A review of the knowledge of Hartwegʼs Pine (Pinus hartwegii Lindl.): current situation and the need for improved future projections

KEY MESSAGE: A systematic review from 1962 to August 2021 summarizes the research on Hartwegʼs pine (Pinus hartwegii). We identify research gaps and propose new direction for future studies and discuss the main study topics. Hartwegʼs pine (Pinus hartwegii Lindl.) is a high-value timber species adapted to the harsh alpine environment of high-elevation mountains (3000–4200 m) in Mexico, where it provides a wide array of ecosystem services to society. However, this species is currently facing temperature increases associated with global warming, with models predicting upward altitudinal shifts to maintain suitable growth conditions. Here, we present a systematic review of Hartwegʼs pine to establish current knowledge, identify research gaps, and indicate directions for future studies. This search recovered 196 scientific references from 1962 to August 2021, which were classified into 21 research topics. References to Hartwegʼs pine increased considerably during the period from 2000 to 2021, representing 77% of the total publications. Most of the references were focused on the management of the species (n = 89) and its relationships with climate change (n = 49). Fewer references were focused on human impacts on the species, taxonomy, and systematics, as well as biogeochemical and hydrological cycles, phenology, and evolution. Most of the study areas were in the Trans-Mexican Volcanic Belt, such as in Izta-Popo National Park, Cofre de Perote National Park, the Nevado de Toluca Flora and Fauna Protection Area, and Cumbres del Ajusco National Park. These results highlight the incipient knowledge that we have about population genetics, phenotypic plasticity, physiology, biotic interactions and about of the specific environmental conditions where P. hartwegii populations develop, which limits our capacity to understand how this species will respond to global warming and whether there are risks to the persistence of these forests and the ecosystem services they provide, both to local human populations and those located farther down the mountain.