Germination associated with season and sunlight for Tamaulipan thornscrub plants in north-eastern Mexico

Seed germination was investigated for 47 herbaceous and woody species, representative of the Tamaulipan thornscrub flora of north-eastern Mexico. More than half of the species had similar germination under spring and autumn conditions, 17 species showed a higher germination percentage under autumn rain conditions. No species had more seeds germinating under spring rain conditions. Germination season response was independent of plant habit, seed size and dispersal syndrome. Sixteen of the species germinated less under the moderate shade of thornscrub canopy than under direct sunlight, and more than half of the species had similar germination under shade and direct sunlight. Germination in autumn, and away from the root competition of thornscrub, may reflect the importance of soil drought in mortality of young seedlings.