Measurement of tree diversity in the Nigerian rainforest

Ojo, L. O.; Ola-Adams, B. A.

doi:10.1007/bf00051575

Cited by 20 publications

(7 citation statements)

References 9 publications

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“…Pianka, 1966; Davidowitz & Rosenzweig, 1998). Lowland tropical forests, for example, may sample a greater area of resource space than other forest types (MacDonald, 2003), and large samples of rain forest may be spatially more variable than other kinds of woodland (Tuomisto et al ., 1995; Ojo & Ola‐Adams, 1996). Relating species diversity to spatial measures of habitat diversity, therefore, may not always be meaningful (Tews et al ., 2004).…”

Section: Discussionmentioning

confidence: 99%

A resource‐based conceptual model of plant diversity that reassesses causality in the productivity–diversity relationship

Lavers¹,

Field²

2006

Global Ecology and Biogeography

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Biogeographical studies frequently reveal positive correlations between species richness and estimates of environmental water and/or energy. A popular interpretation of this relationship relates the supply of water and energy to productivity, and then, in turn, to richness. Productivity-diversity theories are now legion, yet none has proved sufficiently intuitive to gain broad acceptance. Like productivity, heterogeneity is known to influence diversity at fine spatial scales, yet the possibility that richness might relate to water-energy dynamics at coarse spatial scales via a heterogeneity-generating mechanism has received little attention. In this paper we outline such a conceptual model for plants that is internally consistent and testable. We believe it may help to explain the capacity of environments receiving different inputs of water and energy to support variable numbers of species at a range of spatial scales, the pervasive correlation between productivity and richness, some exceptions to the productivity-diversity relationship, the form of productivity-diversity curves and the link between richness and environmental 'harshness' . The model may also provide an answer to one of the most venerable puzzles in the field of diversity studies: why high inputs of water and energy correspond to more species rather than simply more individuals.

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Section: Discussionmentioning

confidence: 99%

A resource‐based conceptual model of plant diversity that reassesses causality in the productivity–diversity relationship

Lavers¹,

Field²

2006

Global Ecology and Biogeography

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“…Tropical forests are the richest and the most diverse ecosystem on earth but are unsustainably over exploited despite legislation to control their exploitation [1] [2]. FAO [3] revealed that ninety percent of the original moist forest in West Africa is gone and the leftover is heavily fragmented and degraded, while in Nigeria, Federal Environmental Protection Agency [4] showed that over 43% of the total geographic area of 923,768 km 2 has been lost in 12 years to human activities [5].…”

Section: Introductionmentioning

confidence: 99%

Assessing and Predicting Changes in the Status of Gambari Forest Reserve, Nigeria Using Remote Sensing and GIS Techniques

Adedeji¹,

Tope-Ajayi²,

Abegunde³

2015

JGIS

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Rapid population growth and increasing economic activities have resulted in unsustainable exploitation and rapid decline in the spatial extent of forest reserves in Nigeria. Studying land use dynamics of these forest reserves is essential for analysing various ecological and developmental consequences over time. Land use/land cover mapping, change detection and prediction are essential for decision-making and implementing appropriate policy responses relating to land uses. This paper aims at assessing and predicting changes in land use/land cover at Gambari forest reserve, Nigeria using remote sensing and GIS techniques. The study determined the magnitude, rate and dynamics of change in the spatial extent of the forest reserve between 1984 and 2014 using multi-temporal datasets (Landsat TM 1984 and 2000 and OLI/TIRS 2014). The imageries were classified using ArcGIS 10.0 version with support of ground truth data and Land use Change Modeller (LCM) and Markovian processes were employed to analyse the pattern and trend of change. Prediction of 2044 scenario carried out using neural network, which is a built-in module in the Idrisi. The study revealed dramatic decline in the extent of the forest reserve as both the plantation of exotic tree species (Tectona grandis and Gmelina) and the indigenous stands have been logged in several places for timber and to make way for cultivation of crops. In addition, pressures from other land uses like settlements have also led to increased non-forest uses particularly bare grounds. The study concluded that increasing loss of the indigenous forest and plantation would continue thus having implications for biodiversity conservation in the study area. There is the need for participation of different stakeholders and sectors to solve conflicting demands on limited forest resources and ensure ecosystem integrity.

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“…In larger areas with an heterogeneity old-growth rainforest, though, a larger number of species, e.g. K = 80, are more likely to occur (Mulder et al, 2004;Ojo and Ola-Adams, 1996;Vanclay, 1989;Wubs and Bezemer, 2018).…”

Section: Methodsmentioning

confidence: 99%

New confidence interval methods for Shannon index

R.¹,

Zocchi²,

Godoy³

et al. 2022

Preprint

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1. Several factors affect the structure of communities, including biological, physical and chemical phenomena, impacting the quantification of biodiversity, measured by diversity indexes such as Shannon's entropy. Then, once a point estimate is obtained, confidence intervals methods such as the bootstrap ones are often used. These methods, however, can have different performances, which many authors have revealed in the last decade. Furthermore, problems such as the asymmetry of the distribution of estimates and the possibility of Shannon's diversity index estimator bias can lead to incorrect recommendations to the research community. Thus, we propose two methods and compare them with seven others using their performances to face these problems.2. The first idea uses the credible interval (CI) method to build a bootstrap confidence interval.The second one starts by correcting the bias and then uses an asymptotic approach. We considered 27 community structures representing scenarios with high dominance, high codominance or moderate dominance, the number of species equal to 4, 20 or 80 and 10, 50 or 500 individuals to compare their performances. Then, we generated 1000 samples, built 95% confidence intervals, and calculated the percentage of times they included the 1 community diversity index (coverage percentage) for each community structure.3. Our results showed the feasibility of both proposed methods to estimate Shannon's diversity. The simulation study revealed the bootstrap-t technique had the best performance, i.e., best coverage percentage, compared with the other methods. Finally, we illustrate the methodology by applying it to an original aphid and parasitoid species dataset.4. We recommend the bootstrap-t when the community structure analysed is similar to the simulated ones. Also, the methods provided high performance for the high dominance scenarios.

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Measurement of tree diversity in the Nigerian rainforest

Cited by 20 publications

References 9 publications

A resource‐based conceptual model of plant diversity that reassesses causality in the productivity–diversity relationship

A resource‐based conceptual model of plant diversity that reassesses causality in the productivity–diversity relationship

Assessing and Predicting Changes in the Status of Gambari Forest Reserve, Nigeria Using Remote Sensing and GIS Techniques

New confidence interval methods for Shannon index

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