Functional assembly of tropical montane tree islands in the Atlantic Forest is shaped by stress tolerance, bamboo presence, and facilitation

Abstract

Aims: Amidst the Campos de Altitude (Highland Grasslands) in the Brazilian Atlantic Forest, woody communities grow either clustered in tree islands or interspersed within the herbaceous matrix. The functional ecology, diversity, and biotic processes shaping these plant communities are largely unstudied. We characterized the functional assembly and diversity of these tropical montane woody communities and investigated how they fit within Grime's CSR (C-competitor, S-stress-tolerant, Rruderal) scheme, what functional trade-offs they exhibit, and how traits and functional diversity vary in response to bamboo presence/absence. Methods:To characterize the functional composition of the community, we sampled five leaf traits and wood density along transects covering the woody communities both inside tree islands and outside (i.e., isolated woody plants in the grasslands community). Then, we used Mann-Whitney test, t test, and variation partitioning to determine the effects of inside versus outside tree island and bamboo presence on community-weighted means, woody species diversity, and functional diversity. Results:We found a general SC/S strategy with drought-related functional tradeoffs. Woody plants in tree islands had more acquisitive traits than those within the grasslands. Trait variation was mostly taxonomically than spatially driven, and species composition varied between inside and outside tree islands. Leaf thickness, wood density, and foliar water uptake were unrelated to CSR strategies, suggesting independent trait dimensions and multiple drought-coping strategies within the predominant S strategy. Islands with bamboo presence showed lower Simpson diversity, lower functional dispersion, lower foliar water uptake, and greater leaf thickness than in tree islands without bamboo. Conclusions:The observed functional assembly hints toward large-scale environmental abiotic filtering shaping a stress-tolerant community strategy, and small-scale biotic interactions driving small-scale trait variation. We recommend | 10165 CHRISTMANN eT Al.

Competição e fatores abióticos influenciam comunidades vegetais nos páramos brasileiros

“…The species pool of Pedra do Pato consisted mainly of pure stress-tolerant species, which was expected because of the harsh conditions found in high elevation areas, such as the poor soil, high radiation, strong wind, and colder temperatures . Additionally, the competitive dimension had a great contribution to the strategy spectrum found, as observed for other campos de altitude and Páramos sites (Christmann et al 2021, Cruz and Lasso 2021. The presence of so many competitive and competitive/stress-tolerant species might be related to the high precipitation during the rainy season and the presence of fog all over the year (Safford 1999, Assis and, and it is an indicator of more productivity in comparison with the high elevation formations of central Brazil, like the campos rupestres, composed primarily of more stress-tolerant species .…”

“…In this case, competition results in convergence for specific traits similarly to what is expected for abiotic filtering(Grime 2006, Mayfield and. In the Brazilian Páramos, for example, the presence of a bamboo species with resprouting ability after fire is associated with low functional diversity in tree islands, where it dominates after wildfires(Safford 2001, Christmann et al 2021.Nonetheless, if no set of traits allows better competitive ability, species are expected to diverge in niches to avoid competition for resources(MacArthur and Levins 1967, Scherrer et al 2019.Pastore et al (…”

Ignition of Forest Fires by Cigarette Butts: Using Pinus massoniana Needles as an Example

“…Mongolian Oak broadleaves and P. koraiensis needles were ignited 72 and 39 times, respectively, with corresponding ignition probabilities of 3.33% and 1.81% [18]. The fuelbed of P. massoniana is more difficult to ignite than the broadleaf bed of Mongolian Oak because of the differing leaf shapes of the broadleaves and conifers [36,37]. Through repeated cigarette butt-throwing experiments, it was found that cigarette butts tended to first smolder, gradually carbonize the litter, and finally transform that smolder into an open flame with the action of wind [38].…”