Identification of "Mixed Tropical Hardwood (MTH)"in paper
Does your paper contain protected tropical wood species? For verifying their presence in paper adequate methods are needed. The scope of the project - sponsored by the “Deutsche Bundesstiftung Umwelt“ - is to establish references for identification of tropical timbers in paper and develop new identification methods.
The worldwide aspiration is to shelter the tropical rainforest as unique ecosystems. But Non-Governmental Organizations (NGOs) report illegal harvesting of timber for production of pulp – including protected species. Consequentially, the European Timber Regulation (EUTR) – implemented in March 2013 for containment of illegal logging – is regulating the import of pulp and paper in addition to that of timber. For the control of and compliance with EUTR methods to identify tropical timbers in paper need to be developed. The identification of timbers in paper depends on reference material for each timber. Before initiating the project existing references were restricted almost exclusively to North-American and European timbers.
The objective of the project is to establish references for identification of tropical timbers in paper and the development of new methods for identification. The project was sponsored by the “Deutsche Bundesstiftung Umwelt“ and executed in cooperation with the University of Hamburg (Wood Science and Technology), the Technische Universität Darmstadt and ISEGA.
The identification of timbers in pulp and paper requires defibration of the material followed by staining. By means of light microscopy the anatomical features of the cells are determined and compared with references. As references for tropical timbers were lacking these timbers couldn´t be identified at first. So the initial objective of project was to produce macerated material and pure paper from authentic material of 22 tropical timbers. The light microscopic preparations of isolated cells are now part of the scientific collection of Thünen Institute and can be used for the direct match with unknown samples. High quality photomicrographs of the distinctive cells and of all their characteristics were produced. These data will be published in future.
Will a well-trained person having the references of our project be able to identify blind samples correctly? Are more characteristics, helpful for the identification, visible in the scanning electron microscope (SEM) in comparison with light microscopy?
Is it possible to identify timbers in pulp by pattern recognition software?
In addition, chemotaxonomy was employed as a method completely independent of the anatomical method. Extractives from wood are known to complement taxonomic evidence. But in the environment of pulp production with chemicals, high temperatures and repeated watering the extractives are washed out. Therefore it was doubtful whether it is possible to elute extractives from pulp in sufficient quantity and quality for chemotaxonomy, and which is the best method to obtain high rates of extractives.
At the end of the project a blind test of the anatomical identification method demonstrated which of the prepared references need further detailing. But a high proportion of timbers were identified correctly. So in general we could confirm that tropical timbers can also be identified in paper by means of their anatomical characteristics.
To expand the basis of the identification of timbers by anatomical characteristics, wood of four genera were studied by scanning electron microscopy. The higher resolution of that microscope facilitates acquisition of further details and precise measurements.
The preliminary chemical investigations conducted by this project evidence the possibility to elute extractives from paper for chemotaxonomic studies. The extractive content of pulp is lower and of different composition than that of timber. But despite this shortcoming the first identification attempts based on chemotaxonomic data proved promising.
To provide paper testing labs worldwide with the newly established anatomical references it is planned to publish descriptions and photomicrographs of the characteristic features of the timbers in form of a fiber atlas and/or software for an interactive identification key.
A follow-up project is envisaged with the objective ofestablishing references for additional tropical timbers by means of light and electron microscopic investigation. Based on the promising preliminary results from chemotaxonomy a chemotaxonomic database is planned as well as further blind tests to review the method.