Effects of agricultural intensification on plant diversity in Mediterranean dryland cereal fields

Abstract

Summary1. Agricultural intensification, at field and landscape scales, has caused a decrease in weed richness and changes in species composition. In order to prevent this loss of diversity and develop efficient management regimes, it is important to understand how both aspects of intensification affect plant diversity and the way in which they interact. 2. This study assessed plant diversity at the centre, edges and boundaries of 29 organic and 29 conventional cereal fields distributed in 15 agrarian localities of the NE Iberian Peninsula. We focused on the composition of plant assemblages and on the specific richness at the field level, which was calculated for the whole set of species and for that of characteristic arable weeds. The percentage of arable land together with human settlements was used as a surrogate for landscape complexity and the amount of nitrogen inputs for land-use intensity. 3. Our results show that both scales of agricultural intensification have a similar negative effect on the total plant species and characteristic arable weed richness, and they also affect plant assemblages. Furthermore, we found no strong interaction between landscape and land-use intensity for explaining total plant richness. 4. The relative importance of farming intensity and landscape varies depending on the location within the field, which can be attributed to differences in the agricultural impact and limited seed dispersal from adjacent habitats. Management is the main factor in explaining differences among field centres, whereas changes at boundaries are mainly due to landscape characteristics, and at edges both factors are relevant. 5. Synthesis and applications. To preserve agricultural plant diversity it is equally important to prevent agricultural intensification at field and landscape scales. Policies enhancing low-intensity management techniques, such as organic farming, are the main way to promote diversity inside the fields and will be equally beneficial in simple and complex landscapes for total plant species richness. To maintain diversity within agricultural areas, it is also important to reduce farming intensity at the edges, which would favour characteristic arable weeds and margins' overall plant diversity.

Evaluation of weed flora changes in Portugal in a 10 year basis

“…Several studies have shown that the intensification of crops, due to the availability of irrigation, leads to a decrease in biodiversity (Storkey and Westbury, 2007;José-María et al, 2010;Plaza et al, 2011;Sans et al, 2013). However, in the present study, an increase of total plant diversity was observed.…”

“…Furthermore, weeds are able to survive and grow in different ecological habitats, with their occurrence being very sensitive to changes in agricultural practices (Fried et al, 2010;Petit et al, 2011). New agricultural management practices lead to new balances and such information is considered to be of major importance (José-María et al, 2010;Sans et al, 2013). Ecological services that this type of vegetation provides to the agro-ecosystems are not negligible.…”

“…Natural vegetation also protects soil from mechanical compaction, while many of the weeds have medicinal and/or other value (Bilalis et al, 2014). In general, more intensive agriculture leads to lower biodiversity and reduces the environmental sustainability (Storkey and Westbury 2007;Stoate et al, 2009;José-María et al, 2010;Sans et al, 2013). Consequently, the maintenance of biodiversity in agro-ecosystems is considered to be of great importance in modern agriculture, based on economic, ecological and social parameters (Firbank et al, 2008).…”

Study of Autumn-Winter Weeds in Portugal and Its Ecological Preferences

“…Another important aspect has to do with the fact that the intensification of agricultural systems leads to a loss of plant biodiversity (Storkey & Westbury, 2007;Stoate et al, 2009;José-Maria et al, 2010;Sans et al, 2013), which threatens the sustainability of the services provided by a current and modern agriculture. Also, the effect of climate change on organisms and on their geographical distribution (Walther et al, 2002) may influence this dynamic.…”

Weed Management in Cereals in Semi-Arid Environments: A Review

“…For instance, arable weeds have suffered a severe decline over all Europe, which has developed concerns over the sustainability and environmental consequences of the intensification of land use in agricultural systems [12]. Plant diversity in dry land Mediterranean cereal fields is affected by agricultural intensification at any of these abovementioned scales, as reflected by a decrease of plant species richness and changes in species composition [13]. But the ecological implications of these changes still remain uncertain, because in such agro systems there is a high variability in the local occurrence of plant species [14,15].…”