Supporting forest inventory in Durango, Mexico by combining in-situ data from cellular phones with satellite image mapping

In this paper, we present a concept how volunteers will gather forest inventory data to be utilized as in-situ data for forest biomass computation from satellite imagery. A VTT-developed forest measurement tool called ‘Relasphone’ will be used to collect in-situ forest inventory data. We will demonstrate the concept in the state of Durango in Mexico that contains natural and managed forest area. We will concentrate on measurements of Cooper’s Pine (Pinus cooperi) trees. The study area includes over 390 permanent sampling plots that will provide reference data for concept validation and verification. Landsat-8 imagery will be used as a proxy for Sentinel-2 data. Forest biomass is widely monitored using a variety of remote sensing data and techniques (Gleason and Im 2011). Remote sensing offers benefits compared to traditional in-situ forest inventories made by experts. One of the main benefits is that the number of ground reference plots can be significantly reduced. Remote sensing of forest biomass can provide reduced costs and time requirement compared to full forest inventories. The amount of biomass in the forests is crucial information for forest owners and managers to understand the value and the use of the forest. The future Biomass mission by ESA, to be launched 2020, aims to take measurements of forest biomass to assess terrestrial carbon stocks and fluxes. The information is needed to understand how forests affect the carbon cycle and climate change. The availability of ground reference data has been a bottleneck in remote sensing analysis over wide forested areas, as the acquisition of this data is an expensive and long process. A report by the Global Forest Observation Initiative (GFOI 2013) identified that many countries suffer from a lack of in-situ calibration and validation data for biomass estimation. Presently the ground data for management plans are collected by forestry professionals, but it can be foreseen that by combining ground based data, UAV (Unmanned Aerial Vehicle) and satellite data, principal material for forest management plans of acceptable quality can be collected without professional foresters’ work on the field. Such opportunity could significantly increase the area coverage of forest management plans, particularly in countries where funds for forest management planning are restricted. Recent advances in information and communication technology (ICT) and increased awareness of the status of the environment, in particular global climate change, have activated people to participate in monitoring (Burke et al. 2006). Nowadays mobile devices are present wherever there are people, which enable new possibilities in building a platform for utilizing citizen observers as a spatially and temporally dense observation network. This opportunity is strengthened by the growing common concern about the state and future of the environment. People are increasingly willing to contribute their time and resources to the analysis and processing of scientifically collected data. This citizen engagement in scientific work – Citizen Science – is becoming more efficient, pervasive and useful with the help of the latest ICT technology. Citizen observations are one promising way to increase both temporal and spatial coverage of collected in-situ forest inventory data. The Relasphone is a forest measurement tool on a mobile phone. The Relasphone concept has been developed in Finland to help forest owners and timber brokers make forest measurements. With the Relasphone application, users gather in-situ forest inventory data including estimated biomass, tree species, tree height and age. The biomass estimation is based on the relascope functionality (Bitterlich 1984). The collected in-situ forest measurements are utilized as a ground reference material for spaceborne or airborne remote sensing data analysis. The measurements are put into a planner engine that outputs forest resources information for every forest stand and feeds them into a GIS. The GPS based location information with measured forest data makes it possible to introduce measurements easily as in-situ reference data. Once the concept is successfully transferred from boreal to tropical forests, it can dramatically change the way forest databases and management plans are produced globally and may lead to major cost reductions. A low-cost solution can increase the coverage of forest management plans particularly in regions where possibilities to invest on expensive planning work are limited. The concept can be easily applied for other purposes that require similar information. The users of this category include the Non-Governmental Organizations that are concerned about nature conservation and illegal cuttings, the European Commission that will fund EU-wide land cover mapping, and the FAO that conducts global survey of forest resources, for instance. One potential commercial use of the tools is the REDD (Reduction of Emissions from avoided Deforestation and Degradation of forests) process that will require inventory of forest resources over wide areas in the tropical zone. For example, in the developing countries inexpensive smart phones and GPS could be given to people free of charge on the condition that they collect data and images from forests to support satellite image mapping that further serves the economy of the country through sustainable use of forest resources. REFERENCES Bitterlich, W. (1984), The Relascope Idea: Relative Measurements in Forestry, Commonwealth Agricultural Bureaux, Farnham Royal. Burke J, Estrin D, Hansen M, Parker A, Ramanathan N, Reddy S, Srivastava M B (2006) Participatory Sensing. In: Proceedings of the International Workshop on World-Sensor-Web (WSW'2006), ACM, Boulder, CO, USA, 31 Oct 2006. Gleason, C. J., Im, J. (2011) A Review of Remote Sensing of Forest Biomass and Biofuel: Options for Small-Area Applications, GIScience & Remote Sensing, 48:2, 141-170. GFOI (2013): Review of Priority Research & Development Topics: R&D Related to the use of Remote Sensing in National Forest Monitoring. Pub. GEO, Switzerland, 2013 ISBN 978-92-990047-5-3.