Wyniki wyszukiwania - Biblioteka Nauki

1

Age and climate sensitivity of radial growth of Picea crassifolia to climate in a transitional climatic zone in Northwest China

100%

Zhang L. , Jiang Y. , Zhao S. , Zhang W.

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nr 2

EN

Study of the radial growth response to climate factors at different tree ages is essential for predicting forest dynamics and formulating correct management policies. In this study, we analysed the growth responsiveness of Picea crassifolia to climate conditions, and evaluated its relationship to tree age at the individual tree scale, in the transitional zone between regions affected by the East Asian monsoon and winds blowing from the west (westerlies) in the Qilian Mountains. On three study sites, 150 cores were taken from 75 trees. Pearson correlation coefficients were calculated between the standardized tree-ring series of each core (and chronology) and climatic factors which were utilized to research the climate-growth relationships. Quadratic polynomial fitting was used to test the relationships between tree age, chronological parameters, and the radial growth response to climate. Radial growth was positively influenced by total precipitation for the previous July-September and the current May-July. Additionally, radial growth was negatively correlated with the total monthly precipitation for the current September, and the mean monthly temperature for the previous July. Trees younger than 80 years old showed a stronger response to accumulative precipitation in the previous July-September, those older than 160 years old showed a stronger response to precipitation at the end of current growing season, while those of 140–160 years old showed a weaker response to precipitation in the current May-July.

2

Radial growth responses of Pinus halepensis Mill. and Pinus pinea l. forests to climate variability in western Albania

100%

Toromani E. , Pasho E. , Alla A. Q. , Mine V. , Çollaku N.

Geochronometria

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2015

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tom Vol. 42, no.1

91--99

EN

In this study are presented chronologies of earlywood (EW), latewood (LW) and tree-ring widths (RW) of a Pinus halepensis (P. halepensis) and Pinus pinea (P. pinea) natural forest stand growing in western Albania. Bootstrapped correlations and pointer year analysis were combined in a dendroclimatological study to evaluate climate-growth relationships in both pine species as well as to assess the spatial outreach of our chronologies evaluating them with those of the same species from other Mediterranean countries. We found that both species responded positively to precipitation and Indexed Percentage Average Precipitation (%AvP) in late summer-early autumn, particularly the LW, whereas summer temperatures constrained the growth of P. halepensis tree-ring features. Current January temperature and Potential Evapotranspiration (PET) showed positive relationship with P. pinea LW and RW. The same association was observed when considering PET in spring and P. halepensis LW and RW. Pointer year analysis showed that inhibitory climatic drivers of radial growth for both species were low precipitation from previous winter and current summer, associated with low temperatures during autumn. Our P. halepensis chronology showed a wider spatial outreach than that of P. pinea when compared to those from other Mediterranean countries. We conclude that current January temperatures and September precipitation are very important for P. pinea growth influencing both EW and LW growth whereas P. halepensis is mostly affected by the summer-early autumn climate conditions.

3

Different responses of the radial growth of conifer species to increasing temperature along altitude gradient: Pinus tabulaeformis in the Helan Mountains (Northwestern China)

84%

Zhang L. , Jiang Y. , Zhao S. , Dong M. , Chen H. Y. H. , Kang X.

Polish Journal of Ecology

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2016

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tom 64

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nr 4

EN

Linking the response of tree growth to global warming is a key to fully appreciating the impact of climate change on forests. To examine the impacts of temperature and precipitation on tree growth, we studied the radial growth of Pinus tabulaeformis along an altitude gradient from 2032 m a.s.l. to 2361 m a.s.l. on the Helan Mountains, which is almost the northwestern limit of P. tabulaeformis distribution in China. The results showed that, radial growth of P. tabulaeformis decreased significantly (P <0.05) at the low altitude (2032 m a.s.l.) and remained almost steady at the middle and high altitude (2200 m a.s.l. and 2361 m a.s.l.) during the past decades, which was attributed to different climate-radial growth relationships at different altitudes. Total precipitation from the previous July to the current June was an important and effective climatic factor for radial growth at all altitudes. Radial growth was negatively correlated with the mean temperature of the current March at the low altitude and was positively and negatively correlated with the mean temperature of the previous October and the current July at the high altitude, respectively. Increasing temperature of the March under the context of global warming was the main reason for growth reduction at the low altitude. Radial growth at the middle and high altitudes didn't suffer from global warming. It was inferred that conifers at low altitudes of the species' dry distribution limit were more vulnerable to global warming. To cope with possible intensified drought in the growing season and growth reduction in the future, thinning and afforestation should be carried out in the forests, especially at low altitudes.

4

Climate influence on radial growth of Fagus sylvatica growing near the edge of its distribution in Bukk Mts., Hungary

84%

Garamszegi B. , Kern Z.

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2014

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tom 72

EN

Future of beech (Fagus sylvatica L.) in a changing climate is one of the greatest debates in Europe among the studies dealing with the climate change generated xeric limit shifting. We investigated a submontane beech stand’s growth response to climate change in Northern Hungary during the past 60 years following dendrochronological methods. Tree-ring width data were processed using three alternatives of standardization. To recover the basic climate-growth relationships for beech we analyzed the correlation between the tree-ring width indices and monthly precipitation and temperature data, furthermore two drought indices were employed. Late spring-early summer precipitation was the primary climatic factor governing the beech growth at the study site since the early 1950s, while summer heat played a secondary obstructive role documented by the significant negative correlation. A 30-years running window correlation was used to identify whether the climate-growth connections changed due to the unfavorable climatic trends. The results indicated no evidence of a distinct decline in radial increment, however, a significant increase in climatic impact on growth has been detected including probable changes and shifts in the vegetation period.

5

Ecology and conservation status of Taxus baccata population in NE Chalkidiki, northern Greece

84%

Katsavou I. , Ganatsas P.

Dendrobiology

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2012

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tom 68

EN

Taxus baccata L. is a rare species threatenedwith extinction in Greece, as in other parts of Europe. This paper deals with the ecological status of the species in the area of NE Chalkidiki northern Greece, where the species appears in one of the greatest populations of the country. Site, standand yew population characteristics were studied in the area that species occupies. Eleven sample plots were marked, and on each plot, the height and diameter at breast height (DBH) were measured for all yew trees, as well as for all the individuals of the rest tree species, with diameter at breast height greater than 4 cm. Tree vitality of all trees was also estimated according to IUFRO classification. Yew radial growth was studied using tree-ring analysis. Tree natural regeneration was investigated within subplots of different dimensions and according to two height classes. Results showed that yew population occurs in stands dominated by beech, presenting a mean density of 301 trees per hectare, with a total population of 430 trees with DBH above 4 cm. It forms the secondary stand, and dominates in the stand understorey, accompanied with Fagus sylvatica and Ilex aquifolium, while it appears rarely in the overstorey. Yew tree vitality was foundto be quite high, and significantly higher than that of beech. Radial growth of the sampled trees follows a slow and constant annual increment gradually decreasing by tree age. Yew natural regeneration was foundto be relatively low, 1341.8 individuals (seedlings and saplings up to 1 m) per hectare. Management and in situ conservation of the species in the area should focus on species protection measures, andon specific silvicultural treatments for creating favourable conditions for species growth.