Forest Fragmentation and Seed Germination of Native Species from the Chaco Serrano Forest

Abstract

Habitat fragmentation is a widespread phenomenon that alters pollination and plant reproductive processes. These effects have demographic and genetic implications that determine offspring fitness and the long-term viability of plant populations in fragmented systems. We evaluated fragmentation effects on early plant offspring fitness traits, individual seed mass, and percentage of seed germination in five native plant species (Acacia caven, Celtis ehrenbergiana, Croton lachnostachyus, Rivina humilis, Schinus fasciculatus) from the Chaco Serrano forest, a subtropical highly fragmented ecosystem. We found evidence of strong negative fragmentation effects on germination in the shrub C. lachnostachyus and the perennial herb R. humilis, after 30 d of controlled tests. No fragmentation effects were found in the studied traits on the remaining three tree species. We found significant maternal effects in offspring fitness traits in all five species. We discuss the relative magnitude of maternal vs. fragmentation effects taking into account both plant species' lifespan and the time elapsed in fragmentation conditions. We emphasize the need to increase the study of early and late plant offspring fitness produced in fragmented habitats coupled with analyses of genetic parameters and the pollination process in order to evaluate the conservation value of remnant forest fragments.

Not all in the same boat: trends and mechanisms in herbivory responses to forest fragmentation differ among insect guilds

“…Cagnolo et al 2006Cagnolo et al , 2009Krauss et al 2010;Marini et al 2012) and reduced plant population size (Piotti 2009;Leimu et al 2010;Vranckx et al 2012) as fragment area decreases. Also, altered abiotic conditions at the edges, including higher temperature, greater light incidence and lower relative humidity (Chen et al 1993;DaviesColley et al 2000;Christianini and Oliveira 2013), could affect plant seed germination (Ashworth and Martí 2011) and tree mortality (Murcia 1995;Laurance et al 2000). Plant species with reduced populations may sustain lower herbivory levels according to the resource concentration hypothesis (Root 1973;Connor and McCoy 2001).…”

Offspring performance and recruitment of the pioneer treeAcacia caven(Fabaceae) in a fragmented subtropical dry forest

“…While seedling performance may also be influenced by maternal effects, our results indicate it would not be the case here. Firstly, seed mass, which was under significant maternal influence (Ashworth & Martí ), had no effect on offspring performance after 60 days of growth. Second, maternal identity included in the model as a random factor showed no effects on seedling performance.…”

“…All forest fragments are immersed in intensively managed matrices, dominated by wheat in winter and soybean or maize in summer. For a map with the spatial distribution of studied sites see Ashworth and Martí (). In each site, we marked five maternal trees of similar size separated by at least 7 m (range 7–30 m).…”

“…). Data for seed germination and mean seed mass (used as covariate) per maternal tree were obtained from Ashworth and Martí ().…”

“…, , ; Ruiz‐Guerra et al . ; Ashworth & Martí ). In the long term, such changes may modify the taxonomic, genetic and functional diversity of plant communities in fragmented forests (e.g.…”