Leaf litter and the small‐scale distribution of carabid beetles (Coleoptera, Carabidae) in the boreal forest

Abstract

Management practices favoring conifers at the expense of deciduous tree species, and the eradication of deciduous trees, especially aspen Populus tremula, from managed forests have resulted in population declines in several species in Fennoscandia. ln addition to species depending on decaying wood of deciduous trees, earlier evidence suggests that leaf litter, especially that of aspen, is favored by many carabid species. We ran a four-year experiment in order to compare carabid assemblages of unchanged forest floor with artificially created leaf-litter plots in central Finland. A total of 18 plots (5 m in diameter) were established in three forest stands without aspen a few kilometers apart. Each stand had 3 litter plots (litter added) and 3 control plots. Pre-treatment samples were compared with those collected after litter addition. The litter addition affected the carabid-assemblage structure by increasing the catches of some species and decreasing the catch of one species. The number of carabid species was similar in control and litter plots. The litter elfect was smaller than variation among forest stands and year-to-year fluctuations. There was a strong temporal constancy among the plots: "rich" plots remained "rich" from year to year and similarly. "poor" plots remained "poor".The significant influence of leaf litter on carabid abundance can be attributable to both abiotic factors (microenvironmental conditions, especially humidity and temperature), and biotic ones (changes in niche structure, improved food supply). Leaf litter seems to have an effect on carabid distribution patterns, and deciduous trees scattered among conifers are likely to be of importance on carabid fauna in boreal IOrests.M. Koiuula (mkoiuula@cc.helsinki.fi) and J. Niemeki,

Habitat structure and neighbor linear features influence more carabid functional diversity in olive groves than the farming system

“…In effect, previous studies have showed that the microhabitat is a determinant factor for carabid beetle diversity and community composition (e.g. Betbeder et al, 2015;Koivula et al, 1999;Kotze et al, 2011;Niemelä et al, 1992;Schirmel et al, 2015). Here we found that carabid abundance and species richness were higher in spots with denser vegetation cover (plot scale).…”

“…Thus, a higher number of poorer dispersers preferred the sheltered habitat conditions promoted by thicker spots of herbaceous plants at the fine plot scale. Previous studies showed that active microhabitat selection explains carabid species distributions at the small scale within the study areas (Koivula et al, 1999;Kotze et al, 2011;Niemelä et al, 1992). Different species characteristics and species interactions may underlie such species distributions and community structuring at local spatial scales (Koivula et al, 1999), as a result of niche partitioning and species tradeoffs (Driscoll, 2008).…”

The interactions between soil–biosphere–atmosphere (ISBA) land surface model multi-energy balance (MEB) option in SURFEXv8 – Part 2: Introduction of a litter formulation and model evaluation for local-scale forest sites

“…The SW net primarily depends on the prescribed albedo for the soil, α g , and the vegetation, α v . In ISBA, the net shortwave radiation is simply defined as SW net = (1 − α eff ) SW ↓, where the effective albedo is simply α eff = veg α v + (1 − veg)α g and veg is the vegetation cover fraction (which is constant in time for forests and varies between 0.95 and 0.99 ac- (2000) leaf Aoyama Japan Pinus thunbergii 4.5 Zhu et al (2003) needle Seirseminen Finland Spruce 3-5 Koivula et al (1999) needle cording to the forest cover). For the MEB simulations, the scheme from Carrer et al (2013) is used which uses the soil and vegetation albedo for two spectral bands (which are aggregated to all-wavelength values for ISBA), along with the LAI (the notion of veg is not applicable to MEB) in order to obtain an estimate of the vegetation optical thickness.…”

Discovering interaction between oaks and carabid beetles on a local scale by point pattern analysis

“…Indeed, previous research carried out in the same Scots pine forest reported that the leaf litter of oak trees does not extend beyond a distance of 15 meters from the oak stem (Schua et al 2007, Wehnert et al 2010, Wagner et al 2011. Thus, an association of the beetles to oaks, in general, may actually reflect the association of beetles to the oak litter (Koivula et al 1999).…”

“…At a species level, those concepts are often founded on habitat elements (McComb 2008, Kraus & Krumm 2013, their availability and spatial arrangement. To increase the ecological effect of C. coriaceus as an antagonist for pest insects in mono-cultured Scots pine forests, the following beneficial objectives should be pursued: (i) to support the vitality and growth dimension of oak trees; (ii) to increase their overall proportion within these forests, and (iii) to reduce the distances between single oak trees (Murcia 1995, Koivula et al 1999.…”