Comparative footprint of alien, agricultural and restored vegetation on surface-active arthropods
Summary (2 min read)
Introduction
- Yet there is little knowledge on the comparative impact, or footprint, of these two types of human-induced land transformations on this biodiversity, so the authors investigate here the comparative impact of IATs and vineyards on soil-surface arthropod diversity, and compare it with patches where IATs had been removed.
- The authors chose this group of arthropods as it is species-rich, occurs in high abundance, and most species are relatively immobile (therefore allowing spatially-explicit interpretation of the arthropod data).
Study area and methods
- Study sites Sampling was in three nature reserves and seven wine estates within the CFR (Table 1).
- This reserve was considered due to the presence of mountain fynbos adjacent to invasive alien trees (i.e. Pinus and Hakea spp.).
- Arthropod samples from each trap set were combined, resulting in one sample per sampling station (i.e. 1000 pitfall traps gave 500 samples per sampling period, making 1 500 samples over the three sampling periods).
- Multiple comparisons of the means were made using Bonferroni methodology (Legendre and Legendre 1998).
- Multivariate analysis, using Primer Ver. 5 (Clarke and Gorley 2001), was used to detect trends and to explore the differences in arthropod assemblages between different vegetation types.
Results
- In turn, IATs and vineyards were significantly different from each other in species richness, and both were not comparable to either fynbos or CIATs (Fig. 1).
- Classification of different vegetation types in terms of arthropod abundance gave three different nodes (Fig. 2).
- Cleared = vegetation cleared of invasive alien trees, natural = fynbos, IATs = invasive alien trees Fig. 2 Classification tree of vegetation in terms of mean arthropod abundance.
- These arthropod species can be considered as typical of associated vegetation types, although L. humile is alien (Table 6).
Discussion
- Species richness and abundance in the different vegetation types.
- In terms of overall abundance, invaded areas were much poorer than vineyards, indicating greater impact of alien trees over that of vineyards.
- Yet species richness of the cleared areas was close to that of fynbos, showing that clearing of alien trees increases species richness, an encouraging sign for restoration.
- This is not surprising because alien trees can impoverish the local terrestrial fauna even over a few metres (Samways et al. 1996).
Conclusions
- This suggests that conversion of vineyards to more biodiversity friendly farming methods, as outlined by Gaigher and Samways (2010), has a good base on which to work.
- In turn, clearing of alien trees will continue to benefit biodiversity recovery, but it will take time for the original set of species to return, as it is only the common, and presumably more habitattolerant, species which readily recover.
- Acknowledgments Financial support was from the Centre for Invasion Biology and the Andrew Mellon Foundation.
- Rejoyce Gavhi, Rozwivhona Magoba, Mbula Tshikalange, Adam Johnson, Tshilidzi Muofhe and Sne Mchunu kindly assisted in the field.
- The authors also appreciate the very constructive criticisms of two anonymous referees which greatly improved the manuscript.
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Citations
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Cites background from "Comparative footprint of alien, agr..."
...Apart from Magoba and Samways (2012), there is little knowledge on how these assemblages recover when the alien trees are removed, a significant mitigation measure in the region which has been assessed using aerial taxa (Samways and Sharrat 2010)....
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7 citations
Cites background from "Comparative footprint of alien, agr..."
...…mainly of non- native invasive species, which probably do not provide habitat for many of the native bee species, as plant species richness and ground- dwelling arthropod diversity decline under stands of alien trees (Magoba & Samways, 2012; Richardson et al., 1989; Schoeman & Samways, 2011)....
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References
11,748 citations
"Comparative footprint of alien, agr..." refers background or methods in this paper
...Rare species were excluded from the PCA, so that the species retained were more comparable with the number of samples (Clarke and Warwick 2001)....
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...Joint absences in the NMDS were ignored to emphasize similarity in common or rare species, comparing only percentage composition (Clarke and Warwick 2001)....
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...Principal Components Analysis (PCA) was used to determine whether arthropods from the different vegetation types fell into distinct groups (Clarke and Warwick 2001)....
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...The main advantage of NMDS is its greater ability to represent complex relations accurately in low-dimensional space (Clarke and Warwick 2001)....
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...Analysis of similarity (ANOSIM) tests the hypothesis that there are no assemblage differences between groups of samples specified, here vegetation type (Clarke and Warwick 2001)....
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8,401 citations
"Comparative footprint of alien, agr..." refers background in this paper
...Agriculture is one of the most significant human-induced disturbances that threatens terrestrial biodiversity (Sala et al. 2000; Tilman et al. 2001), affecting the availability of suitable terrestrial habitats (Feber et al. 1996; Warren et al. 1997; Jeanneret et al. 2003; Kleijn and van Langevelde…...
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...Agriculture is one of the most significant human-induced disturbances that threatens terrestrial biodiversity (Sala et al. 2000; Tilman et al. 2001), affecting the availability of suitable terrestrial habitats (Feber et al....
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6,195 citations
"Comparative footprint of alien, agr..." refers background in this paper
...Invasion by alien tree species is a global environmental problem (Mack et al. 2000; Richardson and Pyšek 2006), affecting movement patterns of animals, including insects (Wood and Samways 1991), and threatening their habitats (Armstrong and van Electronic supplementary material The online version of this article (doi:10....
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...Invasion by alien tree species is a global environmental problem (Mack et al. 2000; Richardson and Pyšek 2006), affecting movement patterns of animals, including insects (Wood and Samways 1991), and threatening their habitats (Armstrong and van Electronic supplementary material The online version…...
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4,245 citations
"Comparative footprint of alien, agr..." refers methods in this paper
...…species richness (Chazdon et al. 1998), whereas Chao2 and Jackknife estimators provide the least biased estimates should insufficient sampling be an issue (Colwell and Coddington 1994), and were calculated here using EstimateS (Colwell 2006) for all vegetation types separately and for all combined....
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...1998), whereas Chao2 and Jackknife estimators provide the least biased estimates should insufficient sampling be an issue (Colwell and Coddington 1994), and were calculated here using EstimateS (Colwell 2006) for all vegetation types separately and for all combined....
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3,606 citations
"Comparative footprint of alien, agr..." refers background in this paper
...Agriculture is one of the most significant human-induced disturbances that threatens terrestrial biodiversity (Sala et al. 2000; Tilman et al. 2001), affecting the availability of suitable terrestrial habitats (Feber et al. 1996; Warren et al. 1997; Jeanneret et al. 2003; Kleijn and van Langevelde…...
[...]
...Agriculture is one of the most significant human-induced disturbances that threatens terrestrial biodiversity (Sala et al. 2000; Tilman et al. 2001), affecting the availability of suitable terrestrial habitats (Feber et al....
[...]