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Forest canopy gaps are important for the ecosystem dynamics. Depending on tree species, 13 small canopy openings might be also associated to intra-crown porosity and to space between 14 crowns. Yet, little is known on the relationships between the fine-scaled pattern of canopy openings 15 and biodiversity features. This research explored the possibility of i)-mapping forest canopy gaps 16 from a very high resolution orthomosaic (10 cm), processed from a versatile imaging platform such 17 as unmanned aerial vehicles (UAV), ii)-to derive patch metrics that can be tested as covariates of 18 variables of interest for forest biodiversity monitoring. This is attempted in a test area of 240 ha 19 covered by temperate deciduous forest types in Central Italy and containing 50 forest inventory 20 plots of about 530 m 2 . Correlation and linear regression techniques were used to explore 21 relationships between patch metrics and understorey (density, development and species diversity) 22 or forest habitat biodiversity variables (density of micro-habitat bearing trees, vertical species 23 profile, tree species diversity). The results revealed that small openings in the canopy cover (75% 24 smaller than 7 m 2 ) can be faithfully extracted from UAV RGB imagery, using the red band and 25 contrast split segmentation. Highest correlations were observed in the mixed forest (beech and 26 turkey oak), while beech forest had the poorest ones and turkey oak forest displayed intermediate 27 results. Moderate to strong linear relationships were found between gap metrics and understorey 28 variables in mixed forest type, with adjusted R 2 from linear regression ranging from 0.52 to 0.87. 29Equally good results, in the same forest types, were observed for forest habitat biodiversity variables 30 (0.52

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FABIO LOMBARDI (*) (°)-GHERARDO CHIRICI (*)-MARCO MARCHETTI (*) ROBERTO TOGNETTI (*)-BRUNO LASSERRE (*)-PIERMARIA CORONA (**) ANNA BARBATI (**)-BARBARA FERRARI (**)-SILVIA DI PAOLO (**) DIEGO GIULIARELLI (**)-FRANCO MASON (***)

Reliable assessment of forest resource stock, productivity and harvesting is a commonly agreed objective of environmental monitoring programs. Distinctively, the assessment of wood harvesting has become even more relevant to evaluate the sustainability of forest management and to quantify forest carbon budget. This paper presents the development and testing of procedures for assessing forest harvesting in coppice forests by very high resolution (VHR) satellite imagery. The study area is located in central Italy over approximately 34,000 km 2 . A set of SPOT5 HRG multispectral images was acquired for the study years (2002)(2003)(2004)(2005)(2006)(2007). Official administrative statistics of coppice clearcuts were also acquired. More than 9500 clearcuts were mapped and dated by on-screen interpretation of the SPOT5 images. In a subset of the study area various methods for semi-automatic clearcut mapping were tested by pixel-and object-oriented approaches. The following results are presented: (i) clearcut map developed by visual interpretation of the SPOT5 images resulted in high thematic (overall accuracy of 0.99) and geometric (root mean square error of clearcut boundary delineation of 5.3 m) reliability; (ii) object-oriented approach achieved significantly better accuracy than pixel-based methods for semi-automatic classification of the coppice clearcuts; (iii) comparison between mapped clearcut area and official forest harvesting statistics proved a significant underestimation by the latter (65% of the total mapped clearcut area). A sample-based procedure exploiting VHR satellite imagery is finally proposed to correct the official statistics of coppice clearcuts.