Trait composition and functional diversity of spiders and carabids in linear landscape elements

2016 ◽  
Vol 235 ◽  
pp. 318-328 ◽  
Author(s):  
Jens Schirmel ◽  
Jan Thiele ◽  
Martin H. Entling ◽  
Sascha Buchholz
1996 ◽  
Vol 5 (6) ◽  
pp. 567-576 ◽  
Author(s):  
Riitta Ruuska ◽  
Juha Helenius

Changes in landscape over a period of 50 years were analysed in a rural area of 324 ha in Central Finland. The data were digitized from aerial photographs of the National Land Survey taken in 1944, 1959, 1979 and 1991, and analysed with the IDRISI™ geographic information system (GIS). The average proportion of land in agricultural use in the sample area was 17.4%. The arable area declined from the maximum of 62.3 ha (1959) to 47.6 ha. The total length of linear landscape elements, predominantly ditch bank habitats, halved, from 876 m/ha of field (1944) to 449 m/ha by the end of the period. The average rate of loss of field boundary habitat was 9.1 m/ha/ year. At the same time, the Shannon-Weaver index of diversity of agricultural landscape elements dropped from 0.37 to 0.24. The number of field parcels declined by 29%, and the mean parcel size increased by 45%, from 1.2 ha to 1.7 ha. The index value of the fractal dimension measuring the complexity of parcel shapes also fell, from 1.88 (1959) to 1.86 (1991). The change in spatial structure reflects the intensification of farming in Finland. Biodiversity at ecosystem level has clearly declined. However, the implications for the agroecosystem and its sustainability are still unknown.


2021 ◽  
Author(s):  
Tobias Naaf ◽  
Jannis Till Feigs ◽  
Siyu Huang ◽  
Jörg Brunet ◽  
Sara A. O. Cousins ◽  
...  

Abstract Context Plant populations in agricultural landscapes are mostly fragmented and their functional connectivity often depends on seed and pollen dispersal by animals. However, little is known about how the interactions of seed and pollen dispersers with the agricultural matrix translate into gene flow among plant populations. Objectives We aimed to identify effects of the landscape structure on the genetic diversity within, and the genetic differentiation among, spatially isolated populations of three temperate forest herbs. We asked, whether different arable crops have different effects, and whether the orientation of linear landscape elements relative to the gene dispersal direction matters. Methods We analysed the species’ population genetic structures in seven agricultural landscapes across temperate Europe using microsatellite markers. These were modelled as a function of landscape composition and configuration, which we quantified in buffer zones around, and in rectangular landscape strips between, plant populations. Results Landscape effects were diverse and often contrasting between species, reflecting their association with different pollen- or seed dispersal vectors. Differentiating crop types rather than lumping them together yielded higher proportions of explained variation. Some linear landscape elements had both a channelling and hampering effect on gene flow, depending on their orientation. Conclusions Landscape structure is a more important determinant of the species’ population genetic structure than habitat loss and fragmentation per se. Landscape planning with the aim to enhance the functional connectivity among spatially isolated plant populations should consider that even species of the same ecological guild might show distinct responses to the landscape structure.


2019 ◽  
pp. 1278-1299
Author(s):  
Sébastien Da Silva ◽  
Florence Le Ber ◽  
Claire Lavigne

Characterizing the spatial distribution of hedgerows over landscapes is important for understanding the effects of this distribution on the dynamics of plant and animal populations. Because hedgerows are planted or managed, the authors hypothesized that their distribution depends on the presence of other linear landscape elements, namely, roads and channels. Using proximity analyses, the authors thus assessed how the spatial distribution of hedgerows was impacted by the position of these linear landscape elements and the spatial extent of this impact for two contrasting agricultural landscapes. The results indicate that hedgerows were generally associated at short distances with other elements (100-150 m). Hedgerows had different association patterns depending on their orientation in one of the two landscapes. In that same landscape, within-landscape heterogeneity was related to different association patterns. These results indicate that models of the spatial distribution of hedgerows would gain from being based on the location of roads and channels in the studied landscape.


2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Krzysztof Kujawa ◽  
Krzysztof Janku ◽  
Mostefa Mana ◽  
Adam Choryński

With the loss of natural and semi-natural habitats, the diversity and the amount of ecosystem services that can be provided in the agricultural landscape are diminishing, and self-regulatory abilities decrease. The aim of the research (72 sample plots – 1 x 1 km squares, mean  time span equal to 8 years) was to recognise the changes in the number and length of woody (tree or shrub) linear landscape elements, and the number of solitary trees in the Wielkopolska region to verify how rapid development of agriculture in Poland in the 21st century affects the landscape structure. The analyses show a decline by 9.3% (from 2.17 to 1.97 km/km2) in length of woody linear elements, 7.4% (from 16.5 to 15.0 per km2) in number of woody linear elements, and 14.6% (from 28.8 to 24.4 per km2) in solitary trees. The loss was significantly faster in the period (2017-2018) of liberalisation of the regulations on tree and shrub removal, mainly due to a high rate of removal in plots located in an urbanized landscape. The decrease in length of woody linear elements occurred in all the categories of their location distinguished in the study (by 9-41% in a category). The highest loss occurred in the woody linear elements located along melioration ditches and water courses, along roads, and in the outskirt of towns. These changes are similar to those occurring in the 20th century in western Europe. The decrease in the number of woody linear landscape elements and solitary trees can be considered an indicator of the unsustainable agriculture management.


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