No abstract

Biomass stored in young forests has enormous potential for the reduction of fossil fuel consumption. However, to ensure long-term sustainability, the measurement accuracy of tree height is crucial for forest biomass and carbon stock monitoring, particularly in young forests. Precise height measurement using traditional field measurements is challenging and time consuming. Remote sensing (RS) methods can, however, replace traditional field-based forest inventory. In our study, we compare individual tree height estimation from Light Detection and Ranging (LiDAR) and Digital Aerial Photogrammetry (DAP) with field measurements. It should be noted, however, that there was a one-year temporal difference between the field measurement and LiDAR/DAP scanning. A total of 130 trees (32 Scots Pine, 29 Norway Spruce, 67 Silver Birch, and 2 Eurasian Aspen) were selected for height measurement in a young private forest in south-east Finland. Statistical correlation based on paired t-tests and analysis of variance (ANOVA, one way) was used to compare the tree height measured with the different methods. Comparative results between the remote sensing methods and field measurements showed that LiDAR measurements had a stronger correlation with the field measurements and higher accuracy for pine (R2 = 0.86, bias = 0.70, RMSE = 1.44) and birch (R2 = 0.81, bias = 0.86, RMSE = 1.56) than DAP, which had correlation values of (R2 = 0.71, bias = 0.82, RMSE = 2.13) for pine and (R2 = 0.69, bias = 1.19, RMSE = 2.08) for birch. The correlation of the two remote sensing methods with the field measurements was very similar for spruce: LiDAR (R2 = 0.83, bias = 0.30, RMSE = 1.17) and DAP (R2 = 0.83, bias = 0.44, RMSE = 1.26). Moreover, the correlation was highly significant, with minimum error and mean difference (R2 = 0.79–0.98, MD = 0.12–0.33, RMSD = 0.45–1.67) between LiDAR and DAP for all species. However, the paired t-test suggested that there is a significant difference (p < 0.05) in height observation between the field measurements and remote sensing for pine and birch. The test showed that LiDAR and DAP output are not significantly different for pine and spruce. Presumably, the time difference in field campaign between the methods was the reason for these significant results. Additionally, the ANOVA test indicated that the overall means of estimated height from LiDAR and DAP were not significantly different from field measurements in all species. We concluded that utilization of LiDAR and DAP for estimating individual tree height in young forests is possible with acceptable error and comparable accuracy to field measurement. Hence, forest inventory in young forests can be carried out using LiDAR or DAP for height estimation at the individual tree level as an alternative to traditional field measurement approaches.

Oil heating systems are abundant in rural Finland and they need to be replaced by renewable energy as Finland aims to be carbon neutral by 2035. Bioenergy, one of the renewable energies, is a common source of energy in Finland as the country is rich in forest resources. In Finland, combined heat and power plants utilize such resource to produce district heat and electricity but Finnish rural areas do not have access to the district heating network. However, there are potential scenarios where community heating could be possible using portable chip-fired heating systems (heat containers). Ultimately, the cost of heating is an important factor for the consumers and the cost of investment is likely to put off any interest from the communities. In this research, we explored the cost and profitability of heat container investments in rural Finland and examined the challenges for the energy transition away from oil heating systems, as well as the opportunities decentralized biomass-fired heating systems might bring. The results of this research indicate that the price of heat produced in heat containers is comparatively higher than district heating, which is commonly used in cities in Finland, but is cost-competitive compared to oil heating depending on the price of oil. For example, the current price of LFO (~1 EUR/l) generates costlier heat than the 300 kW heat container provides. Firing wood pellets in the heat container is not economically viable due to expensive raw material but smaller-sized heat container (110 kW) firing wood chips could provide cost-competitive heat if uptime is raised to >2700 h/year. There are socio-economic impacts and value-added effects on the rural region due to utilization of local resource instead of imported LFO but there remain challenges and barriers such as high initial investment, low investment support and lack of policies focused on decentralised energy enterprises.

No abstract

Portal hypertension results in various complications, gastroesophageal varices being one of them. Although less common than esophageal varices, gastric varices are difficult to obliterate and carry a higher mortality rate when bleeding occurs. They are less amenable to sclerotherapy, endoscopic variceal ligation. Balloon-Occluded Retrograde Transvenous Obliteration (BRTO) has been developed as a minimal invasive procedure to obliterate gastric varices. BRTO is an endovascular procedure where a balloon catheter is inserted into a draining vein of gastric varix, and the sclerosant can be injected into the varices through the catheter during balloon occlusion. We report six cases where BRTO was done for gastric varices obliteration.