The hidden value of trees: quantifying the ecosystem services of tree lineages and their major threats across the continental US

Abstract

Trees provide critical contributions to human well-being. They sequester and store greenhouse gasses, filter air pollutants, and provide wood, food, and other products, among other benefits. However, global change threatens these benefits. To quantify the monetary value of US trees and the threats they face, we combine macroevolutionary and economic valuation approaches using spatially explicit information about species and lineages. We show that the value of ecosystem services generated by trees in forests, orchards, and plantations in the US - $114 billion annually (low: $85 B; high: $137 B; 2010 USD) across five key services for which we had adequate data. The high value of trees is a consequence of both their abundance and diversity. The carbon storage and air pollution removal values of US trees far exceed their commercial value from wood product and food crops. Yet the most valuable US tree species and lineages are also among those most threatened by known pests and pathogens, climate change and increasing fire risk. While US tree crops are often provided by the same lineages in different regions, the high ecosystem service value of carbon and air pollution removal depends on different lineages in different regions. The composition of tree species that provide critical ecosystem services are likely to shift with global change, highlighting the importance of maintaining forest abundance and diversity.