2016/12/14 Dresden, Germany
Reporting by Joana Lapao Rocha, Intern, Soil and Land-Use Management Unit
Globally, forests cover approximately one third of the world’s surface and are home to about 80% of the world’s biodiversity. Many people throughout the world depend on forests for income, housing, and food.
Primary forests are the best niches for rich biodiversity – we have to maintain primary forests as far as possible. Should we fail to do this, the most sustainable strategy is to implement a policy of viable logging, always keeping in mind not to exceed the rate beyond which a forest’s productivity and regeneration capacity are lost. Based on field trials, the extraction rate has to be kept within 10–15 m3/ha to avoid species loss.
These are the main findings from Prof. Goddert von Oheimb’s years of work in forest sciences. In his lecture on “Environmental Protection Strategies under Conditions of Sustainable Land Management” at TU Dresden yesterday, he dealt with several strategies concerning how to sustainably manage land, specifically strategies for the sustainable management of forestland.
His lecture is the 17th installation of the Nexus Seminar series, which is a joint seminar series co-organised by UNU-FLORES and TU Dresden.
Prof. von Oheimb’s project ‘Green Great Wall of China’ aims to fight soil erosion and its subsequent environmental impacts (degradation of soils and a decrease in the quality of water bodies), and increase understanding of the correlation between forest productivity and forest biodiversity.
From previous studies, it is known that primary forests have richer biodiversity than selective logging land, secondary forests, and plantations. Only a few exceptions were noted in certain forest types, such as subtropical forests. What was not known is if forest productivity is a function of biodiversity or the other way around. Prof. von Oheimb’s project explores this question.
The ‘Green Great Wall of China’ project was started in 2007 with the acquisition of two sites. Each site was divided into plots, with each plot having 400 trees. Each of these plots was planted with one, two, four, eight, sixteen, and twenty-four species of trees respectively. On the field, several methods were implemented to analyse the development of the site. Terrestrial laser scanning was used to scan each plot to obtain a 3D-representation of the area. Afterwards, this information was digitalised, allowing researchers to model each tree in their respective sites, and calculate the wood volume and its estimated yield.
It was observed that fast-growing trees use the canopy space in different ways by vertical stratification. Conversely, slow growing trees tended to use horizontal stratification. It was also observed that the plots that had more diversity (more different species of trees) had higher biomass productivity. Particularly worth noting was the positive response of tree growth to the diversity of their neighbouring environment. After seven years, some of the trees even reached the height of 5m; the average is 3.5m.
Looking at these results, Prof. von Oheimb argued that sustainable management of forestland means sustaining tree species diversity. With the adoption of the 2030 Agenda for Sustainable Development last year, seventeen goals have to be met in order to achieve sustainable development. Goal 15 is concerned with the problem of forest degradation and biodiversity loss. Prof. von Oheimb’s seminar clearly demonstrated that conservation of primary forests must be part of any strategy to achieve this goal.
At the Conference of Parties to the Convention on Biological Diversity at Cancún this month, heads of states are currently discussing the need for considering “the impact of the unsustainable use of forests.” Here as well experts are urging Member States to “give due consideration to the conservation and sustainable use of natural forests and native vegetation.”