Vegetation heterogeneity of black alder forests in and around El-Kala Biosphere Reserve, northeastern Algeria

Abstract

Background: Despite its ecological importance, the study of Algerian alder forests has been largely neglected, even though they represent the largest ones of their kind in North Africa. Moreover, few measures have been taken towards the protection of these ecosystems. Questions: How many species are present in the Algerian alder forests? What is the effect of soil properties on species richness and diversity of inventoried plants? Are its spatial patterns related to soil variables variation? Studied species: Polypodiopsida, Gymnospermae, and Angiospermae. Study site and dates: El-Kala Biosphere Reserve (KBR) and surroundings, El-Tarf province, northeastern Algeria, from January 2016 to February 2017. Methods: Twenty-eight localities were sampled using the relevé method. Soil samples were taken from three points at each site. The relationship between species richness and soil factors was statistically evaluated using multiple linear regression and multivariate statistical analysis. Results: The inventory showed a total of 352 species that belong to 236 genera and 89 families. According to NMDS ordination, black alder forests were classified into two groups (marshy and hilly forests, and fluvial forests), in relation to plant species richness. No linear relationships between species richness and soil parameters were observed, except for OM (P = 0.013). Conclusion: The present study demonstrated a relatively high plant diversity characterizing alder forests of this region. To some extent, such diversity is related to the heterogeneous distribution of plant species among different habitat types. Those factors that affect its zonation were identified, for this ecosystem, our study revealed that vegetation diversity is related to the spatial variation of soil variables.