Gallery and spiny forest tree species inventory in Berenty Reserve, Madagascar
Data files
Mar 06, 2024 version files 1.05 MB
Abstract
Madagascar's unique dry forests, particularly gallery and spiny forests, face severe threats and are significantly understudied, leaving only a fraction of the original extent intact. Thus, there is a critical need for characterizing, conserving, and restoring this diverse forest ecosystem. Conducting extensive floristic surveys and environmental analyses, we investigated structural and compositional differences between the gallery and spiny forests, as well as within distinct gallery forest sites in Berenty Reserve in the south of the island. We also evaluated differences in habitat quality between the spiny and gallery forests for three species of diurnal lemurs in the reserve, and analyzed the current population trend of the tamarind trees, a species of ecological and cultural importance in Madagascar. Our findings revealed that the spiny and gallery forests differed in composition and structure, confirming the unique ecological characteristics of gallery forests and the underexplored richness of spiny forests. Spiny forests exhibited higher species richness despite a comparatively lower sampling effort, emphasizing the need for focused conservation efforts in these overlooked ecosystems. Tamarind populations, vital for lemur nutrition, showed signs of inadequate regeneration suggesting a recruitment bottleneck, possibly due to factors like a lowering water table, brown lemur foraging habits, or shifts in environmental conditions. Urgent interventions, including enrichment plantations, were recommended to ensure the survival of this keystone species. Contrasting botanical and lemur-centric perspectives revealed that while spiny and gallery forests differed botanically, they offered comparable habitat quality for ring-tailed and sifaka lemurs. However, brown lemurs exhibit a preference for the gallery forest, highlighting the intricate relationship between plant composition and lemur habitat choices. Our study underscores the urgency of expanding our knowledge of Madagascar´s dry forests, and Berenty Reserve, as one of the few remaining protected areas with gallery and dry forests, serves as a reference for future research in Madagascar's understudied ecosystems.
README: Data of paper: "Structural and Compositional Differences in Gallery and Spiny Forests of Southern Madagascar: Implications for Conservation of Lemur and Tree Species"
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Description of the data and file structure
This csv file contains the data of the forest inventory conducted in Berenty Reserve over the period of 2018-2019. The data contains information about the species present in each forest plot, and measurements of their height, canopy, and circumference, as well as the calculated values for diameter at breast height and basal area. Each of the variables found in the file are detailed below:
- Forest_type: Forest cover type where the plots were located. These include Spiny forest or Gallery forest.
- Forest: Name given to the particular forest area in the Berenty Reserve. Each forest in the reserve is locally identified with a specific name.
- Plot: plot identifier consisting in a combination of letters and numbers
- Decimal latitude: latitudinal coordinates of each plot, expressed in decimal degrees plot under the geodetic datum WGS84.
- Decimal longitude: longitudinal coordinates of each plot, expressed in decimal degrees plot under the geodetic datum WGS84.
- Elevation: Elevation of each plot measured in meters above the sea level of each plot. Data obtained using a GPS device.
- Number: Number of the individual tree. This number can also be found in the tags placed on the individuals in the forest. This will allow measurements of the trees in subsequent years.
- Family: Botanical family to which the tree species belongs
- Genus: Genus of the species (taxonomic rank below family)
- Specific_epithet: second word of the binomial scientific name of the species (following a binomial classification)
- Author: Person to whom the original description of the species is attributed.
- Vernacular_name: local or common name, used to identify the species in Berenty Reserve.
- Height_m: Estimated height of the tree in meters.
- Crown_a_m: Crown diameter 1. It is measured orthogonal (i.e. 90 degree angle) to Crown diameter 2. Measured in meters.
- Crown_b_m: Crown diameter 2. It is measured orthogonal (i.e. 90 degree angle) to Crown diameter 1. Measured in meters.
- CBH_cm: Circumference at Breast Height (CBH) of the tree, measured in centimeters at 1.3 meters above ground level. This column records the circumference of the main stem. For trees branching below 1.3 meters, it includes the circumferences of all branches at breast height.
- Diameter_mm: Diameter of branches measured in the field with a vernier calliper. This measurement was taken ocasionally instead of diameter for multistemmed trees. Unit measured in milimiters.
- DBH_branch_cm: Diameter at breast height (i.e at 1.3 meters above the ground) of stems and branches in centimeters. This measurement was obtained either by converting diameters measured in millimiters to centimeters, by calculating from the Circumference at Breast Height (CBH) using the formula: diameter = CBH / π (where π is approximated as 3.14).
- DBH_individual_cm: This column contains the data for the added diameter at breast height per species.
- Basal area: basal area of each individual tree, calculated using the following formula: =(π*(diameter at breast height^2)/(4*10000). This formula uses the Diameter at Breast Height (DBH), squared, and divides the result by 40,000 to convert the area into square meters.
Note: In this dataset, rows correspond to tree individuals. Each individual receives a unique identifier per plot (column number). When multiple branches were measured per individual each is represented within its own row. This causes the absence of data in some cells. Please note that in columns where data are not applicable, cells have been filled with the term 'null'.
Methods
This data was collected in the private Berenty Reserve (24°58'60''S, 46°16'60''E) in Madagascar. We established 34 0.1 ha (20 x 50 m) plots in the gallery forest and 6 0.1 ha plots in the spiny forest. Floristic surveys were conducted from June to August 2018 and 2019. In each plot we counted, identified, and measured all the trees that met one of two criteria: a) they had a diameter at breast height (DBH) ≥ 10 cm (i.e., 1.3 m from ground level), or b) they had multiple branches below 1.3 m, whose cumulative stem diameters summed to ≥ 10 cm.