The influence of environmental factors on the distribution and composition of plant species in Oued Charef dam, northeast of Algeria

Moualki N, Boukrouma N. 2021. The influence of environmental factors on the distribution and composition of plant species in Oued Charef dam, North East of Algeria. Biodiversitas 22: 346-353. Identification of the primary factors that influence the ecological distribution of species groups is important to managers of Oued Charef dam in northern Algeria. This study aimed to identify main ecological species groups, describe the site conditions associated with these species groups, and the relationships between environmental factors and the distribution of ecological species groups using Ward’s cluster analysis for classification and principal component analysis (PCA). For this purpose, 50 plots (200 m2 each) were sampled using the Braun- Blanquet method. Soil samples were collected and analyzed to study soil properties. Multivariate analysis methods were used to classify and determine the relationship between species composition and environmental factors and to recognize ecological species groups. The R i386 (version 4.0.3) software was used for data analyzing. Ward's cluster analysis when applied on terrestrial species data gives three groups distinctly distributed on ordination plan. In cluster groups of terrestrial species Group (1) is dominated by Daisies chrysanthemum, Group (2) by Cynodon dactylon L, and Group (3) dominated by Fumana thymifolia. The groups of terrestrial species are readily superimposed on PCA ordination plane. The most important environmental factors associated with terrestrial species composition in Oued Charef dam communities were conductivity (EC), FSA, FSI, clay, salinity, phosphorus (PO4), TN (nitrogen), nitrates (NO3), and nitrites (NO2). While among the edaphic factors only pH showed a negative correlation to plant species this may due to the anthropogenic disturbances however further studies are needed to explore the rest of parts of the said regions. This study gives important insights on ecological relationships between plant biodiversity and soil chemical in a primary wetland ecosystem in northeast of Algeria.

Drivers of the Distribution of Ecological Species Groups in Temperate Deciduous Managed Forests in the Western Carpathian Mountains

Managed broadleaf deciduous forests are an important type of forest vegetation in Central Europe, also in the Western Carpathians. These forests are both economically and environmentally valuable. However, little is known about ecological species groups and the inter-specific associations of dominant species in temperate deciduous managed forests in Central Europe. Since the forest stands are in a managed landscape, they are not consistent with the traditionally recognized and used vegetation associations in the Western Carpathians. For these reasons our research contributes to understanding the consequences of broadleaf deciduous forest management. The aim of this research was the determination of ecological species groups and an investigation into the main environmental drivers, in order to explain the distribution of ecological species groups. The numerical TWINSPAN classification was selected to distribute 146 relevés to the five ecological species groups. Of these, 77 relevés were divided into two groups with Fagus sylvatica dominant, while 63 relevés were Quercus petraea dominant. Carpinus betulus, Tilia cordata and Fraxinus excelsior were dominant in 19 relevés. Constrained Analysis of Principal Components was used to explain the vegetation–environment relationship on three transects in the Male Karpaty Mountains. Altitude, pH, Ca, C, K and Mg were selected as the significant environmental drivers responsible for a large part of the species group variability (31.8%). The main requirement for sustainable forest management is knowledge of the vegetation–environment relationship and this research was focused on gaining such understanding. This knowledge can be used as a decision support tool for sustainable management in managed deciduous forests.

Improved tree height estimation of secondary forests in the Brazilian Amazon

ABSTRACT This paper presents a novel approach for estimating the height of individual trees in secondary forests at two study sites: Manaus (central Amazon) and Santarém (eastern Amazon) in the Brazilian Amazon region. The approach consists of adjusting tree height-diameter at breast height (H:DBH) models in each study site by ecological species groups: pioneers, early secondary, and late secondary. Overall, the DBH and corresponding height (H) of 1,178 individual trees were measured during two field campaigns: August 2014 in Manaus and September 2015 in Santarém. We tested the five most commonly used log-linear and nonlinear H:DBH models, as determined by the available literature. The hyperbolic model: H = a.DBH/(b+DBH) was found to present the best fit when evaluated using validation data. Significant differences in the fitted parameters were found between pioneer and secondary species from Manaus and Santarém by F-test, meaning that site-specific and also ecological-group H:DBH models should be used to more accurately predict H as a function of DBH. This novel approach provides specific equations to estimate height of secondary forest trees for particular sites and ecological species groups. The presented set of equations will allow better biomass and carbon stock estimates in secondary forests of the Brazilian Amazon.