Abstract:Mapping of exact tree positions can be regarded as a crucial task of field work associated with forest monitoring, especially on intensive research plots. We propose a two-stage density clustering approach for the automatic mapping of tree positions, and an algorithm for automatic tree diameter estimates based on terrestrial laser-scanning (TLS) point cloud data sampled under limited sighting conditions. We show that our novel approach is able to detect tree positions in a mixed and vertically structured stand with an overall accuracy of 91.6%, and with omission-and commission error of only 5.7% and 2.7% respectively. Moreover, we were able to reproduce the stand's diameter in breast height (DBH) distribution, and to estimate single trees DBH with a mean average deviation of ±2.90 cm compared with tape measurements as reference.

<p>The potential for carbon sequestration (CSP) in soils is limited by several factors like the geological provenience, the climatic conditions and the land management. Based on the methodology provided by FAO, a national map has been developed for Austria. Additionally to the climatic and topographic data provided by FAO, more detailed data sources have been used to increase the accuracy of the map.</p> <p>To model the CSP, scenarios with increasing carbon inputs have been used: Business as Usual (BAU),  plus 5% (low), 10% (medium) and 20% (high) carbon input, projected to 2038 and 2040.  The Austrian Soil Organic Carbon (ASOC) map was used as the starting point for the Soil Organic Carbon (SOC) stocks of the soil in the model.</p> <p>The carbon stocks of Austria's agricultural soils range for the most part between 43 and 103 tC/ha in the BAU scenario, between 43 and 104 tC/ha in the "Low" scenario, between 44 and 105 tC/ha in the "Medium" scenario and between 45 and 108 tC/ha in the "High" scenario. The modelling based on the detailed Austrian data showed the smallest increases in each case (BAU: 43 - 70 tC/ha; Low: 43 - 71 tC/ha; Medium: 44 - 72 tC/ha; High: 45 - 74 tC/ha). The differences between the individual scenarios were also not very pronounced.</p> <p>An evaluation of the results at the regional level allows a basic interpretation of the sequestration potential based on soil and climatic conditions and can be used as a basis for estimating the possible effect of measures that either stabilise or increase the humus content.</p>

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