seed rain
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Biological invasion is a growing problem, and species of the genus <i>Pinus</i> are known to be a problem in the forests southern Brazil, including Conservation Units (CUs). Here, we studied the ecology of <i>Pinus taeda</i> invasion at Rio Canoas State Park (PAERC) based on forest inventory, soil seed bank analysis and seed rain assessment in three distinct successional stages inside the park denoted as “Pinus invasion”, “Old Growth Vegetation” and “Initial Vegetation”. Forest inventory of 33 (20x20m) plots, found <i>Pinus</i> in 2 of the 3 evaluated environments. Seed rain was collected bimonthly using 33 (1x1m) seed traps for a period of one year. The major seed distribution periods were in April and June, confirming data found in the literature. The seed bank was analyzed in February (summer) and June (winter) of 2018. Samples were kept in a greenhouse for a period of 120 days each. Summer evaluation showed no emergence of <i>Pinus taeda</i> seedlings, but the winter evaluation (June) did show the emergence of seedlings. Results showed that the soil seed bank is not persistent. Accordingly, the <i>Pinus</i> invasion reported at PAERC requires a restoration program, as well as one that controls reinfestation.

The natural regeneration of native broadleaved species underneath forest monoculture plantations is important to recover ecosystem functions and to mitigate adverse environmental effects. To understand how seed rain and soil seed banks facilitate natural regeneration, we surveyed their density and composition in a monoculture Chinese fir plantation, a mixed Chinese fir–broadleaf plantation, and an adjacent natural broadleaved forest for two years in southern China. Twenty-eight species (16 families) were in seed rain, and 45 species (27 families) were in soil seed banks. Seed rain density did not differ significantly across stands; however, the number of taxa in seed rain was highest in the mixed plantation and lowest in the natural forest. Seed bank density was significantly higher in the mixed plantation than in the other stands. The Sørensen similarity indices of species composition between seed sources and aboveground vegetation were relatively low (<0.50). In addition, the seeds of native tree species common to the seed banks of the three forests indicated the adjacent natural forest was a seed source for the natural regeneration of native species in forest plantations. To augment regeneration and accelerate the rate of conversion, we recommend direct seeding or planting of desired species.

Abstract The lack of seeds represents one of the highest difficulties to overcome for the ecological restoration of areas that have been deforested. This study evaluates the effectiveness of artificial perches in increasing the abundance and species richness of bird-dispersed seeds and the similitude of seed rain composition (origin and habit of plant seeds), of deforested areas with and without artificial perches in relation to woodland remnants that serve as seeds source. The experiment took place in two sites of the Espinal ecoregion, Argentina. We found that in deforested areas, perches increased seed abundance and species richness in the seed rain in comparison with deforested areas without artificial perches. The species composition under artificial perches was similar to the seed rain dispersed in the woodland. However, a decrease in the richness of native species was significant in the deforested area, probably due to behavioral differences between opportunistic and obligate frugivorous. Seed of trees and shrubs species were well represented in the seed rain under artificial perches. Results from this study contribute to the understanding of nucleation and recovery mechanisms used by nature that reflect ecosystem resilience. We recommend using artificial perches in deforested areas with potential for recovery because it is an efficient technique to promote the entry of birds and increase seed rain, preserving features of the original environment. However, using artificial perches should be avoided in sites with potentially invasive non-native species.

Abstract Human-induced wildfires are increasing in frequency in tropical forests, and their deleterious consequences for biodiversity include decreases in seed rain, which may be affected directly by fire or indirectly by the creation of edges between forest and non-forest environments. Understanding seed rain is key to assess the potential for natural regeneration in plant communities. We assessed the impact of fire and fire-created edges on seed rain species richness, abundance, size, weight, and dispersal syndromes in Atlantic Forest remnants in Bahia, Brazil. We assessed seed rain at monthly intervals for an entire year along seven 300 m-long transects placed perpendicular to the edge. We installed seed traps at the edge and at 20, 40, 60, 80, 100, and 150 m into the burnt area and into the forest from forest edge. We recorded a total of 9,050 seeds belonging to 250 morphospecies. We did not observe edge influence; however, we detected a lower abundance and proportion of animal-dispersed seeds in the burnt than in the unburnt areas. The seed abundance in the burnt areas was lower and seeds were smaller and lighter than those in the unburnt area. Seed rain in the burnt area was not greater near to the forest than far from it. The abundance and richness of seed rain was positively correlated with tree density. Our findings highlight the lack of seed rain in burnt areas and differences in community composition between the burnt and unburnt areas. Collectively, these results indicate negative consequences on natural regeneration, which can lead to permanent secondarization and challenges for early regeneration of burnt areas, which will initially have impoverished forests due to low seed richness.