scholarly journals Fixed or mixed? Variation in tree functional types and vegetation structure in a forest-savanna ecotone in West Africa

2020 ◽  
Vol 36 (4) ◽  
pp. 133-149
Author(s):  
George K.D Ametsitsi ◽  
Frank Van Langevelde ◽  
Vincent Logah ◽  
Thomas Janssen ◽  
Jose A Medina-Vega ◽  
...  
Keyword(s):  
West Africa ◽  
Vegetation Structure ◽  
Basal Area ◽  
Fire Frequency ◽  
Soil Water Storage ◽  
Vegetation Types ◽  
Above Ground Biomass ◽  
Area Index ◽  
Tropical Vegetation ◽  
Species Grouping

AbstractWe analysed thirty-five 400-m2 plots encompassing forest, savanna and intermediate vegetation types in an ecotonal area in Ghana, West Africa. Across all plots, fire frequency was over a period of 15 years relatively uniform (once in 2–4 years). Although woodlands were dominated by species typically associated with savanna-type formations, and with forest formations dominated by species usually associated with closed canopies, these associations were non-obligatory and with a discrete non-specialized species grouping also identified. Across all plots, crown area index, stem basal area and above-ground biomass were positively associated with higher soil exchangeable potassium and silt contents: this supporting recent suggestions of interplays between potassium and soil water storage potential as a significant influence on tropical vegetation structure. We also found an average NDVI cover increase of ~0.15% year−1 (1984–2011) with plots dominated by non-specialized species increasing more than those dominated by either forest- or savanna-affiliated species. Our results challenge the traditional view of a simple forest vs. savanna dichotomy controlled by fire, and with our newly identified third non-specialized species grouping also potentially important in understanding ecotonal responses to climate change.

Effects of biomass extraction on vegetation structure, diversity and composition of forests in Sariska Tiger Reserve, India

2005 ◽  
Vol 32 (3) ◽  
pp. 248-259 ◽  
Author(s):  
RAMAN KUMAR ◽  
GHAZALA SHAHABUDDIN
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Vegetation Structure ◽  
Riparian Forest ◽  
Canopy Cover ◽  
Basal Area ◽  
Vegetation Types ◽  
Tiger Reserve ◽  
Scrub Forest ◽  
Structure Diversity

Despite the fact that tropical dry forests are being exploited on a large scale for various forest products, there has been limited evaluation of the accompanying ecological impacts. In particular, there is no information on the effects of widespread biomass extraction such as grazing and firewood collection. A study was carried out in Sariska Tiger Reserve in northern India, to investigate the effects of biomass extraction on forest vegetation composition, diversity and structure. Biomass extraction caused significant changes in forest vegetation structure and species composition in the tree layer but the extent of these changes varied across the three major vegetation types found in the Reserve. Anogeissus-dominated slope forest showed significantly lower mean canopy cover, tree density, tree basal area and height of trees in disturbed sites in comparison to undisturbed sites. Riparian forest showed lower mean canopy cover, tree basal areas and number of recorded tree species in disturbed sites. Scrub forest had lower mean canopy cover, tree basal area and tree height. There were fewer tall trees but greater number of short trees in disturbed sites of all three vegetation types. Girths of trees similarly shifted towards lower values in riparian and scrub forest. In Anogeissus-dominated forest, disturbed and undisturbed sites did not differ in proportions of trees in various girth-classes. Tree species richness was substantially lower in disturbed sites of Anogeissus-dominated and riparian forest in comparison to undisturbed sites, but was not affected by disturbance in scrub forest. Understorey species richness was higher in disturbed sites of all three vegetation types but understorey changed structurally only in Anogeissus-dominated forest. Overall tree and understorey species composition was significantly different between disturbed and undisturbed sites of Anogeissus-dominated forest, but was unchanged in scrub and riparian forest. Observed changes in vegetation structure, diversity and composition of the different vegetation types due to biomass extraction have implications for biodiversity conservation in tropical dry forest ecosystems, and need to be addressed in future forest management planning.

Inability of fire to control vegetation dynamics in low-productivity mulga (Acacia aneura)-dominated communities of eastern Australia

2017 ◽  
Vol 26 (10) ◽  
pp. 896 ◽  
Author(s):  
J. L. Silcock ◽  
J. Drimer ◽  
J. Fraser ◽  
R. J. Fensham
Keyword(s):  
Vegetation Structure ◽  
Seedling Recruitment ◽  
Fire Severity ◽  
Basal Area ◽  
Fire Frequency ◽  
Historical Record ◽  
Livestock Grazing ◽  
Eastern Australia ◽  
Australian Continent ◽  
Acacia Aneura

Reduced fire frequency and severity associated with livestock grazing are cited as a cause of woody plant encroachment and thickening in rangelands, but such paradigms are difficult to test experimentally owing to limited opportunities to burn. Mulga (Acacia aneura) dominates 25% of the Australian continent and epitomises this quandary. We measured the effect of rare wildfires on tree and shrub mortality and subsequent regeneration in mulga-dominated communities to critically examine prevailing but unsubstantiated paradigms of vegetation structural change. Mortality of mature mulga trees was positively correlated with fire severity, which was negatively correlated with tree basal area per hectare. High-severity fires killed the majority of mulga, but only occurred in more open areas, whereas low-severity fires typical of many mulga communities did not kill substantial proportions of mature mulga. The majority of mulga saplings were killed across all sites regardless of fire severity. Seedling germination was stimulated by fire, but not dependent on it. Green turkey bush (Eremophila gilesii) was the only shrub species with >50% mortality across all sites. Combined with the rarity of fire events in the historical record, our results, particularly limited fire mortality and enhanced post-fire seedling recruitment, suggest that the role of fire in shaping vegetation structure in mulga-dominated communities has been overstated. The decoupling of fire and vegetation structure is consistent with emerging regional studies in low-productivity semiarid environments.

Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas

2020 ◽  
Vol 13 (5) ◽  
pp. 517-524
Author(s):  
Alan N Costa ◽  
Jeane R Souza ◽  
Karyne M Alves ◽  
Anderson Penna-Oliveira ◽  
Geisciele Paula-Silva ◽  
...  
Keyword(s):  
Aboveground Biomass ◽  
Vegetation Structure ◽  
Species Abundance ◽  
Basal Area ◽  
Global Scale ◽  
Woody Vegetation ◽  
Litter Production ◽  
Vegetation Types ◽  
Cylindrical Volume ◽  
Landscape Scales

Abstract Aims Litterfall at a global scale is affected by climate, edaphic features and vegetation structure, with litter production increasing from grasslands to forests following the rise in standing biomass. However, at landscape scales, the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent, structurally distinct communities are lacking. Here, we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado. Methods We evaluated the woody vegetation structure and composition in 48 sites, equally distributed across four physiognomies and monitored the monthly litter production from April 2014 to March 2015. Important Findings Results showed that the density, basal area, cylindrical volume and aboveground biomass of woody vegetation differ among physiognomies, increasing consistently from cerrado ralo, cerrado típico, cerrado denso and cerradão. Indeed, we found a strong and positive relationship between aboveground biomass and annual litter production, with litter yield increasing from 0.9 to 8.4 Mg ha−1 across different physiognomies, following the increment in vegetation structure. Monthly production was seasonal and similar among vegetation types, increasing during the dry season. Leaves comprised the dominant fraction (approx. 85%) and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months. However, the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types, likely following the decrease of deciduous species abundance in the plant community. Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies, which co-occur across the Cerrado landscape, with potential implications for the overall functioning of this ecosystem. Moreover, these findings highlight the use of standardized methods as essential to correctly compare litterfall patterns among different environments.

scholarly journals Vegetation Structure and Carbon Stocks of Two Protected Areas Within the South-Sudanian Savannas of Burkina Faso, West Africa

2016 ◽  
Author(s):  
Mohammad Qasim ◽  
Stefan Porembski ◽  
Dietmar Sattler ◽  
Katharina Stein ◽  
Adjima Thiombiano ◽  
...  
Keyword(s):  
West Africa ◽  
Burkina Faso ◽  
Protected Areas ◽  
Vegetation Structure ◽  
Nature Reserve ◽  
Carbon Stocks ◽  
Vegetation Types ◽  
The South ◽  
Importance Value ◽  
Gallery Forests

Savannas and adjacent vegetation types like gallery forests are highly valuable ecosystems contributing to several ecosystem services including carbon budgeting. Financial mechanisms such as REDD+ have provided an opportunity for developing countries to alleviate poverty through conservation of its forestry resources. For availing this opportunity carbon stock assessments are essential. Therefore, a research study at two protected areas i.e. Nazinga Game Ranch and Bontioli Nature Reserve, in Burkina Faso was conducted with the objective of assessing carbon Mg C ha-1 in aboveground biomass (AGB)dry of trees in different formations of the south-sudanian savanna in Burkina Faso, West Africa. Similarly analysis of various vegetation parameters was also conducted to understand the overall vegetation structure of these two protected areas. For estimating AGBdry, existing allometric equation for dry tropical woody vegetation types was used. The Importance Value Index (IVI) and Family Importance Value (FIV) were estimated through standard procedures. Various linear and non-linear regression analyses were conducted to test the relationships between carbon and other parameters such as DBH, height and basal area (BA). The results showed that both sites collectively contain mean carbon of 3.41 ± 4.98 Mg C ha-1. Amongst different vegetation types, gallery forests recorded the highest mean carbon of 9.38 ± 6.90 Mg C ha-1. The highest IVI of 115.56 at Nazinga Game Ranch was recorded for Anogeissus leiocarpa. Similarly, highest IVI of 98.59 was recorded for Mitragyna inermis at Bontioli Nature Reserve. The highest FIV was recorded for Combretaceae for both of the sites. To our knowledge, this was the first study conducted to assess the carbon stocks at the two protected areas in southern Burkina Faso. The study therefore was an attempt for addressing the knowledge gap particularly on carbon stocks of protected savannas. It could serve as a baseline for carbon stocks for future initiatives such as payment for environmental services and REDD+ at these areas.

scholarly journals Correlating elements content in mosses collected in 2015 across Germany with spatially associated characteristics of sampling sites and their surroundings

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Stefan Nickel ◽  
Winfried Schröder
Keyword(s):  
Land Use ◽  
Population Density ◽  
Atmospheric Deposition ◽  
Vegetation Structure ◽  
Urban Areas ◽  
Explanatory Power ◽  
Spatial Density ◽  
Area Index ◽  
Explanatory Variables ◽  
Tree Layer

Abstract Background The aim of the study was a statistical evaluation of the statistical relevance of potentially explanatory variables (atmospheric deposition, meteorology, geology, soil, topography, sampling, vegetation structure, land-use density, population density, potential emission sources) correlated with the content of 12 heavy metals and nitrogen in mosses collected from 400 sites across Germany in 2015. Beyond correlation analysis, regression analysis was performed using two methods: random forest regression and multiple linear regression in connection with commonality analysis. Results The strongest predictor for the content of Cd, Cu, Ni, Pb, Zn and N in mosses was the sampled species. In 2015, the atmospheric deposition showed a lower predictive power compared to earlier campaigns. The mean precipitation (2013–2015) is a significant factor influencing the content of Cd, Pb and Zn in moss samples. Altitude (Cu, Hg and Ni) and slope (Cd) are the strongest topographical predictors. With regard to 14 vegetation structure measures studied, the distance to adjacent tree stands is the strongest predictor (Cd, Cu, Hg, Zn, N), followed by the tree layer height (Cd, Hg, Pb, N), the leaf area index (Cd, N, Zn), and finally the coverage of the tree layer (Ni, Cd, Hg). For forests, the spatial density in radii 100–300 km predominates as significant predictors for Cu, Hg, Ni and N. For the urban areas, there are element-specific different radii between 25 and 300 km (Cd, Cu, Ni, Pb, N) and for agricultural areas usually radii between 50 and 300 km, in which the respective land use is correlated with the element contents. The population density in the 50 and 100 km radius is a variable with high explanatory power for all elements except Hg and N. Conclusions For Europe-wide analyses, the population density and the proportion of different land-use classes up to 300 km around the moss sampling sites are recommended.

scholarly journals Daily and seasonal patterns of CO2 fluxes and evapotranspiration in maize-grass intercropping

2016 ◽  
Vol 20 (9) ◽  
pp. 777-782 ◽  
Author(s):  
Cássia B. Machado ◽  
José R. de S. Lima ◽  
Antonio C. D. Antonino ◽  
Eduardo S. de Souza ◽  
Rodolfo M. S. Souza ◽  
...  
Keyword(s):  
Soil Water ◽  
Climate Changes ◽  
Carbon Sink ◽  
Soil Water Storage ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Area Index ◽  
Available Energy ◽  
Atmospheric Carbon ◽  
Main Consumer

ABSTRACT Studies that investigate the relationships between CO2 fluxes and evapotranspiration (ET) are important for predicting how agricultural ecosystems will respond to climate changes. However, none was made on the maize-grass intercropping system in Brazil. The aim of this study was to determine the ET and CO2 fluxes in a signal grass pasture intercropped with maize, in São João, Pernambuco, Brazil, in a drought year. Furthermore, the soil water storage (SWS) and leaf area index (LAI) were determined. The latent heat flux was the main consumer of the available energy and the daily and seasonal ET and CO2 variations were mainly controlled by rainfall, through the changes in soil water content and consequently in SWS. The agroecosystem acted as an atmospheric carbon source, during drier periods and lower LAI, and as an atmospheric carbon sink, during wetter periods and higher LAI values. In a dry year, the intercropping sequestered 2.9 t C ha-1, which was equivalent to 8.0 kg C ha-1 d-1. This study showed strong seasonal fluctuations in maize-grass intercropping CO2 fluxes, due to seasonality of rainfall, and that this agroecosystem is vulnerable to low SWS, with significant reduction in CO2 uptake during these periods.

Determinants of spatial variation in fire return period in a semiarid African savanna

2011 ◽  
Vol 20 (4) ◽  
pp. 540 ◽  
Author(s):  
T. G. O'Connor ◽  
C. M. Mulqueeny ◽  
P. S. Goodman
Keyword(s):  
Spatial Variation ◽  
Return Period ◽  
Vegetation Type ◽  
Fire Frequency ◽  
Fuel Load ◽  
Annual Rainfall ◽  
Vegetation Types ◽  
Terrestrial Vegetation ◽  
African Savanna ◽  
Data Set

Fire pattern is predicted to vary across an African savanna in accordance with spatial variation in rainfall through its effects on fuel production, vegetation type (on account of differences in fuel load and in flammability), and distribution of herbivores (because of their effects on fuel load). These predictions were examined for the 23 651-ha Mkuzi Game Reserve, KwaZulu-Natal, based on a 37-year data set. Fire return period varied from no occurrence to a fire every 1.76 years. Approximately 75% of the reserve experienced a fire approximately every 5 years, 25% every 4.1–2.2 years and less than 1% every 2 years on average. Fire return period decreased in relation to an increase in mean annual rainfall. For terrestrial vegetation types, median fire return periods decreased with increasing herbaceous biomass, from forest that did not burn to grasslands that burnt every 2.64 years. Fire was absent from some permanent wetlands but seasonal wetlands burnt every 5.29 years. Grazer biomass above 0.5 animal units ha–1 had a limiting influence on the maximum fire frequency of fire-prone vegetation types. The primary determinant of long-term spatial fire patterns is thus fuel load as determined by mean rainfall, vegetation type, and the effects of grazing herbivores.

scholarly journals Forest Structure, Composition and Above Ground Biomass of Tree Community in Tropical Dry Forests of Eastern Ghats, India

2016 ◽  
Vol 8 (1) ◽  
pp. 125-133 ◽  
Author(s):  
Sudam Charan SAHU ◽  
H.S. SURESH ◽  
N.H. RAVINDRANATH
Keyword(s):  
Forest Structure ◽  
Tree Species ◽  
Basal Area ◽  
Eastern Ghats ◽  
Tropical Dry Forests ◽  
Above Ground Biomass ◽  
Importance Value ◽  
Shorea Robusta ◽  
Ground Biomass ◽  
C Stocks

The study of biomass, structure and composition of tropical forests implies also the investigation of forest productivity, protection of biodiversity and removal of CO2 from the atmosphere via C-stocks. The hereby study aimed at understanding the forest structure, composition and above ground biomass (AGB) of tropical dry deciduous forests of Eastern Ghats, India, where as a total of 128 sample plots (20 x 20 meters) were laid. The study showed the presence of 71 tree species belonging to 57 genera and 30 families. Dominant tree species was Shorea robusta with an importance value index (IVI) of 40.72, while Combretaceae had the highest family importance value (FIV) of 39.01. Mean stand density was 479 trees ha-1 and a basal area of 15.20 m2 ha-1. Shannon’s diversity index was 2.01 ± 0.22 and Simpson’s index was 0.85 ± 0.03. About 54% individuals were in the size between 10 and 20 cm DBH, indicating growing forests. Mean above ground biomass value was 98.87 ± 68.8 Mg ha-1. Some of the dominant species that contributed to above ground biomass were Shorea robusta (17.2%), Madhuca indica (7.9%), Mangifera indica (6.9%), Terminalia alata (6.9%) and Diospyros melanoxylon (4.4%), warranting extra efforts for their conservation. The results suggested that C-stocks of tropical dry forests can be enhanced by in-situ conserving the high C-density species and also by selecting these species for afforestation and stand improvement programs. Correlations were computed to understand the relationship between above ground biomass, diversity indices, density and basal area, which may be helpful for implementation of REDD+ (reduce emissions from deforestation and forest degradation, and foster conservation, sustainable management of forests and enhancement of forest carbon stocks) scheme.

scholarly journals Composition of Vegetation Types and Structures in Gunung Ciremai National Park Forest

2021 ◽  
Vol 748 (1) ◽  
pp. 012009
Author(s):  
Agusyadi Ismail ◽  
Yayan Hendrayana ◽  
Dadan Ramadani ◽  
Sri Umiyati
Keyword(s):  
Plant Species ◽  
Vegetation Structure ◽  
National Park ◽  
Stand Structure ◽  
Complex Structure ◽  
Forest Vegetation ◽  
Intensity Data ◽  
Vegetation Types ◽  
Growth Phases ◽  
High Level

Abstract Mount Ciremai National Park forest that area had been encroached. Because of that condition, stand structure especially the species composition and vegetation structure need to be researched. The aim of this research was to identify plant species and analyze forest vegetation structure. This research was conducted between March–April 2018 in the 15.500 ha area with 0.02% sampling intensity. Data was collected using grid line method that consisted of 34 sample plots with the 10 m distance between the plots and 20 m between the lines. The numbers of identified plant species at the research location were 43 species, classified by 10 families and 24 genera. Cinnamomum sintoc has a high level of dominance species. The forest vegetation was consisting by the different growth phases. The tree phase has the highest density of 3672 species/ha, while the seedling phase was lowest density of 1060 species/ha. The forest crown stratification were consisting of A, B, C, D and E stratum. The highest number of plants were from C strata for 4651 trees and the least from A strata with 25 trees with the highest tree was 42 m. Could be concluded that the composition of Mount Ciremai National Park forest have so many number of species and complex structure vegetation forest.

scholarly journals Algorithm for assessing forest stand productivity index using leaf area index

2019 ◽  
Vol 16 (3) ◽  
pp. 1311
Author(s):  
Faid Abdul Manan ◽  
Muhammad Buce Saleh ◽  
I Nengah Surati Jaya ◽  
Uus Saepul Mukarom
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Basal Area ◽  
Forest Stand ◽  
Productivity Index ◽  
Estimation Model ◽  
Area Index ◽  
Study Objective ◽  
Stand Productivity ◽  
Variable Combination

This paper describes a development of an algorithm for assessing stand productivity by considering the stand variables. Forest stand productivity is one of the crucial information that required to establish the business plan for unit management at the beginning of forest planning activity. The main study objective is to find out the most significant and accurate variable combination to be used for assessing the forest stand productivity, as well as to develop productivity estimation model based on leaf area index. The study found the best stand variable combination in assessing stand productivity were density of poles (X2), volume of commercial tree having diameter at breast height (dbh) 20-40 cm (X16), basal area of commercial tree of dbh >40 cm (X20) with Kappa Accuracy of 90.56% for classifying into 5 stand productivity classes. It was recognized that the examined algorithm provides excellent accuracy of 100% when the stand productivity was classified into only 3 classes. The best model for assessing the stand productivity index with leaf area index is y = 0.6214x - 0.9928 with R2= 0.71, where y is productivity index and x is leaf area index.

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