Contrasting the Effect of Forest Landscape Condition to the Resilience of Species Diversity in a Human Modified Landscape: Implications for the Conservation of Tree Species

Mulugheta Ghebreslassie Araia,Paxie Wanangwa Chirwa,Eméline Sêssi Pélagie Assédé

doi:10.3390/land9010004

Mulugheta Ghebreslassie Araia, Paxie Wanangwa Chirwa + Show 1 more

Open Access

https://doi.org/10.3390/land9010004

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Journal: Land	Publication Date: Dec 22, 2019
Citations: 6	License type: CC BY 4.0

Affiliation: University of Pretoria, Université de Parakou

Abstract

Using landscape moderation insurance and Intermediate Disturbance Hypothesis (IDH) as frameworks, this study assessed the response of local assemblage among different land use regimes (mean β-diversity), using the Jaccard dissimilarity matrix in contrasting Human Modified Forest Landscapes (HMFLs). The study was conducted at the relatively simplified Mafhela Forest Reserve and the complex Thathe Vondo Forest Reserve in South Africa. The patterns of overall β-diversity between HMFL and State-protected Indigenous Forests (SIF) were compared and the leading change drivers were then untangled. This study found that human disturbance affects mean β-diversity of local assemblages among land use regimes between the two HMFLs in an ecologically contrasting manner. The HMFL in Mafhela Forest Reserve had distinct local assemblages among land use regimes and did not conform to the expectation of IDH. On average, HMFL had the same average local species richness as SIF, mainly due to change in species composition (species replacement) induced by land use disturbance. Land use intensity gradient was the leading change driver to explain the overall β-diversity of the Mafhela Forest Reserve. The findings in the Thathe Vondo Forest Reserve were in contrast with the Mafhela Forest Reserve. Although on average the HMFL had the same local species richness as SIFs, this was mainly due to a trade-off of species gain in trees along the rivers and streams and species loss in Culturally Protected Areas (sacred forests) (CPA) as expected by IDH. The contrasting findings imply that the effectiveness of any alternative conservation strategy is context-dependent. The resilience of local assemblages and conservation value of HMFL depends on the condition of the overall forest landscape complexity and cannnot be captured by one theory, nor by one species diversity matrix (e.g., β-diversity or Richness). It thus demands the application of complementary theoretical frameworks and multilevel modeling.

Highlights

It has been argued that protected areas can neither serve as a standalone strategy to protect rare or endangered species [1] nor be effective enough to tackle the global biodiversity loss from anthropogenic disturbance [2]
The response for the effectiveness of both conservation alternatives lies in our understanding and response to the question: under what conditions does anthropogenic disturbance enhance, erode, or remain harmless to the pre-existing natural forest conditions in the human biosphere? The contrasting findings between the simple and the complex human modified forest landscape reflect the contrasting insurance value of existing conditions of forest landscape complexity between the Human Modified Forest Landscapes (HMFLs) of the two Forest Reserves
They reflect that the resilience capacity of local assemblages due to land use pressure can neither be fully explained by one theory nor captured by one species diversity matrix (e.g., Richness or beta-diversity)

Summary

Introduction

It has been argued that protected areas can neither serve as a standalone strategy to protect rare or endangered species [1] nor be effective enough to tackle the global biodiversity loss from anthropogenic disturbance [2]. Despite increasing hope for the conservation potential of forests and trees in modified rural landscapes, there has been growing controversy focusing on the richness, composition, and survival of biodiversity given persistent anthropogenic disturbances [3]. It is counterintuitive to presume that human modified landscapes, under different land use disturbance intensity, can be an alternative or complementary form of biodiversity conservation. Despite the negative connotation of the literal meaning of disturbance as a disruptive force on different biological organizations [5], some have argued that the higher species diversity in the tropical forests is the result of the concurrent effect of natural and anthropogenic disturbance [6].

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