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.
Did you find this useful? Give us your feedback
Citations
346 citations
Cites background from "Comparative footprint of alien, agr..."
...Their advantage is that they can be highly abundant and are sensitive to litter depth and type (Magoba and Samways 2012)....
[...]
...In South Africa, the spider Ozyptilia sp. is indicative of disturbance ecotones (Magoba and Samways 2012)....
[...]
...is indicative of disturbance ecotones (Magoba and Samways 2012)....
[...]
64 citations
38 citations
32 citations
28 citations
Cites background from "Comparative footprint of alien, agr..."
...For example, Magoba & Samways (2012) showed that adult dragonfly species richness was not hampered by riparian alien vegetation, but assemblages changed drastically in sites cleared of IAPs....
[...]
References
618 citations
"Comparative footprint of alien, agr..." refers background in this paper
...Another impact on natural systems is conversion to agriculture, which changes ecosystem composition and function (Donald and Evans 2006), and its biodiversity (Turin and den Boer 1988; Newton 2004; Gaigher and Samways 2010)....
[...]
615 citations
"Comparative footprint of alien, agr..." refers background in this paper
...The incidence based Coverage Estimator (ICE) is a robust and accurate estimator of 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…...
[...]
505 citations
"Comparative footprint of alien, agr..." refers methods in this paper
...Non-parametric species estimators were used to provide the best overall arthropod species estimates for all vegetation types (Hortal et al. 2006)....
[...]
504 citations
485 citations
"Comparative footprint of alien, agr..." refers background in this paper
...However, different ecosystems vary considerably in their susceptibility to invasion (Chytrý et al. 2008), with the impacts of alien tree species in natural systems being dependent on invader attributes and on characteristics of the invaded community (Mason and French, 2008)....
[...]
...However, different ecosystems vary considerably in their susceptibility to invasion (Chytrý et al. 2008), with the impacts of alien tree species in natural systems being dependent on invader attributes and on characteristics of the invaded community (Mason and French, 2008)....
[...]