Tsipe Aavik

Agricultural intensification and biodiversity partitioning in European landscapes comparing plants, carabids, and birds

Effects of agricultural intensification (AI) on biodiversity are often assessed on the plot scale, although processes determining diversity also operate on larger spatial scales. Here, we analyzed the diversity of vascular plants, carabid beetles, and birds in agricultural landscapes in cereal crop fields at the field (n = 1350), farm (n = 270), and European-region (n = 9) scale. We partitioned diversity into its additive components alpha, beta, and gamma, and assessed the relative contribution of beta diversity to total species richness at each spatial scale. AI was determined using pesticide and fertilizer inputs, as well as tillage operations and categorized into low, medium, and high levels. As AI was not significantly related to landscape complexity, we could disentangle potential AI effects on local vs. landscape community homogenization. AI negatively affected the species richness of plants and birds, but not carabid beetles, at all spatial scales. Hence, local AI was closely correlated to beta diversity on larger scales up to the farm and region level, and thereby was an indicator of farm- and region-wide biodiversity losses. At the scale of farms (12.83-20.52%) and regions (68.34-80.18%), beta diversity accounted for the major part of the total species richness for all three taxa, indicating great dissimilarity in environmental conditions on larger spatial scales. For plants, relative importance of alpha diversity decreased with AI, while relative importance of beta diversity on the farm scale increased with AI for carabids and birds. Hence, and in contrast to our expectations, AI does not necessarily homogenize local communities, presumably due to the heterogeneity of farming practices. In conclusion, a more detailed understanding of AI effects on diversity patterns of various taxa and at multiple spatial scales would contribute to more efficient agri-environmental schemes in agroecosystems.

Plant functional group composition and large-scale species richness in European agricultural landscapes

Abstract Question: Which are the plant functional groups respondcing most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes? Location: 25 agricultural landscape areas in seven European countries. Methods: We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied. Results: Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species. Conclusions: Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi-) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields. Nomenclature: Tutin et al. (2001).

Plant diversity in a calcareous wooded meadow – The significance of management continuity

Abstract Questions: What is the contribution of management continuity during the last 30–40 years to variation in species diversity and composition of a calcareous wooded meadow plant community? Is tree cover related to species diversity and composition of the herbaceous layer? What are the effects of local soil gradients on species diversity? Location: Laelatu calcareous wooded meadow, Western Estonian coastal zone. Methods: Plant community composition was assessed in 150 1 m × 1 m plots, located at 30 sites with known management history within Laelatu meadow (7 ha). Light and soil conditions and relative altitude were measured at each plot. DCA was used to analyse variation in species composition and general linear mixed models to analyse the effects of management and environmental parameters on diversity. Results: Management continuity was the primary determinant of plant community composition, followed by light conditions and soil parameters. Species richness, diversity and evenness are positively dependent on management continuity. Spatial autocorrelation is important as well. Diversity started to decline under the tree canopy where 50% or less irradiation reached the level of the herbaceous layer. We did not find significant effects of soil conditions on small-scale diversity. Conclusions: Management continuity, together with the cover of the tree layer, are the most important determinants of diversity. Despite grassland stands with different management history are located side by side, the regeneration of diversity and composition of plant communities after restoring regular management practices is a slow process.

What is the role of local landscape structure in the vegetation composition of field boundaries

ABSTRACT Question: How distinct is the flora of field boundaries? How does the structure of field boundaries determine the composition of vegetation? Location: Estonia, six 4 km × 4 km agricultural areas. Methods: We studied the vegetation of fields and field boundaries using 2 m × 2 m sample plots. We estimated the frequency of species in both habitat types, applied an MRPP test to analyse the vegetation composition of field boundaries with various combinations of landscape features (ditches, roads, tree and bush layers) illustrating this by DCA ordination, and used indicator species analysis to determine the characteristic species of each boundary type. Results: Ca. 45% of the flora of field boundaries comprised species found on agricultural land. Most typical species in fields – agrotolerants – were also the most common in field boundaries. The vegetation of road verges and grassy boundaries consisted mainly of disturbance-tolerant species. Woody boundaries were characterised by shade-tolerant and nitrophilous species. Ditch banks included species typical of moist habitats and semi-natural grasslands. Few threatened or protected species were observed. Conclusions: The vegetation composition of field boundaries varied due to the complex effects of landscape structure around and in these boundaries. Plant species in agricultural landscapes can be classified into two broad emergent groups on the basis of their different responses to agricultural disturbances – agrotolerant species and nature-value species. Agrotolerant species are promoted by agriculture, nature-value species include rare weeds and habitat specialists. We suggest that high-nature-value species should prevail in monitoring the effects of land-use intensification on biodiversity rather than total species richness. Nomenclature: Flora Europaea (Tutin et al. 2001).

Vegetation Change in Boreonemoral Forest during Succession — Trends in Species Composition, Richness and Differentiation Diversity

We compared the diversity and composition of understorey vegetation of four successional stages (recently clearcut, young, middle-aged and old stands) in an Estonian boreonemoral coniferous forest under homogeneous soil conditions. The ordination analysis (NMDS) showed that successional age was the main driver of understorey species composition with soil pH and P content responsible for some variation as well. Species composition in old-growth stands was more similar to the vegetation of young and clear-cut stands than to the composition of mid-aged stands. Species richness in 1-m2 plots was higher in recently disturbed and young stands due to the higher abundance of disturbance-related species. The differentiation diversity, characterising species turnover among plots within a stand, was higher in recently disturbed and young stands than in mid-aged and old stands. The results indicate that earlier successional stages are characterised by spatially heterogeneous and diverse vegetation, whereas older stands develop more homogeneous vegetation composition.

Do Landscape Dissimilarity and Environmental Factors Affect Genetic and Phenotypic Variability in Myosotis laxa s. lato (Boraginaceae)

Myosotis laxa s. lato (Boraginaceae) is a morphologically highly variable taxon. We examined whether, in the Baltic Sea region, the coastal form of M. laxa has a single centre of origin or if it has emerged due to landscape dissimilarity (sea/land ratio) and environmental factors independently in different regions. We used partial Mantels test to investigate correlations between the genetic and phenotypic variability of M. laxa and the mentioned habitat factors. Although the correlation between genetic distance and the sea/land ratio existed (p < 0.01), it was not strong (r = 0.34). Phenotypic distance among populations was not correlated with habitat factors. Similarly, there was no correlation between geographic distance and morphological characteristics of the studied populations. As neither phenotypic nor genetic dissimilarity between sampled locations was correlated with geographic distance, we suggest that the coastal form can arise independently in suitable habitats and its development may be caused by epigenetic regulation. However, gene flow among the coastal and mainland populations most likely prevents stronger adaptive and genetic divergence.