Forest Hotspots in the Biodiversity Hotspot of New Caledonia

Description

This dataset explores threats to New Caledonia's forests, focusing on the probability of deforestation within hotspots of tree community diversity.

The probability of deforestation was derived from the "Spatial scenario of tropical deforestation and carbon emissions for the 21st century"  (Vielledent et al., 2023), available as downloadable GeoTIFFs for New Caledonia for the years 2050 and 2100

Hotspots of tree community diversity were identified using the 'Core Forest' class extracted from the dataset 'Classification of New Caledonia Forests According to Edge and Elevation Effects'. Core forest are defined as forest areas located more than 300 meters from the forest edge, characterized by potentially richer tree communities.

To assess habitat quality, each core forest fragment was surrounded by a 500-meter buffer zone. We evaluated forest habitat metrics including forest cover, forest type distribution, and fragmentation index within these buffer zones. Additionally, we analyzed the areas of forest threatened by deforestation in 2050 and 2100. The resulting maps provide decision-making support for stakeholders involved in conserving New Caledonia's forests. The fragmentation index used is the effective mesh size (meff), originally proposed by Jaeger (2000) and updated by Moser and al. (2007) to address boundary effects.  A higher index value indicates less fragmented forest.

Content

This dataset was generated, analyzed, and validated using a suite of open-source software tools, including QGIS, PostgreSQL, PostGIS, Python, and the GDAL library, operating on a Linux platform. The compressed file includes six essential files formatted for an ESRI GIS system, utilizing the WGS84 international coordinate system. It is compatible for upload into spatial databases such as PostgreSQL/PostGIS.

Each entry in the attribute table represents a buffer area containing one or several core forests, with the following fields (restricted to 10 characters):

Field
Type
Description

id_buffer
INTEGER
Unique identifier for the buffer

area_ha
NUMERIC (2 DECIMALS)
Area of the buffer in hectares

frag_index
NUMERIC
Forest fragmentation meff index within the buffer

forest_cov
NUMERIC (2 DECIMALS)
Proportion of forest within the buffer area (%)

edge_r
NUMERIC (2 DECIMALS)
Proportion of forest area classified as edge forest (%) 

mature_r
NUMERIC (2 DECIMALS)
Proportion of forest area classified as mature forest (%) 

core_r
NUMERIC (2 DECIMALS)
Proportion of forest area classified as core forest (%) 

defor_2050
NUMERIC (2 DECIMALS)
Proportion of forest threatened by deforestation in 2050 (%)

defor_2100
NUMERIC (2 DECIMALS)
Proportion of forest threatened by deforestation in 2100 (%)

pn
BOOLEAN
True or False, indicating if the polygon overlaps with the Northern province

ps
BOOLEAN
True or False, indicating if the polygon overlaps with the Southern province

Limitations

This analysis of forest conservation issues aims to foster dialogue between forest ecologists and forest management strategies in New Caledonia. It should not be applied blindly based solely on the few quantitative variables proposed.

Various scenarios can utilize these metrics, and we urge managers to initially define conservation objectives (such as maximizing biodiversity, reducing fragmentation, restoring disturbed environments, etc.) and consider constraints (such as accessibility, budget, feasibility, etc.) before utilizing this dataset.

While threats was projected for future scenarios, conservation efforts should also prioritize preserving forests in their current state, including addressing increasing fragmentation and biodiversity loss. We encourage users to explore these metrics and their correlation with other quantitative or qualitative variables to gain a deeper understanding of conservation challenges in New Caledonia's forests.