Insect community structures of Carya cathayensis forests with different management modes in Zhejiang Province

Abstract

To provide opinions and suggestions for management of Carya cathayensis forests, this research analyzed differences in insect communities using four different management modes:Type Ⅰ-a wild C. cathayensis forest, Type Ⅱ-vegetation planted under a C. cathayensis forest, Type Ⅲ-a traditional C. cathayensis forest, and Type Ⅳ-an organically managed C. cathayensis forest. Methods of collecting insect specimens included Malaise trap, light lure, and quadrat survey. Characteristic indexes of diversity, stability of insect community, principal components, and similarity were calculated and analyzed using Excel 2013 and SPSS 19.0 software. Results showed a total of 22 283 insect specimens being collected belonging to 163 species, 84 families, and 9 orders. Coleoptera and Hymenoptera were dominant groups for species numbers; whereas, Homoptera and Orthoptera were dominant groups for individual numbers. For the entire insect community the best performance was with management Type Ⅰ, the wild C. cathayensis forest, with a diversity index of 3.64 and an evenness index of 0.74. For Type Ⅱ, the diversity index was 3.12, and the evenness index was 0.61; this forest management type had good performance. For the insect communities in Malaise traps, the individual number and species number with Type Ⅱ management were significantly higher than the other management types (P < 0.05). The diversity index and the evenness index for Type Ⅰ and Type Ⅱ management were not significantly different but were significantly higher than other management types (P < 0.05). The dominance index with Type Ⅲ management was significantly higher than other management types (P < 0.05). For community structure, the Sn/Sp ratio for Type Ⅳ management was best with 0.39 meaning that the complexity and mutual restriction ability of the food network in the community was high. The St/Si ratio of the wild C. cathayensis forest was best with 0.04 meaning the mutual restriction of species number was stronger. The principal component analysis showed differences for different management modes. Also the dominant factors for changes in the insect communities were different. A similarity analysis found that when the measure was five, insect community structures were similar for Type Ⅱ and Type Ⅳ management. Overall, the ecological structure of the wild C. cathayensis forest (Type Ⅰ management) was most stable followed by Type Ⅱ, and because inefficient use of a C. cathayensis forest was forbidden in the actual production process, the management mode of vegetation planted under a C. cathayensis forest (Type Ⅱ) was recommended for farmers.