Prosopis L. woody growth in relation to hydrology in South America: A review

Arboreal species of the genus Prosopis L. have played an important role in the development of tree-ring research in arid and semi-arid ecoregions of South America. Given the distribution of Prosopis across a broad precipitation gradient from 0 to 2000 mm y(-1) and its unique role as a phreatophyte, the relationship between Prosopis species growth and water has been a recurring theme over the past century. We conducted a systematic review of the literature addressing Prosopis and water research in South America, and combined site coordinates with GIS data of mean annual precipitation (MAP), elevation, biome, and soil moisture from online databases to understand the spatial distribution of research to date. We compiled 40 publications from 1931 to 2022, including results from 11 species of Prosopis among four countries, on the relationship between Prosopis spp and precipitation, groundwater levels, soil humidity, among other hydrological parameters. The spatial distribution of research sites spans tropical-subtropical and temperate latitudes from 4 degrees to 35 degrees S, excluding regions where the genus is present in Patagonia and northeastern South America. Studies covered a broad range of elevations from 30 to 3500 m a.s.l. but was limited to 1-730 mm y(-1) MAP, excluding more humid climates where Prosopis occurs. Results obtained from 32 dendrochronological studies and eight studies relating to Prosopis and hydrology, were grouped into sub-disciplines of tree-ring formation and the hydrosystem, dendroclimatology, dendrohydrology, and dendroecology. The review highlights the unique affinities of Prosopis to arid conditions, and the use of tree rings as a proxy for historical droughts and variability in water tables. Nonetheless, there are opportunities to expand the geographical-climatological extent of Prosopis growth research to humid climates, as well as to incorporate novel techniques such as stable isotopes and vessel size chronologies to understand how this genus records hydrological change throughout South America.