Species Distribution Modeling of Native Vegetation

Changing ranges and phenology of culturally important shrubs in the Pacific Northwest 

Climate change is altering both the suitable habitat and phenology of plant species around the world, with cascading effects on the people and wildlife for whom those plants may be an important food source. Using citizen scientist observations, USFS monitoring plot data, and gridded contemporary (1971-2000) climate data, the current bioclimatic niche and timing of flowering and fruit ripening were identified for four culturally important edible shrubs: black huckleberry, salal, Oregon grape, and hazelnut. The maximum entropy (MaxEnt) bioclimatic niche models developed for each species were projected  over future climate space using 20-model ensemble average future climate projections over two time periods (2040-2069 and 2070-2099) and two emissions scenarios (RCP 4.5 and RCP 8.5) to identify changes in species range; these same climatic data were used to assess shifts in species phenology under future climate change.

The modeled bioclimatic niches over the contemporary period were reasonably well matched to observations, with the model showing high environmental suitability where species were observed relative to locations where species were not observed. Suitable habitat for the highest elevation species, black huckleberry, was predicted to substantially contract across the Pacific Northwest in the future, irrespective of time period or emissions scenario, with the greatest losses occurring at later time periods and under higher emissions scenarios. In all instances of range contraction, the most significant reduction in habitat suitability was at lower elevation and drier sites within the current range. Further, preliminary phenology models indicate that by 2055, under RCP 8.5, the four species will bloom and ripen approximately 25 days earlier on average. This advancement in phenology is in keeping with earlier flowering and fruiting in Oregon grape observed in the central Willamette Valley over the 1963-2016 period. Such large shifts in phenology and suitable habitat may alter the timing and location of harvests in the future, with implications for trophic relationships within the natural system and cultural traditions within Northwest social systems.

This work will be presented at a special session at the Northwest Science Association meeting in Seattle in March, and at the Ecological Society of America annual meeting in New Orleans in August. A manuscript is in preparation. Co-authors are Connie Harrington and Janet Prevéy with the US Forest Service Pacific Northwest Research Station.