The relationship of bird biodiversity to the assignment of farmland as High Nature Value

Positive link between High Nature Value farmland and bird biodiversity

High Nature Value (HNV) farmland is agricultural land that supports biodiversity and can be identified by its environmentally sound farming practices. New research on bird biodiversity on French HNV farmland has concluded that conservation of HNV farmland is important as well as conserving areas that were previously HNV and have undergone recent agricultural intensification.

HNV farmland supports, or is associated with, either a high species and habitat diversity or the presence of species that are rare or endangered. Typical examples of HNV farmland are extensively grazed uplands, alpine meadows and pastures, and areas combining crops, trees and pasture (agro-silvo-pastoral areas) in Spain and Portugal (dehesas and montados). It can be identified with a score or index which assesses the use of environmentally sound practices such as minimum use of chemical pesticides and fertilisers, crop rotation and farmland structure in terms of presence of natural and semi-natural vegetation. Due to agricultural intensification there have been dramatic losses in HNV farmland.

The study was funded by the Joint Research Centre of the European Commission, Institute for Environment and Sustainability1 and investigated the relationship of bird biodiversity to the assignment of farmland as High Nature Value. It investigated the relationship between measures of bird biodiversity and past changes in HNV farmland in France within a 30-year period. Three farmland types were analysed: (1) land that has experienced intensified agriculture, (2) land with relatively recent history of agricultural intensification and (3) land with low-intensity agriculture identified as HNV. Across the three farmland types, researchers compared farmland bird species abundances as measured by the French Farmland Bird Index (FBI) and examined the composition of bird communities as measured by the community specialisation index (CSI) in relation to the HNV indicator.

According to the study, in 1970 there was over 21.3 million hectares of HNV farmland in France, compared to 6.9 million hectares in 2000. Between 2001 and 2008 there has been an increase in bird species abundance in both HNV farmland (9.9 % increase) and land that has only recently been intensively farmed (4.5 % increase). However on land that has historically been non-HNV there was a decrease in species abundance of 5.4%. The study analysed the effect of temporal changes in value (as measured by the HNV score) and community structure of species. In lands where the HNV score has been increasing i.e. there has been an improvement in environmentally sound practices and presence of semi-natural vegetation including landscape elements, there has also been an increase in birds that are habitat specialists, indicating that HNV farmland plays a role in supporting these specialist species. The opposite is true in lands where the HNV score has been decreasing and the community has become more dominated by habitat generalists.

This indicates that past and current HNV farmland positively affects the composition of bird communities. In areas that have recently lost their value due to agricultural intensification bird abundances were maintained at higher levels than in areas that have never reached the HNV status in the analysed period. The study suggests that in areas currently considered HNV farmland, conservation efforts should target the preservation of crop diversity and extensive farming practices that use less fertilisers. In farmlands of relatively recent agricultural intensification, conservation measures should focus on the preservation of landscape elements that may potentially buffer the effects of intensification for some bird species.

The results are positive as they suggest that, to some extent, it is possible to reverse biodiversity decline caused by agricultural intensification, if appropriate management actions take place in the near future. Benefits of HNV farmland could be maximised by identifying large-scale conservation areas or HNV farmland networks.

1. See http://ies.jrc.ec.europa.eu/

Source: Doxa A., Paracchini M.L., Pointereau P., Devictor V. & Jiguet F. (2012) Preventing biotic homogenization of farmland bird communities: The role of High Nature Value farmland. Agriculture, Ecosystems and Environment 148: 83–88
Contact: aggeliki.doxa @ imbe.fr
Theme(s): Agriculture, Biodiversity