Vertical Distribution of Insect Assemblages in the Cryptomeria japonica D. Don Plantation in Xitou

• Main Authors: Chi-Chou Chuang, 莊棨州
• Other Authors: Ping-Shih Yang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/96192529335095052820

碩士 === 國立臺灣大學 === 昆蟲學研究所 === 102 === Forest canopy has significant contributions to forest productivity, ecosystem function and global climate condition. However, due to the difficulty of vertical movement in forests, the forest canopy is widely recognized as one of poorly known ecosystems on earth. Previous studies have showed that the differentiation of forest strata affects the vertical distribution of forest animals. In order to study the vertical stratification of insect in artificial plantations at Xitou, the investigation was carried out at the flux tower located in a Cryptomeria japonica forest in Xitou by using sticky traps, which were set up at various layers (1, 5, 15, 25 and 34 meters heights) from 16 March 2011 to 16 March 2012. The information of insect community and microclimate data were collected for the comparison associated with insects collected in various times and heights. During the sampling period, a total of 111,525 insects belonging to 16 orders were collected. Moreover, Diptera was the most dominant order (total 93,207 individuals). Samples of Diptera were identified to family level, and the values of abundance, taxa richness, density, Pielou’s evenness, Shannon diversity index and dominant taxon ratio were calculated. One-way ANOVA, multi-dimensional scaling (MDS), cluster analysis, canonical correspondence analysis (CCA) were conducted to analyze the variations of Diptera community, feeding guilds and climate factors. In order level, Hemipteran insects were most abundant under 5 m; most Lepidoptera were found at 25 m, Hymenoptera and Psocoptera were more abundant above 25 m; Diptera were abundant at 1 and 25 m; most Thysanoptera were collected at 5 and 34 m; the Coleopteran insects showed no preference between five locations. In conclusion, most insects were collected at 1 and 25 m, and few individuals appeared at 15 m. According the results of one-way ANOVA, only the abundance of Coleoptera showed no difference among sampling heights. The abundance of different orders were significantly different in time and height. In diptera, there were 93,207 individuals belonging to 50 families. Top 10 dominant families were Psychodidae (56.29 %), Sciaridae (14.58 %), Phoridae (9.44 %), Ephydridae (5.70 %), Drosophilidae (2.37 %), Muscidae (2.27 %), Empidae (1.75 %), Chloropidae (1.26 %), Ceratopogonidae (1.24 %) and Mycetophilidae (1.11 %). According the results of one-way ANOVA, the taxon richness, density, evenness, diversity and dominant taxon ratios of dipterans were significantly different in sampling height. In addition, only the abundances of families were significantly different in sampling time. In the results of multivariate analysis, The MDS plot showed four groups of samples: 1 m group, 5-15 m group, 25 m group and 34 m group. Likewise, the results of ANOSIM indicated all paired samples of height were significantly different except the 5-15 m pairs. In contrast, the results of cluster analysis showed that samples from 1, 5 and 15 m formed a cluster. Moreover, samples from 5 and 15 m also merged into a cluster. On the other hand, samples from 25 and 34 m could be clustered into another group. In conclusion, the key families of Diptera were Empididae, Chloropidae, Drosophilidae, Ephydridae, Muscidae, Phoridae, Tipulidae, Mycetophilidae, Sciaridae, Psychodidae, Ceratopogonidae, and Simulidae. In the abundances of five feeding guilds, the results of one-way ANOVA showed significant differences in different heights. In addition, the results of one-way ANOVA showed significant differences in sampling time in Fungivore-Saproxylic insect group, Herbivore-Nectarivore group, and Predator-Parasitoid group. Furthermore, the results of cluster analysis in indicated that the samples from 1 m, 5-15 m, 25 m, and 34m formed clusters individually. In the relationship between the community of Diptera and climatic variables, correlation analysis results showed that the dipteran insect’s abundance, evenness index, diversity index and dominant taxon ratio were more related to average relative humidity (R.H.). BIO-ENV analysis indicated that the major climatic factors affecting the distribution of dipteran insects were average temperature and average relative humidity. Moreover. In the CCA diagram, the first axis constrained the maximum value on the variation of taxa and the data indicated that the major climatic factors affecting the distribution of taxa were average temperature and average daily rainfall. The second axis represented the sum of average relative humidity. The abundances of Lonchaeidae and Dolichopodidae were positively related with average relative humidity and average temperature; Cecidomyiidae, Mycetophilidae and Stratiomyidae were negatively related with average relative humidity and average temperature; Anthomyiidae, Drosophilidae and Anisopoididae were positively related with average daily rainfall; Chironomidae, Psychodidae and Simuliidae were negatively related with average daily rainfall; Besides, most families were not significantly related with these climatic factors. This research is the first study about insect vertical distributions in Taiwan, and the sampling method can be promoted to the investigation of canopy biota in other CO2 flux towers in Taiwan. This study has showed the importance of canopy biodiversity and reveals some defects of traditional forest 2survey methods. In addition, based on this research, NTU Experimental Forest should continue to carry out the study of canopy biota. Moreover, NTU Experimental Forest could take advantage of the results to improve the interpretation and education of canopy ecology in the canopy walkway in Xitou. It will make Xitou an important site to develop canopy ecology study in Taiwan.