Effects of cover crops on spider communities in tea plantations

In agroecosystems, spiders are important predators that play a role in the control of agricultural pests. Modifying the vegetation around crops is an effective measure that can increase plant diversity and enhance the abundance and diversity of spider species. In this study, spiders were sampled monthly from May 2006 through April 2008 from tea canopies and ground covers in four tea plantation treatments in Xingchun (27°38′51.4″ N and 117°54′29.9″ E), which is in the Wuyi Mountains, Fujian Province, Southeastern China. The first tea plantation was intercropped with Paspalum notatum, the second with Cassia rotundifolia, and the third with natural ground cover. All ground cover was removed by hand in the fourth tea plantation. The spiders collected in the tea canopies numbered 21,170 individuals, representing 21 families and 158 species, whereas a total of 978 individual spiders, representing 16 families and 74 species, were collected in the ground cover treatments. Subsequent analysis revealed that Coleosomaoctomacutatum (Boesenberg et Strand, 1906), Telamonia bifurcilinea Bosenberg et Strand, 1999, and Erigone sp. 1 were the dominant spider species in these tea plantations. There were no significant differences among cover crop treatments with respect to the species richness, species abundance, or absolute abundance of spiders in either study year. In this work, all fourteen communities sampled had similar types of species abundance distributions, which followed bell-shaped and left-truncated lognormal distributions, with an almost identical modal octave on a log₂ scale and a missing zero class. The results of the present study do not support the natural enemy hypothesis, but rather indicate that ground covers do not have adverse effects on the tea plantations.