Xylem Anomalies as Indicators of Maladaptation to Climate in Forest Trees: Implications for Assisted Migration

Abstract

Xylem anomalies that are caused by unusual climate events have long been used to aid cross-dating in tree ring research. Here, we analyzed a range of xylem anomalies in a 39-year-old common garden experiment of white spruce (Picea glauca [Moench] Voss) in central Alberta, Canada, designed to investigate local adaptation. We extracted wood cores from trees representing 24 provenances covering much of the species range across the Canadian boreal forest. Using a double stain and light microscopy analysis, four xylem anomalies and their causes could be distinguished: (1) frost rings indicate issues with synchronizing the onset of growth with the start of the growing season, and were prevalent in young trees; (2) light rings represent thin cell walls caused by an insufficient growing season length, most prevalent in southern sources; (3) blue rings were caused by a failure to complete lignification of new wood due to an early end of the growing season; and (4) double rings represent density fluctuations due to drier than normal summers. Local provenances showed the least amount of xylem anomalies, indicating that they are correctly adapted to the environment in which they occur. In contrast, trees moved to the test site from other climate regions showed various types of xylem anomalies depending on their origin. In particular, populations originating from warmer regions showed an increased presence of latewood anomalies, consistent with a more extensive use of the growing season in the fall. We conclude that xylem anomalies may serve as a sensitive early indicator of maladaptation to climate before populations experience tree dieback or mortality. They may therefore be useful to monitor the health of natural populations, or to evaluate the success of assisted migration in reforestation to address climate change.

Morpho-anatomical characterization, gene expression and protein cell wall modifications associated with natural finger drop in bananas

“…Here, the astra blue dye associated with safranin made it possible to distinguish cellulosic cell walls (primary) from lignified ones (secondary). Observations from other authors reveal the efficiency of the staining methods with Safranin-Astra Blue in distinguishing the primary cellulose cell walls (blue) from the lignified secondary xylem (red) (Ployet et al, 2017;Crespo-Martíne, Sobczak, Różańska, Forneck, & Griesser, 2019;Sebastian-Azcona, Hacke, & Hamann, 2020). These results highlight the fact that it is probably the variations of the vascular bundles among the two analyzed genotypes which may be related to mechanisms of resistance to finger drop.…”

Picturing local adaptation: Spectral and structural traits from drone remote sensing reveal clinal responses to climate transfer in common‐garden trials of interior spruce (Picea engelmannii × glauca)

“…We see great potential in tree‐ring datasets for establishing causal links between differences in growth and resilience among genotypes and underlying traits related to phenology and tolerance to extremes. In P. glauca , xylem anomalies have been analyzed as early indicators of maladaptation by attributing mismatches in growing season phenology to different patterns of damage during annual ring growth (Sebastian‐Azcona et al, 2020). By combining genecology and dendroecology approaches, Housset et al (2018) attributed differences in diameter growth among genotypes to separate adaptations to growing season length and summer drought, highlighting the dynamism of the relationship between annual tree growth and the environment.…”

Provenance and family variations in early growth of Manchurian walnut (Juglans mandshurica Maxim.) and selection of superior families

“…Provenance tests are crucial for species that have high economic or ecological value [ 21 ]. Systematic provenance test can explore the adaptability of different provenance materials to the local environment, quantify the genetic population differentiation, and provide materials for forest breeding and ex-situ protection [ 22 , 23 ]. Provenance test for J .…”

“…Provenance tests are crucial for species that have high economic or ecological value [21]. Systematic provenance test can explore the adaptability of different provenance materials to the local environment, quantify the genetic population differentiation, and provide materials for forest breeding and ex-situ protection [22,23]. Provenance test for J. mandshurica began in the 1980s ~1990s [24] by investigating and analyzing phenotypic growth traits of eight J. mandshurica provenances, which resulted in selection of two best provenances in Kuandian and Shulan.…”