DSpace Collection: 2009-03
http://hdl.handle.net/2115/38221
2009-032024-03-28T18:29:47ZRaman spectroscopic characterization of Japanese cedar wood heat-treated at low temperatures
http://hdl.handle.net/2115/38225
Title: Raman spectroscopic characterization of Japanese cedar wood heat-treated at low temperatures
Authors: Yamauchi, Shigeru; Koizumi, Akio
Abstract: Raman spectra of Japanese cedar (Cryptomeria japonica) sapwood and heartwood heated at low temperatures (50-160℃) were recorded, and spectral changes of Raman bands due to heat treatment were analyzed through a difference spectrum method. Although the heat treatment intensified fluorescence emitted from heartwood much more strongly than that from sapwood, there was no significant difference in vibrational Raman band contours between sapwood and heartwood. The Raman spectral changes associated with heat treatment of Japanese cedar were quite similar to those of Japanese larch (Larix leptolepis). The most characteristic and important spectral change was a decrease in intensity of the Raman band at 1655 cm^[-1], which can be attributed mainly to stretching vibrations of C=C and C=O groups in lignin molecules. The intensity at 1655 cm^[-1] decreased with increasing heat-treatment temperature and time, and the decrease rate had a strong dependence on water content.2009-02-28T15:00:00ZYamauchi, ShigeruKoizumi, AkioRaman spectra of Japanese cedar (Cryptomeria japonica) sapwood and heartwood heated at low temperatures (50-160℃) were recorded, and spectral changes of Raman bands due to heat treatment were analyzed through a difference spectrum method. Although the heat treatment intensified fluorescence emitted from heartwood much more strongly than that from sapwood, there was no significant difference in vibrational Raman band contours between sapwood and heartwood. The Raman spectral changes associated with heat treatment of Japanese cedar were quite similar to those of Japanese larch (Larix leptolepis). The most characteristic and important spectral change was a decrease in intensity of the Raman band at 1655 cm^[-1], which can be attributed mainly to stretching vibrations of C=C and C=O groups in lignin molecules. The intensity at 1655 cm^[-1] decreased with increasing heat-treatment temperature and time, and the decrease rate had a strong dependence on water content.Photosynthetic productivity of three coniferous species in Baikal Siberia, Eastern Russia
http://hdl.handle.net/2115/38224
Title: Photosynthetic productivity of three coniferous species in Baikal Siberia, Eastern Russia
Authors: Suvorova, Galina G.; Yankova, Ludmila S.; Kopytova, Lidia D.
Abstract: This paper explores changes in photosynthetic productivities of common pine (Pinus sylvestris L.), Siberian spruce (Picea obovata Ledeb.) and Siberian larch (Larix sibirica Ledeb.) during several successive years. Considered are both inter-annual and intra-annual changes, with intra-annual periods defined as early spring (April-May 15), spring-summer (May 16-June 15), summer (June 16-August 31), and autumn (September 1-the first week of November). The study has revealed that high annual photosynthetic productivities in the different species concerned correlates with particular weather conditions during the vegetation periods. The total amount of carbon dioxide assimilated by the two evergreen coniferous species in the early spring, spring-summer and autumn exceeded the amount assimilated in the summer and was as large as 50-70% of the annual value. Meanwhile larch has been found to assimilate more than half of the total annual CO2 in the summer. It is concluded that the characteristics of inter- and intra-annual dynamics of photosynthetic productivity identified in this study offer an opportunity to account for some of the ecosystem-specific features of the coniferous species under investigation, for instance, their ability to co-exist with deciduous plants in mixed communities, as well as the possibility of long-term preservation of boreal ecosystems on the same territories.2009-02-28T15:00:00ZSuvorova, Galina G.Yankova, Ludmila S.Kopytova, Lidia D.This paper explores changes in photosynthetic productivities of common pine (Pinus sylvestris L.), Siberian spruce (Picea obovata Ledeb.) and Siberian larch (Larix sibirica Ledeb.) during several successive years. Considered are both inter-annual and intra-annual changes, with intra-annual periods defined as early spring (April-May 15), spring-summer (May 16-June 15), summer (June 16-August 31), and autumn (September 1-the first week of November). The study has revealed that high annual photosynthetic productivities in the different species concerned correlates with particular weather conditions during the vegetation periods. The total amount of carbon dioxide assimilated by the two evergreen coniferous species in the early spring, spring-summer and autumn exceeded the amount assimilated in the summer and was as large as 50-70% of the annual value. Meanwhile larch has been found to assimilate more than half of the total annual CO2 in the summer. It is concluded that the characteristics of inter- and intra-annual dynamics of photosynthetic productivity identified in this study offer an opportunity to account for some of the ecosystem-specific features of the coniferous species under investigation, for instance, their ability to co-exist with deciduous plants in mixed communities, as well as the possibility of long-term preservation of boreal ecosystems on the same territories.Quantifying sediment production in steepland environments
http://hdl.handle.net/2115/38223
Title: Quantifying sediment production in steepland environments
Authors: De Rose, Ronald C.
Abstract: Five published contributions to our understanding of the impacts of erosion processes on sustainable land management are reviewed and discussed. These focus on rapid shallow landsliding and gully erosion which are among the most prevalent forms of environmental degradation in New Zealand's hill country. The over-arching goal of this research has been to quantify the on-site (e.g., soil erosion, land productivity) impacts of these processes. Rather than measure erosion rates over long periods of time, geomorphic techniques such as 'space-for-time substitution' and paired catchment approaches have been employed to overcome the naturally high spatial and temporal variability in erosion processes. Digital elevation models (DEMs) have proven invaluable as a means of measuring rates of gully erosion and of quantifying landform properties at small and large catchment scales. The spatial variability in shallow landslide erosion, recovery of soil on scar surfaces, and long-term evolution of hillslopes is investigated in an area of sandstone hill country in the North Island of New Zealand, to help elucidate the role that vegetation plays in maintaining slope stability. Hillslope evolution is primarily by landsliding on steep slopes and by diffuse creep processes on gentle slopes, punctuated by periods of slope instability related to climatic and vegetative variability. Variation in slope form near to channels, with over-steepened sideslopes and higher benches, implies a history of fluctuating erosion rates, driven by changes in stream base level. Systematic variation in soil depth and slope angle measured at the hillslope scale implies spatial variability in erosion rates and a landscape that is not in morphologic equilibrium. There is about an order of magnitude difference in long-term erosion rates between relatively steep (> 30°) and gentle (< 30°) hillslopes. Steep slopes are located at the head of 1st-order drainage basins and are more closely coupled to base level changes in the drainage network and erode at about the rate of tectonic uplift. A novel 'paired hillslope' approach is used to directly measure the net loss of soil caused by post-deforestation landslide erosion and conclusively show that, had the forest remained, the landslides would not have occurred. Over an 85-year period since deforestation, average net soil loss per unit hillslope area was 0.15 ± 0.04 m, equivalent to a depletion rate of 1.8 ± 0.5 mm yr^[-1]. The rate was higher at 2.7 ± 0.8 mm yr^[-1] on slopes above 28° where most landslides are concentrated. Contemporary erosion rates are at least 3 to 10 times, or more, the long-term rates of erosion depending on hillslope location. The distribution and average depths of soils to bedrock are measured and used to derive a logarithmic function of increasing soil depth with landslide scar age. The rate of soil recovery is found to diminish with time: from 3.5 mm yr^[-1] over the first 40 years after slipping to 1.2 mm yr^[-1] over the following 50 years. The functional form of the relationship implies continued decrease in the accumulation rate with time. When averaged at the scale of hillslopes, accumulation rates are much less than erosion rates implying that there are semipermanent losses in soil depth and associated soil properties, something that has important consequences for sustainable land management of this landslide prone hill country. A further study investigates the methodology and errors involved in determining the amount of sediment produced from gully complexes in catchments at the headwaters of the Waipaoa River basin. Multi-date DEMs constructed from historical aerial photography are used to determine the volume and mass of sediment produced from gullies of varying size over timescales of decades. Results show that the average denudation rate of gullies is proportional to the square root of gully area: large gullies are producing a disproportionately large amount of sediment, not only because of their larger area, but also because of their higher denudation rates. This simple power-law relationship provides an efficient and quick means of estimating the total amount of sediment producted from gullies (of similar morphology) at the catchment scale, from the measurement of gully area alone, and this has direct application to catchment scale sediment budgets. Many of the smaller gullies were found to have stabilized, became smaller, and reduced in sediment yield after tree plantations were established, demonstrating that reforestation should be a major conservation strategy wherever gully erosion is encountered. Large gullies produce a disproportionately large amount of sediment and are less affected by reforestation. Measured sediment yields from the two largest gullies when compared to the basin yield, demonstrate that these gullies have neither individually nor collectively dominated the sediment budget of the Waipaoa River. This is because greater contributions are made by numerous contemporary gullies and/or by diverse sources in other parts of the Waipaoa River basin. Research findings presented in this paper provide information that is valuable for the sustainable land management of areas subject to accelerated erosion processes. Being able to identify and map areas of land that are sensitive to disturbance, and evaluate the on-site and off-site impacts, is an important part of assessing soil sustainability in these steep topographic settings.2009-02-28T15:00:00ZDe Rose, Ronald C.Five published contributions to our understanding of the impacts of erosion processes on sustainable land management are reviewed and discussed. These focus on rapid shallow landsliding and gully erosion which are among the most prevalent forms of environmental degradation in New Zealand's hill country. The over-arching goal of this research has been to quantify the on-site (e.g., soil erosion, land productivity) impacts of these processes. Rather than measure erosion rates over long periods of time, geomorphic techniques such as 'space-for-time substitution' and paired catchment approaches have been employed to overcome the naturally high spatial and temporal variability in erosion processes. Digital elevation models (DEMs) have proven invaluable as a means of measuring rates of gully erosion and of quantifying landform properties at small and large catchment scales. The spatial variability in shallow landslide erosion, recovery of soil on scar surfaces, and long-term evolution of hillslopes is investigated in an area of sandstone hill country in the North Island of New Zealand, to help elucidate the role that vegetation plays in maintaining slope stability. Hillslope evolution is primarily by landsliding on steep slopes and by diffuse creep processes on gentle slopes, punctuated by periods of slope instability related to climatic and vegetative variability. Variation in slope form near to channels, with over-steepened sideslopes and higher benches, implies a history of fluctuating erosion rates, driven by changes in stream base level. Systematic variation in soil depth and slope angle measured at the hillslope scale implies spatial variability in erosion rates and a landscape that is not in morphologic equilibrium. There is about an order of magnitude difference in long-term erosion rates between relatively steep (> 30°) and gentle (< 30°) hillslopes. Steep slopes are located at the head of 1st-order drainage basins and are more closely coupled to base level changes in the drainage network and erode at about the rate of tectonic uplift. A novel 'paired hillslope' approach is used to directly measure the net loss of soil caused by post-deforestation landslide erosion and conclusively show that, had the forest remained, the landslides would not have occurred. Over an 85-year period since deforestation, average net soil loss per unit hillslope area was 0.15 ± 0.04 m, equivalent to a depletion rate of 1.8 ± 0.5 mm yr^[-1]. The rate was higher at 2.7 ± 0.8 mm yr^[-1] on slopes above 28° where most landslides are concentrated. Contemporary erosion rates are at least 3 to 10 times, or more, the long-term rates of erosion depending on hillslope location. The distribution and average depths of soils to bedrock are measured and used to derive a logarithmic function of increasing soil depth with landslide scar age. The rate of soil recovery is found to diminish with time: from 3.5 mm yr^[-1] over the first 40 years after slipping to 1.2 mm yr^[-1] over the following 50 years. The functional form of the relationship implies continued decrease in the accumulation rate with time. When averaged at the scale of hillslopes, accumulation rates are much less than erosion rates implying that there are semipermanent losses in soil depth and associated soil properties, something that has important consequences for sustainable land management of this landslide prone hill country. A further study investigates the methodology and errors involved in determining the amount of sediment produced from gully complexes in catchments at the headwaters of the Waipaoa River basin. Multi-date DEMs constructed from historical aerial photography are used to determine the volume and mass of sediment produced from gullies of varying size over timescales of decades. Results show that the average denudation rate of gullies is proportional to the square root of gully area: large gullies are producing a disproportionately large amount of sediment, not only because of their larger area, but also because of their higher denudation rates. This simple power-law relationship provides an efficient and quick means of estimating the total amount of sediment producted from gullies (of similar morphology) at the catchment scale, from the measurement of gully area alone, and this has direct application to catchment scale sediment budgets. Many of the smaller gullies were found to have stabilized, became smaller, and reduced in sediment yield after tree plantations were established, demonstrating that reforestation should be a major conservation strategy wherever gully erosion is encountered. Large gullies produce a disproportionately large amount of sediment and are less affected by reforestation. Measured sediment yields from the two largest gullies when compared to the basin yield, demonstrate that these gullies have neither individually nor collectively dominated the sediment budget of the Waipaoa River. This is because greater contributions are made by numerous contemporary gullies and/or by diverse sources in other parts of the Waipaoa River basin. Research findings presented in this paper provide information that is valuable for the sustainable land management of areas subject to accelerated erosion processes. Being able to identify and map areas of land that are sensitive to disturbance, and evaluate the on-site and off-site impacts, is an important part of assessing soil sustainability in these steep topographic settings.Temporal heterogeneity of Populus euphratica seed rain in Ejina Oasis, China
http://hdl.handle.net/2115/38222
Title: Temporal heterogeneity of Populus euphratica seed rain in Ejina Oasis, China
Authors: Cao, Dechang; Li, Jingwen; Chen, Weiqiang; Li, Junqing
Abstract: The seed rain of Populus euphratica in Ejina Oasis was continuously studied in the years of 2004, 2006, 2007, and 2008. The duration of P. euphratica seed rain in a community was usually 2 to 3 weeks, with a peak period of 7 to 14 days. Approximately 90% of the total number of seeds were dispersed in the peak period, and for a single day most seeds fell between the hours of 10:00 to 16:00. It was found that the seed rain of P. euphratica was determined by a combination of biological rhythms and weather conditions. Wind speed and atmospheric humidity were the two main meteorological factors influencing seed dispersal. More seeds fell when there was higher wind speed and lower RH. After we completed our comprehensive study of the P. euphratica seed rain, temporal heterogeneity was found not only in different populations but also in different individuals, and not only in different phases of the seed rain but also in different times of the day. P. euphratica extends its seed rain season by these different kinds of temporal heterogeneity to ensure some propagules survive and germinate when floods occur. Furthermore, marked inter-annual fluctuation in the seed rain exists in P. euphratica in the study area. Finally, in relation to the water supply for P. euphratica in Ejina in recent years, we concluded that there is no dislocation in time of water supply and the seed rain of P. euphratica in Ejina Oasis, and the reason for the failure of sexual reproduction of P. euphratica may lie in the human disturbances of channeling and the cement lining of the channels.2009-02-28T15:00:00ZCao, DechangLi, JingwenChen, WeiqiangLi, JunqingThe seed rain of Populus euphratica in Ejina Oasis was continuously studied in the years of 2004, 2006, 2007, and 2008. The duration of P. euphratica seed rain in a community was usually 2 to 3 weeks, with a peak period of 7 to 14 days. Approximately 90% of the total number of seeds were dispersed in the peak period, and for a single day most seeds fell between the hours of 10:00 to 16:00. It was found that the seed rain of P. euphratica was determined by a combination of biological rhythms and weather conditions. Wind speed and atmospheric humidity were the two main meteorological factors influencing seed dispersal. More seeds fell when there was higher wind speed and lower RH. After we completed our comprehensive study of the P. euphratica seed rain, temporal heterogeneity was found not only in different populations but also in different individuals, and not only in different phases of the seed rain but also in different times of the day. P. euphratica extends its seed rain season by these different kinds of temporal heterogeneity to ensure some propagules survive and germinate when floods occur. Furthermore, marked inter-annual fluctuation in the seed rain exists in P. euphratica in the study area. Finally, in relation to the water supply for P. euphratica in Ejina in recent years, we concluded that there is no dislocation in time of water supply and the seed rain of P. euphratica in Ejina Oasis, and the reason for the failure of sexual reproduction of P. euphratica may lie in the human disturbances of channeling and the cement lining of the channels.