Diversity of useful plant resources, threatened reasons and solutions for conservation of plants at the Yokdon national park

In this paper, 565 useful species representing 66,16% of total (854) species of flora at Yokdon national park were listed, they include 476 species for medicine, 158 timber species, 141 edible species and 57 ornamental species. 304 species were added in old data.  From the table 2, the number of endangered species of this flora is 36. By analysis the data in 5WHYS methods, the threatened and solutions for conservation of this flora were suggeted: 1) the direct threatened: logging, extending agricultural lands, exploitation of NTFPs, forestry fire and invation of exotic and grazing; 2) the undirect threatened: populational pressure, famine, low awereness of community, weak laws - unsuitable policies and commecial economic; 3) the solutions: increasing of education for local people and increasing the effects of laws, change of habit of local people about utilization of forestry products by the rising of life values, control the market requies and creasing population,  planning of ihabitants and productive areas.