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CHAPTER 1
All farming systems
Key messages
Support or maintain low intensity agricultural systems
We have captured no evidence for the effects of supporting or maintaining low intensity agricultural systems on farmland wildlife.
Increase the proportion of semi-natural habitat in the farmed landscape
Of five studies monitoring the effects of the Swiss Ecological Compensation Areas scheme at a landscape scale (including three replicated site comparisons), one found an increase in numbers of birds of some species, two found no effect on birds and three found some species or groups increasing and others decreasing.
Pay farmers to cover the cost of conservation measures (as in agri-environment schemes)
For birds, twenty-four studies (including one systematic review) found increases or more favourable trends in bird populations, while eleven studies (including one systematic review) found negative or no effects of agri-environment schemes. For plants, three studies found more plant species, two found fewer plant species and seven found little or no effect of agri-environment schemes. For invertebrates, five studies found increases in abundance or species richness, while six studies found little or no effect of agri-environment schemes. For mammals, one replicated study found positive effects of agri-environment schemes and three studies found mixed effects in different regions or for different species.
Apply 'cross compliance' environmental standards linked to all subsidy payments
We have captured no evidence for the effects of applying 'cross compliance' environmental standards for all subsidy payments on farmland wildlife.
Implement food labelling schemes relating to biodiversity-friendly farming (organic; LEAF Marque)
We have captured no evidence for the effects of implementing food labelling schemes relating to biodiversity-friendly farming (organic; LEAF Marque) on farmland wildlife.
Reduce field size (or maintain small fields)
We have captured no evidence for the effects of reducing field size (or maintaining small fields) on farmland wildlife.
Provide or retain set-aside areas in farmland
Thirty-seven studies (one systematic review, no randomized, replicated, controlled trials) compared use of set-aside areas with control farmed fields. Twenty-one (including the systematic review) showed benefits to or higher use by all wildlife groups considered. Thirteen studies found some species or groups used set-aside more than crops, others did not. Two found higher Eurasian skylark reproductive success and one study found lower success on set-aside rather than control fields. Four studies found set-aside had no effect on wildlife, one found an adverse effect. Two studies found neither insects nor small mammals preferred set-aside areas.
Connect areas of natural or semi-natural habitat
All four studies (including two replicated trials) from the Czech Republic, Germany and the Netherlands investigating the effects of linking patches of natural or semi-natural habitat found some colonization by invertebrates or mammals. Colonization by invertebrates was slow or its extent varied between taxa.
Manage hedgerows to benefit wildlife (includes no spray, gap-filling and laying)
Ten studies from the UK and Switzerland (including one randomized, replicated, controlled trial) found managing hedges for wildlife increased berry yields, diversity or abundance of plants, invertebrates or birds. Five UK studies (including one randomized, replicated, controlled trial) found plants, bees and farmland birds were unaffected by hedge management. Two replicated studies found hedge management had mixed effects on invertebrates or reduced hawthorn berry yield.
Manage stone-faced hedge banks to benefit wildlife
We have captured no evidence for the effects of managing stone-faced hedge banks to benefit wildlife on farmland wildlife.
Manage ditches to benefit wildlife
Five studies (including one replicated, controlled study) from the UK and the Netherlands found ditch management had positive effects on numbers, diversity or biomass of some or all invertebrates, amphibians, birds or plants studied. Three studies from the Netherlands and the UK (including two replicated site comparisons) found negative or no clear effects on plants or some birds.
Restore or maintain dry stone walls
We have captured no evidence for the effects of restoring or maintaining dry stone walls on farmland wildlife.
Plant new hedges
Two studies (including one replicated trial) from France and the UK found new hedges had more invertebrates or plant species than fields or field margins. A review found new hedges had more ground beetles than older hedges. However, an unreplicated site comparison from Germany found only 2 out of 85 ground beetle species dispersed along new hedges. A review found lower pest outbreaks in areas with new hedges.
Protect in-field trees (includes management such as pollarding and surgery)
We have captured no evidence for the effects of protecting in-field trees on farmland wildlife.
Plant in-field trees (not farm woodland)
We have captured no evidence for the effects of planting in-field trees on farmland wildlife.
Maintain in-field elements such as field islands and rockpiles
We have captured no evidence for the effects of maintaining in-field elements such as field islands and rockpiles on farmland wildlife.
Manage woodland edges to benefit wildlife
We have captured no evidence for the effects of managing woodland edges to benefit wildlife on farmland wildlife.
Plant wild bird seed or cover mixture
Fifteen studies (including a systematic review) from the UK found fields sown with wild bird cover mix had more birds or bird species than other farmland habitats. Six studies (including two replicated trials) from the UK found birds used wild bird cover more than other habitats. Nine replicated studies from France and the UK found mixed or negative effects on birds. Eight studies (including two randomized, replicated, controlled studies) from the UK found wild bird cover had more invertebrates; four (including two replicated trials) found mixed or negative effects on invertebrate numbers. Six studies (including two replicated, controlled trials) from the UK found wild bird cover mix benefited plants; two replicated studies did not.
Plant nectar flower mixture/wildflower strips
Forty-one studies (including one randomized, replicated, controlled trial) from eight countries found flower strips increased invertebrate numbers or diversity. Ten studies (two replicated, controlled) found invertebrates visited flower strips. Fifteen studies (two randomized, replicated, controlled) found mixed or negative effects on invertebrates. Seventeen studies (one randomized, replicated, controlled) from seven countries found more plants or plant species on flower strips, four did not. Five studies (two randomized, replicated, controlled) from two countries found bird numbers, diversity or use increased in flower strips, two studies did not. Five studies (four replicated) found increases in small mammal abundance or diversity in flower strips.
Manage the agricultural landscape to enhance floral resources
A large replicated, controlled study from the UK found the number of long-tongued bumblebees on field margins was positively correlated with the number of 'pollen and nectar' agri-environment agreements in a 10 km square.
Create uncultivated margins around intensive arable or pasture fields
Twenty studies (including one randomized, replicated, controlled trial) from seven countries found uncultivated margins support more invertebrates, small mammal species or higher plant diversity than other habitats. Four studies (including two replicated studies from the UK) found positive associations between birds and uncultivated margins. Fifteen studies (including one randomized, replicated, controlled trial) from four countries found naturally regenerated margins had lower invertebrate or plant abundance or diversity than conventional fields or sown margins. Six studies (one randomized, replicated, controlled) from three countries found uncultivated margins did not have higher plant or invertebrate abundance or diversity than cropped or sown margins.
Plant grass buffer strips/margins around arable or pasture fields
Twenty studies (including two randomized, replicated, controlled studies) from four countries found grass margins benefited invertebrates, including increases in abundance or diversity. Nine studies (including two replicated, controlled trials) from the UK found grass buffer strips benefit birds, with increased numbers, diversity or use. Seven replicated studies (four controlled, two randomized) from two countries found grass buffer strips increased plant cover and species richness, a review found benefits to plants. Five studies (two replicated, controlled) from two countries found benefits to small mammals. Six (including three replicated, controlled trials) from two countries found no clear effect on invertebrate or bird numbers.
Provide supplementary food for birds or mammals
Nine studies (two randomized, replicated, controlled) from France, Sweden and the UK found providing supplementary food increased abundance, overwinter survival or productivity of some birds. Two of the studies did not separate the effects of several interventions. Four studies (one replicated, controlled and one randomized, replicated) from Finland and the UK found some birds or mammals used supplementary food. Six replicated studies (three controlled) from Sweden and the UK found no clear effect on some birds or plants.
Make direct payments per clutch for farmland birds
Two replicated, controlled studies from the Netherlands found per clutch payments did not increase overall bird numbers. A replicated site comparison from the Netherlands found more birds bred on 12.5 ha plots under management including per-clutch payments but there were no differences at the field-scale.
Provide other resources for birds (water, sand for bathing)
A small study in France found grey partridge density was higher in areas where water, shelter, sand and food were provided.
Mark bird nests during harvest or mowing
A replicated study from the Netherlands found that marked northern lapwing nests were less likely to fail as a result of farming operations than unmarked nests.
Provide refuges during harvest or mowing
A replicated study from France found mowing refuges reduced contact between mowing machinery and unfledged quails and corncrakes. A replicated controlled study and a review from the UK found Eurasian skylark did not use nesting refuges more than other areas.
Provide foraging perches (eg. for shrikes)
We have captured no evidence for the effects of providing foraging perches on farmland wildlife.
Provide nest boxes for birds
Two studies (including one before-and-after trial) from the Netherlands and the UK found providing nest boxes increased the number of clutches or breeding adults of two bird species. A replicated study from Switzerland found nest boxes had mixed effects on the number of broods produced by two species. Eight studies (six replicated) from five countries found nest boxes were used by birds. A controlled study from the UK found one species did not use artificial nest sites. Three replicated studies (one paired) from the UK and Sweden found box location influenced use or nesting success.
Provide nest boxes for bees (solitary bees or bumblebees)
Ten studies (nine replicated) from Germany, Poland and the UK found solitary bee nest boxes were used by bees. Two replicated trials from the UK found bumblebee nest boxes had very low uptake. Two replicated studies found the local population size or number of emerging red mason bees increased when nest boxes were provided. A replicated trial in Germany found the number of occupied solitary bee nests almost doubled over three years with repeated nest box provision.
Introduce nest boxes stocked with solitary bees
We have captured no evidence for the effects of introducing nest boxes stocked with solitary bees on farmland wildlife.
Provide red squirrel feeders
We have captured no evidence for the effects of providing red squirrel feeders on farmland wildlife.
Provide otter holts
We have captured no evidence for the effects of providing otter holts on farmland wildlife.
Provide badger gates
We have captured no evidence for the effects of providing badger gates on farmland wildlife.
1.1 Support or maintain low intensity agricultural systems
• We have captured no evidence for the effects of supporting or maintaining low intensity agricultural systems on farmland wildlife.
1.2 Increase the proportion of semi-natural habitat in the farmed landscape
• Five studies monitored the effects of the Swiss Ecological Compensation Areas scheme at a landscape scale, including three replicated site comparisons. Of these, one found an increase in numbers of birds of some species. Two found no effect on the number of bird species or population densities of farmland birds. Three studies found mixed effects, with some species or groups of species increasing and others decreasing.
A before-and-after study in 6 km2 of mixed farmland in Switzerland (1) found that the populations of corn bunting Miliaria calandra, whitethroat Sylvia communis and common stonechat Saxicola torquata all increased following an increase in the proportion of land under the Ecological Compensation Areas (ECA) Scheme from 0.7% to 8.2% between 1992 and 1996 (corn buntings: 6 pairs in 1992 vs 26 in 1996; whitethroat: 15 vs 44; stonechat: 14 vs 35). In addition, across 23 study areas in Switzerland, ECA land and a 25 m buffer around it occupied only 17% of farmland but contained more 37–38% of 68 red-backed shrike Lanius collurio territories, 598 yellowhammer Emberiza citrinella territories and 35 whitethroat territories. Only 6% of Eurasian skylarks Alauda arvensis territories were found on ECA land.
A review on effects of the Swiss Ecological Compensation Areas (ECA) scheme on biodiversity in arable landscapes in Switzerland (2) found that effects differed between species and taxa. Bird species breeding in hedgerows (dominated by yellowhammer Emberiza citrinella, linnet Carduelis cannabina, red-backed shrike Lanius collurio and common whitethroat Syliva communis) and wetlands (mainly reed warbler Acrocephalus scirpaceus and marsh warbler A. palustris) had more territories than expected near ECAs (hedgerows: 143 territories expected vs 293 observed; wetlands: 31 territories expected vs 52 observed). For species preferring open agricultural habitats (skylark Alauda arvensis, common quail Coturnix coturnix and common kestrel Falco tinnunculus), fewer territories than expected were recorded near ECAs (151 expected vs 68 observed). Many compensation areas were located near vertical structures (such as hedgerows or forest edges), which may bias these results. A correlation between the proportion of ECAs in the landscape and presence of the meadow grasshopper Chorthippus parallelus was found but there was no such correlation for the bowwinged grasshopper C. biguttulus. The report reviews results from a number of studies. No details on study design, monitoring techniques or other methods were given.
A 2007 site comparison study of 23 sites in the lowlands north of the Alps, Switzerland (3) found that the percentage of farmland designated as Ecological Compensation Area (ECA) had no effect on the population density of farmland bird species or bird species with territories incorporating several habitat types. ECAs are areas managed for the primary function of providing plant and animal habitat – these include meadows farmed at a low intensity. For 37 species surveyed in 1998–1999 and again in 2003–2004, population densities in wetlands and rivers were not affected by vicinity to ECAs, although hedges and traditional orchards close to ECAs did have higher bird population densities than those further away. The 23 selected sites (covering up to 3 km2 each) were randomly selected and surveyed 3 times each between April and June in both years of study.
(Continues…)
Excerpted from "Farmland Conservation"
by .
Copyright © 2014 William J. Sutherland.
Excerpted by permission of Pelagic Publishing.
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