Lachenbruch Barbara, St Clair J Bradley, Harrington Constance A
Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA.
USDA-Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331, USA.
Tree Physiol. 2022 Feb 9;42(2):351-364. doi: 10.1093/treephys/tpab106.
To better understand hydraulic adaptations of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) to local climate, we examined genetic (G) and environmental (E) responses of branch hydraulic architecture of 7-year-old saplings from dry and wet climates of origin grown at a relatively dry and a relatively wet common garden site in western Oregon. We sampled 2 years of branch growth from three dry-source and three wet-source families grown at both sites (72 branches, total). Overall, only 4 of the 11 traits had significant genetic (G) effects, whereas 9 traits had significant environmental (E) effects (P < 0.05). Both dry and wet sources had higher leaf-specific conductance (kl) at the dry than the wet site, but the values were achieved by different mechanisms and driven by G × E effects for leaf area/sapwood area (Al/As), shoot length (L), specific conductivity (Ks) and leaf-specific conductivity (Kl). Dry sources achieved higher kl in the dry site through higher Kl (via a lower Al/As and no change in Ks) with no difference in L. Wet sources achieved higher kl at the dry site through no difference in Kl (via no effect on Al/As, despite decreases in Al and As, and lower Ks) with lower L. Vulnerability to embolism (measured as percentage loss of conductivity at 4 MPa) had no G effect but an E effect, with slightly lower values at the dry site. Specific leaf area had G and E effects, with lower values for the dry sources and site. There were no G or E effects on wood density. The different responses of dry and wet sources to site aridity suggest that populations are differentially adapted to the aridity of growing sites. Population variation in response to aridity should be considered when selecting seed sources for establishing forests for future climates.
为了更好地理解沿海花旗松（Pseudotsuga menziesii var. menziesii (Mirb.) Franco）对当地气候的水力适应性，我们研究了来自干燥和湿润气候源地的7年生幼树的树枝水力结构的遗传（G）和环境（E）响应，这些幼树种植在俄勒冈州西部一个相对干燥和一个相对湿润的共同园地里。我们从种植在两个地点的三个干燥源和三个湿润源家族中采集了两年的树枝生长样本（共72个树枝）。总体而言，11个性状中只有4个具有显著的遗传（G）效应，而9个性状具有显著的环境（E）效应（P < 0.05）。干燥源和湿润源在干燥地点的叶比导率（kl）均高于湿润地点，但通过不同机制实现，且受叶面积/边材面积（Al/As）、枝长（L）、比导率（Ks）和叶比导率（Kl）的G×E效应驱动。干燥源在干燥地点通过较高的Kl（通过较低的Al/As且Ks无变化）且L无差异来实现较高的kl。湿润源在干燥地点通过Kl无差异（通过对Al/As无影响，尽管Al和As降低且Ks较低）且L较低来实现较高的kl。栓塞脆弱性（以4 MPa下的电导率损失百分比衡量）没有G效应但有E效应，在干燥地点的值略低。比叶面积有G和E效应，干燥源和地点的值较低。木材密度没有G或E效应。干燥源和湿润源对地点干旱的不同响应表明，种群对生长地点的干旱有不同的适应性。在为未来气候选择造林种子源时，应考虑种群对干旱响应的差异。
