scispace - formally typeset
Search or ask a question
Topic

Tree canopy

About: Tree canopy is a research topic. Over the lifetime, 4720 publications have been published within this topic receiving 166702 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a stand growth model, called 3-PG (Use of Physiological Principles in Predicting Growth), calculates total carbon fixed (gross primary production; PG) from utilizable, absorbed photosynthetically active radiation (φp.a.u.), obtained by correcting the photosyntically active radiation absorbed by the forest canopy for the effects of soil drought, atmospheric vapour pressure deficits and stand age.

1,548 citations

Journal ArticleDOI
TL;DR: The results of a comparative phenological investigation of the trees in Wet and Dry forest sites in lowland Costa Rica are reported here to provide a unified analysis of the leafing, flowering, and fruiting periodicities of most species at both sites.
Abstract: The dearth of plant phenological studies in tropical latitudes has been pointed out by various authors (Gibbs & Leston 1970; McClure 1966; Nevling 1971; Rees 1964). A review and brief evaluation of the few available investigations is presented by Frankie, Baker & Opler (1974). In most of these studies, a partial analysis of leafing, flowering or fruiting data is offered for a limited number of species and for limited time periods only. The results of a comparative phenological investigation of the trees in Wet and Dry forest sites in lowland Costa Rica are reported here. An attempt has been made to provide a unified analysis of the leafing, flowering, and fruiting periodicities of most species at both sites. The Wet forest site, Finca La Selva, is situated in the Atlantic watershed, while the Dry forest site, Comelco Property, is situated in the Pacific watershed. The study, which began in 1968, is part of a larger investigation aimed at analysing the biological organization of Wet and Dry forest ecosystems from the standpoint of plant reproductive biology. In this study the definition of a tree put forward by Lindley & Moore (1884, p. 1161) as 'any woody plant of perennial duration which rises from the ground with a trunk' has been adopted in part. To this we have added a minimum height qualification of approximately 3 m. We were unable to recognize distinct layers within the forest canopy at either site. Stratification, in which three or more tiers are generally designated, has been described by investigators working in various Tropical Rain forests (Beard 1955; Jones 1955; Lundell 1937; Richards 1952; Webb 1959). Other workers have been unable to discern definite layers clearly (Cain & Castro 1959; Grubb et al. 1963; Paijmans 1970; Schulz 1960). However, because trees are subject to different environmental conditions depending upon their position in the canopy and also for ease in recording data, tree species at the Wet forest site were arbitrarily divided into two categories: overstorey and understorey species. The first group consisted of canopy and subcanopy species, with the understorey comprising trees generally less than 15 m in height. Croat (1969) also divided trees at Barro Colorado Island into two layers for similar reasons. No layering effect was observed in the Dry forest and, because of the lesser tree heights, all trees in this forest were considered to belong to a single layer.

1,236 citations

Journal ArticleDOI
TL;DR: Interest in the role of adaptations by species to different regeneration sites in structuring plant assemblages in general and tropical tree communities in particular is heightened by rising rates of deforestation throughout the tropics and a critical need for management strategies of the remaining preserves.
Abstract: Evolutionary hypotheses about how so many species of tropical rainforest trees might have arisen include (a) genetic drift (71), (b) habitat specialization (8) in benign environments, or (c) repeated geographic isolation followed by remixing of species during Pleistocene climatic fluctuations (144). Ecological hypotheses about how these species continue to coexist are often cast into equilibrium or non-equilibrium frameworks: Do tropical forests comprise " . . . sets of highly coevolved niche-differentiated tree species in stable or semistable floristic assemblages," or do they consist of " . . . diffusely coevolved, broadly generalist species which slowly drift in relative abundance within a few large life-history guilds" (67, 102)? In this context, there has been considerable recent interest in the role of adaptations by species to different regeneration sites in structuring plant assemblages in general (83, 84, 86, 141), and tropical tree communities in particular (62, 89, 90, 150). The immediacy of this interest is heightened by rising rates of deforestation throughout the tropics and a critical need for management strategies of the remaining preserves, for ecologically sound harvesting procedures, and for the tools with which to restore degraded forests. Openings in the forest canopy are widely recognized as important for the establishment and growth of rainforest trees (5, 33, 62, 90). Hartshorn (89) suggests that perhaps 75% of the tree species at La Selva Biological Station, Costa Rica are dependent on canopy opening for seed germination or for growth beyond sapling size. Similar statements are found in descriptions of forest dynamics in Queensland, Australia (185), Malaysian dipterocarp forests (195), and West African rain forest (108). Demographic studies demon-

1,197 citations

Journal ArticleDOI
TL;DR: In this article, a wall-to-wall, global map of canopy height at 1-km spatial resolution, using 2005 data from the Geoscience Laser Altimeter System (GLAS) aboard ICESat (Ice, Cloud, and land Elevation Satellite).
Abstract: [1] Data from spaceborne light detection and ranging (lidar) opens the possibility to map forest vertical structure globally. We present a wall-to-wall, global map of canopy height at 1-km spatial resolution, using 2005 data from the Geoscience Laser Altimeter System (GLAS) aboard ICESat (Ice, Cloud, and land Elevation Satellite). A challenge in the use of GLAS data for global vegetation studies is the sparse coverage of lidar shots (mean = 121 data points/degree2 for the L3C campaign). However, GLAS-derived canopy height (RH100) values were highly correlated with other, more spatially dense, ancillary variables available globally, which allowed us to model global RH100 from forest type, tree cover, elevation, and climatology maps. The difference between the model predicted RH100 and footprint level lidar-derived RH100 values showed that error increased in closed broadleaved forests such as the Amazon, underscoring the challenges in mapping tall (>40 m) canopies. The resulting map was validated with field measurements from 66 FLUXNET sites. The modeled RH100 versus in situ canopy height error (RMSE = 6.1 m, R2 = 0.5; or, RMSE = 4.4 m, R2 = 0.7 without 7 outliers) is conservative as it also includes measurement uncertainty and sub pixel variability within the 1-km pixels. Our results were compared against a recently published canopy height map. We found our values to be in general taller and more strongly correlated with FLUXNET data. Our map reveals a global latitudinal gradient in canopy height, increasing towards the equator, as well as coarse forest disturbance patterns.

915 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compared light regimes beneath closed canopies and tree-fall gaps for five temperate and tropical forests using fish-eye photography of intact forest canopie and a model for calculating light penetration through idealized gaps.
Abstract: Light regimes beneath closed canopies and tree-fall gaps are compared for five temperate and tropical forests using fish-eye photography of intact forest canopies and a model for calculating light penetration through idealized gaps. Beneath intact canopies, analyses of canopy photographs indicate that sunflecks potentially contribute 37–68% of seasonal total photosynthetically active radiation. In all of the forests, potential sunfleck duration is brief (4–6 min), but the frequency distributions of potential sunfleck duration vary because of differences in canopy geometry and recent disturbance history. Analysis of the photographs reveals that incidence angles for photosynthetically active radiation beneath closed canopies are not generally vertical for any of the forests, but there was considerable variation both among and within sites in the contribution of overhead versus low-angle lighting. Calculations of light penetration through idealized single-tree gaps in old growth Douglas-fir – hemlock forests...

910 citations


Network Information
Related Topics (5)
Vegetation
49.2K papers, 1.4M citations
92% related
Ecosystem
25.4K papers, 1.2M citations
85% related
Species richness
61.6K papers, 2.1M citations
81% related
Species diversity
32.2K papers, 1.2M citations
81% related
Biodiversity
44.8K papers, 1.9M citations
81% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023152
2022213
2021239
2020252
2019229
2018205