhang

Hao

Sun³

et al. 2009

Ann. For. Sci.

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Abstract• Density dependence is a major mechanism for shaping plant communities. However, its role in regulating diverse, mixed natural tree communities is less certain.• In this study we investigated density-dependent effects in a large-scale (25 ha) old-growth temperate forest in northeastern China. Spatial patterns of neighborhood distribution in the plot were analyzed using various methods for inferring competition, including (1) pair correlation function to determine spatial patterns of pre-mortality and post-mortality and (2) neighborhood analysis of individuals to examine the extent to which tree survival is correlated with other covariates.• Results showed that, for common species, 3 of 5 canopy species and 3 of 8 midstory and understory species were random in mortality. Negative density-dependent mortality was not found when trees reach 1 cm in DBH. There was no significant correlation for canopy species between tree survival and conspecific abundance, but largely positive correlations for midstory and understory species. In contrast, tree survival was found to negatively correlate with conspecific basal area for most species, indicating strong intraspecific competition. No strong interspecific density dependence was found in the forest. Mots-clés :compétition / mortalité dépendante de la densité / effets du voisinage / analyse du modèle spatial / forêt tempérée Résumé -La survie des arbres dépend de la densité dans une ancienne forêt tempérée du nordest de la Chine.• La dépendance par rapport à la densité est un important mécanisme pour la formation des communautés végétales. Toutefois, son rôle dans la régulation de diverses communautés mélangées d'arbre est moins certain.• Dans cette étude, nous avons enquêté sur les effets densité-dépendance à une grande échelle (25 ha) dans une ancienne forêt tempérée, dans le nord de la Chine. Les modes de distribution spatiale de voisinage ont été analysés en utilisant diverses méthodes pour estimer la concurrence, y compris : (1) des paires de fonction de corrélation afin de déterminer les structures spatiales de pré et postmortalité et (2) l'analyse du voisinage des individus pour examiner dans quelle mesure la survie de l'arbre survivant est corrélée avec d'autres variables.• Les résultats ont montré que, pour les espèces communes, 3 des 5 espèces de la canopée et 3 des 8 de l'étage moyen et du sous-étage, la mortalité était aléatoire. Aucune mortalité densité-dépendante négative n'a été détectée lorsque les arbres atteignent 1 cm de diamètre à hauteur d'homme. Il n'y avait pas de corrélation significative pour les espèces de la canopée entre la survie des arbres et l'abondance conspécifique, mais il y avait des corrélations positives pour l'étage moyen et le sous-étage.• En revanche, la survie des arbres était corrélée négativement avec la surface terrière conspécifique pour la plupart des espèces, indiquant une forte concurrence intraspécifique. Aucune dépendance visible de la densité interspécifique n'a été détectée dans la forêt.

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“…In other forests, the woody sub-canopy may influence spatial patterns of regeneration, for example Rhododendron hodgsonii Hook. in Central Bhutan [66]. Here other subcanopy species such as Alnus fruticosa and Salix udensis Trautv.…”

Section: Subcanopymentioning

confidence: 93%

Boreal Forests of Kamchatka: Structure and Composition

Eichhorn

2010

Forests

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Central Kamchatka abounds in virgin old-growth boreal forest, formed primarily by Larix cajanderi and Betula platyphylla in varying proportions. A series of eight 0.25-0.30 ha plots captured the range of forests present in this region and their structure is described. Overall trends in both uplands and lowlands are for higher sites to be dominated by L. cajanderi with an increasing component of B. platyphylla with decreasing altitude. The tree line on wet sites is commonly formed by mono-dominant B.ermanii forests. Basal area ranged from 7.8-38.1 m 2 /ha and average tree height from 8.3-24.7 m, both being greater in lowland forests. Size distributions varied considerably among plots, though they were consistently more even for L. cajanderi than B. platyphylla. Upland sites also contained a dense subcanopy of Pinus pumila averaging 38% of ground area. Soil characteristics differed among plots, with upland soils being of lower pH and containing more carbon. Comparisons are drawn with boreal forests elsewhere and the main current threats assessed. These forests provide a potential baseline to contrast with more disturbed regions elsewhere in the world and therefore may be used as a target for restoration efforts or to assess the effects of climate change independent of human impacts.

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Density-dependent mortality versus spatial segregation in early life stages of Abies densa and Rhododendron hodgsonii in Central Bhutan

Cited by 27 publications

References 71 publications

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

Density dependence on tree survival in an old-growth temperate forest in northeastern China

Boreal Forests of Kamchatka: Structure and Composition

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