Abstract
The Araucaria Forests in southern Brazil are part of the Atlantic Rainforest, a key hotspot for global biodiversity. This habitat has experienced extensive losses of vegetation cover due to commercial logging and the intense use of wood resources for construction and furniture manufacturing. The absence of precise taxonomic tools for identifying Araucaria Forest tree species motivated us to test the ability of DNA barcoding to distinguish species exploited for wood resources and its suitability for use as an alternative testing technique for the inspection of illegal timber shipments. We tested three cpDNA regions (matK, trnH-psbA, and rbcL) and nrITS according to criteria determined by The Consortium for the Barcode of Life (CBOL). The efficiency of each marker and selected marker combinations were evaluated for 30 commercially valuable woody species in multiple populations, with a special focus on Lauraceae species. Inter- and intraspecific distances, species discrimination rates, and ability to recover species-specific clusters were evaluated. Among the regions and different combinations, ITS was the most efficient for identifying species based on the ‘best close match’ test; similarly, the trnH-psbA + ITS combination also demonstrated satisfactory results. When combining trnH-psbA + ITS, Maximum Likelihood analysis demonstrated a more resolved topology for internal branches, with 91% of species-specific clusters. DNA barcoding was found to be a practical and rapid method for identifying major threatened woody angiosperms from Araucaria Forests such as Lauraceae species, presenting a high confidence for recognizing members of Ocotea. These molecular tools can assist in screening those botanical families that are most targeted by the timber industry in southern Brazil and detecting certain species protected by Brazilian legislation and could be a useful tool for monitoring wood exploitation.
Highlights
The Brazilian Atlantic Rainforest is one of 34 global biodiversity hotspots and is among the most seriously threatened biomes on the planet
Despite laws restricting the exploitation of these forest resources, clandestine logging continues almost unrestrained, and many other types of natural resources are still being exploited [9], with special focus on the internal market. Due to this global problem, since 2013, new European Union rules limit the import of illegally harvested timber and products derived from illegal timber on the EU market, including some native Brazilian species
Regardless, based on the practicality and viability of barcoding as a routine technique, we recommend the internal transcribed spacer (ITS) region for barcode identification of these species, as it demonstrated a high degree of identification success using TAXONDNA and a better resolution of species-specific clusters in the phylogenetic tree generated by Maximum Parsimony, a computational method currently used in practice
Summary
The Brazilian Atlantic Rainforest is one of 34 global biodiversity hotspots and is among the most seriously threatened biomes on the planet. One of its forest formations, the Mixed Ombrophilous Forest (MOF), known as the Araucaria Forest, is found in the southern region of Brazil; well-preserved fragments of MOF occupy only 0.8% of their original range [2, 3]. Much of this drastic reduction is associated with the expansion of agriculture and livestock, a major contribution to the intensive exploitation is the fact that MOF has been the main source of wood for furniture making and civil construction in the southern states of Brazil for more than 150 years [3, 4]. In Lauraceae in particular, the precise identification of different Ocotea species has remained a difficult task for non-specialists, as the vegetative morphologies of these plants are very similar, their flowers are very small, and species complex delimitations are poorly defined [6, 7, 8]
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