Effects of plant diversity on productivity strengthen over time due to trait-dependent shifts in species overyielding.

Plant diversity effects on community productivity often increase over time. Whether the strengthening of diversity effects is caused by temporal shifts in species-level overyielding (i.e., higher species-level productivity in diverse communities compared with monocultures) remains unclear. Here, using data from 65 grassland and forest biodiversity experiments, we show that the temporal strength of diversity effects at the community scale is underpinned by temporal changes in the species that yield. These temporal trends of species-level overyielding are shaped by plant ecological strategies, which can be quantitatively delimited by functional traits. In grasslands, the temporal strengthening of biodiversity effects on community productivity was associated with increasing biomass overyielding of resource-conservative species increasing over time, and with overyielding of species characterized by fast resource acquisition either decreasing or increasing. In forests, temporal trends in species overyielding differ when considering above- versus belowground resource acquisition strategies. Overyielding in stem growth decreased for species with high light capture capacity but increased for those with high soil resource acquisition capacity. Our results imply that a diversity of species with different, and potentially complementary, ecological strategies is beneficial for maintaining community productivity over time in both grassland and forest ecosystems.

Successional, spatial, and seasonal changes in seed rain in the Atlantic forest of southern Bahia, Brazil.

Seed arrival is a limiting factor for the regeneration of diverse tropical forests and may be an important mechanism that drives patterns of tree species' distribution. Here we quantify spatial and seasonal variation in seed rain of secondary forests in southern Bahia, Brazil. We also examine whether secondary forest age enhances seed dispersal and whether seed rain density and diversity in secondary forests decay with distance from mature forest. Across a chronosequence of 15 pairs of mature and secondary forests, 105 seed traps were installed and monitored for one year. We tested the effects of secondary forest age, distance from mature forest, and seasonality on monthly seed rain density, diversity, seed dispersal mode, and diaspore size. We found that secondary forest age had strong, positive effects on the diversity of seed rain, which was generally higher during the wet season. Moreover, contrasting patterns among diversity indices revealed that seeds of rare species occurred more often in 40 yr old secondary forests and mature forests. While the proportion of biotically and abiotically dispersed seeds did not change significantly with distance from mature forest across all forest age classes, we found that biotically dispersed seeds contributed disproportionately more to seed rain diversity. Our results emphasize the importance of biotic dispersal to enhance diversity during secondary succession and suggest that changes in secondary forest structure have the potential to enhance the diversity of tropical secondary forests, principally by increasing dispersal of rare species.

Author Correction: Diversity-dependent temporal divergence of ecosystem functioning in experimental ecosystems.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Diversity-dependent temporal divergence of ecosystem functioning in experimental ecosystems.

The effects of biodiversity on ecosystem functioning generally increase over time, but the underlying processes remain unclear. Using 26 long-term grassland and forest experimental ecosystems, we demonstrate that biodiversity-ecosystem functioning relationships strengthen mainly by greater increases in functioning in high-diversity communities in grasslands and forests. In grasslands, biodiversity effects also strengthen due to decreases in functioning in low-diversity communities. Contrasting trends across grasslands are associated with differences in soil characteristics.

Payments for environmental services in Latin America as a tool for restoration and rural development.

Payments for Environmental Services (PES) can encourage projects that enhance restoration, production, and rural development. When projects promote differentiated systems by paying farmers for the provision of services, the application of PES requires evaluation of the environmental services provided by each system. We present evaluations of carbon stocks and biodiversity in pure and mixed native tree plantations in Costa Rica. To illustrate how monetary values can be assigned, we discuss a project that awarded PES to silvopastoral systems in Costa Rica, Nicaragua, and Colombia based on carbon stocks and biodiversity. PES can promote positive environmental attitudes in farmers. Currently this project is being scaled up in Colombia based on their positive experiences with PES as a tool to promote adoption. Compared to PES systems that include only one environmental service, systems that incorporate bundling or layering of multiple services can make sustainable land uses more attractive to farmers and reduce perverse incentives.

Strategies for the recovery of degraded ecosystems: experiences from Latin América

Barreras físicas o biológicas pueden demorar la recuperación de ecosistemas degradados. Las plantaciones tropicales pueden restaurar suelos y acelerar la regeneración natural. En un programa sobre rehabilitación de ecosistemas en América Latina, aproximadamente la mitad de las 29 especies examinadas afectó positivamente los suelos y tuvo buen crecimiento, siendo así atractivas para reforestación. En plantaciones con especies nativas en Costa Rica, la regeneración arbórea fue mayor en pasturas abandonadas. La regeneración fue elevada en plantaciones mixtas. Las pasturas tuvieron mayor proporción de semillas dispersadas por viento, mientras que la dispersión por pájaros y murcielagos fue predominante en plantaciones. La acumulación de hojarasca en plantaciones disminuyó el crecimiento de pastos y favoreció la regeneración arbórea.En regiones con campos agrícolas mayores y lejanos de fuentes semilleras, cortinas rompeviento y árboles residuales en pasturas pueden ser reservorios de especies nativas. Los rompevientos son atractivos para los pájaros si incluyen árboles nativos con frutos, si tienen alto número de especies y complejidad estructural, y si se encuentran entre parches de bosque facilitando el movimiento de los pájaros. Las estrategias para recuperación de ecosistemas degradados deben considerar factores que influyen sobre la regeneración, otros efectos sobre el ecosistema, y los limitantes económicos, sociales y ambientales