Pinyon-juniper woodland (Pinus edulis, Juniperus monosperma) is the most common forest cover in the Southwest United States. Recent drought episodes have caused spikes of mortality in both juniper or pinyon. How seedlings respond to mortality could shape the future of these woodlands under climate change. We designed an experiment in which we killed trees by girdling in 15-m radius circular plots. The treatments encompassed three controls, three juniper-girdle and three pinyon-girdle. In 2018, we did an initial inventory of seedlings and saplings in these plots.
Results/Conclusions
The initial assessment included 3090 individuals of which 70% were pinyon and 30% were juniper. There were no differences in plant abundance between treatments. However, we did document that seedlings and saplings were found far more often where there was litter on the ground. Seedlings of both species were found under similar cover, however, larger juniper saplings associated more often with pinyon trees and larger pinyon saplings more often with juniper trees. This suggests that sapling mortality rates may be affected differently by the girdling treatments. We will repeat the census this summer to test this hypothesis.