Table 1.

Estimated standing biomass of the global spider community based on grams per square meter values ($\overline{\mathrm{x}}$ ± SE, all values expressed as fresh weight)

Biome type	Number of assessments	$\overline{\mathrm{x}}$ Biomass (g m-2)	Area in m2	Biomass subtotal (g)
		(B)	(Y)	(B) × (Y)
Tropical forestsa	7	0.38 ± 0.147	17.5 × 1012	6.65 × 1012
Temperate and boreal forestsb	18	0.40 ± 0.054	24.1 × 1012	9.64 × 1012
Tropical grasslands and savannasc	11	0.18 ± 0.046	27.6 × 1012	4.97 × 1012
Temperate grasslands and Mediterranean shrublandsd	8	0.16 ± 0.013	17.8 × 1012	2.85 × 1012
Annual croplande	13	0.017 ± 0.004	13.5 × 1012	0.23 × 1012
Desertsf	3	0.020 ± 0.006	27.7 × 1012	0.55 × 1012
Arctic tundrag	5	0.035 ± 0.009	5.6 × 1012	0.20 × 1012
Global total (without ice-covered area)			133.8 × 1012	25.09 × 1012

^aAnichkin et al. (2007); Raub and Höfer (2010); Göltenboth et al. (2006)

^bvan der Drift (1951); Kitazawa (1967); Gist and Crossley (1975); Huhta and Koskenniemi (1975); Luczak (1975); Miller and Obrtel (1975); Persson et al. (1980); Axelsson et al. (1984); Meyer et al. (1984); Ellenberg et al. (1986); Niijima (1998); Huhta (2002); Scheu et al. (2003)

^cGillon and Gillon (1967); Malaisse and Benoit (1979); Decaëns et al. (2001)

^dStöckli (1950); Cherrett (1964); Delchev and Kajak (1974); Persson and Lohm (1977); Hutchinson and King (1980); Curry (1986)

^eBasedow et al. (1991); Basedow (1993); Blumberg et al. (1997); Decaëns et al. (2001); Nyffeler and Sunderland (2003)

^fChew (1961); Mispagel and Sleeper (1983); combined data Polis (1991)/Boulton and Polis (1999)

^gPetersen and Luxton (1982); Byzova et al. (1995)