Plant Diversity Changes during the Postglacial in East Asia: Insights from Forest Refugia on Halla Volcano, Jeju Island

Understanding how past climate changes affected biodiversity is a key issue in contemporary ecology and conservation biology. These diversity changes are, however, difficult to reconstruct from paleoecological sources alone, because macrofossil and pollen records do not provide complete information about species assemblages. Ecologists therefore use information from modern analogues of past communities in order to get a better understanding of past diversity changes. Here we compare plant diversity, species traits and environment between late-glacial Abies, early-Holocene Quercus, and mid-Holocene warm-temperate Carpinus forest refugia on Jeju Island, Korea in order to provide insights into postglacial changes associated with their replacement. Based on detailed study of relict communities, we propose that the late-glacial open-canopy conifer forests in southern part of Korean Peninsula were rich in vascular plants, in particular of heliophilous herbs, whose dramatic decline was caused by the early Holocene invasion of dwarf bamboo into the understory of Quercus forests, followed by mid-Holocene expansion of strongly shading trees such as maple and hornbeam. This diversity loss was partly compensated in the Carpinus forests by an increase in shade-tolerant evergreen trees, shrubs and lianas. However, the pool of these species is much smaller than that of light-demanding herbs, and hence the total species richness is lower, both locally and in the whole area of the Carpinus and Quercus forests. The strongly shading tree species dominating in the hornbeam forests have higher leaf tissue N and P concentrations and smaller leaf dry matter content, which enhances litter decomposition and nutrient cycling and in turn favored the selection of highly competitive species in the shrub layer. This further reduced available light and caused almost complete disappearance of understory herbs, including dwarf bamboo

Stand structure and regeneration of a mixed forest (Abies alba-Fagus sylvatica) in the Central Pyrenees, Ordesa National Park, Spain

24 páginas, 6 figuras[FR] Dans une parcelle de 1, 4 Ha au versant nord de la vallée d'Ordesa nous avons cartographie à petite échelle et pris des données biométriques sur 2391 hêtres (Fagus sylvatica) et sapins (Abies alba) vivants ou morts mais tous s'élevant à plus de 1,3 m, ainsi que sur 378 arbustes de Buxus sempervirens dans le sous-bois. Puis nous avons tenté quelques hypothèses concernant la structure et la dynamique de la parcelle forestière, la régénération des arbres et leur coexistence. Bien que la parcelle fasse partie d'une vieille forêt peu altérée, dans sa partie inférieure quelques surfaces ont été pâturées. Le sapin montre beaucoup de jeunes individus et progressivement moins d'arbres grande taille, à l'opposé, le hêtre présente un plus grand nombre d'arbres appartenant aux classes de haute taille et de grande ancienneté. En supposant que les deux espèces aient des taux de mortalité similaires, cela indiquerait une tendance vers la dominance du sapin sur l'hêtre. Sur la coexistence de deux espèces écologiquement similaires, deux hypothèses peuvent être avancées: (1) differentiation de niches de régénération et (2) stratèges biologiques différentes (préférence pour la survivance ou la fécondité). Par la voie d'une analyse de type redundancy analysis (RDA) nous avons essayé de découvrir si les deux espèces préféraient des habitats différents. Pour évaluer le rôle de la concurrence entre arbres et son influence sur la dynamique de la forêt, nous nous sommes servis des modèles spatiaux et associations interspécifiques liées à la fonction K de Ripley. Il est vrai que les résultats obtenus peuvent supporter empiriquement les deux hypothèses précitées, mais nous avons démontré comment l'importance de chacune varie suivant le degré d'hétérogénéité environnemental du versant a travers la parcelle et de bas en haut. Les différentes stratégies de vie s'avèrent critiques pour le succès de la coexistence sur des pentes douces à basse altitude, précisément dans les zones oîi les espèces co-dominantes recouvrent leurs niches de régénération.[ES] En una parcela de 1,4 ha de la vertiente N del Valle de Ordesa se cartografiaron detalladamente y se tomaron datos biométricos de 2391 árboles de haya (Fagus sylvatica) y abeto (Abies alba) vivos o muertos -todos ellos de altura superior a 1,3 m- así como de 378 arbustos de Buxus sempervirens en el sotobosque. Se tantearon después varias hipótesis sobre la estructura y dinámica de la parcela forestal, de la regeneración de los árboles y de su coexistencia. Aunque la parcela forma parte de un bosque viejo poco alterado, en su parte inferior alberga algunas áreas que fueron objeto de pastoreo. Abies muestra típicamente muchos individuos jóvenes y progresivamente menor número de árboles en las clases de mayor tamaño, opuestamente, Fagus presenta mayor número de árboles en las clases de mayor tamaño y de mayor edad. Suponiendo que ambas especies tuvieran tasas de mortalidad similares, ello indicaría ima tendencia a dominar el abeto sobre el haya. Respecto a esta coexistencia de dos especies ecológicamente similares, hemos planteado dos hipótesis: (1) diferenciación de nichos de regeneración y (2) desarrollo de estrategias biológicas diferentes (preferencia por la supervivencia o por la fecundidad). Mediante análisis de redundancia (RDA) hemos intentado averiguar si las dos especies prefieren habitats diferentes. Para estimar el papel de la competencia entre árboles de cara a la dinámica del bosque, usamos el análisis de modelos espaciales y asociaciones interespecíficas por medio de la función K de Ripley. Los datos obtenidos dan un soporte empírico a ambas hipótesis, pero hemos podido mostrar que la importancia de cada una de ellas depende del grado de heterogeneidad ambiental que se observa de abajo arriba en la ladera de la parcela. Así, en condiciones ambientales normales, a baja altitud, donde las especies codominantes solapan sus nichos de regeneración, desarrollar estrategias biológicas diferentes resulta crítico para el éxito de su coexistencia.Peer reviewe

Interpolation with Specified Error of a Point Series Belonging to a Monotone Curve

The paper addresses the problem of modeling a smooth contour interpolating a point series belonging to a curve containing no special points, which represents the original curve with specified accuracy. The contour is formed within the area of possible location of the parts of the interpolated curve along which the curvature values are monotonously increased or decreased. The absolute interpolation error of the point series is estimated by the width of the area of possible location of the curve. As a result of assigning each intermediate point, the location of two new sections of the curve that lie within the area of the corresponding output section is obtained. When the interpolation error becomes less than the given value, the area of location of the curve is considered to be formed, and the resulting point series is interpolated by a contour that lies within the area. The possibility to shape the contours with arcs of circles specified by characteristics is investigated

Signatures of post-zygotic structural genetic aberrations in the cells of histologically normal breast tissue that can predispose to sporadic breast cancer

Sporadic breast cancer (SBC) is a common disease without robust means of early risk prediction in the population. We studied 282 females with SBC, focusing on copy number aberrations in cancer-free breast tissue (uninvolved margin, UM) outside the primary tumor (PT). In total, 1162 UMs (1-14 per breast) were studied. Comparative analysis between UM(s), PT(s), and blood/skin from the same patient as a control is the core of the study design. We identified 108 patients with at least one aberrant UM, representing 38.3% of cases. Gains in gene copy number were the principal type of mutations in microscopically normal breast cells, suggesting that oncogenic activation of genes via increased gene copy number is a predominant mechanism for initiation of SBC pathogenesis. The gain of ERBB2, with overexpression of HER2 protein, was the most common aberration in normal cells. Five additional growth factor receptor genes (EGFR, FGFR1, IGF1R, LIFR, and NGFR) also showed recurrent gains, and these were occasionally present in combination with the gain of ERBB2. All the aberrations found in the normal breast cells were previously described in cancer literature, suggesting their causative, driving role in pathogenesis of SBC. We demonstrate that analysis of normal cells from cancer patients leads to identification of signatures that may increase risk of SBC and our results could influence the choice of surgical intervention to remove all predisposing cells. Early detection of copy number gains suggesting a predisposition toward cancer development, long before detectable tumors are formed, is a key to the anticipated shift into a preventive paradigm of personalized medicine for breast cancer.De 2 första författarna delar förstaförfattarskapet.</p

The effect of fire severity on first-year seedling establishment in a Pinus canariensis forest on Tenerife, Canary Islands

The Canarian pine (Pinus canariensis) exhibits a striking combination of high adult resistance to fire and intermediate serotiny. Hence, the study of its post-fire regeneration can support valuable new insights about functional adaptations to fire. Here, we analyse the firstyear seedling establishment after fire in a P. canariensis forest on the northern slope of Tenerife, Canary Islands. The effects of fire severity and other explanatory variables on the seedling density recorded 9 months after fire were examined. We detected a clear unimodal relationship between seedling density and fire severity, with maximum regeneration associated with intermediate fire severity and no regeneration associated with very high crown damage. The results suggested that high severity fires may have caused the partial destruction of the aerial seed bank and/or the creation of unfavourable seedbed conditions for germination and seedling emergence. The density of large pine trees, reflecting seed availability, was the second most important factor explaining the distribution of seedlings. Cover of scorched needle litter on the ground correlated strongly and positively with pine seedling density and negatively with fire severity. The complete lack of regeneration at sites most strongly affected by fire does not represent a major threat for the stand recovery of the Canarian pine, due to the very high tree resistance to fire and the tremendous capacity of the Canarian pine to resprout after fire. The observed very high seedling densities at sites with intermediate fire impacts can probably be related to both the complete liberation of the seed bank (including seeds stored in serotinous cones) and favourable micro-environmental conditions for seed germination and seedling establishment