Plant species diversity as a driver of early succession in abandoned fields: a multi-site approach

Abstract

Succession is one of the most studied processes in ecology and succession theory provides strong predictability. However, few attempts have been made to influence the course of succession thereby testing the hypothesis that passing through one stage is essential before entering the next one. At each stage of succession ecosystem processes may be affected by the diversity of species present, but there is little empirical evidence showing that plant species diversity may affect succession. On ex-arable land, a major constraint of vegetation succession is the dominance of perennial early-successional (arable weed) species. Our aim was to change the initial vegetation succession by the direct sowing of later-successional plant species. The hypothesis was tested that a diverse plant species mixture would be more successful in weed suppression than species-poor mixtures. In order to provide a robust test including a wide range of environmental conditions and plant species, experiments were carried out at five sites across Europe. At each site, an identical experiment was set up, albeit that the plant species composition of the sown mixtures differed from site to site. Results of the 2-year study showed that diverse plant species mixtures were more effective at reducing the number of natural colonisers (mainly weeds from the seed bank) than the average low-diversity treatment. However, the effect of the low-diversity treatment depended on the composition of the species mixture. Thus, the effect of enhanced species diversity strongly depended on the species composition of the low-diversity treatments used for comparison. The effects of high-diversity plant species mixtures on weed suppression differed between sites. Low-productivity sites gave the weakest response to the diversity treatments. These differences among sites did not change the general pattern. The present results have implications for understanding biological invasions. It has been hypothesised that alien species are more likely to invade species-poor communities than communities with high diversity. However, our results show that the identity of the local species matters. This may explain, at least partly, controversial results of studies on the relation between local diversity and the probability of being invaded by aliens.

Separating the chance effect from other diversity effects in the functioning of plant communities

“…Identical experiments were carried out on five formerly cultivated sites, one in each of five European countries (Table 1, see also Van der Putten et al 2000). The last crop was harvested from each site in 1995, the sites were then ploughed or cultivated and in spring 1996 the treatments were established.…”

“…A reasonable way to deal with this problem is to have replications over a wide range of environmental conditions. The present study was part of a large project on enhancement of ecosystem development at abandoned arable fields throughout Europe ( Van der Putten et al 2000). Consequently, our experiments were carried out simultaneously on formerly cultivated land in five different European countries.…”

Non-Native Plants Disrupt Dual Promotion of Native Alpha and Beta Diversity

“…Therefore, although we have focused on patterns of diversity in this study, the multiscale effects of non-native species we have described here may have broader implications for ecosystem functioning, affecting productivity, decomposition, and nutrient cycling (Van der Putten et al 2000;Lepš et al 2001).…”

Connell and Slatyer's models of succession in the biodiversity era

“…In spite of intense research on BEF (Naeem et al 2009), few studies have examined the consequences of biodiversity change for successional dynamics (e.g., Van der Putten et al 2000). Revealing the community-level effects of inhibitory and facilitative mechanisms can offer important information in the light of present rates of deterioration or loss of natural habitats.…”

“…These concepts can help to elucidate how changes in the biodiversity of assemblages of early colonists affect subsequent patterns of assemblage recovery. According to the classic formulation of the BEF theory (Hooper et al 2005), increasing richness of early colonists is expected to increase saturation of available resources through identity or complementary effects, thus slowing down or even preventing successional change (Stachowicz et al 1999, Van der Putten et al 2000.…”