Obstruction of biodiversity conservation by minimum patch size criteria

Area of Science:

• Ecology
• Conservation Biology
• Biodiversity Science

Background:

• The single large (SL) > several small (SS) habitat patches principle is a cornerstone of conservation, guiding minimum patch size criteria.
• However, this principle is frequently challenged, with evidence suggesting SS > SL may be more effective for biodiversity conservation.

Purpose of the Study:

• To assess the validity of the SL > SS principle using a global dataset of species abundances across numerous habitat patches.
• To evaluate how biodiversity accumulation differs between configurations of large versus small habitat patches, particularly those below typical conservation thresholds.

Main Methods:

• Utilized a global database of species abundances across 1190 patches within 76 metacommunities, encompassing 4401 species.
• Resampled species-area accumulation curves for each metacommunity to compare biodiversity responses to SL vs. SS habitat configurations.
• Focused analysis on patches significantly smaller than conventional minimum size criteria (approx. 85% < 100 ha).

Main Results:

• Species richness accumulated more rapidly when adding several small patches compared to equivalent areas of large patches (SS > SL in 45.2% of cases vs. SL > SS in 19.9%).
• This finding held true even for very small habitat patches, contradicting the established SL > SS principle.
• Taxonomic groups exhibited varied responses to habitat fragmentation, indicating a nuanced approach to conservation is necessary.

Conclusions:

• The study provides strong evidence that prioritizing numerous small habitat patches is generally more effective for maximizing biodiversity conservation than adhering to minimum large patch size criteria.
• Current minimum patch size criteria may inadvertently hinder biodiversity protection efforts by excluding valuable small habitat areas.
• Conservation strategies should emphasize the protection of a diverse range of patch sizes, with a significant focus on incorporating numerous small patches alongside a few large ones.