Sustainability and biodiversity assessment on forest utilization options

Yakushima Island is a granite island (ca. 505 km²) surrounded by sedimentary rocks and is located approximately 70 km south of Kyushu, Japan (Fig. 1). The island has precipitous terrain, including mountains approximately 2000 m in elevation, and about 90% of the island is covered by forest. On the plains, the average annual temperature is 19.1°C and the average annual precipitation exceeds 4000 mm, with 10,000 mm of precipitation in the mountainous areas. In 1993, UNESCO designated 21% of Yakushima as a world natural heritage site because of the unique fauna, flora, and landscape (http://whc.unesco.org/en/list/662 accessed at 15, July, 2017).

Figure 1.  

Study area and monitoring sites.

Fig. 1

Insect traps were set at five sites in three regions: old-growth evergreen forests (Aikodake and Han-yama) and neighboring 40-year-old Japanese cedar (Cryptomeria japonica) plantation forests (Aikodake and Kankake) in the low mountainous region (150-250 m elevation), and an old-growth mixed forest (Arakawa) higher in the mountains (1200 m elevation) (Fig. 1). The old-growth evergreen forest and the Japanese cedar plantation in Aikodake are part of a continuous forest, and they are only 100 m away from each other.

A Townes-type Malaise trap and IBOY-type window trap were used for sampling spiders. These types of trap are suited to a monitoring program in forest habitat because they capture a wide range of spiders, excluding some ground-dwelling forms. The Malaise trap had openings with a height of 1.8 m and a length of 1.8 m on both sides, and the attached bottles contain a mixture of 70% ethanol and a small amount of ethylene glycol for fixation and preservation of samples. Three Malaise traps were set at each study site at intervals of about 20 m (15 in total). Malaise traps were set continuously from July 2006 to March 2008, and samples were collected about once every month. The IBOY window trap consists of crossed transparent acrylic collision boards on a yellow bucket with a diameter of 36 cm, in which 1.5 L of water containing 10 ml of neutral detergent and 10% acetic acid aqueous solution is placed. We hunged these window traps at a height of about 30 cm above the ground. The window traps were set for 3 days in the latter half of each month from July 2006 to February 2008. The samples collected by each trap were brought back to the laboratory, and spiders were identified and counted.

The census was conducted in three regions on Yakushima: Aikodake, with both natural (30.381°N, 130.627°E) and cedar plantation forest (30.384°N, 130.627°E); Kankake, with Japanese cedar plantation forest (30.381°N, 130.412°E); Han-yama, with natural forest (30.364°N, 130.389°E); and Arakawa, with natural forest (30.299°N, 130.556°E) (Fig. 1).

In total, 3487 individuals belonging to 162 species, including morphotypes from 31 families, were collected during the censuses. Of these collections, two records have already been published as papers (Baba et al. 2016, Baba et al. 2015).

All specimens were identified by the authors according to Ono (2009) and scientific names were determined according to the World Spider Catalog Natural History Museum (2017). If we could not obtain sufficient information for proper identification, we determined the order, family, and genus of each species on the basis of the relevant morphotypes. Thus, some records have only order, family, or genus rank for the taxonomic information. The species name genus and family sequence are arranged in alphabetical order.

Order: Araneae

Family: Agelenidae, Anyphaenidae, Araneidae, Atypidae, Clubionidae, Ctenidae, Ctenizidae, Dictynidae, Eutichuridae, Gnaphosidae, Leptonetidae, Linyphiidae, Liphistiidae, Lycosidae, Miturgidae, Mysmenidae, Oonopidae, Oxyopidae, Philodromidae, Phrurolithidae, Pimoidae, Pisauridae, Salticidae, Segestriidae, Sparassidae, Tetragnathidae, Theridiidae, Theridiosomatidae, Thomisidae, Zodariidae.

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