Unprecedented plant species loss after a decade in fragmented subtropical Chaco Serrano forests

Abstract

Current biodiversity loss is mostly caused by anthropogenic habitat loss and fragmentation, climate change, and resource exploitation. Measuring the balance of species loss and gain in remaining fragmented landscapes throughout time entails a central research challenge. We resurveyed in 2013 plant species richness in the same plots of a previous sampling conducted in 2003 across 18 forest fragments of different sizes of the Chaco Serrano forest in Argentina. While the area of these forest remnants was kept constant, their surrounding forest cover changed over this time period. We compared plant species richness of both sampling years and calculated the proportion of species loss and gain at forest edges and interiors. As in 2003, we found a positive relationship between fragment area and plant richness in 2013 and both years showed a similar slope. However, we detected a net decrease of 24% of species’ richness across all forest fragments, implying an unprecedentedly high rate and magnitude of species loss driven mainly by non-woody, short-lived species. There was a higher proportion of lost and gained species at forest edges than in forest interiors. Importantly, fragment area interacted with percent change in surrounding forest cover to explain the proportion of species lost. Small forest fragments showed a relatively constant proportion of species loss regardless of any changes in surrounding forest cover, whereas in larger fragments the proportion of species lost increased when surrounding forest cover decreased. We show that despite preserving fragment area, habitat quality and availability in the surroundings is of fundamental importance in shaping extinction and immigration dynamics of plant species at any given forest remnant. Because the Chaco Serrano forest has already lost 94% of its original cover, we argue that plant extinctions will continue through the coming decades unless active management actions are taken to increase native forest areas.

Habitat fragmentation reduces plant progeny quality: a global synthesis

“…In other words, if these environments fail to increase natural habitat and connectivity, these plant populations will steadily decline and remain as ghost populations on their way to extinction (Jackson & Sax ; Aguilar et al . ; Auffret et al . ).…”

Relevance of the Cell Neighborhood Size in Landscape Metrics Evaluation and Free or Open Source Software Implementations

“…The value of the cell neighborhood parameter was specified in eight different papers: seven chose a Moore definition [13][14][15][16][17][18][19][20] and one a von Neumann definition [21]. The 16 papers which exclusively employed LecoS [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] used an 8-cells neighborhood rule, as it is the only setting available in the add-on; a similar hypothesis is applicable to the four works which used r.li in GRASS [38][39][40][41], which uses a 4-cells neighborhood definition. The papers which did not specify the definition of the neighborhood in FRAGSTATS are assumed to have used a 8-cells definition, since this is the default setting [42], although it is not possible to prove this assumption.…”

A social-ecological approach to identify and quantify biodiversity tipping points in South America's seasonal dry ecosystems

“…Habitat quality and the land cover characteristics surrounding the forest fragments are important for maintaining species richness. Conserving forest fragments alone will likely not halt species loss in the Chaco (Aguilar et al, 2018), even though dominant tree species could be maintained (Alves et al, 2018). Ecosystem functionality takes 15 years to recover after land use is abandoned in the Dry Chaco (Basualdo et al, 2019).…”