Ring-based versus disc-based separation of spatial scales: a case study on the impact of arable land proportions on invertebrates in freshwater streams
Author
Summary, in English
The impact of different land-use types on
species is traditionally estimated by correlating
landscape proportions recorded in buffer areas around
focal points with species data observed at these sites.
If a high proportion of a specific land-use type exists
within a small radius, it will be accumulated in larger
buffers and may confound the interpretation at larger
scales. We sampled freshwater invertebrates in ten
streams using cages with artificial substrate and
compared the effects of arable land proportions
calculated in disc-shaped buffers of increasing radius
versus areas calculated from non-overlapping rings of
increasing radius. We hypothesize that (1) the
accumulative disc-based approach leads to confounding
effects across increasing buffer size and that (2)
the use of ring-based methods facilitates the identification
of relevant scales for conservation measures.
The abundance of crustaceans showed a positive
relationship with arable land proportions, but Plecoptera
abundance and the taxonomic richness of
Ephemeroptera and Plecoptera decreased with
increasing arable land proportions in the surrounding
landscape. Our results further support the presence of
confounding effects in disc-based analyses, as correlations
between arable land proportions and Crustacea,
or Plecoptera, respectively, were affected by the
accumulation of small-scale area proportions. The
distance at which arable land proportions significantly
affected benthic fauna in freshwater streams
was consistently shorter if calculated from rings
rather than from discs. Although an a priori definition
of ring width introduces new challenges, a combined
use of disc- and ring-based techniques for the
estimation of land-use effects may substantially
improve the realization of conservation and protection
measures in terrestrial and aquatic systems.
species is traditionally estimated by correlating
landscape proportions recorded in buffer areas around
focal points with species data observed at these sites.
If a high proportion of a specific land-use type exists
within a small radius, it will be accumulated in larger
buffers and may confound the interpretation at larger
scales. We sampled freshwater invertebrates in ten
streams using cages with artificial substrate and
compared the effects of arable land proportions
calculated in disc-shaped buffers of increasing radius
versus areas calculated from non-overlapping rings of
increasing radius. We hypothesize that (1) the
accumulative disc-based approach leads to confounding
effects across increasing buffer size and that (2)
the use of ring-based methods facilitates the identification
of relevant scales for conservation measures.
The abundance of crustaceans showed a positive
relationship with arable land proportions, but Plecoptera
abundance and the taxonomic richness of
Ephemeroptera and Plecoptera decreased with
increasing arable land proportions in the surrounding
landscape. Our results further support the presence of
confounding effects in disc-based analyses, as correlations
between arable land proportions and Crustacea,
or Plecoptera, respectively, were affected by the
accumulation of small-scale area proportions. The
distance at which arable land proportions significantly
affected benthic fauna in freshwater streams
was consistently shorter if calculated from rings
rather than from discs. Although an a priori definition
of ring width introduces new challenges, a combined
use of disc- and ring-based techniques for the
estimation of land-use effects may substantially
improve the realization of conservation and protection
measures in terrestrial and aquatic systems.
Department/s
Publishing year
2011
Language
English
Pages
351-356
Publication/Series
Aquatic Ecology
Volume
45
Issue
3
Links
Document type
Journal article
Publisher
Springer
Topic
- Ecology
Keywords
- Arthropod diversity
- Crustacea
- EPT taxa
- Landscape analysis
- Land-use type
- Multi-scale analysis
- Spatial analysis
- Spatial memory
Status
Published
ISBN/ISSN/Other
- ISSN: 1386-2588