Entity

Time filter

Source Type


Feurdean A.,Senckenberg Institute | Tantau I.,Babes - Bolyai University | Farcas S.,Romanian Institute of Biological Research
Quaternary Science Reviews | Year: 2011

This paper examines fourteen fossil pollen datasets from Romania. It aims to investigate the temporal and spatial variability in the range distribution and abundance of three forest taxa, Pinus, Picea abies, and Quercus, during the Holocene. This is essential for understanding their current status in the forests of Eastern Europe, the conditions under which they arose, and the timing and processes responsible for their variability. Results from this synthesis do not indicate any apparent time lag in the establishment of Pinus diploxylon type (Pinus sylvestris and Pinus mugo), Pinus cembra, P. abies, and Quercus across Romania within the limits of the dating resolution. However, the onset of the mass expansion of P. abies was not uniform, spreading earlier from sites in the western and north-western Carpathians (11,000-10,500 yr BP) than in the east (10,000 yr BP). We found that sites from the western, north-western, and northern Carpathians contained higher abundances of P. abies, whilst Quercus was in higher abundances in sites from the east, but there was no regional distinctiveness in the abundance of Pinus across the study area. However, P. diploxylon type was found in much higher abundance than P. cembra. Additionally, results indicate a greater proportion of Pinus (mainly P. diplxylon type) at high elevations, P. abies at mid to high elevations, and Quercus at low elevations (<500 m). The dominance of Pinus in the early Holocene boreal forest is likely the legacy of its local glacial refugia, fast life history strategies, high stress tolerance, and large habitat availability. In contrast, Pinus exhibited poor competitive abilities and was quickly replaced with P. abies and temperate deciduous taxa after 10,500 yr BP. P. abies has persisted in large abundances at higher elevations (above 1000 m) until the present day, as a result of good competitive abilities, and resilience to climate change and disturbance. The long-term dominance of P. abies appears to have been spatially constrained, as populations below ca 1000 m were replaced by Fagus sylvatica from ca 4000 years ago, Recently, Pinus (mainly P. sylvestris) and P. abies have both experienced range expansions a consequence of forest management. Quercus is the only continental deciduous tree that has maintained high abundance throughout the whole Holocene. Members of this genus demonstrated high resilience to climate change and disturbance; following a period of decline it was capable of recovery during subsequent intervals of warm conditions or disturbance. © 2011 Elsevier Ltd. Source


Feurdean A.,Senckenberg Institute | Feurdean A.,Romanian Academy Emil Racovita Institute of Speleology | Tamas T.,Romanian Academy Emil Racovita Institute of Speleology | Tamas T.,Babes - Bolyai University | And 2 more authors.
Journal of Biogeography | Year: 2012

Aim We used fossil records to explore patterns of change in vegetation composition, turnover and diversity along an elevational gradient during the late-glacial to early Holocene, and to locate the elevations most sensitive to past climate changes. Location Romania. Methods Changes in the late-glacial vegetation communities were inferred from seven published pollen records distributed within the main vegetation belts of the Romanian Carpathians, at elevations from 275 to 1840m. Principal components analysis, detrended canonical correspondence analysis (DCCA) and rarefaction analysis were undertaken on these data. Results DCCA indicates that compositional change is strongest (SD 1.2, c.70%) at the late-glacial/Holocene transition (c.11,500cal. yr bp), but significant shifts also occur at c.14,700, c.13,800 and c.12,700cal. yr bp (SD 0.4-0.8, 25-50%). Palynological turnover is greater for mid-elevation records (730-1100m) than at low and high elevations. Intervals of greater palynological richness occur between c.13,800 and 12,500cal. yr bp and after 11,500cal. yr bp, and intervals of lower richness occur before c.14,000cal. yr bp and between c.12,900 and 11,500cal. yr bp. Main conclusions Variations in species composition during repeated climate changes of the late-glacial suggest that community composition at a given time was not only a result of the environmental conditions of that period, but also the legacy of previous cumulative recruitment and extirpation events. Turnover estimates suggest that mid-elevations have been the most sensitive to climate change during the late-glacial and early Holocene. Palynological richness estimates show a less clear elevational pattern and no evidence for a greater sensitivity of this measure of biodiversity at high elevations to past climate change. However, results may have been affected by taxa with high pollen productivity and distance dispersability. Our finding concurs with other palaeoecological and local-scale modelling studies in suggesting that small populations have survived in favourable microhabitats embedded within larger unsuitable areas during the late-glacial, features not captured by broad-scale model predictions. © 2011 Blackwell Publishing Ltd. Source


Callaway R.M.,University of Montana | Waller L.P.,University of Montana | Diaconu A.,Romanian Institute of Biological Research | Pal R.,University of Pecs | And 3 more authors.
Ecology | Year: 2011

The greater abundance of some exotic plants in their nonnative ranges might be explained in part by biogeographic differences in the strength of competition, but these competitive effects have not been experimentally examined in the field. We compared the effects of neighbors on the growth and reproduction of spotted knapweed (Centaurea stoebe) in Europe, where it is native, and in Montana, where it is invasive. There were strong negative competitive effects of neighboring vegetation on C. stoebe growth and reproduction in Europe. In contrast, identical experiments in Montana resulted in insignificant impacts on C. stoebe. Although the mechanisms that produce this dramatic biogeographic difference in competitive outcome remain unknown, our results indicate that differences in net competitive interactions between ranges may contribute to the striking dominance of C. stoebe in parts of North America. © 2011 by the Ecological Society of America. Source


Valimareanu S.,Romanian Institute of Biological Research
Notulae Botanicae Horti Agrobotanici Cluj-Napoca | Year: 2010

Reliable methods of transferring cloned genes into plants are essential for engineering crops with desired traits. In order to induce sap-sucking insect resistance Agrobacterium tumefaciens LBA 4404 (1065) strain containing the binary vector pMOG 23 and hypervirulent pTOK 47 plasmid was used. pta (Pinellia ternata agglutinin), salmon ct (calcitonin) and cgrp (calcitonin gene related protein) genes were successfully integrated into Lactuca sativa plants. This genetic modification conferred lettuce resistance to orthopteran and homopteran insects like Nilaparvata lugens Stl or Myzus persicae Sulzer. Lactuca sativa could be routinely transformed using Ti plasmids of A. tumefaciens containing a chimeric kanamycin resistance gene (nos nptII. nos). Source


Muntean C.M.,Romanian Institute of Isotopic And Molecular Technology | Leopold N.,Babes - Bolyai University | Halmagyi A.,Romanian Institute of Biological Research | Valimareanu S.,Romanian Institute of Biological Research
Journal of Raman Spectroscopy | Year: 2011

Ultrasensitive Raman measurements of nucleic acids are possible by exploiting the effect of surface-enhanced Raman scattering (SERS). In this work, the vibrational spectra of eight genomic DNAs from in vitro grown apple leaf tissues (Malus domestica Borkh., Fam Rosaceae, cvs. Florina, Idared, Rebra, Goldrush, Romus 3, Romus 4 and the rootstocks M9 and M26) were analyzed using surface-enhanced Raman spectroscopy, in the wavenumber range 200-1800 cm -1. SERS signatures, spectroscopic band assignments and structural interpretations of these plant genomic DNAs are reported. Strong dependences of the SERS spectra on genomic DNA amount in the measured sample volume and on time were observed. Similarities of the SERS signals of DNAs from Rebra and Romus 3 leaves were detected. To our knowledge, this is the first SERS study on genomic DNA from leaf tissues. The present work provides a basis for future use of surface-enhanced Raman spectroscopy to analyze specific plant DNA-ligand interactions or DNA structural changes induced by plants' stress conditions associated with their natural environment. Besides, this study will generate information that is valuable in the development of low-level plant DNA-based analytical sensors. Eight genomic DNAs from leaves of in vitro grown apple plants have been analyzed using surface-enhanced Raman spectroscopy. SERS signatures, spectroscopic band assignments and structural interpretations of these genomic DNAs are reported. Copyright © 2010 John Wiley & Sons, Ltd. Source

Discover hidden collaborations