A well-known problem in numerical ecology is how to recombine presence-absence matrices without altering row and column totals. A few solutions have been proposed, but all of them present some issues in terms of statistical robustness (that is, their capability to generate different matrix configurations with the same probability) and their performance (that is, the computational effort that they require to generate a null matrix). Here we introduce the ‘Curveball algorithm’, a new procedure that differs from existing methods in that it focuses rather on matrix information content than on matrix structure. We demonstrate that the algorithm can sample uniformly the set of all possible matrix configurations requiring a computational effort orders of magnitude lower than that required by available methods, making it possible to easily randomize matrices larger than 10⁸ cells.

Islands harbour evolutionary and ecologically unique biota, which are currently disproportionately threatened by a multitude of anthropogenic factors, including habitat loss, invasive species and climate change. Native forests on oceanic islands are important refugia for endemic species, many of which are rare and highly threatened. Long-term monitoring schemes for those biota and ecosystems are urgently needed: (i) to provide quantitative baselines for detecting changes within island ecosystems, (ii) to evaluate the effectiveness of conservation and management actions, and (iii) to identify general ecological patterns and processes using multiple island systems as repeated ‘natural experiments’. In this contribution, we call for a Global Island Monitoring Scheme (GIMS) for monitoring the remaining native island forests, using bryophytes, vascular plants, selected groups of arthropods and vertebrates as model taxa. As a basis for the GIMS, we also present new, optimized monitoring protocols for bryophytes and arthropods that were developed based on former standardized inventory protocols. Effective inventorying and monitoring of native island forests will require: (i) permanent plots covering diverse ecological gradients (e.g. elevation, age of terrain, anthropogenic disturbance); (ii) a multiple-taxa approach that is based on standardized and replicable protocols; (iii) a common set of indicator taxa and community properties that are indicative of native island forests’ welfare, building on, and harmonized with existing sampling and monitoring efforts; (iv) capacity building and training of local researchers, collaboration and continuous dialogue with local stakeholders; and (v) long-term commitment by funding agencies to maintain a global network of native island forest monitoring plots.

The main objectives of this review are: 1) the compilation and updating of a reference database for Italian saproxylic beetles, useful to assess the trend of their populations and communities in the next decades; 2) the identification of the major threats involving the known Italian species of saproxylic beetles; 3) the evaluation of the extinction risk for all known Italian species of saproxylic beetles; 4) the or- ganization of an expert network for studying and continuous updating of all known species of saproxylic beetle species in Italy; 5) the creation of a baseline for future evaluations of the trends in biodiversity conservation in Italy; 6) the assignment of ecological categories to all the Italian saproxylic beetles, useful for the aims of future researches on their communities and on forest environments. The assess- ments of extinction risk are based on the IUCN Red List Categories and Criteria and the most updated guidelines. The assessments have been carried out by experts covering different regions of Italy, and have been evaluated according to the IUCN standards. All the beetles whose larval biology is sufficiently well known as to be considered saproxylic have been included in the Red List, either the autochtho- nous species (native or possibly native to Italy) or a few allochthonous species recently introduced or probably introduced to Italy in his- toric times. The entire national range of each saproxylic beetle species was evaluated, including large and small islands; for most species, the main parameters considered for evaluation were the extent of their geographical occurrence in Italy, and the number of known sites of presence. 2049 saproxylic beetle species (belonging to 66 families) have been listed, assigned to a trophic category (Table 3) and 97% of them have been assessed. On the whole, threatened species (VU + EN + CR) are 421 (Fig. 6), corresponding to 21 % of the 1988 as- sessed species; only two species are formally recognized to be probably Regionally Extinct in Italy in recent times. Little less than 65% of the Italian saproxylic beetles are not currently threatened with extinction, although their populations are probably declining. In forest environments, the main threats are habitat loss and fragmentation, pollution due to the use of pesticide against forest pests, and habitat simplification due to economic forest management. In coastal environments, the main threats are due to massive touristic exploitation such as the excess of urbanization and infrastructures along the seashore, and the complete removal of woody materials as tree trunks stranded on the beaches, because this kind of intervention is considered an aesthetic amelioration of seaside resorts. The number of spe- cies whose populations may become impoverished by direct harvest (only a few of large forest beetles frequently collected by insect traders) is very small and almost negligible. The Red List is a fundamental tool for the identification of conservation priorities, but it is not a list of priorities on its own. Other elements instrumental to priority setting include the cost of actions, the probability of success,and the proportion of the global population of each species living in Italy, which determines the national responsibility in the long-term conservation of that species. In this scenario, information on all species endemic to Italy, to Corso-Sardinia, to the Tuscan-Corsican ar- eas, and to the Siculo-Maltese insular system are given. A short analysis on relationships among beetle species traits, taxonomy, special- ist approaches, and IUCN Categories of Risk is also presented.