Abstract

The importance of the sowing method (broadcasting or burying) for seedling establishment, and the extent to which environmental conditions modulate differences between these sowing methods, are understudied. When seeds are buried, they may be exposed to soil conditions with higher moisture content than broadcast. This advantage may occur especially under drier soil conditions within a semiarid climate, such as with less precipitation, open sites, and in presence of herbaceous layer. In this study we conducted an experiment to compare the seedling establishment of 13 woody species between a buried sowing and broadcast, under different conditions of precipitation, shade, and herbaceous layer in a degraded semiarid grassland of central Chile. For each species, some seeds were sown by burying them to a depth of 1 cm and others were broadcast. Orthogonally, we applied two irrigation treatments to simulate a dry and a rainier year, two shade treatments simulating the canopy of woody plants and open sites (with vs. without), and two treatments of herbaceous layer (without vs. with). Establishment was monitored for 10 months between July 2016 and March 2017. Species richness of established seedlings was greater when seeds were buried than broadcast under all environmental conditions. The seedling density per species was greater when seeds were buried than broadcast in nine species, although in some cases this depended on environmental conditions. We conclude that, burying seeds of woody species is more effective and can be a widely applicable restoration method for different environmental conditions and species in semiarid ecosystems.