Earthworms’ place on Earth

After revolutionizing our understanding of life on Earth, Charles Darwin studied earthworms. In 1881, he published his last scientific book, a treatise on earthworms (1) whose sales at the time rivaled those of On the Origin of Species. Nearly 140 years later, enthusiasm for earthworms persists, fueled by the recognition of their importance in terrestrial systems as different as backyards and tropical rainforests. On page 480 of this issue, Phillips et al. document an impressive group effort by 141 researchers from 35 countries to develop a global-scale atlas of earthworms (2). Darwin’s legacy continues.

By Noah Fierer

Oct 25th, 2019

Earthworm distribution in global soils

Earthworms are key components of soil ecological communities, performing vital functions in decomposition and nutrient cycling through ecosystems. Using data from more than 7000 sites, Phillips et al. developed global maps of the distribution of earthworm diversity, abundance, and biomass (see the Perspective by Fierer). The patterns differ from those typically found in aboveground taxa; there are peaks of diversity and abundance in the mid-latitude regions and peaks of biomass in the tropics. Climate variables strongly influence these patterns, and changes are likely to have cascading effects on other soil organisms and wider ecosystem functions.

By Michael Funk, et al.

Oct 25th, 2019

Global distribution of earthworm diversity

Soil organisms, including earthworms, are a key component of terrestrial ecosystems. However, little is known about their diversity, their distribution, and the threats affecting them. We compiled a global dataset of sampled earthworm communities from 6928 sites in 57 countries as a basis for predicting patterns in earthworm diversity, abundance, and biomass. We found that local species richness and abundance typically peaked at higher latitudes, displaying patterns opposite to those observed in aboveground organisms. However, high species dissimilarity across tropical locations may cause diversity across the entirety of the tropics to be higher than elsewhere. Climate variables were found to be more important in shaping earthworm communities than soil properties or habitat cover. These findings suggest that climate change may have serious implications for earthworm communities and for the functions they provide.

By Helen R. P. Phillips, et al.

Oct 25th, 2019