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Theoretical tree crop ideotypes have long and narrow live crowns with a high total leaf area. This crown form allows more efficient exploitation of site resources, in part by physically occupying less growing space per unit leaf area and by packing a greater number of trees into a given area. Genetic selection for crop ideotypes has been proposed as a strategy for maximizing productivity per unit area in stands managed under intensive silviculture. The primary objective of this study was to test the relationship between the relative growth performance of different families in a Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) progeny test and morphological crown attributes that conform to a theoretical crop ideotype. The overarching goal was to identify attributes conferring superior height and diameter growth on families and to facilitate the incorporation of these attributes and associated growth mechanisms into hybrid growth models for intensively managed plantations. Crown structural attributes were measured on destructively sampled trees and averaged for the entire crown and each third of live crown length among families. Multivariate analysis revealed that crown attributes averaged over the entire crown performed best for identifying families with different height and diameter growth, followed successively by the bottom, middle, and top crown third. Trees with relatively short branch lengths and steep branch angles tended to have higher total leaf area per unit crown length (TLACL), and this structural attribute showed a strong positive correlation with cumulative diameter growth. The ratio of crown width to crown length (CWL) was moderately and negatively correlated with cumulative height growth. The families displaying the most rapid diameter growth in this progeny test conformed to a theoretical crop ideotype, while those with the most rapid height growth displayed crown attributes with a less obvious relationship to the crop ideotype concept. TLACL implied one possible mechanism driving genetic gain in Douglas-fir families, given its high heritability and strongly positive correlation with growth performance. Incorporating TLACL as an explanatory variable in diameter growth models could at least partly represent different genetic levels. TLACL is less strongly correlated with height growth rate, so incorporating CWL may better represent genetic effects on height growth models. [ABSTRACT FROM AUTHOR]

Seed transfer zones ensure that germplasm selected for restoration is suitable and sustainable in diverse environments. In this study, seed zones were developed for mountain brome (Bromus carinatus Hook. & Arn.) in the Blue Mountains of northeastern Oregon and adjoining Washington. Plants from 148 Blue Mountain seed source locations were evaluated in common-garden studies at two contrasting test sites. Data on phenology, morphology, and production were collected over two growing seasons. Plant traits varied significantly and were frequently correlated with annual precipitation and annual maximum temperature at seed source locations (P < 0.05). Plants from warmer locations generally had higher dry matter production, longer leaves, wider crowns, denser foliage, and greater plant height than those from cooler locations. Regression models of environmental variables with the first two principal components (PC 1 and PC 2) explained 46% and 40% of the total variation, respectively. Maps of PC 1 and PC 2 generally corresponded to elevation, temperature, and precipitation gradients. The regression models developed from PC 1 and PC 2 and environmental variables were used to map seed transfer zones. These maps will be useful in selecting mountain brome seed sources for habitat restoration in the Blue Mountains. Key words: genecology, Bromus carinatus, seed zones, plant adaptation. Les zones de transfert des semences assurent qu'un germoplasme selectionne pour la restauration convient et demeure durable dans divers environnements. Dans cette etude, les auteurs ont developpe des zones d'ensemencement pour le brome (Bromus carinatus Hook. & Arn.) des Blue Mountains du nord-est de l'Oregon et de l'etat de Washington voisin. Dans des jardins communs situes sur deux sites fortement contrastes, ils ont evalue des plants provenant de 148 provenances de semences recoltees dans les Blue Mountains. Ils ont reuni les donnees sur la phenologie, la morphologie et la productivite au cours de deux saisons de croissance. Les caracteres des plantes varient significativement et montrent souvent des correlations avec la precipitation annuelle et les temperatures maximales annuelles prevalant sur les sites de provenance des semences. Les plantes venant des localites plus chaudes montrent generalement une productivite en matiere seche plus grande, des feuilles plus longues, des cimes plus larges, un feuillage plus dense et des plants plus hauts, que ceux provenant de localites plus froides. Les modeles de regression des variables environnementales portant sur les deux premieres composantes principales (PC 1 et PC 2) expliquent respectivement 46 % et 40 % de la variation totale. Les cartes des PC 1 et PC 2 correspondent generalement aux gradients d'elevation, de temperature et de precipitation. Les auteurs ont utilise; les modeles de regression developpes a partir des PC 1 et PC 2 avec les variables environnementales pour cartographier les zones de transfert des sources de semences destinees a la restauration des habitats dans les Blue Mountains. Mots-cles: genecologie, Bromus carinatus, zones des semences, adaptation vegetale. [Traduit par la Redaction], Introduction Native forest and rangeland plant communities are increasingly threatened by overgrazing (Belsky and Blumenthal 1997), uncharacteristic frequent wildfires (Hessburg et al. 2005), invasive weeds (Mack 1981; Keeley 2006), and [...]

Abstract: Genetic variation in fall cold damage in coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) was measured by exposing excised branches of seedlings from 666 source locations grown in [...]

Provides some insights into the history of seed zone development in forest trees with emphasis on the Pacific Northwest. Transfer guidelines for native plants; Seed movement guidelines for restoration activities; Forestry; Forest and plant restoration.

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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., (Published by Oxford University Press 2021.)

There is a general assumption that intraspecific populations originating from relatively arid climates will be better adapted to cope with the expected increase in drought from climate change. For ecologically and economically important species, more comprehensive, genecological studies that utilize large distributions of populations and direct measures of traits associated with drought-resistance are needed to empirically support this assumption because of the implications for the natural or assisted regeneration of species. We conducted a space-for-time substitution, common garden experiment with 35 populations of coast Douglas-fir (Pseudotsuga menziesii var. menziesii) growing at three test sites with distinct summer temperature and precipitation (referred to as 'cool/moist', 'moderate', or 'warm/dry') to test the hypotheses that (i) there is large genetic variation among populations and regions in traits associated with drought-resistance, (ii) the patterns of genetic variation are related to the native source-climate of each population, in particular with summer temperature and precipitation, (iii) the differences among populations and relationships with climate are stronger at the warm/dry test site owing to greater expression of drought-resistance traits (i.e., a genotype × environment interaction). During midsummer 2012, we measured the rate of water loss after stomatal closure (transpiration(min)), water deficit (% below turgid saturation), and specific leaf area (SLA, cm(2) g(-1)) on new growth of sapling branches. There was significant genetic variation in all plant traits, with populations originating from warmer and drier climates having greater drought-resistance (i.e., lower transpiration(min), water deficit and SLA), but these trends were most clearly expressed only at the warm/dry test site. Contrary to expectations, populations from cooler climates also had greater drought-resistance across all test sites. Multiple regression analysis indicated that Douglas-fir populations from regions with relatively cool winters and arid summers may be most adapted to cope with drought conditions that are expected in the future., (Published 2014. This article is a U.S. Government work and is in the public domain in the USA.)

The timing of periodic life cycle events in plants (phenology) is an important factor determining how species and populations will react to climate change. We evaluated annual patterns of basal-area and height growth of coast Douglas-fir (Pseudotusga menziesii var. menziesii (Mirb.) Franco) seedlings from four seed sources that were planted in four diverse environments as part of the Douglas-fir Seed-Source Movement Trial. Stem diameters and heights were measured periodically during the 2010 growing season on 16 open-pollinated families at each study installation. Stem diameters were measured on a subset of trees with electronic dendrometers during the 2010 and 2011 growing seasons. Trees from the four seed sources differed in phenology metrics that described the timing of basal-area and height-growth initiation, growth cessation and growth rates. Differences in the height-growth metrics were generally larger than differences in the basal-area growth metrics and differences among installations were larger than differences among seed sources, highlighting the importance of environmental signals on growth phenology. Variations in the height- and basal-area growth metrics were correlated with different aspects of the seed-source environments: precipitation in the case of height growth and minimum temperature in the case of basal-area growth. The detailed dendrometer measurements revealed differences in growth patterns between seed sources during distinct periods in the growing season. Our results indicate that multiple aspects of growth phenology should be considered along with other traits when evaluating adaptation of populations to future climates.