Wyniki wyszukiwania - Biblioteka Nauki

1

Sinusoidal phase modulating interferometer for real-time surface profile measurement

100%

He G. , Jiang H. , Tan X.

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2008

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tom Vol. 38, nr 2

413-420

EN

The optical interferometry for the surface profile measurement is high accuracy, non-contact, and has a wide application in industry and scientific research. In this paper, a sinusoidal phase modulating (SPM) interferometer to realize real-time surface profile measurement is proposed, and its measuring principle is analyzed theoretically. In the SPM interferometer, the interferencje signal is detected by a high speed image sensor based on a low-speed CCD and a signal processing circuit is used to obtain the phase of each point on the surface. Therefore, the surface profile can be measured real time. The experiments measuring the surface profile of a wedge-shaped optical flat show that the measurement time of the SPM interferometer is less than 10 ms, the repetitive measurement accuracy is 5.2 nm. The experimental results confirm the validity of the SPM interferometer, and the merits of the interferometer is simple structure, high measurement accuracy.

2

Forecasting carbon budget under climate change and CO2 fertilization for subtropical region in China using Integrated Biosphere Simulator (IBIS) model

63%

Zhu Q. , Jiang H. , Liu J. , Peng C. , Fang X. , Yu S. , Zhou G. , Wei X. , Ju W.

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2011

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tom Vol. 59, nr 1

3-23

EN

The regional carbon budget of the climatic transition zone may be very sensitive to climate change and increasing atmospheric CO2 concentrations. This study simulated the carbon cycles under these changes using process-based ecosystem models. The Integrated Biosphere Simulator (IBIS), a Dynamic Global Vegetation Model (DGVM), was used to evaluate the impacts of climate change and CO2 fertilization on net primary production (NPP), net ecosystem production (NEP), and the vegetation structure of terrestrial ecosystems in Zhejiang province (area 101,800 km2, mainly covered by subtropical evergreen forest and warm-temperate evergreen broadleaf forest) which is located in the subtropical climate area of China. Two general circulation models (HADCM3 and CGCM3) representing four IPCC climate change scenarios (HC3AA, HC3GG, CGCM-sresa2, and CGCM-sresb1) were used as climate inputs for IBIS. Results show that simulated historical biomass and NPP are consistent with field and other modelled data, which makes the analysis of future carbon budget reliable. The results indicate that NPP over the entire Zhejiang province was about 55 Mt C yr[^-1] during the last half of the 21st century. An NPP increase of about 24 Mt C by the end of the 21st century was estimated with the combined effects of increasing CO2 and climate change. A slight NPP increase of about 5 Mt C was estimated under the climate change alone scenario. Forests in Zhejiang are currently acting as a carbon sink with an average NEP of about 2.5 Mt C yr[^-1]. NEP will increase to about 5 Mt C yr[^-1] by the end of the 21st century with the increasing atmospheric CO2concentration and climate change. However, climate change alone will reduce the forest carbon sequestration of Zhejiang.s forests. Future climate warming will substantially change the vegetation cover types; warm-temperate evergreen broadleaf forest will be gradually substituted by subtropical evergreen forest. An increasing CO2 concentration willhave little contribution to vegetation changes. Simulated NPP shows geographic patterns consistent with temperature to a certain extent, and precipitation is not the limiting factor for forest NPP in the subtropical climate conditions. There is no close relationship between the spatial pattern of NEP and climate condition.

3

Carbon storage of cycad and other gymnosperm ecosystems in China: implications to evolutionary trends

63%

Ma Y. , Jiang H. , Wang B. , Zhou G. , Yu S. , Peng S. , Hao Y. , Wei X. , Liu J. , Yu Z.

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2009

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tom Vol. 57, nr 4 (2

635-646

EN

Cycads are an ancient lineage of plants that originated in the Permian, which are vital to the interpretation of plant ecology. The evidence in the fossil records indicates that the morphological and anatomical features of cycads are remarkably similar to the extant taxa, which has been instrumental in our understanding the connections between the early origins of seed plants and their present-day counterparts. The cycad ecosystem is an important vegetation type throughout geological time. Research on the ecological function of the cycad plays a significant role in the study of evolutionary ecology. In this study, we investigated the biomass, productivity and total carbon storage (total of vegetation, litter, and soil carbon) of cycad (Cycas panzhihuaensis L. Zhou et S.Y. Yang) ecosystems in the National C. panzhihuaensis Reserve of China (latitude 26[degrees]37', longitude 101[degrees]35', at 1635 m altitude) by applying the site-standard tree sampling harvest. Cycads are considered to be rare and endangered species, and are in the list of key protected wild plants in the world. The National C. panzhihuaensis Reserve is in Southwestern China, which area approximately 1358 ha, growing approximately 20 000 C. panzhihuaensis individuals. 20 sample plots, each 5 x 5 m were established in the spring of 2006. The mean height of cycads within the stand was 0.44 m and the mean basal diameter was 23.2 cm. The biomass and productivity data for other communities was compiled from references published over the past 20 years throughout China. The biomass and productivity of cycad ecosystems (8.102 [plus or minus] 6.880 t C ha[^-1] and 1.183 [plus or minus] 0.975 t C ha[^-1] yr[^-1], respectively) are smaller than tree fern (Alsophila spinulosa (Wall. ex Hook.) R. M. Tryon) or gymnosperm (Pinaceae, Cupressaceae or Taxodiaceae for representative) ecosystems. The community biomass of Pinaceae-, Cupressaceae- or Taxodiaceae-dominated ecosystems are 6.8, 5.4, and 5.3 times larger than the cycad ecosystem, respectively. The productivity of each is 2.3, 2.8 and 3.8 times larger than the cycad ecosystem. Cycad is an ancient dioecious plant. However, the results show that the differences between the biomass of male and female cycads, as well as the productivity, are not significant.

4

Leaf litter decomposition along the temperate - tropical transect (East China) : the influence of stand succession, litter quality and climate

63%

Song X. , Jiang H. , Peng C. , Zhou G. , Chang S. , Yu S. , Ma Y. , Peng S. , Wei X.

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2012

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tom Vol. 60, nr 2

265-276

EN

The relationship between litter decomposition and forest succession in addition to the influence of climate variables on the rate of litter decomposition in forest ecosystems are poorly understood. In this study, the effects of forest successional stages, climate, and litter quality on litter decomposition rates were investigated in five sites located in China. The selected sites cover 29 degrees of latitude from 18[degrees]N to 47[degrees]N and spans more than 5,000 km in length along a temperature gradient that transverses across eastern China. This zonal gradient includes five climate zones from temperate to subtropical to tropical zones. Forest types include broad-leaved Korean pine, deciduous broad-leaved, evergreen broad-leaved, monsoon evergreen broad-leaved, and tropical rain forests. The North-South Transect of Eastern China (NSTEC) is one of fifteen international standard transects setup by Global Change and Terrestrial Ecosystems (GCTE). NSTEC is a key component of the International Geosphere-Biosphere Programme (IGBP). The litterbag method was used in this study to determine mass loss and annual decomposition rates of eight tree species (Pinus massoniana Lamb., Cunninghamia lanceolata (Lamb.) Hook., Schima superba Gardn. et Champ., Cinnamomum camphora (L.) Presl., Cyclobalanopsis glauca (Thunb.) Oerst., C. gracilis (Rehd. et Wils.) Cheng et T. Hong, Michelia chapensis Dandy, and Castanopsis eyeri (Champ.) Tutch. through a timeframe starting in May, 2006, and ending in May, 2008. Litterbags 15 x 15 cm and 0.5 x 1.0 mm mesh were filled with 10 g of leaf litter collected from the subtropical forest region and then placed onto the forest floor in triplicate samples for each eight species in all five sites. Three litterbags per species were retrieved from each of the five sites at two month intervals during the two year experimental period. Results suggest that species litter in the climax stage (C. glauca, C. gracilis, and M. chapensis) tended to decompose faster than those in the pioneer stage (P. massoniana and C. lanceolata). Initial phosphorous (P) and nitrogen (N) concentrations of leaf litter were the most critical variables of litter quality in relation to the impact on the rate of litter decomposition. Litter decomposition at different successional stages was found to be directly related to climatic variables such as mean annual precipitation (MAP) and mean annual temperature (MAT). MAP and initial P and N concentrations could therefore be considered good indicators of rates of decomposition.