China has a distinctly varied flora, especially in the subtropical mountain regions in the South. This is particularly the case with the indigenous poplars, for example in the Southern and Western regions of the Qinghai- Tibet plateau. The natural forests were however displaced to a very great extent by various anthropogenic influences in earlier times. Lack of forests and shortage of wood have led in many parts of the country to the establishment of monoclonal plantations with fast growing tree species. But these have created unstable forest structures with a high cultivation risk. The aim of the Chinese-German cooperative project begun in 1984 is both to preserve still existent natural poplar sources and also to use them for breeding and afforestation purposes. Attention is paid to achieving a well balanced relationship of timber yield to yield stability. Great importance is attached to building up multiclonal varieties with high growing potential and good adaptation to the continental, semi-arid climatic conditions in the project region. In the course of the project up till now numerous fastgrowing and healthy sources of 19 indigenous poplar species and 3 natural species hybrids have been recorded in nine provinces and autonomous regions of Central and North China. Preservation measures have been started. In the project centre Jinshatan extensive living collections have been assembled containing about 650 indigenous and 170 exotic poplar clones. In several hybridization programmes we have produced up till 1995 roughly 400 different intra and interspecific combinations. The trial plots set up so far show considerable differentiation in growth both among the clones and among the hybrid progenies. The resulting consequences and prospects for practical afforestation measures are pointed out.
