G.R. de Snoo

Abundance of invertebrate prey for birds on organic and conventional arable farms in the Netherlands

As a result of agricultural intensification, populations of farmland birds have been in steep decline for several decades. Reduction in food abundance has been mentioned as one factor behind these declines. Extensive farm management, such as use of organic methods, is expected to provide more food for birds. In this study we compared invertebrate prey abundance for birds during the breeding season between organic and conventional arable farms. We made comparisons for three different groups of birds: (1) birds feeding on soil-living invertebrates (earthworms), (2) birds feeding on ground-dwelling invertebrates and (3) birds feeding on aerial invertebrates. Invertebrate abundance was compared between organic and conventional farms, crop and non-crop habitats, and between crop and non-crop habitats under the same farm management. On organic sites, earthworm abundance was 2–4 times higher than on conventional sites, but no differences were found between crop types. Total abundance of ground-dwelling invertebrates did not differ between organic and conventional sites, but positive effects were found for several individual taxonomic groups, such as carabid beetles and spiders. On organic farms, invertebrate abundance was higher in carrots, cereals and onions compared to other crops; on conventional farms this was true for onions. When compared with most crops, ground-dwelling invertebrate abundance was low in uncropped field margins and on ditch banks. On organic farms, aerial invertebrate abundance was approximately 70% higher than on conventional farms. On cereal fields, aerial invertebrates were especially abundant

A quantitative survey of semi-natural habitats on Dutch arable farms

Abstract To enhance biodiversity, guidelines for farm-based nature management recommend that farmers manage at least 5% of their land as semi-natural habitat, in tandem with other measures. Semi-natural habitats are defined here as those areas of a farm that are non-productive, i.e. areas with no intentional inputs of pesticides or nutrients and remaining effectively undisturbed. Reliable information on the actual amount of semi-natural habitat on arable farms was lacking, however. To address this lacuna the absolute and relative area of such habitats was assessed on 105 arable farms in seven regions of The Netherlands. The results on the national level, showed that on conventional Dutch arable farms 2.1% of the holding was managed as semi-natural habitat, a disappointing figure. No marked interregional differences were found, reflecting the high intensity of land use throughout the country. On average, 1.7% of farm holdings were taken up by farmyards, buildings and farm roads and 96.2% by cropped land. Ditch banks were the most common semi-natural habitat on the farms, followed by ditches, hedgerows and dry ditches. Farms participating in field margin projects maintained twice the average figure (5.3±2.7%) as semi-natural habitat, compared to 2.4±0.8% without field margins. Comparing conventional with integrated and organic farms revealed no essential difference in the relative amount of semi-natural habitat on each type of farm.

A concept of food-web structure in organic arable farming systems

A proposal for a descriptive or topological farm food web is derived from field observations and from references in literature. Important themes in the food-web theory are tentatively applied to this preliminary model, explaining differences between local farm food-web structures and how they are related to farm and/or ecological infrastructure (EI) management. Predictions are made for four different farm food-web structures for extremes of farm and environmental gradients corresponding to the length of organic duration and amount/quality of EI. The implications with regard to farming practices and nature conservation are that both organic duration and the amount/quality of ecological infrastructure may contribute to ecosystem services and nature conservation. However, an optimisation of the farm food web with regard to ecosystem services, may possibly run counter to nature conservation goals.

Morphological markers for the detection of introgression from cultivated into wild carrot (Daucus carota L.) reveal dominant domestication traits

Hybridisation and subsequent introgression have recently received much attention in the context of genetically modified crops. But crop-wild hybrid detection in the field can be difficult, as most domestication traits seem to be recessive, and the hybrid phenotype may also depend on the direction of the cross or environmental factors. Our aim was to develop a reliable set of morphological markers that differ between two wild and 13 cultivated carrots (Daucus carota L.) and to evaluate their inheritance in hybrid lines. We then examined these morphological markers in four F1 hybrids obtained by fertilising plants from the two wild accessions with pollen from two common carrot cultivars. Of the 16 traits that differed between the two carrot subspecies, three took intermediate values in the hybrids, eight resembled the cultivar parent (dominant domestication traits), two resembled the wild parent (domestication traits recessive), and three were not significant or growth condition-dependent. Root:shoot ratio was seven times higher for cultivars than for wild plants, while still attaining equivalent total dry weight, which shows that dry matter production by the shoot is much higher in cultivars than in wild plants. High root:shoot ratios were also present in the hybrids. While we found no maternal effects, the type of cultivar used for pollination had an impact on hybrid characteristics. The morphological markers developed here provide insights into the mode of inheritance of ecologically relevant traits and can be useful for pre-screening wild populations for hybrid detection prior to genetic analysis.

The Potential of Sustainable Forestry Certification for Smallholder Tree Growing

This chapter’s aim is to investigate the potential of sustainable forestry certification for smallholder tree growing. Certification can be important for different stakeholders in the value chain of timber and timber products. By certification, consumers can choose on the basis of more sustainable behavior. For the manufacturing industry, certification can help to improve its image, and in the long run assure its resource input. For the producers of the timber resources, certification can help in achieving market access and can be the basis for long-term sales agreements. There are a number of certification systems for sustainable forestry, some of them operating on a global level, like particularly the Forest Stewardship Council (FSC) and the Programme for Endorsement of Forest Certification schemes (PEFC). However, certification in developing countries lags behind: in 2006 these countries only comprised two percent of the certified forests. A recent FSC program was aimed at timber production by Smallholders and Low Intensity Forests (FSC-SLIMF). This may alleviate the barriers faced by producers in developing countries, for both individual and community forestry. Before starting a process of certification, the costs and benefits along the chain need to be carefully examined, including market perspectives. In general, certification is only useful to an international market, which with others sets requirements on the choice of tree species and timber quality. As a case study, special attention is paid to the potentials of certification of forestry plantations in the Philippines.

Eco-labelling of agricultural food products

Abstract: This chapter discusses eco-labelling of food products from different types of agriculture, together with the underlying certification systems. Three types of agricultural production are on various points compared with conventional agricultural practice: organic farming, integrated agriculture and regional products. For comparison reasons, three related eco-labelling schemes are added that are relevant for agricultural products: industrial eco-labelling, sustainability certification of natural resources and Fair Trade labelling. Thereafter the effectiveness of the schemes is discussed. The chapter ends with a discussion of some perspectives, particularly of the ever increasing number of labelling schemes.

Food Availability for Meadow Bird Families in Grass Field Margins

Agricultural intensification in grasslands has led to the decline of meadow bird populations in The Netherlands in the last 60 years. Habitat for meadow bird chicks has declined in quality and quantity, thereby reducing food availability. Agri-environment schemes (AES) to halt the decline in meadow bird numbers have thus far been insufficient. These AES are on the level of entire fields, but recent research suggests that margins of fields may be more suitable chick habitat than centres of fields. Therefore, it could be productive to specifically target grass field margins as part of meadow bird AES. Our study examined the differences in food availability for meadow bird families in different portions of a grass field. Invertebrates were sampled in different locations on the field and results were compared to known dietary preferences of four species of meadow bird chicks. We show strong differences in food availability within fields, depending on meadow bird species. The preferred prey species of chicks of Black-tailed Godwit Limosa limosa and Redshank Tringa totanus predominantly occurred in field margins, whereas those of Oystercatcher Haematopus ostralegus chicks were found mostly in the main part of the field. The prey species of Northern Lapwing Vanellus vanellus chicks showed no clear pattern within fields. We conclude that food availability within a field differs spatially between meadow bird species. Particularly for Black-tailed Godwit and Redshank, grass field margins constitute an important part of the field. Therefore, specific management to further enhance food availability in these margins may constitute an important addition to the existing mosaic approach.

Evaluation of smallholder farming systems in the Western Highlands of Cameroon

Small scale farming systems in the Western Highlands of Cameroon (WHC) are influenced by many factors. Understanding the determinants that influence the system is essential when targeting appropriate intervention strategies for improvement. A field survey was carried out and analysed to understand the forces that drive the farming systems in this area. The impacts of farming practices on farm sustainability were used as indicators to score sustainability. The results revealed that the household characteristics were very similar across the villages while the sustainability differed depending on the intensity of off-farm inputs in the production systems and other socio-economic factors. Sustainability had significant negative relationships with the intensity of land use, off-farm inputs, and sole cropping practice and a positive relationship with the age of the head of the household. The determinants of the system which explained 62.15% of the total variation of sustainability in the study area were grouped to indicate a number of underlying common factors influencing sustainability. The villages of the WHC had much in common and could benefit equally from the same improved technologies and recommendations.

Do Field Margins Enrich the Diet of the Eurasian Skylark Alauda arvensis on Intensive Farmland

To help restore food availability for birds, arable field margins (extensively managed strips of land sown with grasses and forbs) have been established on European farmland. In this study we describe the effect of field margins on the diet of Eurasian Skylark nestlings and adults living on intensively managed Dutch farmland. We tested the hypotheses that field margins offer a higher diversity of invertebrate prey than intensively managed crops, and that the diet of nestlings receiving food from field margins will therefore be more diverse than that of other nestlings. Field margins had a greater variety of invertebrate prey groups to offer than the intensively managed crops. Coleoptera were the most frequently and most abundantly eaten prey group by both adults and nestlings. Together, Coleoptera, Diptera, Lepidoptera, Hymenoptera and Araneae accounted for 91% of the nestling diet. Nestlings ate larger prey items and a larger proportion of larvae than adults. Almost 75% of both adults and nestlings consumed plant material, perhaps indicating a scarcity of invertebrate resources. When provided with food from field margins, the mean number of invertebrate orders in the nestling diet increased significantly from 4.7 to 5.5 and the number of families from 4.2 to 5.8 per sample. Thus, birds that used field margins for foraging could indeed provide their young with more invertebrate prey groups than birds only foraging in crops and grassland.