Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2011
Authors
Karl Hilding Thunes Fred Midtgaard Lawrence R. Kirkendall Oscar Leveron Vicente EspinoAbstract
Next to expansion of agricultural land and natural disasters, forest fires, illegal logging and bark beetles constitute the largest threat to the pine forests of Central America. Every year, 80-100.000 ha disappears due to the combined activity of the three factors. Natural disasters such as hurricanes and droughts, as well as poor forest management and wildfires lead to a stressed forest which in turn is advantageous for the increase in bark beetle population levels. Epidemic population levels of attacking beetles are able to kill large quantities of forests within weeks. Moreover, dead wood material acts as fuel for wildfires that have escaped control. We propose a monitoring and control regime which aims holistically and directly to the root causes of wildfires, bark beetle outbreaks and subsequent illegal logging in the pine forests of Central America. Monitoring activities focus on community participation and communication, while control of bark beetles is a combination of both long-term sustainable forest management procedures as well as direct and non-destructive control measures of the beetles to reduce their population levels to an endemic level.
Abstract
We used two datasets of 14C analyses of archived soil samples to study carbon turnover in O horizons from spruce dominated old-growth stands on well-drained podzols in Scandinavia. The main data set was obtained from archived samples from the National Forest Soil Inventory in Sweden and represents a climatic gradient in temperature. Composite samples from 1966, 1972, 1983 and 2000 from four different regions in a latitude gradient ranging from 57 to 67º N were analysed for 14C content. Along this gradient the C stock in the O horizon ranges from 2.1 kg m-2 in the north to 3.7 kg m-2 in the southwest. The other data set contains 14C analyses from 1986, 1987, 1991, 1996 and 2004 from the O horizons in Birkenes, Norway. Mean residence times (MRT) were calculated using a two compartment model, with a litter decomposition compartment using mass loss data from the literature for the threefirst years of decomposition and a humus decomposition compartment with a fitted constant turnover rate. We hypothesized that the climatic gradient would result in different C turnover in different parts of the country between northern and southern Sweden. The use of archived soil samples was very valuable for constraining the MRT calculations, which showed that there were differences between the regions. Longest MRT was found in the northernmost region (41 years), with decreasing residence times through the middle (36 years) and central Sweden (28 years), then again increasing in the southwestern region (40 years). The size of the soil organic carbon (SOC) pool in the O horizon was mainly related to differences in litter input and to a lesser degree to MRT. Because N deposition leads both to larger litter input and to longer MRT, we suggest that N deposition contributes significantly to the latitudinal SOC gradient in Scandinavia, with approximately twice as much SOC in the O horizon in the south compared to the north. The data from Birkenes was in good agreement with the Swedish dataset with MRT estimated to 34 years.
Abstract
We used two datasets of 14C analyses of archived soil samples to study carbon turnover in O horizons from spruce dominated old-growth stands on well-drained podsols in Scandinavia. The main data set was obtained from archived samples from the National Forest Soil Inventory in Sweden and represents a climatic gradient in temperature. Composite samples from 1966, 1972, 1983 and 2000 from four different regions in a latitude gradient ranging from 57 to 67oN were analysed for 14C content. Along this gradient the C stock in the O horizon ranges from 2.1 kg m-2 in the north to 3.7 kg m-2 in the southwest. The other data set contains 14C analyses from 1986, 1987, 1991, 1996 and 2004 from the O horizons in Birkenes, Norway. Mean residence times (MRT) were calculated using a two compartment model, with a litter decomposition compartment using mass loss data from the literature for the three first years of decomposition and a humus decomposition compartment with a fitted constant turnover rate. We hypothesized that the climatic gradient would result in different C turnover in different parts of the country between northern and southern Sweden. The use of archived soil samples was very valuable for constraining the MRT calculations, which showed that there were differences between the regions. Longest MRT was found in the northernmost region (41 years), with decreasing residence times through the middle (36 years) and central Sweden (28 years), then again increasing in the southwestern region (40 years). The size of the soil organic carbon (SOC) pool in the O horizon was mainly related to differences in litter input and to a lesser degree to MRT. Because N deposition leads both to larger litter input and to longer MRT, we suggest that N deposition contributes significantly to the latitudinal SOC gradient in Scandinavia, with approximately twice as much SOC in the O horizon in the south compared to the north. The data from Birkenes was in good agreement with the Swedish dataset with MRT estimated to 34 years.
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Authors
Ole Tobias Rannestad May Sæthre Amon P. MaerereAbstract
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Jutta KapferAbstract
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