Abstract
We investigate orthopteran communities in the natural landscape of the Russian Far East and compare the habitat requirements of the species with those of the same or closely related species found in the largely agricultural landscape of central Europe. The study area is the 1,200 km2 Lazovsky State Nature Reserve (Primorsky region, southern Russian Far East) 200 km east of Vladivostok in the southern spurs of the Sikhote-Alin Mountains (134°E/43°N). The abundance of Orthoptera was recorded in August and September 2001 based on the number present in 20 randomly placed 1 m2 quadrates per site. For each plot (i) the number of species of Orthoptera, (ii) absolute species abundance and (iii) fifteen environmental parameters characterising habitat structure and microclimate were recorded. Canonical correspondence analysis (CCA) was used first to determine whether the Orthoptera occur in ecologically coherent groups, and second, to assess their association with habitat characteristics. In addition, the number of species and individuals in natural and semi-natural habitats were compared using a t test. A total of 899 individuals of 31 different species were captured, with numbers ranging between 2 and 13 species per plot. Species diversity was higher in semi-natural habitats than natural habitats. There was a similar but non-significant pattern in species density. Ordination analysis indicated four orthopteran communities, which were clearly separable along a moisture and vegetation density gradient. The natural sites in the woodland area of the Lazovsky Zapovednik are characterized by species-poor and low-density orthopteran assemblages compared to the semi-natural sites. But, the natural sites have a higher diversity of habitat specialists. Our findings corroborate the hypothesis that intermediate habitat disturbance levels support particularly species-rich animal communities at high densities. Under such regimes, orthopterans presumably mostly profit from the high diversity in plant species, which generates great structural and microclimatic heterogeneity.
Highlights
While natural forests in Europe were to a great extent transformed by man into agricultural land and settlement, huge areas of the East Palaearctic are still forested (Newell, 2004; Yan & Shugart, 2005) and are important reference areas for the study of temperate woodland landscapes
The majority of Orthoptera in the boreal and temperate forest zones of the Palaearctic are associated with open habitats (Sergeev, 1992, 1997)
These grassland habitats often are created and maintained by disturbance (Theuerkauf & Rouys, 2006), which is especially important at the microhabitat scale
Summary
While natural forests in Europe were to a great extent transformed by man into agricultural land and settlement, huge areas of the East Palaearctic are still forested (Newell, 2004; Yan & Shugart, 2005) and are important reference areas for the study of temperate woodland landscapes. The Far East is one of the three biodiversity hotspots in Russia (Venevsky & Venevskaia, 2005) and a centre of diversity and endemism of Orthoptera in Eurasia (Sergeev, 1998). Their taxonomy and distribution are well studied, and the ease with which they can be sampled and their functional importance make Orthoptera suitable subjects for ecological and biogeographical studies (Sergeev, 1997; Lockwood & Sergeev, 2000). Habitat selection in Orthoptera is based on a complex combination of different and often interrelated environmental factors Of these parameters, the microclimate at oviposition sites, which is often affected by vegetation structure, plays a crucial role (Uvarov, 1977; Willott & Hassall, 1998).
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