Maritime Pine Trees Research Articles

Hydraulic responses to height growth in maritime pine trees

ABSTRACTAs trees grow taller, decreased xylem path conductance imposes a major constraint on plant water and carbon balance, and is thus a key factor underlying forest productivity decline with age. The responses of stomatal conductance, leaf area: sapwood area ratio (AL : AS) and soil–leaf water potential gradient (ΔΨS–L) to height growth were investigated in maritime pine trees. Extensive measurements ofin situsap flow, stomatal conductance and (non‐gravitational) needle water potential (L = ΨL − ρwgh) were made during 2 years in a chronosequence of four even‐aged stands, under both wet and dry soil conditions. Under wet soil conditions,Lwas systematically lower in taller trees on account of differences in gravitational potential. In contrast, under dry soil conditions, our measurements clearly showed thatLwas maintained above a minimum threshold value of −2.0 MPa independently of tree height, thus limiting the range of compensatory change in ΔΨS–L. Although a decrease in theAL : ASratio occurred with tree height, this compensation was not sufficient to prevent a decline in leaf‐specific hydraulic conductance,KL(50% lower in 30 m trees than in 10 m trees). An associated decline in stomatal conductance with tree height thus occurred to maintain a balance between water supply and demand. Both the increased investment in non‐productive versus productive tissues (AS : AL) and stomatal closure may have contributed to the observed decrease in tree growth efficiency with increasing tree height (by a factor of three from smallest to tallest trees), although other growth‐limiting responses (e.g. soil nutrient sequestration, increased respiratory costs) cannot be excluded.

Somatic Embryogenesis from 20 Open-Pollinated Families of Portuguese Plus Trees of Maritime Pine

Immature zygotic embryos from 20 open-pollinated (OP) families of maritime pine (Pinus pinaster) plus trees were screened for their somatic embryogenic capacity. The best time for zygotic embryo collection was between 30th June and 16th July 1999 when most embryos were at a pre-cotyledonary stage of development. The somatic embryogenesis (SE) initiation frequency was highest on DCR basal medium with 13.6 µM 2,4-dichlorophenoxyacetic acid (2,4-D) and 4.4 µM 6-benzylaminopurine (BAP) supplemented with L-glutamine and casein hydrolysate. On this medium, initiation frequencies among OP families ranged from 4.6 to 49.1%. Initiation of embryogenic cell lines from all 20 OP families was possible only on DCR based medium, but the addition of L-glutamine and casein hydrolysate significantly increased the number of zygotic embryos producing SE. Most families showed a similar behaviour on different initiation media; however, a few exceptions were observed. Further development of somatic embryos on maturation medium, consisting of DCR with 120 µM abscisic acid (ABA), 100 g l−1 polyethylene glycol (PEG) and 10 g l−1 gellan gum, occurred in 29% of 896 embryogenic lines representing all 20 OP families. However, development into cotyledonary somatic embryos was observed in only 11% of the cell lines, but this still represented 18 OP families.

An improved method for high-quality RNA isolation from needles of adult maritime pine trees

When conventional RNA isolation methods optimized for pine seedlings are applied to needles of adult pine trees, poor-quality RNA results. Here we describe a modified procedure to isolate high-quality RNA from needles of 30-year-old maritime pines, exhibiting high levels of phenolics, polysaccharides, and RNases. Major changes are the inclusion of proteinase K in the extraction medium followed by incubation at 42°C. Integrity and purity were evaluated by using denaturing gel electrophoresis and spectrophotometry (A260/A230 and A260/A280). The total RNA could be successfully used for poly(A)+-RNA isolation and cDNA library construction.

Studying within-stand structure and dynamics with geostatistical and molecular marker tools

We established a circular experimental plot (radius=100 m) that consists of 380 trees of maritime pine ( Pinus pinaster Ait.). The plot is located in central Spain (Segovia province) and within a pure, even-aged and naturally regenerated stand of the species. Every tree was initially mapped using polar coordinates. The objective of the study was to explore the spatial arrangement of some stand attributes such as age of trees, diameter at breast height (DBH), total height, diameter increment and number of female strobili and cones. Genetic data (three highly polymorphic nuclear microsatellites) were used to investigate extend of relatedness within the stand and differentiate between genetic and environmental causes of spatial aggregation. We employed, in the analysis of tree attributes, only geostatistical tools (direct and cross variograms as well as their indicator counterparts). The results revealed that all the studied attributes are spatially correlated and some of them cross-correlated. Competition and height were found to be key-variables in stand dynamics, which influence the rest of the attributes. Fine-scale genetic structure exists within the stand (0–30 m range). Relatedness between neighboring trees can partially explain the spatial aggregation of individual tree attributes. Geostatistical tools are recommended for this type of spatial analysis of forest stands. Their use can provide useful insights into the nature of stand organization and can guide future silvicultural treatment toward higher stand productivity or better and faster regeneration.

Allometric relationships for branch and tree woody biomass of Maritime pine ( Pinus pinaster Aı̈t.)

Modelling biomass repartition in a tree is either done using theories regarding carbon transfer and allocation or through empirical repartition coefficients. The latter can be derived from the study of the allometric relationships inside a tree, which reflect the equilibrium between tree structure and biomass. In order to quantify the biomasses of the main aerial compartments (needles, stem wood, stem bark, branch wood and buds) of a Maritime pine tree ( Pinus pinaster Aı̈t.) and to assess their relationships with tree structure, we undertook some destructive measurements of architecture and biomass. The study of leaf area was presented in a specific paper [Porté et al., Ann. For. Sci. 57 (1) (2000) 73], and the present paper is dealing with the woody compartments (branch wood, stem bark and wood). We collected biomass samples on thirty 5-year-old, sixteen 26-year-old and ten 32-year-old Maritime pines. Allometric equations were developed per site to estimate branch wood biomass. It depended only on the branch basal diameter and the models were very satisfying. Using these equations, we estimated the total branch wood biomass of each sampled tree. A single relationship for all sites was found to model crown or trunk biomass. A power function of tree diameter at breast height (DBH) and the inverse of tree age was fitted to the branch wood data. A power function of DBH and tree age was used for the stem wood and bark models, which takes into account the differences in vitality with different ages. All models performed quite well. Input variables were easy to measure so that the models could be applied to estimate the aerial biomass of a whole stand, per compartment, over a 20-year-long period. The allometric relationships presented here can be derived to be used as biomass repartition laws, for a 5–30-year-old Maritime pine stand in humid Lande.

An age-independent basal area increment model for maritime pine trees in northwestern Spain

An individual tree basal area increment model for pure stands of maritime pine ( Pinus pinaster Ait.) is presented. The data used to fit the model were collected from 67 temporary 0.05 ha plots installed in regularly stocked, even- and uneven-aged stands located in Galicia (northwestern Spain). Explanatory variables used to predict the basal area increment are breast-height diameter outside bark, a diameter-squared term, a distance-independent competition index, crown spread ratio, and effective soil depth. Age and site index are intentionally omitted to obtain generality for a wide range of even- and uneven-aged stand conditions. The resulting model explains more than 78% of the total growth variation, corresponds to current hypotheses about tree growth, and is expected to provide reliable site-specific predictions for most of the pure maritime pine stands found in the study area.

Geographic variation in growth, carbon isotope discrimination, and monoterpene composition in Pinus pinaster Ait. provenances

The geographic variation in monoterpene composition, growth, and carbon isotope discrimination (Δ) was assessed for trees of maritime pine, Pinus pinaster Ait., from five provenances (one Portuguese, Corsican, and Tuscan and two Sardinian: Telti and Limbara) grown on four different field sites in Sardinia island, Italy. Analysis of monoterpenes as biochemical markers revealed differentiation among the provenances and suggest four groupings, corresponding to the pooled Sardinian provenances (Telti and Limbara) and the other individually separated provenances. The five provenances exhibited statistically significant variation for height and diameter. Significant variation for growth parameters were also observed among the locations studied. The five provenances showed weak variations for Δ (range 17.1-17.5‰), while highly significant differences were observed amongst the four sites. A strong negative correlation was observed between mean tree height and mean Δ for the five provenances only at one site (the coolest and highest); the relationship was weak for the five seed sources at the other three locations. The Portuguese provenance that showed the highest potential for growth amongst the seed sources studied had a distinct terpene pattern and a tendency for lower Δ (higher WUE) than the other populations.

Testing a new competition index for Maritime pine in northwestern Spain

A distance-independent competition index is derived from the basal area in larger trees (BAL) index combining individual tree's basal area percentiles with a relative-spacing stand-density measure. Empirical increment data from Maritime pine trees (Pinus pinaster Ait.) sampled from regular, naturally regenerated stands in the province of Pontevedra, northwestern Spain, are used to compare the performance of the two competition indices in the context of basal area growth modelling. The basal area increment of individual trees was first predicted exclusively as a response to competition using a two-parameter exponential function and then as a function of potential growth reduced by competition. For the criteria evaluated in this paper, the new competition index has shown superior qualities. The main improvement over BAL is the incorporation of the relative spacing measure.

Within-ring δ13C spatial variability and interannual variations in wood cellulose of two contrasting provenances of Pinus pinaster

The carbon isotope composition (δ13C) of cellulose extracted from wood samples was measured on 26-year-old maritime pine trees (Pinus pinaster Ait.) of the mesic French provenance Landes and of the drought-resistant Moroccan provenance Tamjoute, all growing at the same location in France. Analysis of spatial variability revealed that intra-ring δ13C values varied over a range of about 0.5%o (mean SD = 0.12%o) for circumference and of about 1%o (mean SD = 0.22%o) for height and that interannual variability of δ13C was 3%o. The successive year-to-year δ13C values on four trees (from 1972 to 1991) were found to roughly parallel the variations of a water stress index, calculated by taking into account climatic variables as well as the level of the water table in the soil: δ13C increased with drought. The two provenances (30 trees per provenance) were compared at a juvenile stage (old rings) and at a mature stage (recent rings). The drought-resistant provenance (Tamjoute) presented lower δ13C values, independent of ring age. Relationships between δ13C and tree height are discussed both at the within- and between-provenance levels.

Hardness and basic density variation in the juvenile wood of maritime pine

This paper investigates the within- and between-tree variability of hardness and basic den- sity in two stands of 11-year-old and 20-year-old maritime pine trees grown in the south-west of France. A slight increase was found in the inner core hardness of the 11-year-old trees (+13.9 %) and in basic density of the 20-year-old pines (6.5 %) with decreasing tree height. Between the 1st and 13th annual rings of the 20-year-old trees, hardness increased by +49.8 % and basic density by +18.7 % on average. These variations were strongly tree-dependent. A significant correlation was found between hardness and basic density, even when each sampling position was considered indepen- dently. (© Inra/Elsevier, Paris.)

Transverse shrinkage in maritime pine juvenile wood

This paper reports experimental results concerning the transverse shrinkage variability within and between trees of two samples composed of 17 eleven-year-old and 20 twenty-year-old maritime pine trees harvested in two stands at the Forest Research Centre of INRA Pierroton in Aquitaine. The within tree variations are divided into a height effect and a radial effect, both related to the occurrence of juvenile wood. It is shown that the tangential shrinkage and the anisotropic ratio between radial and tangential dimensional variations are increasing from the top to the base of the stems (+14.9% and +16.9%, respectively), and that this effect is independent of the tree. The variations from the pith outward are also significant for these parameters (+25.0% for at and −9.5% for the ratio) and for the radial shrinkage (+37.2% ), but in this case, the amplitude of the effect is depending on a tree effect. The relationship between shrinkage and density is also studied, showing poorly significant correlation when considering each sampling positions independently.

Genetic polymorphism in maritime pine (Pinus pinaster Ait.) assessed by two-dimensional gel electrophoresis of needle, bud, and pollen proteins

Using two-dimensional polyacrylamide gel electrophoresis, the genetic variation of proteins was examined in three organs (needle, bud, and pollen) from 18 trees of maritime pine. Three types of variation were noted: presence/absence, staining intensity, and position variation of the spots. Of the 902 polypeptides scored in the three organs, 245 (27.2%) were polymorphic. Moreover, among these variable spots, 117 were found in a single organ, demonstrating an increased polymorphism of the organ-specific polypeptides (56.0% vs 18.4% for the organ-unspecific polypeptides). Finally, a positive correlation was found between variability level and subunit molecular weight for spots showing position variation but not for spots showing presence/absence or staining intensity variations. Possible explanations for this observation are discussed.

Linkage relationships of loci controlling protein amounts in maritime pine (Pinus pinaster Ait.)

The comparison of two-dimensional protein patterns of 56 haploid megagametophytes from a single maritime pine tree allowed the analysis of genetic determinism of qualitative and quantitative variation. One hundred and nineteen loci were localized in 12 linkage groups while two other loci were unlinked. Among the 81 qualitative variants, 58 could be interpreted as allelic products of structural genes. Their distribution in the linkage groups appeared to be non-random, since most of them clustered at a common point in two groups. The remaining 23 qualitative and 40 quantitative variants could best be explained by assuming monogenic determinism of protein amounts. Pleiotropic effects could be responsible for some of the variations in amounts of proteins which cosegregate.

Variations qualitatives et quantitatives des carbures terpéniques au cours de la croissance des rameaux et des aiguilles du Pin maritime: étude comparée de huit phénotypes

The variations of the monoterpene and sesquiterpene hydrocarbons have been studied during the growth of the needles and shoots of eight trees of maritime pine. These trees represent the eight possible phenotypic associations for 3-carene, myrcene and limonene. The 'monoterpene profiles' under genetic control are very comparable for a same individual but the differences between phenotypes are more important in oils from cortical tissues than in those from leaves mainly for the 3-carene content.α- and β-Pinene are synthetized very early in the three kinds of organs and tissues studied; needles, wood, and cortical tissues of young shoots. On the contrary, 3-carene, myrcene, and limonene are mainly elaborated in the needles and cortical tissues. The synthesis of limonene and myrcene starts later than that of pinenes and 3-carene. The sesquiterpenes are mainly elaborated in the needles and their accumulation is progressive.These variations during the growth of the organs suggest the existence of several paths for the synthesis of C10 and C15 hydrocarbons.

Effect of Experimental and Wild Fires in Pine Plantations on Wood Characteristics

SUMMARY Sawn timber losses due to degrade were investigated in a 28 year-old stand of radiata pine (Pinus radiata D.Don) subjected to a series of experimental fires covering a wide range of intensities. The effect of the burning treatment on radial growth rate and density characteristics was also studied and augmented by 44 year old material of the same species which had been burnt in a wild fire. These wood characteristics were also investigated in 17 year-old trees of maritime pine (P. pinaster Aiton). The experimental fires caused a reduction of 0.4 per cent of the total possible sawn volume. There was no effect on growth rate and only a slight reduction in density in the immediate post-fire year. The accumulation of traumatic resin is discussed.