Forest fragmentation in the Argentine Chaco: recruitment and population patterns of dominant tree species

Abstract

The forest in the Central Argentine Chaco has been dramatically fragmented and persists only as isolated patches in an agricultural matrix. In this study, we evaluated the effects of fragmentation on total density, recruitment, and size-class structure of its dominant tree species, a key issue, although little explored, for forest conservation in the region. We particularly analyzed the effects of fragment size and forest cover at landscape level on seven of the most important tree species of the forest. Our results suggest that forest cover at landscape level is more important than fragment size to explain the population patterns of the main tree species. Fragment size was relevant in only one species, Cordia americana, whereas forest cover resulted relevant in five species. The size-class structure of Schinopsis balansae, one of the dominant species of the upper stratum, appeared to be affected in landscapes with less forest cover, showing lower densities of the smaller classes. Our results show that for the conservation of the forest it would be important to increase their protection degree against the expansion of agriculture, attempting to preserve as much of the forest as possible, to promote the forest cover at landscape level and give relevance even to the smallest fragments.

Direct and indirect relationships between logging intensity and regeneration of two timber species in the Dry Chaco of Argentina

“…Neither does our data support the idea that both of the studied timber species are truly shade-intolerant species, and therefore depend on direct sunlight to establish and grow. Our results are supported by a study carried out in another fragmented Chaco forest, where both A. quebracho-blanco and a congeneric species of S. lorentzii might also be capable of regenerating under the canopy of the forest (Torrella et al, 2015). Manipulative controlled studies might confirm the trends reported in this study and help advance our understanding regarding the causal relationship between natural regeneration and sunlight.…”

Pollen diet assessment and flower association in Melipona orbignyi and recommendations on management and conservation of stingless bees in the Chaco dry forest of South America

“…Although large forest fragments provide better habitats for many forest species, the small ones are also important to be preserved particularly in cases when they function as stepping stones for connecting large forest remnants (Piquer-Rodríguez et al 2015). For instance, Torrella et al (2015) showed that small fragments in the Three Quebrachos Forest of the Central Chaco presented the same density and size-class structure than the larger ones in the dominant trees Schinopsis balansae , Aspidosperma quebrachoblanco , Prosopis kuntzei among others, but these forest remnants are strongly threatened by agriculture expansion. In this context, the usage of non-timber forest resources, such as the meliponiculture, would allow the gene flow by pollen dispersal among isolated individuals and patches and therefore enhance the resistance to the negative effects of the fragmentation.…”

Aerial Bud Bank and Structural Changes of Woody Species from Argentine Chaco in Response to Disturbances

“…The overgrazing, logging, deforestation and fires are the most common disturbances of the Argentine Chaco forests [10][11][12]. Fire is used from pre-Colombian times to promote new growth of grasses and to control shrubby encroachment in Chaco savannas [13].…”