Abstract:
Forests are a vital source of food, fuel, and medicine and play a crucial role in climate
change mitigation. Strategic and policy decisions on forest management and conservation require
accurate and up-to-date information on available forest resources. Forest inventory data such as
tree parameters, heights, and crown diameters must be collected and analysed to monitor forests
effectively. Traditional manual techniques are slow and labour-intensive, requiring additional personnel,
while existing non-contact methods are costly, computationally intensive, or less accurate.
Kenya plans to increase its forest cover to 30% by 2032 and establish a national forest monitoring
system. Building capacity in forest monitoring through innovative field data collection technologies
is encouraged to match the pace of increase in forest cover. This study explored the applicability of
low-cost, non-contact tree inventory based on stereoscopic photogrammetry in a recently reforested
stand in Kieni Forest, Kenya. A custom-built stereo camera was used to capture images of 251 trees in
the study area from which the tree heights and crown diameters were successfully extracted quickly
and with high accuracy. The results imply that stereoscopic photogrammetry is an accurate and
reliable method that can support the national forest monitoring system and REDD+ implementation.