Abstract:

Objective: The paper was intended to reveal the species composition and diversity characteristics of semi-natural mixed forest of Pinus massoniana and broad-leaved trees,especially the characteristics of the naturally regenerated broad-leaved trees,aimed to provide a scientific basis for the management and utilization of this type of forest. Method: A 50 m×160 m plot was set up in semi-natural mixed forest of Pinus massoniana and broad-leaved trees in Lingtou village,Yong'an municipality,Fujian Province. The plot was divided into 80 10 m×10 m quadrats,then the arbor and shrub layer of each quadrat were investigated. 128 small quadrats of 2 m×2 m were set up in the plot for the investigation of the herb layer. By using maximum light receiving plane (MLRP) method,the arbor layer was divided into two sub-layers,called sub-layer Ⅰ (light receiving layer) and sub-layer Ⅱ (non-light receiving layer). Then,the tree species composition and diversity of arbor layer (including the sub-layer Ⅰ and Ⅱ) and shrub layer were analyzed by importance value and several commonly used diversity indices. Result: The species richness of arbor layer,shrub layer and herb layer were 47,109,and 56. The Shannon-Wiener index,evenness index and dominance index of arbor layer were 2.93,0.53,and 0.26,respectively. The density of arbor layer was 2 686 per hectare,and there were only 9 shrub species,whose totaled density was 28 per hectare and importance value was 1.58%. Among all the species in the arbor layer,the top five of importance values were as follows:Pinus massoniana (37.87%),Cunninghamia lanceolata (16.85%),Alniphyllum fortunei (10.40%),Sassafras tzumu (7.01%) and Schima superba (4.91%). The height of maximum light receiving plane was 12.6 m. The species richness,Shannon-Wiener index,evenness index,and dominance index of sub-layer Ⅰ were 23,1.80,0.40,and 0.47,respectively. In sub-layer Ⅰ,the top five of importance values were P. massoniana (55.49%),A. fortunei (13.38%),S. tzumu (10.69%),C. lanceolata (9.04%),and C. fargesii (2.00%). The species richness,Shannon-Wiener index,evenness index and dominance index of sub-layer Ⅱ were 45,3.17,0.77and 0.23,respectively,and the top five of importance values in this sub-layer were C. lanceolata (38.84%),A. fortunei (10.73%),S. superba (9.21%),Styrax confusus (8.29%) and C. fargesii(4.26%).The Shannon-Wiener index,evenness index and dominance index of shrub layer were 4.44,0.65,and 0.08,respectively. The density of shrub layer was as high as 9 651 per hectare,and the density and the total importance values of shrubs were only 3 143 per hectare and 28.23%,respectively. Among all the species in shrub layer,the top five of importance values were C. lanceolate (15.47%),S. confuses (11.10%),C. fargesii (5.75%),Eurya loquaiana (7.84%) and A. fortunei (5.61%); the number of herbaceous plants counts 37.90% in the herb layer. Conclusion: The semi-natural mixed forest of P. massoniana and broad-leaved trees have formed a multi-stories mixed uneven-aged structure,the arbor layer,shrub layer and herb layer all have high species richness. The arbor layer was dominated by P. massoniana; and the majority of the naturally-regenerated trees were A. fortunei,S. tzumu,S. superba and S. confusus. The species composition and diversity of the naturally regenerated broad-leaved trees in the arbor layer were close to the broad-leaved forest with regeneration promoted by artificial measures at similar age. The species richness of sub-layer Ⅰ and Ⅱ were 23 and 45,respectively,P. massoniana had an absolute advantage in the sub-layer Ⅰ,and C. lanceolata had the largest importance value in the sub-layer Ⅱ. The majority of the shrub layer were saplings,and there were few herbaceous plants in the herb layer.

Key words: semi-natural forest, Pinus massoniana, broad-leaved trees, natural regeneration, mixed forest, species composition, diversity