The most commonly used old‐growth forest indicators are structural attributes; nevertheless, they do not necessarily represent the biodiversity value of old‐growth forests. The aim of this study is to analyse the relationships between species richness data of different taxa and structural indicators of old‐growth and to identify taxonomic/functional groups, species and structural attributes that may be used as indicators of old‐growth. To achieve this goal we sampled forest structure, vascular plants, lichens, bryophytes, fungi, saproxylic beetles and birds in mature and old‐growth stands in southern Italy. We calculated Spearman’s correlation coefficients between species richness data and structural attributes. Analyses of indicator species, co‐occurrences and two‐way clusters were performed on the multi‐taxonomic list. The group of vascular plants most significantly correlated with other groups in terms of species richness; furthermore, it displays the highest proportion of between‐group co‐occurrences. The resulting multi‐taxonomic list of potential indicators may serve as an effective means of detecting and monitoring forest ecosystems; however, for this goal, structure‐based indicators, such as forest structural attributes and vascular plant species composition, are of primary importance.

In forests with dense mixed canopies, laser scanning is often the only effective technique to acquire forest inventory attributes, rather than structure-from-motion optical methods. This study investigates the potential of laser scanner data collected with a low-cost unmanned aerial vehicle laser scanner (UAV-LS), for individual tree crown (ITC) delineation to derive forest biometric parameters, over two-layered dense mixed forest stands in central Italy. A raster-based local maxima region growing algorithm (itcLiDAR) and a point cloud-based algorithm (li2012) were applied to isolate individual tree crowns, compute height and crown area, estimate the diameter at breast height (DBH) and the above ground biomass (AGB) of individual trees. To maximize the level of detection rate, the ITC algorithm parameters were tuned varying 1350 setting combinations and matching the segmented trees with field measured trees. For each setting, the delineation accuracy was assessed by computing the detection rate, the omission and commission errors over three forest plots. Segmentation using itcLiDAR showed detection rates between 40% and 57%, while ITC delineation was successful at segmenting trees with DBH larger than 10 cm (detection rate ~78%), while failed to detect trees with smaller DBH (detection rate ~37%). The performance of li2012 was quite lower with the higher detection rate equal to 27%. Errors and goodness-of-fit between field-surveyed and flight-derived biometric parameters (AGB and tree height) were species-dependent, with higher error and lower r² for shorter species that constitute the lowermost layer of the forest. Overall, while the application of UAV-LS to delineate tree crowns and estimate biometric parameters is satisfactory, its accuracy is affected by the presence of a multilayered and multispecies canopy that will require specific approaches and algorithms to better deal with the added complexity.

The maintenance of certain levels of old forest represents a cornerstone of the EU’s biodiversity management strategy. A consensus on a single general ecological definition of old‐growth is particularly difficult in Mediterranean Europe. The present paper deals with old‐growth forests and persistent woodlands in the Cilento and Vallo di Diano National Park (PNCVD) to give an ecological understanding of forest complexity and dynamics under a multiscale and multidisciplinary perspective. The multiscale approach ranged from the identification and mapping of potential old‐growth stands at landscape scale to a two‐level field review of forest stand features. Field sampling involved a multidisciplinary team of researchers in forest structure, pedologic environment, soil microbial activity, flora and vegetation and deadwood components. The research provided sound knowledge about old‐growthness features in the PNCVD that constitutes a unique case study in the whole Mediterranean basin. The integration of results allowed to: identify main ecosystem functions and the related services of the old‐growth forests in the study area; distinguish persistent woodlands, multi‐aged stands with old trees deriving from nineteenth‐century management practices, from old‐growth forests sensu strictu; recognize indicators of direct and indirect impacts of human activities; suggest effective practices for sustainable management in the Mediterranean context.

The fundamental ecological significance of deadwood decomposition in forests has been highlighted in several reviews, some conclusions regarding silviculture being drawn. Old‐growth forests are natural centres of biodiversity. Saproxylic fungi and beetles, which are vital components of these ecosystems, occupy a variety of spatial and trophic niches. Fungal and beetle diversity on coarse woody debris (CWD) was analysed in 36 forest sites in the Cilento and Vallo di Diano National Park, Italy. The data were analysed by DCA and Spearman’s rank correlation. The results provide empirical evidence of the existence of a pattern of joint colonization of the woody substrate by fungi and beetles, which includes an assemblage of reciprocal trophic roles within fungal/beetle communities. These organisms act together to form a dynamic taxonomical and functional ecosystem component within the complex set of processes involved in wood decay. The variables most predictive of correlations between management‐related structural attributes and fungal/beetle species richness and their trophic roles for old‐growth forest are: number of logs, number of decay classes and CWD total volume. Deadwood spatio‐temporal continuity should be the main objective of forest planning to stop the loss of saproxylic fungal and insect biodiversity.