Climate lags and genetics determine phenology in quaking aspen (Populus tremuloides)

Abstract

Spatiotemporal patterns of phenology may be affected by mosaics of environmental and genetic variation. Environmental drivers may have temporally lagged impacts, but patterns and mechanisms remain poorly known.We combine multiple genomic, remotely sensed, and physically modeled datasets to determine the spatiotemporal patterns and drivers of canopy phenology in quaking aspen, a widespread clonal dioecious tree species with diploid and triploid cytotypes.We show that over 391 km 2 of southwestern Colorado: greenup date, greendown date, and growing season length vary by weeks and differ across sexes, cytotypes, and genotypes; phenology has high phenotypic plasticity and heritabilities of 31-61% (interquartile range); and snowmelt date, soil moisture, and air temperature predict phenology, at temporal lags of up to 3 yr.Our study shows that lagged environmental effects are needed to explain phenological variation and that the effect of cytotype on phenology is obscured by its correlation with topography. Phenological patterns are consistent with responses to multiyear accumulation of carbon deficit or hydraulic damage.

Sex-dependent phenological responses to climate vary across species’ ranges

“…We used linear mixed-effect models to examine the inter- and intraspecies variation in phenological sensitivities to climate change between sex and among ecoregions across species’ ranges. Prior studies and our preliminary analyses suggested that the phenology of P. fremontii populations strongly associate with winter and spring precipitation ( 61 , 62 ), in contrast to the other seven species in our study whose phenologies are mainly affected by temperature ( 63 , 64 ). Thus, we conducted separate analyses on P. fremontti .…”

Exploring the role of biotic factors in regulating the spatial variability in land surface phenology across four temperate forest sites

“…This finding contradicts previous observations that suggest shorter understory vegetation displays earlier leaf emergence and later senescence to avoid light competition with canopy trees (Seiwa, 1999; Osada & Hiura, 2019), but it aligns with studies that focus on upper canopy trees (Ding et al ., 2020; Adams et al ., 2021), which is our primary focus. The rationale could be that larger trees incur a higher carbon cost and necessitate a longer growth period to maintain carbon balance (Blonder et al ., 2023). However, a recent study with field observations revealed that the relationship between vegetation height and phenology could vary across species (Marchand et al ., 2020).…”

Steve Strauss

“…A brilliant PhD student, Michael Nagle, led a team of about two-dozen staff and scientists, and it was amazing to watch him grow during that time (Nagle et al, 2024). I was struck by a paper by Blonder et al (2023) dealing with one of my favourite plants, quaking aspen, that dissected the roles of ploidy, genotype, and environment on the determination of crown phenology in the Rocky Mountains. Amazingly, the large effect of the environment had a multi-year lag, due to complex interactions between tree biology and the aerial and root environments.…”