Canadian Forest Service Publications
Integration of Landsat time series and field plots for forest productivity estimates in decision support models. 2016. Boisvenue, C.; Smiley, B.P.; Kurz, W.A.; White, J.C.; Wulder, M.A. Forest Ecology and Management, Volume 376, 15 September 2016, pp 284–297. .
Issued by: Pacific Forestry Centre
Catalog ID: 37002
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Forests provide an array of services ranging from forest products to greenhouse gas absorption. The reliability and appropriateness of management decisions concerning ecosystem services and resources are directly correlated with the accuracy and extent of the available information on forests and related dynamics. Historically, forest resource management activities informed by decision support systems, have largely relied on field measurements, often with sparse geographical, temporal, and ecological coverage. In contrast, remotely-sensed data can provide dense temporal coverage over large areas. Landsat data in particular have spatial and temporal characteristics well-suited to capturing forest changes on the landscape. Since 2008 free and open access to analysis-ready data representing more than 40 years of data in the Landsat archive has created new opportunities for forest monitoring. There is however, a need to link forest information generated from remotely-sensed data to the data input needs of decision support systems. Here, we develop such a linkage between field and remotely-sensed observations to characterize one of the main drivers of forest change: growth. The goal of this research is to produce above-ground biomass (AGB) change estimates that integrate the information of re-measured field plots and that of the Landsat time series. Over a large test area (∼3.3 Mha) in Saskatchewan, Canada, we demonstrate how information from a dense Landsat time series (1984–2012) can be used with a network of field plots to estimate change in AGB over the broad geographical, temporal, and ecological range of these forests. Our approach expands forest growth estimation both spatially and temporally, and results in information layers that are directly ingestible in decision support models. Our results show that trends match between the field plots and the remote-sensing-field-combined estimate, but that the more encompassing spatial estimates give more varied and lower average estimates of AGB change for our study region. We hypothesize that integrating both remotely-sensed information and repeated field measurements covers a wider range of ecological conditions, forest productivity, and forest developmental stages present on the landscape and through time than the field plots alone. The next step in our research is to integrate our findings into the forest resource management decision support tools, with the aim of increasingly spatializing what are usually spatially-referenced models. Our findings highlight emergent synergies between complementary data sources that foster the generation of new information products for forest resources management decision support.
Plain Language Summary
Historically we have made forest management decisions based on the information summarized from a series of field plots that monitored forest growth. Due to the difficulty in collecting field information, especially in large expanses of forest like Canadian forests, the number of hectares samples only represented a very small proportion of the actual forested land base, and a short snapshot of growing forests since our forests in Canada growth very slowly. Despite well designed sampling plans, these plots have been shown to fall short of representing the diversity of forests that are under our care. The resources and services we now extract and expect from our forest has also expanded and forest have been shown to change under changing environmental condition, making the field-plot based decisions even less reliable. There is a new source of forest observations now available via new technologies and remote sensing. Some of this information is starting to be used to identify forest disturbances through time to inform decision support, but this information can also inform our decision models that are driven by forest growth. The goal of our research is to produce a forest growth estimate that combines the field plot and remotely-sensed information recently available via the Landsat time series. Our approach expands forest growth estimation both spatially and temporally, and results in information layers that are directly ingestible in decision support models. We hypothesize that integrating both remotely-sensed information and repeated field measurements covers a wider range of ecological conditions, forest productivity, and forest developmental stages present on the landscape and through time than the field plots alone.