The wealth of complementary data available from remote sensing missions can hugely aid efforts towards accurately determining land use and quantifying subtle changes in land use management or intensity. This study reviewed 112 studies on fusing optical and radar data, which offer unique spectral and structural information, for land cover and use assessments. Contrary to our expectations, only 50 studies specifically addressed land use, and five assessed land use changes, while the majority addressed land cover. The advantages of fusion for land use analysis were assessed in 32 studies, and a large majority (28 studies) concluded that fusion improved results compared to using single data sources. Study sites were small, frequently 300–3000 km 2 or individual plots, with a lack of comparison of results and accuracies across sites. Although a variety of fusion techniques were used, pre-classification fusion followed by pixel-level inputs in traditional classification algorithms (e.g., Gaussian maximum likelihood classification) was common, but often without a concrete rationale on the applicability of the method to the land use theme being studied. Progress in this field of research requires the development of robust techniques of fusion to map the intricacies of land uses and changes therein and systematic procedures to assess the benefits of fusion over larger spatial scales.
Wild food constitutes a substantial part of household food consumption around the world, but rapid land use changes influence the availability of wild foods, which has implications for smallholders' food and nutrient intake. With increasing commercial agriculture and biodiversity conservation efforts in forested tropical regions, many shifting cultivation systems are being intensified and their extent restricted. Studies examining the consequences of such pressures commonly overlook the diminishing role of wild food. Using a combination of collection diaries, participant observation, remote sensing, and interviews, we examined the role of agriculture-forest landscapes in the provision of wild food in rapidly transforming shifting cultivation communities in northern Laos. We found that wild food contributed less to human diets in areas where pressure on land from commercial agriculture and conservation efforts was more intense. Our results demonstrate that increasing pressure on land creates changes in the shifting cultivation landscape and people's use thereof with negative effects on the quality of nutrition, including protein deficiency, especially in communities adjacent to core conservation areas. Our study shows the importance of adopting a more nutrition-sensitive approach to the linkages between commercial agriculture and biodiversity conservation (and the policies that promote them), wild food provisioning, and food security
Earth Observation (EO) data is a critical information source for mapping and monitoring water resources over large inaccessible regions where hydrological in-situ networks are sparse. In this paper, we present a simple yet robust method for fusing optical and Synthetic Aperture Radar (SAR) data for mapping surface water dynamics over mainland China. This method uses a multivariate logistic regression model to estimate monthly surface water extent over a four-year period (2017 to 2020) from the combined usages of Sentinel-1, Sentinel-2 and Landsat-8 imagery. Multi-seasonal high-resolution images from the Chinese Gaofen satellites are used as a reference for an independent validation showing a high degree of agreement (overall accuracy 94%) across a diversity of climatic and physiographic regions demonstrating potential scalability beyond China. Through inter-comparison with similar global scale products, this paper further shows how this new mapping technique provides improved spatio-temporal characterization of inland water bodies, and for better capturing smaller water bodies (< 0.81 ha in size). The relevance of the results is discussed, and we find this new enhanced monitoring approach has the potential to advance the use of Earth observation for water resource management, planning and reporting.