Genetic variation for carbon isotope composition in Juglans regia L.: relationships with growth, phenology and climate of origin

Among the traits of breeding interest for the common walnut tree Juglans regia L., characteristics such as timing of budbreak and leaf fall, water-use efficiency and growth performance are regarded as being of utmost relevance in Mediterranean conditions. The authors evaluated intraspecific variation in $\delta$13C (carbon isotope composition, surrogate of intrinsic water-use efficiency, WUE$_{\rm i}$) for 22 J. regia families grown in a progeny test under supplementary irrigation, and investigated whether such variation correlated with climatic indicators of native habitats. The genetic relationships between $\delta$13C, growth and phenology were also assessed during two consecutive years. Overall, the most water-use-efficient families (i.e. with higher $\delta$13C), which originated mainly from drought-prone provenance regions which have a high vapour pressure deficit and low rainfall, exhibited less height growth and smaller DBH. Using a stepwise regression procedure, $\delta$13C was included as the main explanatory variable of genotypic variation in growth traits, together with growing season duration (for DBH in both years) and flushing (for height in 2007). It was concluded that WUE$_{\rm i}$ is largely unconnected to phenology effects in the explanation of growth performance for J. regia, therefore suggesting the opportunity of simultaneously selecting for low WUE$_{\rm i}$ and extended growing period to maximise productivity in non-water-limited environments.

Spatial variability of tree hight at treeline ecotones in the Pyrenees.

We describe the spatial distribution of tree height of Pinus uncinata at two undisturbed altitudinal treeline ecotones in the southern Pyrenees (Ordesa, O, and Tessó, T). At each site, a rectangular plot (30 x 140 m) was located with its longest side parallel to the slope and encompassing treeline and timberline. At site O, height increased abruptly going downslope with a high spatial autocorrelation at short distances. In contrast, the changes of tree height across the ecotone at site T were gradual, and tree height was less spatially autocorrelated. These results can be explained by the greater importance of wind and snow avalanches at sites O and T, respectively.

Variability of the radius growth at 25 years old Pinus uncinata Miller ex Mirbel in the North-East Spanish Pyrenees

It has been studied the variability of stem radial growth in four radius orientations at the age of 25 years old trees. The species was Pinus uncinata. The sampling sites, located in the North East Spanish Pyrenees belong to different plant communities. An ANOVA analysis was performed in order to find out which factors, the radio orientation, plant community of the site and tree itself are significative or have some kind of influence on the tree radial growth.

Real-time tree-foliage surface estimation using a ground laser scanner

The optimization of most pesticide and fertilizer applications is based on overall grove conditions. In this work we measurements. Recently, Wei [9, 10] used a terrestrial propose a measurement system based on a ground laser scanner to LIDAR to measure tree height, width and volume developing estimate the volume of the trees and then extrapolate their foliage a set of experiments to evaluate the repeatability and surface in real-time. Tests with pear trees demonstrated that the accuracy of the measurements, obtaining a coefficient of relation between the volume and the foliage can be interpreted as variation of 5.4% and a relative error of 4.4% in the linear with a coefficient of correlation (R) of 0.81 and the foliar estimation of the volume but without real-time capabilities. surface can be estimated with an average error less than 5 %.

Caracterización del comportamiento agroforestal de doce genotipos de nogal (Juglans sp.) en dos localidades de Cataluña

El comportamiento agroforestal de 10 genotipos de J. regia y dos híbridos comerciales de Juglans, Ng23xRa y Mj209xRa, se ha evaluado desde 1995 a 2000 en dos localidades: Massanes (Girona) y Prades (Tarragona). Se establecen tres grupos de genotipos diferenciados de acuerdo a su tasa de crecimiento en altura: 1) crecimiento medio superior a 60 cm/año, que corresponde a los dos híbridos; 2) crecimiento medio de unos 50 cm/año, que corresponde a las progenies de J. regia con brotaciones anteriores al 20 de abril; y 3) crecimiento medio inferior a los 40 cm/año, que corresponde a los genotipos de J. regia con brotación posterior al 20 de abril. La evolución de las progenies en altura y diámetro está significativamente ligada a la localidad. El orden en la clasificación de las progenies por su crecimiento, en altura y en grosor, es prácticamente idéntico en ambas localidades. El diámetro a 2,50 m, al sexto período vegetativo, presenta una dependencia significativa de localidad y genotipo: en Massanes se alcanza un mayor crecimiento que en Prades y el diámetro a 2,50 m de los híbridos es el doble que el del mejor J. regia. La dominancia y la rectitud dependen de los genotipos. Sólo dos J. regia tienen una aptitud forestal aceptable, concretamente dos genotipos italianos, «Bleggiana» y «Boschi Maria Grazia». Los híbridos Ng23xRa y Mj209xRa presentan un mejor comportamiento agroforestal que los genotipos de J. regia estudiados: menor mortalidad en plantación, superiores crecimientos primario y secundario y buena dominancia apical y rectitud.

Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest

A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

Effects of increased drought and selective thinning on growth and resprouting of two coexisting Mediterranean oaks with contrasting leaf habit (Quercus ilex and Quercus cerrioides)

According to the IPCC (2007), the Mediterranean basin is expected to suffer important changes in temperature and precipitation in the next few decades, leading the climate warmer and dryer. Therefore, it is necessary to determine the possible effects of increased drought on species with different structural and physiological traits, to be able to predict possible changes in the structure and composition of Mediterranean forests. Moreover, it will be necessary to assess whether traditional management practices can mitigate the effects of climate change on these forests. The main aim of this study has been to analyze the effects of increased drought on the mortality, growth and resprouting patterns of two co-occurring Mediterranean oak species with contrasting leaf habit (the evergreen Quercus ilex and the winter-deciduous Quercus cerrioides), and to assess the effects of selective thinning on their response to increased drought. Our results show a differential effect of increased drought between species: no differences were observed in the growth of Q. ilex while Q. cerrioides reduced its growth under increased drought conditions. Selective thinning reduced the negative effects of increased drought on tree growth, although this beneficial effect tended to decrease during the experiment. Our results show that increasing aridity in Mediterranean areas can be a constraining factor for deciduous oaks, thus potentially causing their decline in mixed forests and favouring their substitution by the evergreen congeneric species. However, as seen in this study, management can strongly encourage growth both for deciduous and evergreen species, thus reversing the effects of increased water stress on Mediterranean coppices.

Generational effects on adult height in individual heterogeneity

As adult height is a well-established retrospective measure of health and standard of living, it is important to understand the factors that determine it. Among them, the influence of socio-environmental factors has been subjected to empirical scrutiny. This paper explores the influence of generational (or environmental) effects and individual and gender-specific heterogeneity on adult height. Our data set is from contemporary Spain, a country governed by an authoritarian regime between 1939 and 1977. First, we use normal position and quantile regression analysis to identify the determinants of self-reported adult height and to measure the influence of individual heterogeneity. Second, we use a Blinder-Oaxaca decomposition approach to explain the `gender height gap¿ and its distribution, so as to measure the influence on this gap of individual heterogeneity. Our findings suggest a significant increase in adult height in the generations that benefited from the country¿s economic liberalization in the 1950s, and especially those brought up after the transition to democracy in the 1970s. In contrast, distributional effects on height suggest that only in recent generations has ¿height increased more among the tallest¿. Although the mean gender height gap is 11 cm, generational effects and other controls such as individual capabilities explain on average roughly 5% of this difference, a figure that rises to 10% in the lowest 10% quantile.

Coherent Stranski-Krastanov growth in 1+1 dimensions with anharmonic interactions: An equilibrium study

The formation of coherently strained three-dimensional (3D) islands on top of the wetting layer in the Stranski-Krastanov mode of growth is considered in a model in 1 + 1 dimensions accounting for the anharmonicity and nonconvexity of the real interatomic forces. It is shown that coherent 3D islands can be expected to form in compressed rather than expanded overlayers beyond a critical lattice misfit. In expanded overlayers the classical Stranski-Krastanov growth is expected to occur because the misfit dislocations can become energetically favored at smaller island sizes. The thermodynamic reason for coherent 3D islanding is incomplete wetting owing to the weaker adhesion of the edge atoms. Monolayer height islands with a critical size appear as necessary precursors of the 3D islands. This explains the experimentally observed narrow size distribution of the 3D islands. The 2D-3D transformation takes place by consecutive rearrangements of mono- to bilayer, bi- to trilayer islands, etc., after the corresponding critical sizes have been exceeded. The rearrangements are initiated by nucleation events, each one needing to overcome a lower energetic barrier than the one before. The model is in good qualitative agreement with available experimental observations.

Generational effects on adult height in individual heterogeneity

As adult height is a well-established retrospective measure of health and standard of living, it is important to understand the factors that determine it. Among them, the influence of socio-environmental factors has been subjected to empirical scrutiny. This paper explores the influence of generational (or environmental) effects and individual and gender-specific heterogeneity on adult height. Our data set is from contemporary Spain, a country governed by an authoritarian regime between 1939 and 1977. First, we use normal position and quantile regression analysis to identify the determinants of self-reported adult height and to measure the influence of individual heterogeneity. Second, we use a Blinder-Oaxaca decomposition approach to explain the `gender height gap¿ and its distribution, so as to measure the influence on this gap of individual heterogeneity. Our findings suggest a significant increase in adult height in the generations that benefited from the country¿s economic liberalization in the 1950s, and especially those brought up after the transition to democracy in the 1970s. In contrast, distributional effects on height suggest that only in recent generations has ¿height increased more among the tallest¿. Although the mean gender height gap is 11 cm, generational effects and other controls such as individual capabilities explain on average roughly 5% of this difference, a figure that rises to 10% in the lowest 10% quantile.

Effect of growth selection on morphology in Pirenaica cattle

Twelve variables were identified to define morphology in 109 calves sired by eight Pirenaica bulls widely used in artificial insemination. The effect of selection for weight at 210 days of age (W210) was detected from the regression coefficient between the 12 variables and the selection index for W210 used in the breeding plan. Unbiased estimates of the genetic correlated responses on the morphology were obtained without previously estimating the genetic correlation among traits. In Pirenaica cattle, selection for W210 increased slaughter live weight, chest depth and corporal length. The expected changes on height (withers, back and rump), rump width and thoracic perimeter were lower but positive and statistically significant.

Growth and yield models in Spain: historical overview, contemporary examples and perspectives

En el presente trabajo se presenta una revisión sobre los modelos forestales desarrollados en España durante los últimos años, tanto para la producción maderable como no maderable y, para la dinámica de los bosques (regeneración, mortalidad). Se presentan modelos tanto de rodal completo como de clases diamétricas y de árbol individual. Los modelos desarrollados hasta la fecha se han desarrollado a partir de datos procedentes de parcelas permanentes, ensayos y el Inventario Forestal Nacional. En el trabajo se muestran los diferentes submodelos desarrollados hasta la fecha, así como las plataformas informáticas que permiten utilizar dichos modelos. Se incluyen las principales perspectivas de desarrollo de la modelización forestal en España.

Growth variability of Scots pine (Pinus sylvestris) along a West-East gradient across northern Fennoscandia: a dendroclimatic approach

We performed a spatiotemporal analysis of a network of 21 Scots pine (Pinus sylvestris) ring-width chronologies in northern Fennoscandia by means of chronology statistics and multivariate analyses. Chronologies are located on both sides (western and eastern) of the Scandes Mountains (67°N-70°N, 15°E-29°E). Growth relationships with temperature, precipitation, and North Atlantic Oscillation (NAO) indices were calculated for the period 1880-1991. We also assessed their temporal stability. Current July temperature and, to a lesser degree, May precipitation are the main growth limiting factors in the whole area of study. However, Principal Component Analysis (PCA) and mean interseries correlation revealed differences in radial growth between both sides of the Scandes Mountains, attributed to the Oceanic-Continental climatic gradient in the area. The gradient signal is temporally variable and has strengthened during the second half of the 20th century. Northern Fennoscandia Scots pine growth is positively related to early winter NAO indices previous to the growth season and to late spring NAO. NAO/growth relationships are unstable and have dropped in the second half of the 20th century. Moreover, they are noncontinuous through the range of NAO values: for early winter, only positive NAO indices enhance tree growth in the next growing season, while negative NAO does not. For spring, only negative NAO is correlated with radial growth.

Spatiotemporal variability in radial growth of trees in the Central Pyrenees: climatic and site influences.

To understand how tree growth has responded to recent climate warming, an understanding of the tree-climate-site complex is necessary. To achieve this, radial growth variability among 204 trees established before 1850 was studied in relation to both climatic and site factors. Seventeen forest stands were sampled in the Spanish Central Pyrenees. Three species were studied: Pinus uncinata, Abies alba, and Pinus sylvestris. For each tree, a ring-width residual chronology was built. All trees cross-dated well, indicating a common influence of the regional climate. For the 1952-1993 period, the radial growth of all species, especially P. uncinata, was positively correlated with warm Novembers during the year before ring formation and warm Mays of the year the annual ring formed. Differences in species-stand elevation modulated the growth-climate associations. Radial growth in P. uncinata at high elevation sites was reduced when May temperatures were colder and May precipitation more abundant. In the 20th century, two contrasting periods in radial growth were observed: one (1900-1949) with low frequency of narrow and wide rings, low mean annual sensitivity, and low common growth variation; and another (1950-1994) with the reverse characteristics. The increased variability in radial growth since the 1950s was observed for all species and sites, which suggests a climatic cause. The low shared variance among tree chronologies during the first half of the 20th century may result from a"relaxation" of the elevation gradient, allowing local site conditions to dominate macroclimatic influence. These temporal trends may be related to the recently reported increase of climatic variability and warmer conditions. This study emphasizes the need to carefully assess the relationships between radial growth and site conditions along ecological gradients to improve dendroclimatic reconstructions.

Disentangling the formation of contrasting tree line physiognomies combining model selection and Bayesian parameterization for simulation models.

Alpine tree-line ecotones are characterized by marked changes at small spatial scales that may result in a variety of physiognomies. A set of alternative individual-based models was tested with data from four contrasting Pinus uncinata ecotones in the central Spanish Pyrenees to reveal the minimal subset of processes required for tree-line formation. A Bayesian approach combined with Markov chain Monte Carlo methods was employed to obtain the posterior distribution of model parameters, allowing the use of model selection procedures. The main features of real tree lines emerged only in models considering nonlinear responses in individual rates of growth or mortality with respect to the altitudinal gradient. Variation in tree-line physiognomy reflected mainly changes in the relative importance of these nonlinear responses, while other processes, such as dispersal limitation and facilitation, played a secondary role. Different nonlinear responses also determined the presence or absence of krummholz, in agreement with recent findings highlighting a different response of diffuse and abrupt or krummholz tree lines to climate change. The method presented here can be widely applied in individual-based simulation models and will turn model selection and evaluation in this type of models into a more transparent, effective, and efficient exercise.