Regeneration dynamics of mixed stands of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. and <Emphasis Type="Italic">Pinus pinea</Emphasis> L. in Central Spain

The dynamics of mixed stands are more complex and less studied than those of monospecific stands. The objective of this work was to analyze the variables involved in seedling occurrence and seedling survival in mixed stands of Pinus pinaster and P. pinea in Mediterranean areas. From 2011 to 2016, regeneration of both species was monitored at two sites located in Central Spain. We installed 72 regeneration plots where seedling dynamics were monitored. All the trees in the study areas were measured and mapped. Additionally, we took hemispherical photographs in each regeneration plot. The average density of P. pinea seedlings over the study period was almost 20 times larger than that of P. pinaster. Our results indicate that the seedlings of both species grow under moderate light conditions. In addition, we found that the occurrence of seedlings of both species was related to the structure of the stand. P. pinea seedlings grew where the density and size of P. pinaster trees were low and where P. pinea trees provided moderately sheltered conditions, whereas the number of P. pinaster seedlings was related to under intermediate densities of P. pinaster trees. Furthermore, seedling survival was positively associated with age of the seedlings and negatively with the August average maximum temperature. The temporal continuity of mixed stands of P. pinea and P. pinaster in the study area is compromised by the observed lack of regeneration of P. pinaster.     

Considering neighborhood effects improves individual dbh growth models for natural mixed-species forests in Mexico

Key message

More accurate diameter at breast height (dbh)-growth models are needed for developing management tools for mixed-species forests in Mexico. Individual distance-dependent dbh growth models that quantify local neighborhood effects have been developed for four species groups in such forests. The performance of the models is improved by distinguishing between inter- and intraspecific group competitions.

Context

The management of mixed-species forests in the northwest of Durango, Mexico, is mainly based on the selection method. Understanding the interspecific and intraspecific competition is critical to developing management tools for such mixed-species forests.

Aims

An individual-based distance-dependent modeling approach was used to model the growth of dbh and to evaluate neighborhood effects for four species groups in Mexican mixed-species stands.

Methods

Twenty-two species were classified into four groups: Pinus (seven species), other conifers (three species), other broadleaves (four species), and Quercus (eight species). Four methods were used to select neighboring trees and 12 competition indices (CIs) were calculated. Comparisons of the neighboring trees selection methods and CIs and tests of assumptions about neighborhood effects were conducted.

Results

Intra-species-group competition significantly reduced diameter growth for all species groups, except for the Quercus group. The Pinus, other conifers, and Quercus groups had significant and negative neighborhood effects on the other broadleaves species group, and not vice versa. The Quercus group also had negative neighborhood effect on the Pinus and other conifers species groups, and not vice versa. The Pinus and other conifers species groups had negative neighborhood effects on each other. All fitted age-independent dbh growth models showed a good of fit to the data (adjusted coefficient of determination larger than 0.977).

Conclusion

The growth models can be used to predict dbh growth for species groups and competition in mixed-species stand from Durango, Mexico.

     

Sprouting characteristics of <Emphasis Type="Italic">Quercus pubescens</Emphasis> Willd. and <Emphasis Type="Italic">Quercus frainetto</Emphasis> Ten. trees after a wildfire: To cut or not to cut the burned trees?

The aims of this study were to analyze the sprouting characteristics of Quercus pubescens and Q. frainetto trees after a wildfire and to recommend the appropriate silvicultural treatments in order to achieve dense sprout origin regeneration. This study was carried out in the area that was burned in a wildfire in northeastern Greece. Three years later, 140 Q. pubescens trees and 140 Q. frainetto trees were selected. Seventy trees for each species were individuals that were cut after the fire and were in the form of stumps, while 70 trees were intact top-killed trees, as a result of fire. In each stump and intact tree that was selected, various parameters were measured or counted: the diameter at the level of ground, the number of the developed sprouts (if any) and the height as well as the basal diameter of the tallest sprout, etc. Both species have similar sprouting behavior after a wildfire. Mother tree dimensions positively influenced the number of sprouts and the growth of the tallest sprout per individual. The mean height of the tallest sprout per stump, after three growing seasons from the forest fire, is high in both species (2.08 m for Q. pupescens and 2.29 m for Q. frainetto). Cut stumps had more sprouts than intact trees in both species. Forest practice, in order to maximize the sprouting of Q. pubescens and Q. frainetto trees after a forest fire, should cut the burned trees before the next growing season.     

Possible coexistence of native and exotic parasitoids and their impact on control of <Emphasis Type="Italic">Halyomorpha halys</Emphasis>

Introduction of exotic natural enemies for biological control of invasive pests may disrupt existing ecological interactions, which may influence the outcome of biological control introductions. The interactions between Asian egg parasitoids, proposed as classical biological control agents of the highly polyphagous invasive pest Halyomorpha halys (Stål), and parasitoids native to the introduced area are largely unknown. Therefore, adult and larval interspecific competition between the exotic Trissolcus japonicus (Ashmead) and the European Anastatus bifasciatus (Geoffroy) was assessed (1) by observing aggressive interactions between adults of the two species following parasitization and (2) by providing each parasitoid species with previously parasitized H. halys egg masses at various time intervals. The results suggest that T. japonicus and A. bifasciatus engage in counterbalance competition, with the former being a superior extrinsic competitor (egg guarding and aggressiveness) and the latter being a superior intrinsic competitor (successful development from multiparasitized eggs of all ages). We suggest that the presence of T. japonicus is unlikely to have a negative impact on A. bifasciatus, and that those two species can coexist and potentially act synergistically in the biological control of H. halys.     

Symptoms and fungi associated with elm trees decline in Iran

Elm (Ulmus, Ulmaceae) is one of the most popular and important trees in urban and landscape areas in Iran. A severe decline of elm trees has recently been observed in some areas of Kerman and Shiraz cities. However, the identity of the causal agents has not yet been investigated. The purpose of this study, carried out in the years 2012–2014, was to isolate and identify fungal trunk pathogens associated with decline symptoms observed in elm trees. Samples were collected from trunks and branches of trees showing various disease symptoms and internal wood lesions. Fungal isolations were made from discolored or decayed wood tissue. In Kerman some elm trees were attacked by the beetle Aeolesthes sarta; therefore, samples were also collected from larvae and adults of beetles associated with trees showing wood damage. Fungal isolates were identified by morphological, cultural and molecular characteristics. Thirteen fungal species, Phaeoacremonium (P.) minimum, P. parasiticum, P. sicilianum, P. alvesii, P. fraxinopennsylvanicum, Spencermartinsia viticola, Dothiorella (Do.) sarmentorum, Neoscytalidium hyalinum, Diatrype (Di.) whitmanensis, Cosmospora viridescens, Phoma (Pho.) herbarum, Phellinus (Phe.) tuberculosus and Inonotus levis were identified. Phaeoacremonium parasiticum was the only species isolated from both larvae and adult beetles. Pathogenicity trials were performed on detached shoots of elm under greenhouse conditions. Dothiorella sarmentorum was the most virulent species based on the length of wood necrosis. This study is the first report of P. sicilianum, C. viridescens and Phe. tuberculosus in Iran. In addition, most of the isolated species are reported for the first time on elm trees in the world.     

Effect of light,fire and weed control on establishment of <Emphasis Type="Italic">Pericopsis elata</Emphasis> Harms regeneration

Pericopsis elata (a.k.a. African teak) is one of the most valuable timber species in Central Africa. Like other shade intolerant tropical tree species, P. elata could play a vital role in economic development, and ecological sustainability, but regenerates poorly following selective logging. Now endangered, there is a critical need for sustainable silvicultural systems to restore this once prominent timber species. To assess management options for P. elata we analyzed growth performance and survival in primary and secondary forest plots under burning and weeding treatments in Yoko Forest Reserve, Ubundu Democratic Republic of Congo. We transplanted nursery-grown seedlings of P. elata to experimental gaps and followed their growth and survival for 1 year. Seedlings in large canopy gaps 50 × 50 m were taller (mean difference; P = 0.006) and more likely to survive (mean difference; P < 0.001). Weeding improved both diameter (P = 0.024) and height (P = 0.007) growth rates; however, burning alone did not significantly improve the performance of P. elata seedlings. Our data suggest that P. elata regeneration is compatible with shelterwood harvesting and traditional swidden agricultural systems widely practiced in the region.     

Effects of planting food crops on survival and early growth of timber trees in eastern Panama

Restoration of degraded pasture lands in the tropics through afforestation is widely supported. The greatest obstacle to afforestation, however, is the long delay before initial financial returns from wood harvesting are realized. Interplanting young trees with food or energy crops has been proposed as a strategy to help overcome this obstacle. We investigated the impact of this practice on the survival and growth performance of young tropical tree seedlings in Panama. Five native timber tree species and the exotic species Tectona grandis were interplanted with four different crop rotations and monitored over 2 years. Survival of young tree seedlings was up to eight times higher when planted in association with Manihot esculenta. Only during the first 3 months after maize sowing was a significant negative effect of intercropping on tree seedling survival found. Here, survival rate of tree seedlings was up to four times lower than in the pure plantation. Tree growth was not adversely affected by crops. In fact, Astronium graveolens, Cedrela odorata and Terminalia amazonia showed significantly superior growth performance in association with both Zea mays and Cajanus cajan. When combined with the latter, the height increment of these tree species was up to four times that achieved in pure plantations. We conclude that intercropping can be an important silvicultural practice to facilitate forest restoration. Multi-purpose shrubby crop species with cropping cycles of more than 6 months are particularly beneficial, as they quickly shade out grasses, thus reducing the need for herbicides.     

Diversity and structural composition of species in dipterocarp forests: a study from Fasiakhali Wildlife Sanctuary,Bangladesh

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large,old Garjan(Dipterocarpus spp.)trees.The present study assessed composition,structure and diversity of the species in this protected area.A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 families.The forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance indices.Dipterocarpus turbinatus was the most dominant species with maximum relative density,frequency,dominance,and importance value index.Syzygium firmum and Tectona grandis followed in terms of dominance.The structural composition indicated higher number of individuals in the medium growth classes(41 to 511 cm DBH and 16–20 m height ranges),whereas D.turbinatus was the only species that dominated most of the growth classes.Poor stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation,increased grazing and encroachments.This study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of Bangladesh.It will also contribute to identifying threatened plants to undertake D.turbinatus based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.     

Efficiency of sample-based indices for spatial pattern recognition of wild pistachio (<Emphasis Type="Italic">Pistacia atlantica</Emphasis>) trees in semi-arid woodlands

The efficiency of sample-based indices proposed to quantify the spatial distribution of trees is influenced by the structure of tree stands, environmental heterogeneity and degree of aggregation. We evaluated 10 commonly used distance-based and 10 density-based indices using two structurally different stands of wild pistachio trees in the Zagros woodlands, Iran, to assess the reliability of each in revealing stand structure in woodlands. All trees were completely stem-mapped in a nearly pure (40 ha) and a mixed (45 ha) stand. First, the inhomogeneous pair correlation function [g(r)] and the Clark–Evans index (CEI) were used as references to reveal the true spatial arrangement of all trees in these stands. The sampled data were then evaluated using the 20 indices. Sampling was undertaken in a grid based on a square lattice using square plots (30 m × 30 m) and nearest neighbor distances at the sample points. The g(r) and CEI statistics showed that the wild pistachio trees were aggregated in both stands, although the degree of aggregation was markedly higher in the pure stand. Three distance- and six density-based indices statistically verified that the wild pistachio trees were aggregated in both stands. The distance-based Hines and Hines statistic (h _t ) and the density-based standardised Morisita (I _p ), patchiness (IP) and Cassie (C _A ) indices revealed aggregation of the trees in the two structurally different stands in the Zagros woodlands and the higher clumping in the pure stand, whereas the other indices were not sensitive enough.     

Radial growth of <Emphasis Type="Italic">Cinnamomum kanehirae</Emphasis> Hayata displays a larger temperature sensitivity in dominant than codominant trees

Key message

The radial wood growth curves of Cinnamomum kanehirae Hayata (an endangered species of subtropical Taiwan) exhibit an S shape. The dominant trees displayed a larger radial growth than the codominant trees, and their growth was more sensitive to air temperature.

Context

Knowledge of wood radial growth is important for evaluating the factors that limit tree growth performance. The relevant experiments have mostly been conducted in cold and temperate ecosystems, but rarely in subtropical ecosystems.

Aims

In this study, we aimed to construct a unified radial growth model for Cinnamomum kanehirae Hayata and to identify its sensitivity to temperature.

Methods

The wood radial increments were quantified for 3 years by either pinning or microcoring. The radial wood growth curves were modelled integratively by semiparametric regression and individually by curve fitting. The effects of tree social class, interannual and environmental factors on radial growth were analysed quantitatively.

Results

A unified S-shaped growth model for C. kanehirae was successfully constructed. By including the social class effect, the model was significantly improved. The maximum radial increment (A) was significantly correlated with the maximum growth rate (μ); both A and μ were significantly higher in dominant than in codominant trees. The time-varying radial growth rate was more sensitive to air temperature in dominant than in codominant trees.

Conclusion

Semiparametric models revealed an S-shaped growth curve of C. kanehirae and confirmed the higher temperature sensitivity of dominant trees compared to codominant trees in humid subtropical areas.

     

Flammability of some companion species in cork oak (<Emphasis Type="Italic">Quercus suber</Emphasis> L.) forests

Key message

The high flammability of some companion species in Quercus suber forests, estimated in laboratory tests, could potentially generate an increase in fire vulnerability and in fire risk.

Context

Recurrent wildfire is one of the main causes of forest degradation, especially in the Mediterranean region. Increased fire frequency and severity due to global change could reduce the natural resilience of cork oak to wildfire in the future. Hence, it is important to evaluate the flammability of companion species in cork oak forests in the particularly dry bioclimatic conditions of North Africa.

Aims

This study aimed to assess and compare flammability parameters at laboratory scale among ten companion frequent species in cork oak forests.

Methods

Fuel samples were collected in a cork oak (Quercus suber L) forest in the southern part of the mountains of Tlemcen (Western Algeria). A series of flammability tests were carried out using a Mass Loss Calorimeter device (FTT ®). A cluster analysis to classify flammability of the selected species was conducted using the K-means algorithm.

Results

The results revealed differences in the four flammability parameters (ignitability, sustainability, combustibility and consumability), in both fresh and dried fine fuel samples from Quercus suber, Pinus halepensis, Quercus ilex, Quercus faginea, Erica arborea, Arbutus unedo, Pistacia lentiscus, Calicotome spinosa, Juniperus oxycedrus and Tetraclinis articulata. Application of the K-means clustering algorithm showed that C. spinosa, T. articulata, J. oxycedrus and P. halepensis are highly flammable because of their high combustibility and sustainability.

Conclusion

The findings identify species that could potentially increase the vulnerability of cork oak forests to forest fires.

     

Physiological regulation of poplar species to experimental warming differs between species with contrasting elevation ranges

Climate warming has resulted in rapid range shifts of plant species, but it is not well known how species with different natural distribution ranges adapt to increase in temperature through physiological adjustment. We experimentally imposed a 1.8 °C increase of air temperature to the cuttings of two common poplar species Populus yunnanensis and Populus szechuanica naturally growing in southwest China using open-top chambers. Populus yunnanensis is distributed along a narrower elevation range compared with P. szechuanica. We determined some key physiological parameters and plant growth regulator activities during the growing season without soil water limitation. Our results showed that a 1.8 °C increase in air temperature increased shoot growth of P. szechuanica through an extension of its growth period but did not affect the growth of P. yunnanensis. Malondialdehyde content, guaiacol peroxidase activities and abscisic acid content increased while indoleacetic acid content decreased in P. yunnanensis. Our results suggest that the two common poplar species in southwest China should be able to adapt to the moderate increase in temperature projected for future climate. The growth of P. szechuanica may benefit through phenological adjustment but a further increase in temperature may inhibit the growth of P. yunnanensis. For poplar plantation management, selecting species with a wide natural distribution range could provide an adaptive alternative for buffering anthropogenic induced increase in temperature and help in sustaining productivity for the long term.     

Contributions to the knowledge of conifer aphid fauna in Turkey and their zoogeographical distribution

The Aphidoidea (Homoptera) has 29 species which attack coniferous trees in Turkey. The family Aphididae has 25 (Aphidinae, 1; Lachninae, 22; Mindarinae, 2) species and the Adelgidae, 4. The tribe Cinarini in Lachninae has alone 22 species most of which are important. Especially Cinara cedri Mimeur on Cedrus libani and C. pilicornis (Hartig) on Picea spp. are harmful species. Schizolachnus pineti (Fabricius) is also very important. An Eastern Palearctic species in the tribe Macrosiphini in Aphidinae, Elatobium momii (Shinji), is numerous on Abies bornmülleriana in Bursa-Uluda? forests. Pineus orientalis (Dreyfus) in the family of Adelgidae (Chermesidae) is the most destructive in our Picea orientalis forests in Artvin area (Eastern Black-Sea Section). 21 species out of 29 aphids on coniferous trees are of European origin; only 4 are Mediterranean, 2 Caucasus and Turkistan, one Eastern Palearctic and one of Cosmopolitan origin.     

Clonal propagation of mastic tree (<Emphasis Type="Italic">Pistacia lentiscus</Emphasis> var. <Emphasis Type="Italic">chia</Emphasis> Duham.) in outdoor beds using different rootstock and grafting techniques

We assessed different rootstocks and grafting techniques to clonally propagate mastic tree (Pistacia lentiscus var. chia). Mastic tree is a dioecious tree but the quantity and quality of the resin secreted by female trees are very low; therefore, male trees that are clonally propagated are used to establish commercial plantations for mastic production. Conventional long branch cuttings for clonal production requires too much materials and has a very low rooting rate. Rooting with tissue culture and green cuttings has also failed outdoors. Grafting of mastic on other Pistacia species has not been tried so far; therefore, this study was aimed at developing grafting methods for the clonal propagation of mastic. P. atlantica and P. lentiscus rootstocks were grafted from 15 February to 15 October every 15 days using three grafting methods and a two-factor randomized block trial design. Early spring (15 February–15 March) proved to be the best time for grafting using either of the rootstocks. The highest grafting success was attained using the scions grafted on P. atlantica from 15 February to 15 March. The best bud-burst percentage was obtained using P. atlantica and P. lentiscus rootstocks.     

Spittlebugs as vectors of <Emphasis Type="Italic">Xylella fastidiosa</Emphasis> in olive orchards in Italy

The recent introduction of Xylella fastidiosa in Europe and its involvement in the Olive Quick Decline Syndrome (OQDS) in Apulia (Salento, Lecce district, South Italy) led us to investigate the biology and transmission ability of the meadow spittlebug, Philaenus spumarius, which was recently demonstrated to transmit X. fastidiosa to periwinkle plants. Four xylem-sap-feeding insect species were found within and bordering olive orchards across Salento during a survey carried out from October 2013 to December 2014: P. spumarius was the most abundant species on non-olive vegetation in olive orchards as well as on olive foliage and was the only species that consistently tested positive for the presence of X. fastidiosa using real-time PCR. P. spumarius, whose nymphs develop within spittle on weeds during the spring, are likely to move from weeds beneath olive trees to olive canopy during the dry period (May to October 2014). The first X. fastidiosa-infective P. spumarius were collected in May from olive canopy: all the individuals previously collected on weeds tested negative for the bacterium. Experiments demonstrated that P. spumarius transmitted X. fastidiosa from infected to uninfected olive plants. Moreover, P. spumarius acquired X. fastidiosa from several host plant species in the field, with the highest acquisition rate from olive, polygala and acacia. Scanning electron microscopy (SEM) revealed bacterial cells resembling X. fastidiosa in the foreguts of adult P. spumarius. The data presented here are essential to plan an effective IPM strategy and limit further spread of the fastidious bacterium.     

Effects of competition and climate variables on modelling height to live crown for three boreal tree species in Alberta,Canada

Using tree data from permanent sample plots and climate data from the ClimateWNA model, mixed-effects height to live crown (HTC) models were developed for three boreal tree species in Alberta, Canada: trembling aspen (Populus tremuloides Michx.), lodgepole pine (Pinus contorta var. latifolia Engelm.) and white spruce (Picea glauca (Moench) Voss). Three model forms, the Wykoff model, a logistic model and an exponential model, were evaluated for each species. Tree height was the most significant predictor of HTC and was used in all models. In addition, we investigated the effects of competition and climatic variables on HTC modelling. Height–diameter ratio and either total stand basal area or basal area of coniferous trees were used as competition measures in the models. Different climate variables were evaluated, and spring degree-days below 0 °C, mean annual precipitation and summer heat–moisture index were incorporated into the aspen, lodgepole pine and white spruce models, respectively. Site index was only significant in lodgepole pine models. Residual variances were modelled as functions of tree height to account for heteroscedasticity still present in the mixed-effects models after the inclusion of random parameters. Based on model fitting and validation results as well as biological realism, the mixed-effects Wykoff models were the best for aspen and white spruce, and the mixed-effects logistic model was the best for lodgepole pine.     

The populations and distribution of <Emphasis Type="Italic">Pieris japonica</Emphasis>, a poisonous tree protected from herbivore browsing pressure,increase slowly but steadily

Pieris japonica is a poisonous tree species that is rarely eaten by herbivorous animals, a fact that could enable the expansion of its distribution range and influence ecosystems into which it encroaches. In a regional-scale study, 300 P. japonica trees from 13 populations were sampled at the University of Tokyo Chichibu Forest, Japan, and were analyzed using 11 microsatellite markers. Genetic differentiation among the populations was low (F _ST = 0.022 and G′ _ST = 0.024). A plot (30 × 30 m) was established for a fine-scale study, in which all P. japonica trees and saplings were measured and genetically analyzed using the microsatellite markers. Using this approach, we detected 84 genotypes among the 121 P. japonica trees in the plot. A few genotypes had expanded by more than 5 m, indicating that the ability to reproduce asexually could facilitate P. japonica trees to remain in a given location. Autocorrelation analysis showed that the extent of nonrandom spatial genetic structure was approximately 7.0 m, suggesting that seed dispersal was limited. KINGROUP analyses showed that 44 genotype pairs were full siblings, 23 were half-siblings, and 40 were parent-offspring. Only 32 seedlings were observed, of which 15 had reproduced asexually. The number of P. japonica trees has been increasing gradually for more than half a century in our study areas.     

Fungal root pathogen (<Emphasis Type="Italic">Heterobasidion parviporum</Emphasis>) increases drought stress in Norway spruce stand at low elevation in the Alps

Tree-ring patterns of Picea abies (L.) Karst. both unaffected and affected by Heterobasidion parviporum were analysed in three mature stands located at different elevations in the Eastern Alps. The main objectives were (1) to clarify the role of climatic conditions on infected trees; (2) to estimate indirect volume losses due to the prolonged presence of the fungus within the wood. The low elevation site showed the highest growth decline in the last decade, whereas all infected trees at medium and high elevation showed a slow growth decline over many decades. We hypothesise that infection could be dated over 80 years at the highest site. Fungal attack made P. abies more susceptible to drought stress at low elevation site. Both infected and healthy P. abies at medium and high elevation showed similar climate–growth relationships, suggesting that the same driving environmental factors influence their growth. At low elevation, H. parviporum was seemingly more aggressive, causing a more rapid decline, decreasing the ability of host trees to cope with drought and, in some cases, inducing cambial activity to stop. P. abies at higher elevation, however, exhibited a very slow decline and no sign of increasing water stress since the influence of climate on tree growth was the same for both infected and healthy trees.     

Climate and population origin shape pine tree height-diameter allometry

Tree height-diameter allometry, the link between tree height and trunk diameter, reflects the evolutionary response of a particular species’ allocation patterns to above and belowground resources. As a result, it differs among and within species due to both local adaptation and phenotypic plasticity. These phenotypic variations in tree height-diameter allometry determine tree productivity, resistance and resilience to climate variation and, ultimately, the success of plant material used in restoration projects. We tested the effect of climate change and population origin on the phenotypic variation of tree allometry in four pine species at an early stage of development (ca. 11 years old) based upon data originated from multi-site provenance tests and planted along a wide climatic range in south-western Europe. For a representative sample of populations from each species, we used already-developed species-specific height-diameter allometric models to assess changes in allometry between present and future climatic conditions. We found that Pinus halepensis and Pinus pinaster were the most plastic species, while Pinus sylvestris and Pinus nigra showed negligible plastic responses. In addition, our models stressed that pine tree height-diameter allometry will change and phenotypic variation could increase, except in P. sylvestris, under future environmental conditions. For some of the species, this might allow the selection of phenotypes better suited to novel climatic conditions. These foreseeable changes in tree height-diameter allometry (among and within-species) could entail eco-evolutionary effects on the early forest plantation dynamics. Therefore, restoration and reforestation plans should consider these effects, as they may interfere with production and/or environmental goals.     

<Emphasis Type="Italic">Pinus halepensis</Emphasis> somatic embryogenesis is affected by the physical and chemical conditions at the initial stages of the process

Pinus halepensis has been described as a drought-tolerant species with high plasticity to growth in different environments. Its eco-physiological characteristics could facilitate the use of this species in large afforestations in the future scenery of climate change. Somatic embryogenesis is a biotechnological tool with potential for large-scale clonal propagation. In order to establish an improved regeneration protocol for Pinus halepensis, the effects of different temperatures (18, 23, and 28 °C) and water availability conditions (2, 3, and 4 g L^?1 Gelrite^®), during initiation of embryonal masses on the rate of initiation, proliferation, maturation, and the number of embryos developed, were evaluated. It was found that environmental conditions during the initiation stage of Pinus halepensis somatic embryogenesis influence the success of initiation and proliferation. In contrast, there was no effect of these conditions on the maturation rates and the number of somatic embryos. Somatic embryos were obtained in all treatments tested, indicating that plants can be produced from extreme conditions of induction, such as high temperatures (28 °C) and low water availability conditions (4 g L^?1).