Effects of canopy species dominance on understorey light availability in low-elevation secondary forest stands in Costa Rica

1996 ◽  
Vol 12 (6) ◽  
pp. 779-788 ◽  
Author(s):  
Randy P. Kabakoff ◽  
Robin L. Chazdon
Keyword(s):  
Costa Rica ◽  
Forest Canopy ◽  
Light Availability ◽  
Basal Area ◽  
Light Transmittance ◽  
Stem Density ◽  
Secondary Forests ◽  
Canopy Architecture ◽  
Species Dominance ◽  
Canopy Species

ABSTRACTThe effect of canopy species dominance on understorey light availability in secondary forests was examined for Pentaclethra macroloba and Goethalsia meiantha, two common tree species with contrasting canopy architecture at La Selva Biological Station in the Atlantic lowlands of Costa Rica. In each of six 12- to 16-year-old successional stands dominated by one of these species, relative abundance and basal area of the focal species were determined within a 20 m × 50 m plot. Light availability at 1 m height was measured within each plot using a Licor-2000 Plant Canopy Analyzer at 27 locations and by analysing hemispherical photographs taken at 10 locations. Across stands, mean LAI values were significantly negatively correlated with canopy openness. Understorey microsites beneath Pentaclethra had significantly higher light availability than microsites beneath Goethalsia. Across stands, however, light availability was not correlated with either total basal area or stem density of trees ≥10 cm DBH. These results indicate that basal area and stem density of trees in the upper levels of the forest canopy are poor predictors of light penetration to the understorey. One hypothesis suggested here is that dense subcanopy and understorey vegetation in tropical secondary forests can strongly influence understorey light levels. Alternatively, light transmittance characteristics of the upper forest canopy may be influenced by species-specific differences in canopy architecture or foliage density that vary independently from tree diameter and density.

Gap-phase regeneration in selectively logged lowland swamp forest, northeastern Costa Rica

1998 ◽  
Vol 14 (2) ◽  
pp. 247-260 ◽  
Author(s):  
EDWARD L. WEBB
Keyword(s):  
Costa Rica ◽  
Tree Species ◽  
Structural Damage ◽  
Basal Area ◽  
Abundant Species ◽  
Selective Logging ◽  
Stem Density ◽  
Swamp Forest ◽  
Gap Phase ◽  
Multiple Tree

For sustainable logging to be achieved in tropical forests, there must be successful gap-phase regeneration to restock the logged-over area. This study examined three aspects of gap-phase regeneration in selectively logged lowland swamp forest of northeast Costa Rica. First, logging gaps were censused immediately after extraction to determine the density of advanced regeneration. Stem density and basal area of residual trees ≥ 10 cm dbh in logging gaps was >85% lower than undisturbed forest, and all trees in gaps had sustained structural damage. The common canopy species Pentaclethra macroloba (Fabaceae) was the most abundant species in gaps whereas the timber tree Carapa nicaraguensis (Meliaceae) was absent from all censused gaps. This suggests that canopy replacement, particularly by Carapa, will depend on trees <10 cm dbh or by seed input into logging gaps. Second, the diversity of the understorey was compared with 6-y old single-tree and multiple-tree logging gaps. Multiple-tree logging gaps were the most diverse, but dominated by two ruderal species; however many shade-tolerant species were present in those gaps. This indicates that controlled selective logging can result in a localized shift in species composition, but that logging gaps should return to pre-logging composition with time under a carefully implemented, controlled harvesting regime. Finally, this study found a significant effect of a fringing Carapa tree on logging gap seedling density. Thus, seed arrival into gaps is a barrier to logging gap regeneration, particularly for a large-seeded tree species. Gap-phase regeneration by a large-seeded tree species in managed forest would benefit from seed broadcasting into gaps.

A re-assessment of effects of fire on miombo regeneration in the Zambian Copperbelt

1988 ◽  
Vol 4 (4) ◽  
pp. 361-372 ◽  
Author(s):  
E. N. Chidumayo
Keyword(s):  
Species Diversity ◽  
Plant Growth ◽  
Fire Protection ◽  
Woody Plant ◽  
Basal Area ◽  
Abundant Species ◽  
Stem Density ◽  
Miombo Woodland ◽  
Breast Height ◽  
Canopy Species

ABSTRACTIn 1933/34 eight coppice plots were established in Brachystegia-Julbemardia (miombo) woodland at Ndola in the Copperbelt area of Zambia by the Forestry Department. These plots have been maintained under fire protection, annual early or late dry season burning since 1934/35. Before establishment stems over 20.3 cm girth at breast height were enumerated. Three of the eight plots (one fire protected and two annually early burnt) were enumerated in 1982, 48–49 years after establishment. In addition, a coppice plot at Chitwi, 16 km southwest of the Ndola plots, cleared in 1972 and left to regenerate naturally was enumerated in May 1982 and August 1986 to assess woody plant growth.The density of stems over 20.0 cm girth in the 13-year-old coppice at Chitwi was 2.5 times that in an adjacent shelterbelt woodland. The stem density in the fire protected plot at Ndola in 1982 was 86% of the pre-felling density while in one of the early burnt plots it was 95% of the pre-felling density. The protected plot had the lowest species diversity after 49 years, largely because of the loss of 11 understorey species that were present before felling.There were no significant differences in stem mean girth at breast height (gbh) of canopy species in the Ndola plots under fire protection and early burning regimes. Mean annual gbh increments of abundant species were estimated at 1.17–2.21 cm yr−1 and 0.59–1.42 cm yr−1 during 0–9 and 0–49 year age-periods, respectively. Estimated mean annual basal area increments for stems over 30 cm gbh were 0.35 m2 ha−1 for the 13-year-old coppice and 0.24–0.27 m2 ha−1 for the 49-year-old coppice. These results indicate a decrease in both gbh and basal area increment with increasing age of miombo coppice

Liana density declined and basal area increased over 12 y in a subtropical montane forest in Argentina

2017 ◽  
Vol 33 (4) ◽  
pp. 241-248 ◽  
Author(s):  
Sergio Javier Ceballos ◽  
Agustina Malizia
Keyword(s):  
Light Availability ◽  
Basal Area ◽  
Anthropogenic Disturbances ◽  
Montane Forest ◽  
Forest Recovery ◽  
Permanent Plots ◽  
Stem Density ◽  
Mature Forest ◽  
Shade Tolerant Species ◽  
North Western

Abstract:Changes in density and basal area of lianas ≥2 cm diameter were monitored in two 1-ha permanent plots in a subtropical montane mature forest of north-western Argentina. Liana stems were identified and measured at 130 cm from the main rooting point in two censuses conducted in 2003 and 2015. Between censuses, the density of liana stems decreased 13.3%, while basal area increased 11.5%. Density and basal area decreased mainly among lianas of 2–3 cm diameter, but increased in lianas ≥4 cm diameter. Quechualia fulta (Asteraceae), Serjania meridionalis (Sapindaceae) and Chamissoa altissima (Amaranthaceae) suffered large reductions in stem density and basal area. Dissimilar responses of density and basal area of lianas might be a consequence of the suppression of anthropogenic disturbances (e.g. livestock browsing) and the decrease of treefall gap frequency in the studied forest in recent decades. Light-demanding liana species decreased and shade-tolerant species increased possibly in response to the decline in the light availability associated with forest recovery from past disturbance. Lianas increased in basal area to a lesser extent compared with reports from several tropical and subtropical forests where lianas are increasing dramatically.

scholarly journals What deters plant colonization in a tropical pine plantation?

2016 ◽  
Vol 64 (2) ◽  
pp. 461
Author(s):  
Zdravko Baruch
Keyword(s):  
Species Richness ◽  
Light Availability ◽  
Basal Area ◽  
Protective Role ◽  
Plant Colonization ◽  
Stem Density ◽  
Native Forest ◽  
Pine Plantation ◽  
Pinus Caribaea ◽  
Successional Trajectory

<p>A forty year old <em>Pinus caribaea</em> plantation, surrounding the Universidad Simón Bolívar campus in Caracas (Venezuela), provides effective protection from erosion and mudslides. Owing primarily to past mismanagement, mainly lack of thinning, this exotic pine plantation is senescing rapidly. Assisted restoration aiming to attain a successional trajectory towards the neighbouring montane forest is the most realistic option for maintaining the plantation’s protective service and increase local biodiversity. Within the experimental constraints imposed by the small area of the plantation and its central protective role, we describe and analyse the effects of light and fertility limitation, litter accumulation and access to seed on plantation restoration. This experimental restoration trial is the first for a Neotropical pine plantation. Light availability was manipulated by clearing and thinning three 800 m<sup>2</sup> main plots. Fertilization and needle litter removal (by fire and raking) was applied to sub-plots within the light plots. Soils were analysed, microclimate was monitored and, across 4 years, stem density, species richness and basal area were tallied. Light accessibility was the main factor predicting the successional trajectory of the plots, with varying grades of interaction with the sub-treatments. By the end of the fourth year, the cleared plot showed the largest responses in all traits (three times higher stem density and basal area and up to twenty times higher species richness) as compared to the thinned and control plots. Although difficult to establish, unimpeded access to seed dispersers probably contributed to this result. The main colonizers were <em>Croton megalodendron</em>, <em>Ocotea</em> <em>fendleri</em>, and <em>Clusia spp</em>; all dominant trees in the nearby native forest. At this stage, our results permit us to recommend the use of small sized clearings, repeated in 3-4 year cycles, for similar restoration schemes. They would generate a mosaic of patches at different successional stages maintaining the protective role of the vegetation cover while increasing local biodiversity. </p>

scholarly journals Forest structural parameters and aboveground biomass in old-growth and secondary forests along an elevational gradient in Mexico

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Martina Alrutz ◽  
Jorge Antonio Gómez Díaz ◽  
Ulf Schneidewind ◽  
Thorsten Krömer ◽  
Holger Kreft
Keyword(s):  
Climate Change ◽  
Forest Structure ◽  
Aboveground Biomass ◽  
Basal Area ◽  
Elevational Gradient ◽  
Stem Density ◽  
Secondary Forests ◽  
Old Growth ◽  
Old Growth Forest ◽  
Old Growth Forests

Background: Tropical montane forests are important reservoirs of carbon and biodiversity but are threatened by deforestation and climate change. It is important to understand how forest structure and aboveground biomass change along gradients of elevation and succession. Questions: What are the interactive effect of elevation and two stages of succession on forest structure parameters? Studied species: Tree communities. Study site and dates: Cofre de Perote, Veracruz, Mexico. August to December 2015. Methods: We studied four sites along an elevational gradient (500, 1,500, 2,500, and 3,500 m). At each elevation and each forest type, we established five 20 × 20 m plots (n = 40 plots). Within each plot, we measured stem density, mean diameter at breast height (dbh), and tree height and derived basal area and aboveground biomass (AGB). Results: AGB peaked at 2,500 m and was significantly related to elevation and succession, with higher values in old-growth forests than in secondary forests at higher altitudes. Lower values of mean dbh and basal area were found at higher elevations. At the lowest elevation, both successional stages had the same values of stem density and AGB. At both lower elevations, secondary forests had higher values of dbh and basal area. There were high biomass stocks in the old-growth forest at 2,500 and 3,500 m. Conclusions: Old-growth forests at higher elevations are threatened by deforestation, consequently these remaining fragments must be preserved because of their storage capacity for biomass and their ability to mitigate climate change.

scholarly journals Successional trajectories of secondary forests and tree plantations in Costa Rican lowlands

2019 ◽  
Vol 67 (6) ◽  
Author(s):  
J. Benjamin Longworth ◽  
G. Bruce Williamson
Keyword(s):  
Species Richness ◽  
Carbon Sequestration ◽  
Functional Groups ◽  
Relative Abundance ◽  
Basal Area ◽  
Tree Plantations ◽  
Stem Density ◽  
Secondary Forests ◽  
Forest Types ◽  
Successional Trajectory

Tree plantations used for carbon sequestration or forest restoration often support diverse plant communities. However, it is unknown how rates of successional change in tree plantations compare to secondary forests. In this study, we compared the successional trajectory of tree plantations to that of secondary forests that were between 8 and 23 years old. Censuses of woody plants (≥2 cm dbh) in seven tree plantation plots and seven secondary forest plots (30 x 30 m) were conducted over three years (May 2013 – July 2016) in a lowland tropical forest. Secondary forests were naturally regenerating from abandoned cattle pastures. Tree plantations were monocultures of two different native species (Vochysia guatemalensis and Hieronyma alchorneoides) planted for carbon sequestration. We measured the change in stem density, basal area, species density, rarefied species richness, and relative abundance of different functional groups. We found that differences between these two forests types in stem density and basal area were declining. We did not find evidence for differences between forest types in the rate of accumulation of species richness when accounting for sample size. Although, the successional trajectory in tree plantations was very similar to secondary forests, there were differences between forest types in species composition. The rate of change in relative abundance of different functional groups was similar in both forest types. Overall, our results suggest that structural but not compositional differences between tree plantations and secondary forests are converging during the second decade of succession.

scholarly journals Quantifying Understory Complexity in Unmanaged Forests Using TLS and Identifying Some of Its Major Drivers

2021 ◽  
Vol 13 (8) ◽  
pp. 1513
Author(s):  
Dominik Seidel ◽  
Peter Annighöfer ◽  
Christian Ammer ◽  
Martin Ehbrecht ◽  
Katharina Willim ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Structural Equation Models ◽  
Light Availability ◽  
Structural Complexity ◽  
Basal Area ◽  
Ecosystem Functions ◽  
Canopy Openness ◽  
Seasonal Precipitation ◽  
Wide Range ◽  
Precipitation And Temperature

The structural complexity of the understory layer of forests or shrub layer vegetation in open shrublands affects many ecosystem functions and services provided by these ecosystems. We investigated how the basal area of the overstory layer, annual and seasonal precipitation, annual mean temperature, as well as light availability affect the structural complexity of the understory layer along a gradient from closed forests to open shrubland with only scattered trees. Using terrestrial laser scanning data and the understory complexity index (UCI), we measured the structural complexity of sites across a wide range of precipitation and temperature, also covering a gradient in light availability and basal area. We found significant relationships between the UCI and tree basal area as well as canopy openness. Structural equation models (SEMs) confirmed significant direct effects of seasonal precipitation on the UCI without mediation through basal area or canopy openness. However, annual precipitation and temperature effects on the UCI are mediated through canopy openness and basal area, respectively. Understory complexity is, despite clear dependencies on the available light and overall stand density, significantly and directly driven by climatic parameters, particularly the amount of precipitation during the driest month.

Exploring the Recruitment Dynamics of Sugar Maple and Yellow Birch Saplings into Merchantable Stems Following Harvesting in the Acadian Forest Region of New Brunswick, Canada

2021 ◽  
Author(s):  
Alex Noel ◽  
Jules Comeau ◽  
Salah-Eddine El Adlouni ◽  
Gaetan Pelletier ◽  
Marie-Andrée Giroux
Keyword(s):  
New Brunswick ◽  
Sugar Maple ◽  
Basal Area ◽  
Stem Density ◽  
Yellow Birch ◽  
Probability Of Occurrence ◽  
Silvicultural Treatment ◽  
Forest Region ◽  
Wide Range ◽  
Acadian Forest

The recruitment of saplings in forest stands into merchantable stems is a very complex process, thus making it challenging to understand and predict. The recruitment dynamics in the Acadian Forest Region of New Brunswick are not well known or documented. Our objective was to draw an inference from existing large scale routine forest inventories as to the different dynamics behind the recruitment from the sapling layer into the commercial tree size layer in terms of density and occurrence of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.) following harvesting, by looking at many factors on a wide range of spatial and temporal scales using models. Results suggest that the variation in density and probability of occurrence is best explained by the intensity of silvicultural treatment, by the merchantable stem density in each plot, and by the proportion of merchantable basal area of each group of species. The number of recruits of sugar maple and yellow birch stems tend be higher when time since last treatment increases, when mid to low levels of silvicultural treatment intensity were implemented, and within plots having intermediate levels of merchantable stem density. Lastly, our modeling efforts suggest that the probability of occurrence and density of recruitment of both species tend to increase while its share of merchantable basal area increases.

Tree density, basal area and species diversity in a disturbed dry tropical forest of northern India: implications for conservation

2006 ◽  
Vol 33 (3) ◽  
pp. 256-262 ◽  
Author(s):  
R. SAGAR ◽  
J.S. SINGH
Keyword(s):  
Species Diversity ◽  
Tropical Forest ◽  
Basal Area ◽  
Tree Density ◽  
Dry Forest ◽  
Conservation Strategies ◽  
Stem Density ◽  
Dry Tropical Forest ◽  
Number Of Species ◽  
Northern India

Dry tropical forest communities are among the world's most threatened systems and urgent measures are required to protect and restore them in degraded landscapes. For planning conservation strategies, there is a need to determine the few essential measurable properties, such as number of species and basal area, that best describe the dry forest vegetation and its environment, and to document quantitative relationships among them. This paper examines the relationships between forest basal area and diversity components (number of species and evenness) for a disturbed dry tropical forest of northern India. Data were collected from five sites located in the Vindhyan dry tropical forest of India, selected on the basis of satellite images and field observations to represent the entire range of conditions in terms of canopy cover and disturbance regimes. These sites represented different communities in terms of species composition. The forest was poorer in species richness, and lower in stem density and basal area than wet forests of the tropics. Across sites (communities), the diversity components and tree density were positively related with total tree basal area. Considering basal area as a surrogate of biomass and net production, diversity is found to be positively associated with productivity. A positive relationship between basal area, tree density and species diversity may be an important characteristic of the dry forest, where recurring disturbance does not permit concentration of biomass or stems in only a few strong competitors. However, the relationships of basal area with density, alpha diversity and evenness remain statistically significant only when data from all sites, including the extremely disturbed one, are used in the analysis. In some sites there was a greater coefficient of variation (CV) of basal area than in others, attributed to patchy distribution of stems and resultant blanks. Therefore, to enhance the tree diversity of these forests, the variability in tree basal area must be reduced by regulating local disturbances. Conservation activities, particularly fuelwood plantations near human settlements, deferred grazing and canopy enrichment through multi-species plantations of nursery-raised or wild-collected seedlings of desirable species within the forest patches of low basal area, will be needed to attain restoration goals, but reforestation programmes will have to be made attractive to the forest-dwelling communities.

Elevational gradients of bryophyte diversity, life forms, and community assemblage in the southern Appalachian Mountains

2010 ◽  
Vol 40 (11) ◽  
pp. 2164-2174 ◽  
Author(s):  
Sarah E. Stehn ◽  
Christopher R. Webster ◽  
Janice M. Glime ◽  
Michael A. Jenkins
Keyword(s):  
Community Composition ◽  
Elevation Gradient ◽  
Light Availability ◽  
Basal Area ◽  
Life Forms ◽  
High Elevation ◽  
Canopy Openness ◽  
Fine Scale ◽  
Elevational Gradients ◽  
Community Assemblage

We investigated the influence of fine-scale elevational gradients and overstory disturbance on bryophyte distribution, diversity, and community composition. Bryophyte species cover and richness were sampled across 60 randomly selected plots within high-elevation spruce–fir ( Picea – Abies ) forests of Great Smoky Mountains National Park. Ordination and regression analyses revealed a fine-scale elevation gradient (700 m) in bryophyte community composition. Observed changes in bryophyte diversity and community composition were also associated with variation in deciduous basal area and thus litter composition, the prevalence of herbaceous plants, and the degree of canopy openness resulting from balsam woolly adelgid ( Adelges piceae Ratz.) infestation. Although overstory disturbances, such as those caused by the adelgid, create suitable substrate for bryophyte colonization, the corresponding increase in light availability and deciduous basal area may alter bryophyte diversity and community assemblages.

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