Ecological Adaptability of Cunninghamia lanceolata and Accompanied Broad-leaved Tree Species in Sichuan

The interspecific ecological relationship between Cunninghamia lanceolata(Cl) and accompanied broad-leaved trees in Cl plantation was studied to explore the suitable broad-leaved trees accompanied with Cl, and to provide basis for the reconstruction and management of mixed forest of Cl and broad-leaved species from the perspective of ecological niche. A community survey of Chinese fir plantations in Qionglai, Hongya and Xuyong was carried out by the combination method of sample line and sample quadrat. The Levins and Shaanon niche breadth index, niche overlap index, Schoener niche similarity index were used to study and analyze the niche characteristics of the Cl and accompanied broad-leaved trees respectively, with different typical sampled plots as the resource sites. The results showed that: 18 species were selected from the 45 accompanied tree species according to the criterion that the important value of tree species was greater than 1. And the Levins and Shaanon niche breadth index reflected the same result. Nine tree species such as Litsea pungens, Mallotus japonicus, Ficus heteromorpha, Rhus chinensis, Sassafras tzumu, Cornus controversa, Betula luminifera, Camellia japonica and Eurya nitida Korthals were the most important accompanied broad-leaved species of Cl, and their important value was B_(sw)>0.6 and B_(L)>0.3). Their niche breadth and important values were both large and had strong ecological adaptability. The niche overlap between the main accompanied broad-leaved species of Cl was not high, and the niche overlap between Cl and the main accompanied broad-leaved trees was high (Lih>0.05). The Schoener niche similarity index between Cl and Litsea pungens, Mallotus japonicus, Ficus heteromorpha, Rhus chinensis, Sassafras tzumu was high (Cih>0.4), which indicated that Cl and these species had certain similarity in habitat requirements and shared the resources. Among the main accompanied broad-leaved tree species, deciduous tree species had larger niche breadth, niche overlap index and Schoener niche similarity than evergreen tree species, which indicated that deciduous broad-leaved tree should be more selected as the accompanied tree species for the cultivation of mixed Cl and broad-leaved forest.