Wyniki wyszukiwania - Biblioteka Nauki

1

Activated carbon prepared from semi-coke as an effective adsorbent for dyes

100%

Dong M. , Zhou H. , Liu W. , He C.

Polish Journal of Environmental Studies

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2020

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tom 29

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nr 2

2

Effect of alpine treeline conditions on the response of the stem radial variation of Picea meyeri Rebd. et Wils to environmental factors / Manyu Dong [et al.]

88%

Dong M. , Jiang Y. , Zhang W. , Yang Y. , Yang H.

Polish Journal of Ecology

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2011

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tom Vol. 59, nr 4

729-739

EN

Alpine treeline is an important ecological boundary, marked by a change in site conditions and plant communities when crossing the forest limit, and tree growth at treeline is strongly constrained by the harsh environment. Finer resolution studies of tree radial variation on short temporal scales can be useful to explore the main physical variables that trigger the radial growth. From 19th Oct. 2008 to 25th Oct. 2009, we continuously monitored the stem radial variation of Picea meyeri Rebd. Et Wils trees using point dendrometers, at the treeline of Luya Mountains (altitude 2700 m a.s.l.), North China. Our results showed that there were two reverse daily variation patterns in the warm and cold seasons, which were related to the daily transpiration course and daily stem freeze-thaw cycles, respectively. Annual stem radial growth of Picea meyeri was divided into the four distinct periods: 1) spring stem rehydration, 2) summer stem rapid growth, 3) autumn stem dehydration contraction and 4) winter stem stagnation. The stem radial variation of Picea meyeri at the alpine treeline was closely dependent on climate conditions. Soil temperature was the most important factor affecting radial growth, which determined the initiation of radial growth and the cambial activity during the growing season.

3

Seasonal dynamics in cambial activity and the formation of xylem and phloem in the branches of Cinnamomum camphora

88%

Dong M. , Xu Y. M. , Lin H. , Li X. Q. , Xia Q. Q.

Dendrobiology

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2016

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tom 75

EN

The cambial activity and periodicity of secondary xylem and phloem formation have been less studied in tropical tree species than in temperate ones. Cambium activity is the only source of timber production. Studies on its activity and xylem formation can provide helpful data for dendrochronology and possible factors that control tree growth, the yield and quality of wood. Cinnamomum camphora is an important fast-growing tree for furniture and sculpture wood in South China. Its dynamics of cambial activity was not reported. During the growth season in 2011, five trees of Cinnamomum camphora plantation were monitored on the campus of Huazhong Agricultural University in central china (located on 113°41’ to 115°05’ E and 29°58’ to 31°22’ N). Sampling time was from 13, February 2011 to 13, February 2012. Some small stems of 15–20 cm length were selected to sample in the middle of 2–3 years old health branches in the central crown of these trees. The observational study found that the cambium of camphor trees was active from March to October and dormant from November to February. Onset of cambial cell division was observed in early March, one week after sprouting of new buds. The morphology of the cells and number of cell layers in the cambium zone varied throughout the year. In early March, cambium reactivated with the rising of temperature, the cell wall was relative thick. The number of cell layers increased from 2–3 in middle Feb. to 3–5. In June, the number of cell layers in cambium reached the maximum of 5–7 in a radial direction. In mid March, phloem cells began to differentiate, followed by xylem three weeks later. The number of cell layers in immature phloem and xylem increased dramatically before mid June and the increment of cell layers in xylem was almost fifth times of phloem in the differentiating process. The phloem cells mainly stopped dividing new cells in end of October, but xylem cells were still in the activity a week later. The annual activities of cambium was in accordance with the air mean temperature change in 2011–2012. The results showed that the cambial activity and formation of xylem and phloem were related to the environmental factors, especially the temperature.

4

Effect of alpine treeline conditions on the response of the stem radial variation of Picea meyeri Rebd. et Wils to environmental factors

88%

Dong M. , Jiang Y. , Zhang W. , Yang Y. , Yang H.

Polish Journal of Ecology

|

2011

|

tom 59

|

nr 4

EN

Alpine treeline is an important ecological boundary, marked by a change in site conditions and plant communities when crossing the forest limit, and tree growth at treeline is strongly constrained by the harsh environment. Finer resolution studies of tree radial variation on short temporal scales can be useful to explore the main physical variables that trigger the radial growth. From 19th Oct. 2008 to 25th Oct. 2009, we continuously monitored the stem radial variation of Picea meyeri Rebd. Et Wils trees using point dendrometers, at the treeline of Luya Mountains (altitude 2700 m a.s.l.), North China. Our results showed that there were two reverse daily variation patterns in the warm and cold seasons, which were related to the daily transpiration course and daily stem freeze-thaw cycles, respectively. Annual stem radial growth of Picea meyeri was divided into the four distinct periods: 1) spring stem rehydration, 2) summer stem rapid growth, 3) autumn stem dehydration contraction and 4) winter stem stagnation. The stem radial variation of Picea meyeri at the alpine treeline was closely dependent on climate conditions. Soil temperature was the most important factor affecting radial growth, which determined the initiation of radial growth and the cambial activity during the growing season.

5

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

75%

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.

6

Different Responses of the Radial Growth of Conifer Species to Increasing Temperature along Altitude Gradient : Pinus tabulaeformis in the Helan Mountains (Northwestern China)

75%

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

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2016

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tom Vol. 64, nr 4

509--525

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.

7

Climatic Response of Tracheid Features of Picea meyeri Along Altitude Gradient of Luyashan Mountains of North China

75%

Wang M. , Jiang Y. , Zhang W. , Dong M. , Kang M. , Xu H.

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tom Vol. 65, nr 4

345--358

EN

Changing localized environmental conditions along altitude gradients could modify the responses of tree xylem structures to climate variations. To explore how trees adapt to local environment and respond to climate variants, we analysed the variation of Picea meyeri xylem tracheid features and the relationships with climate variables along an altitude gradient (1970, 2240, 2490 and 2650 m above sea level) of the Luyashan Mountains in the North China. The results mainly indicated the following: (1) tracheid number and diameter of P. meyeri showed significant differences among the four sites along the altitude gradient; (2) trees at site 2 (2240 m) and site 3 (2490 m) are similar in age, but the xylem tracheid number and diameter of these trees were significantly different, which may indicate different functional adaptation; (3) the relationships between xylem features' residual chronologies and the monthly climate data were inconsistent along altitude gradients, which indicated that the limiting factor of P. meyeri growth along the altitude gradients, shifted from drought stress at lower altitudes to low-temperature stress at higher altitudes.

8

Climatic response of tracheid features of Picea meyeri along altitude gradient of Luyashan Mountains of North China

75%

Wang M. , Jiang Y. , Zhang W. , Dong M. , Kang M. , Xu H.

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2017

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tom 65

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nr 4

EN

Changing localized environmental conditions along altitude gradients could modify the responses of tree xylem structures to climate variations. To explore how trees adapt to local environment and respond to climate variants, we analysed the variation of Picea meyeri xylem tracheid features and the relationships with climate variables along an altitude gradient (1970, 2240, 2490 and 2650 m above sea level) of the Luyashan Mountains in the North China. The results mainly indicated the following: (1) tracheid number and diameter of P. meyeri showed significant differences among the four sites along the altitude gradient; (2) trees at site 2 (2240 m) and site 3 (2490 m) are similar in age, but the xylem tracheid number and diameter of these trees were significantly different, which may indicate different functional adaptation; (3) the relationships between xylem features' residual chronologies and the monthly climate data were inconsistent along altitude gradients, which indicated that the limiting factor of P. meyeri growth along the altitude gradients, shifted from drought stress at lower altitudes to low-temperature stress at higher altitudes.