Needle Traits Research Articles

Environmental Controls on Needle Gas Exchange and Growth of White Spruce (Picea glauca) on a Riverside Terrace near the Arctic Treeline

Recent studies have revealed positive and negative trends in the radial growth of treeline white spruce (Picea glauca) as temperatures have warmed in recent decades. Investigators have speculated that negative growth trends reflect the increasing importance of temperature-induced drought stress, yet direct observations of drought-induced stomatal closure have not been made in white spruce near the Arctic treeline. In this study, we measured needle gas exchange, a variety of needle traits, and branch growth in contrasting growing seasons on a riverside terrace near the Arctic treeline in Noatak National Preserve, northwest Alaska. Needle gas exchange was limited by cold soils (<7 °C), nighttime frosts, large vapor pressure deficits (VPD) and/or low soil water contents during the majority of our midday measurements. Near optimal conditions for needle gas exchange were consistently found in late August, when soils were relatively warm, air temperatures were moderate, and the VPD was relatively small. Defoliation during a two-year bud moth infestation (Zeiraphera spp.) substantially reduced branch growth, obscured potential relationships between needle gas exchange and growth, and revealed the importance of whole canopy gas exchange measurements. Results of our study show there is a very narrow window of environmental conditions for near optimal needle gas exchange in white spruce near the Arctic treeline. Although we identified many abiotic constraints on needle gas exchange, a single biological factor likely had the greatest effect on annual branch growth.

Outbreeding Depression Caused by Intraspecific Hybridization Between Local and Nonlocal Genotypes in Abies sachalinensis

To evaluate the effects of intraspecific hybridization of local and nonlocal genotypes on growth traits of progeny in Abies sachalinensis, we performed reciprocal crossing between nonlocal trees in a high‐elevation zone (1,100–1,200 m asl) and local trees in a low‐elevation zone (530 m asl) in Hokkaido, northern Japan, in 1979 and established a common garden experiment using local × local (female × male ), local × nonlocal , nonlocal × local , and nonlocal × nonlocal progeny in the low‐elevation zone in 1986. Survival, height, diameter at breast height (dbh), needle nitrogen content, specific leaf area (SLA), and needle area per shoot diameter (NA) of 25‐year‐old progeny were measured in 2005. The survival rate was consistently high (&gt;85% on average). Reductions in height and dbh were apparent in F1 hybrids compared with local × local progeny. Furthermore, outbreeding depression was significant in height growth of nonlocal × local F1 hybrids and in dbh of both F1 hybrids. Reductions in growth traits may be related to morphological needle traits, such as the low values of SLA and NA. Elevation guidelines for A. sachalinensis seed zones are discussed to ensure the long‐term viability of both restored and native populations.

Needle anatomy suggests hybridization between the relict turfosa form of Pinus sylvestris L. from the Gązwa peat bóg and typical Scots pine

The aim of this study was to characterize the turfosa form of &lt;em&gt;Pinus sylvestris&lt;/em&gt; from the Gazwa peat bog reserve in terms of 16 anatomical needle traits and to determine whether pines with a typical morphotype inhabiting the peat bog have been so successful thanks to hybridization with the unique tufosa ecotype. Investigations were conducted on three phenotypic groups of Scots pine growing in the peat bog. The first two groups consisted of 30 tufosa trees at the age of 117-217 years and 20 trees at the age of 30-85 years. The third group consisted of typical pines represented by 10 trees at the age of 20-55 years. In total 30 trees of typical pine, surrounding the peat bog, at the age of 100-150 years served as outgroup. Descriptive statistics, analysis of variance with the F test, Tukey's test, and a number of multivariate analyses were used to estimate differences between the studied groups of trees based on 16 anatomical needle characteristics. The old turfosa form from the Gazwa reserve proved to be a unique and relict peat bog pine, as it was shown by the differences in 10 analyzed needle traits in comparison to pine with a typical morphotype growing in the areas surrounding the peat bog. The young typical pines have adapted to conditions found in the peat bog owing to hybridization with the turfosa forms. The young turfosa trees differed from the old turfosa trees and also they have probably been of a hybrid origin. The old turfosa form from the Gazwa reserve is a threatened ecotype due to its hybridization with pines from the population surrounding the peat bog.

Phenotypic analysis of first-year traits in a pseudo-backcross {(slash x loblolly) x slash} and the open-pollinated families of the pure-species progenitors

A single test, including one pseudo-backcross (Pinus elliottii x Pinus taeda) x P. elliottii and open-pollinated families of the pure species progenitors, was established in North Central Florida in December 2007 to study the transfer of the fast-growing characteristics from a P. taeda L. (loblolly pine) parent into the P. elliottii Engelm. (slash pine) background. Several traits were measured in the first growing season: height growth, phenology, tip moth incidence, stem traits, crown architectural and needle traits. Heterosis was evaluated for each trait using analyses of variance by fitting a linear mixed model. All traits were significantly (p value < 0.05) different among families while the significance for heterosis varied by trait. Positive heterosis was found for average rate of shoot elongation (ASRE), total growth (TG), total height and number of needles per fascicle while the opposite was true for base diameter, top diameter, fascicle length, fascicle diameter, crown projected area and phenological traits (cessation, duration and day to reach 50% of the height). Average performance (i.e., no heterosis) was found for initiation of growth, number of branches, number of nodes, tip moth incidence, sheath length and specific leaf area. The analyses indicated that introgression of loblolly pine alleles into slash pine was effective and novel trait combinations were achieved. The pseudo-backcross had larger variation in early height growth than the slash pine families and was taller than all open-pollinated families at the end of the first season. Tip moth incidence was much lower than the loblolly pine family.

Cryptic hybrids between Pinus uncinata and P. sylvestris

We tested the performance of molecular markers and biometric traits in the identification of hybrids between closely related mountain pine (Pinus uncinata) and Scots pine (Pinus sylvestris). A plastid DNA marker and a set of morphological and anatomical needle traits were applied in analyses of individuals from several sympatric stands of the species and a single-species' population from southern Europe, used as a reference. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) marker from the plastid trnL–trnF region and morphological and anatomical traits clearly discriminated between the pure species. Significant differences were found between P. uncinata and P. sylvestris, mostly in the shape of epidermal cells and the number of stomata. Four putative hybrids with P. sylvestris morphology, but with P. uncinata plastid DNA haplotypes, were found in a population from Sierra de Gudar near Valdelinares, the southernmost locality of the latter species in eastern Spain. Discrimination analyses between and within populations placed these individuals on the edge of an agglomeration of P. sylvestris individuals. The results suggest that hybridization between the species is rare, but can result in cryptic hybrids morphologically similar to the maternal species. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163, 473–485.

Variability of three natural populations of Pinus sylvestris L. from different sites of Białowieża Primeval Forest estimated using needle traits

Zmienność trzech naturalnych populacjiPinus sylvestrisL. z różnych siedlisk Puszczy Białowieskiej oszacowana cechami igieł

Morphometric traits and sexual dimorphisms do not strongly differentiate populations of Zeravshan juniper ( Juniperus seravschanica Kom.) in Kyrgyzstan

Intra- and among-population variations of Juniperus seravschanica were morphologically examined in eight populations originating from elevations of 1300–2200 m a.s.l. in Kyrgyzstan. Eleven traits of needles and cones were studied on 70 vouchers. In addition, height, diameter, stem form, and sex of 172 trees were recorded in the field in order to test whether male trees invest more in vegetative growth than females and if sex ratio is shaped by (limited) environmental resources. Morphological differences among populations were small, but needle length, width and thickness were statistically different. However, differences based on needle traits were independent from geographical, altitudinal and environmental distances. In sharp contrast to studies in other Juniperus species, sex ratio in J. seravschanica was strongly female biased (3.5 females : 1 male). Moreover, no correlation between the habitat conditions and the sex ratio was detected, suggesting that within the altitudinal range of this species, females occur more frequently. This has implications for sustainable use and the conservation of J. seravschanica populations. It is likely, that due to the higher investment of male individuals in vegetative growth males are more exploited than females. An average effective population size of 70% of the respective census suggests that conservation measures and non-selective logging regimes are required to allow reproduction and a natural regeneration of this species.

Needle traits of an evergreen, coniferous shrub growing at wind‐exposed and protected sites in a mountain region: does Pinus pumila produce needles with greater mass per area under wind‐stress conditions?

Snow depth is one of the most important determinants of vegetation, especially in mountainous regions. In such regions, snow depth tends to be low at wind-exposed sites such as ridges, where stand height and productivity are limited by stressful environmental conditions during winter. Siberian dwarf pine (Pinus pumila Regel) is a dominant species in mountainous regions of Japan. We hypothesized that P. pumila produces needles with greater mass per area at wind-exposed sites than at wind-protected sites because it invests more nitrogen (N) in cell walls at the expense of N investment in the photosynthetic apparatus, resulting in increased photosynthetic N use efficiency (PNUE). Contrary to our hypothesis, plants at wind-exposed site invested less resources in needles, as exhibited by lower biomass, N, Rubisco and cell wall mass per unit area, and had higher photosynthetic capacity, higher PNUE and shorter needle life-span than plants at a wind-protected site. N partitioning was not significantly different between sites. These results suggest that P. pumila at wind-exposed sites produces needles at low cost with high productivity to compensate for a short leaf life-span, which may be imposed by wind stress when needles appear above the snow surface in winter.

From desert to cloud forest: the non-trivial phenotypic variation of Canary Island pine needles

Pine needles reflect some of the most outstanding xeromorphic characteristics of sclerophyllous plants. Detailed descriptive studies about their anatomy and morphology were carried out since the beginning of the past century but the role the different tissues play in adaptation to diverse environments is still little known. In this work we analyzed morphological and anatomical needle traits of seventeen natural populations of Pinus canariensis Chr. Sm. Ex DC to identify adaptive traits related to drought resistance and determine their variability throughout a wide range of ecological conditions. A Principal Component Analysis revealed two groups of traits, one related to drought adaptation: maximizing gas exchange, avoiding water loss and storing water and the other to photosynthesis. Results support a predominantly mechanical function of hypodermis and a possible role of transfusion tissue to withstand dry conditions, thanks to its water storing capacity. The inversion of the patterns of the relative area of the dermal and transfusion tissues in the xeric region was justified due to the influence of the extreme dry Saharan wind from the East. A clear adaptation of Pinus canariensis needles to contrasted environments is evidenced suggesting distinct phenotypic needle features in the most xeric stands.

Variation in Scots pine needle longevity and nutrient conservation in different habitats and latitudes

Within-species variation in needle traits is an important characteristic of conifers enabling trees to grow in different environments. We compared mean needle age (NA), shoot growth, and nutrient conservation in Scots pine ( Pinus sylvestris L.) populations in different habitats and latitudes (peatlands and Vaccinium -type stands in Estonia (59°N) and Lapland (66°30′N)). In Vaccinium-type stands, trees with higher NA (mostly in Lapland) had lower shoot length increment and lower concentration of nitrogen and phosphorus in current-year needles than trees with low NA (mostly in Estonia). However, in peatlands, variation in NA (which was as high as in the Vaccinium-type stands) was weakly or insignificantly related to shoot growth and needle nutrient concentration. Within latitudes, pines with different shoot length increments and needle nutrient concentrations tend to have similar NAs. Resorption efficiency and concentration of nitrogen and phosphorus in senescent needles decreased with the initial concentrations of these nutrients in green needles. Our results demonstrate that slow growth and low needle nutrient concentration are not necessarily followed by higher NA and greater nutrient conservation in Scots pine. This is the opposite of the results often obtained in among-species comparisons or within species along latitudinal and altitudinal gradients.

Crown structure and biomass allocation patterns modulate aboveground productivity in young loblolly pine and slash pine

Crown architecture affects tree growth through control of leaf area and its display for effective light capture and photosynthesis. It may be important to quantify crown traits for effective use of intensive silvicultural practices to improve tree growth in forest plantations. We examined growth and crown characteristics in two families of loblolly pine ( Pinus taeda L.) with contrasting growth—superior and average, and one slash pine ( Pinus elliottii Engelm.) family, growing at three experimental sites in the West Gulf Coastal Plain of Texas and Louisiana, USA. The families were subjected to two contrasting silvicultural treatments—repeated fertilization and control of competing vegetation (high intensity), and control (low intensity). Families differed in height and diameter growth after the second growing period in the field, and high intensity treatment in general increased tree growth, although family ranks and silvicultural effects were dependent on the experimental site. The families differed in crown and needle traits, and biomass partitioning patterns. Aboveground biomass accumulation was related to crown structure among families, but biomass partitioning was independent of the crown traits. Cultural treatment generally had no effect on crown properties or aboveground biomass partitioning. Slash pine produced significantly smaller crowns than loblolly pine at a given tree size, but was capable of maintaining larger needle area and producing more bole-wood biomass for a given crown volume. Tree growth was highly correlated with accumulated foliage area, but bole-wood production per unit leaf area (growth efficiency) was similar for both pine species. The superior loblolly pine family had the largest number of flushes and a different crown shape than two other families that most likely led to better light-capture and greater carbon assimilation, as this family also produced the greatest aboveground biomass.

Biogeographic differences in cone, needle and seed morphology among natural Picea asperata populations in Western China

This study represents a geographical approach to morphological variation of cones, needles and seeds in natural dragon spruce (Picea asperata Mast.) populations across western China and the relationship between morphological traits and weather variation for the origins of populations. Significant differences were found for all cone, needle and seed traits among populations and trees within populations. The coefficients of variation in 2 higher latitude populations were higher than those in other populations in all traits except for needle width and seed width. Fairly high within-population variability was also detected for cone dry weight, seed dry weight and needle traits in this study. Cone length, cone width, cone dry weight, seed scale length, seed scale width and seed wing length were strongly positively intercorrelated. Seed length and seed dry weight showed a significantly positive correlation with seed wing length. And needle width showed a significant negative correlation with cone traits, seed scale length, seed wing length and seed length. The higher the annual mean temperature, the higher the average cone length. This study also revealed a negative linear dependence on latitude: the higher the latitude, the lower the population average seed length. Seed dry weight was positively and linearly related with altitude.

Morphology of Pinus uliginosa (Pinaceae) needles from populations exposed to and isolated from the direct influence of Pinus sylvestris

Eleven needle traits of two contrasting populations of Pinus uliginosa (P. mugo complex), one located in a Pinus sylvestris forest, the other isolated from the influence of this species, were compared to quantify the degree of hybridization. Statistically significant differences between the studied populations were found, but both of them differed by a similar degree from P. sylvestris. Surprisingly, the P. uliginosa population surrounded by the P. sylvestris forest, which was expected to consist of individuals with intermediate traits, appeared to be more closely related to P. mugo than those isolated from the direct influence of P. sylvestris. Large differences in the distances between the analysed pair of populations of P. uliginosa and P. sylvestris have not influenced the morphological traits of the species. Gene flow from P. sylvestris to P. uliginosa is possible, but is likely to be small and does not differ compared with populations of P. uliginosa. The decline observed during the last three decades in both populations of the species has not influenced their needle morphological traits. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142, 83–91.

Effects of nursery environment on needle morphology of Pinus monticola Dougl. and implications for tree improvement programs

Statistically significant differences were found in 14 needle traits of western white pine (Pinus monticola Dougl.) seedlings grown from the same seed orchard source in the three nurseries in northern Idaho. Traits with significant variation included needle length and width, number of stomatal rows, number of stomata per row, total stomata per needle, adaxial surface area, stomatal density, major axes of stomata, stomatal shape, stomatal area, stomatal occlusion, epistomatal wax degradation, weight of wax per dry weight of needle, and the contact angles of water droplets placed on adaxial needle surfaces. Wax crystallites on needle surfaces were hollow and tubular and the amount of surface wax appeared to be associated with surface wettability. Our results may have important implications for tree improvement programs that require successful inoculation of nursery-grown seedlings with spores of Cronartium ribicola J. C. Fisch. ex Rabenh. to reliably screen white pines for resistance to blister rust.

Differences in needle morphology between blister rust resistant and susceptible western white pine stocks

Needle traits were evaluated on three groups of western white pine (Pinus monticola Dougl.) seedlings: four open-pollinated families that ranked high for the "reduced needle lesion frequency" type of resistance to blister rust; four blister rust susceptible families; and two bulk lots from a seed orchard selected for blister rust resistance. No statistically significant differences were found for most traits in pairwise comparisons among the three groups. However, needles of susceptible families had significantly wider and larger stomata (greater area) than did those of resistant families and seed orchard lots; their stomata were also rounder (smaller ratio of stomatal length to width) than those of the seed orchard lots. Needles of the resistant stocks were significantly shorter than those from seed orchard bulks. Contact angles of water droplets on adaxial needle surfaces were also significantly larger on resistant families compared with the other genetic stocks. Results suggest the possibility of some threshold stomatal size and (or) critical stomatal shape related to infection by the blister rust fungus, Cronartium ribicola J.C. Fisch. ex Rabenh., and possible differences among the groups in wax chemistry and (or) surface textures, both of which may alter behavior of blister rust germ tubes and (or) be altered by blister rust infection.

Differences in needle morphology between blister rust resistant and susceptible western white pine stocks

Needle traits were evaluated on three groups of western white pine (Pinus monticola Dougl.) seedlings: four open-pollinated families that ranked high for the reduced needle lesion frequency type ...

How Does Immigration Influence Local Adaptation? A Reexamination of a Familiar Paradigm

How Does Immigration Influence Local Adaptation? A Reexamination of a Familiar Paradigm

Flavonoids and morphological traits of needles, as markers of natural hybridization between Pinus uncinata Ram. and Pinus sylvestris L.

Continuing our work on the flavonoids of Pinus sylvestris and Pinus uncinata, further analysis of flavonoid variability leads us to suggest the existence of natural hybrids between these two species, because the flavonoid characters of some individuals are inconsistent with their morphology. The hybrids Pinus uncinata X Pinus sylvestris usually show strong affinities with one parental species, there are very few intermediate individuals. This could be a mark of introgression.

Phenotypic variation in cone and needle characters of Pinus banksiana (jack pine) in northwestern Ontario

To investigate the pattern of natural variation of jack pine (Pinus banksiana Lamb.), 64 natural stands from northwestern Ontario were compared based on phenotypic variation of cone and needle morphology. Cone and needle traits were determined for 10 trees from each stand. Vegetation and soil data for the stands were determined following the procedures established by the Ontario Ministry of Natural Resources Forest Ecosystem Classification program. Climatic data for each stand were interpolated using a geographic information system based on 1951 to 1980 data for Ontario and Minnesota weather stations. Nested analyses of variance indicated that most of the variation was expressed between trees and within trees, with relatively little (1.6 – 18.9% depending on the trait) expressed between sampled populations. Discriminant analysis of cone and needle data indicated that the 64 populations generally varied longitudinally with a steep cline in the Nipigon area (ca. 88°15′W) apparent for cone data. A corresponding irregularity in the pattern of needle variation suggested that the modern pattern may be the result of separate lineages, i.e., descendents from two migration routes along eastern and western shores of Lake Superior or from two refugia. However, temperature data follows a similar pattern in this area of Ontario, and multiple regression of the discriminant analysis score means for the 64 sampled populations against elevation, climatic, and soil data indicated that much of the cone and needle variation expressed between populations could be accounted for by the regressions. Thus, the observed patterns of phenotypic variation may simply be the result of local adaptations to a variable environment. Key words: jack pine, Pinus banksiana, phenotypic variation, cone traits, needle traits, northwestern Ontario.

The taxonomic status of closely related closed cone pines in Mexico and Central America

A taxonomic study on 14 cone and needle traits of 281 trees from 33 provenances of Pinus oocarpa, P. oocarpa var. ochoterenae, P. patula var. longipedunculata, P. patula var. patula and P. tecunumanii in Central America and Mexico was conducted to quantify the affinity between closely related species. A second objective was to determine the geographic range of P. tecunumanii in Mexico. Cluster analysis placed 52% of all provenances in taxa different from those assigned by field foresters. Trees from 15 provenances of what was locally known as Pinus oocarpa var. ochoterenae from Chiapas were statistically indistinguishable from high elevation Central American sources of P. tecuncumanii when assessed for cone and needle characteristics. However, trees from two provenances known locally as P. oocarpa var. ochoterenae from southwestern Oaxaca, Juquila and Tlacuache, were found to be distinct from P. tecunumanii and may be a variant of P. patula. Canonical discriminant analysis was used to determine the taxonomic affinity among newly formed clusters. The spatial (Mahalanobis) distance between P. tecunumanii and P. patula var. patula, P. patula var. longipedunculata, and P. oocarpa was 42.0, 44.4, and 109.4 respectively, and highly significant. The geographic range of Pinus tecunumanii in Mexico appears to be confined to the state of Chiapas.