Effects of changes in grassland management

on plant diversity. 

Åsmund Asdal,

Norwegian Crop Research Institute,

Norwegian program for PGRFA

• PGR diversity in grasslands • changes in use of grasslands• effects on species• efforts in the national PGR- program

• Natural grasslands do not exist in Norway – all grasslands with their species and genetic diversity have been created through agriculture.

When agriculture cease the diversity gets lost.

Norwegian agricultural history• Livestock introduced 6000 years ago• Manure from livestock used as fertilizer inploughed fields started 2000

years ago• Technological and biological improvements in the beginning of 19th

century, main principles remained• Industrial revolution; mineral fertilizer, biocides etc. caused

extensivation of grass fields outside the farms and intensive use of areas near the farm, less dependent on outlying fields

• Huge areas of traditional agricultural fields and landscape abandoned and recaptured by forest.

Species adapted to open grasslands through 6000 years, grazed or mowed, or a combination, variation of species / genotypes;

related to climatic / edaphic conditions and agricultural practices

Changes in agriculture and landscape- latest 50 years

- Significant decrease in number of farms- Grazing in outlying fields – reduced with 50%

from 1959 to 1979. - Number of mountain farms dramatically reduced

(approx. 45000 in 1900, 1000 in 2000)- Some increase in grazing by sheeps in mountain

areas since 1979- Continued decline in grazing close to the farm;

forest pasture, fragmented pastures etc.

1992: Overgrowing have started in a former cultvated field with pioneer stoneheeps and signs of cultivation. Small spruce trees have established and benefit from sheep grazing.

1992: Granplanter på gammal innmarkmed rydningsrøyser og spor etter eldreåkerbruk. Sauebeite gir raskarebartrevekst då sau held gras, urter oglauvoppslag nede

Valle i Aust-Agder

2002: Grantre dekkjer den øvredelen av den tidlegare innmarka, skjuler kulturminne og redusererutsynet.

2002: Spruce trees are covering and supress plant species, hide signs of previous agriculture and alter the view and landscape.

1992:Residues of a spring cowhouse in front of another intact cowhouse, in a partly grazed field.

1992: Restar av vårfjøs mot intaktvårfjøs i lysopen gammal og brattinnmark

Valle i Aust-Agder

2002: Restar av vårfjøs mot intaktvårfjøs i tilgrodd gammal og brattinnmark

2002:Residues of a spring cowhouse can still be seen between fast growing trees/bushes. The other house is still intact but hidden by bigger trees.

Norwegian flora

• About 1800 vascular plant species in the wild flora (2500 when crops are included)

• 6-700 species in permanent grasslands • About 350 species exclusive to pastures and

meadows• Crop species; mainly grasses and legumes

• Species of socio economic value; medicinal and aromatic plants etc.

Agricultural landscapes outside the farms

• Mowed grasslands• Pastured grasslands• Heather mountanous fields (Calluna-moors)• Hill farms• Mowed marshes• Grasslands near seashores

Growing conditions in permanent grasslands

• Under agricultural influence– Light open– Cutting, grazing and trampling– Competitive species are hindered

A common flora of light demanding species, but differences between mowed and grazed fields, and also different soils and practices of mowing/grazing.

Traditional agricultural landscape in Norway

1. Mowed meadows – • “landscape of the scythe”, • fodder supply for the winter

2. Grazed pastures –• “landscape of the muzzle”, • fodder supply in summertime

Both mowing and grazing keep the landscape and fields open and prevent forestation of grasslands

Mowed field in the western part of Norway

Different impact on plant species- grazing vs mowing:

• Animals choose plant species when grazing, while mowing cuts all species:

tasty, juicy and nutritious species are preferred poisonous, bad tasting, woody plants, plants

with thorns etc are left back

Different impact on plant species- grazing vs mowing:

• More plant nutrients (N & P) is removed from mowed fields than from grazed fields leguminous plants and less nutrient demanding

plants will dominate a mowed field

• Grazed fields affected by trampling trampling sensitive plants survive easier in

mowed fields plants dependant on open soil to germinate can

be established in grazed fields

High numbers of grazing animals supress certain species, low numbers allow overgrowing and invasive species. Fields with short evolutionary history allow a lower pasturing pressure.

Diversitet, miljø og beitetrykk

Diversitet, miljø og beitetrykk

High productive fields (soils) needs a higher number of grazing animals to maintain an optimal species diversity.

Species in permanent grasslandsSuggested target taxa in PGR-Forum; more or less dependant on fields with agricultural influence

• Humulus lupulus L

• Ribes sp.. • Rubus sp.• Trifolium sp.• Carum carvi L.• Arnica montana L.

• Angelica archangelica Satureja hortensis L.

• Thymus vulgaris L.• Digitalis purpurea L.• Tanacetum vulgare L.• Artemisia absinthium L.• Allium sp.• Festuca pratensis Hudson• Phleum pratense L.

Species in permanent grasslands

• Endangered species, grassland the only habitat • Melampyrum cristatum L.• Ajuga reptans L.• Botrychium simplex E. Hitchc.• Herminum monorchis (L.) R.Br.• Nigritella nigra (L.) Reichenb.fil.• Liparis loeslii (L.) L.C.M. Richard• Isolepis setacea (L.) R.Br.• Carex extensa Good.• Vulpia bromoides (L.) S.F.Gray• Listera ovata

Species in permanent grasslands, cont.

• Fodder crops, gene pool for breeding• Agrostis capillaris• Poa pratensis• Phleum alpinum• Anthoxanthum odoratum• Dactylis glomerata• Trifolium repens• Festuca rubra• Trifolium pratense• Festuca ovina• Lotus corniculatus

Species in permanent grasslands, cont.

• MAP, gene pool for extended use• Carum carvi• Arnica montana• Humulus lupulus• Angelica archangelica ssp. archangelica • Veronica officinalis• Achillea millefolium• Allium oleraceum• Mentha arvensis• Festuca ovina• Lotus corniculatus

Arnica montana, traditional and current medicinal plant

• Habitats:– Lightopen and nutrient

poor/acidic soils– 14. Antropogenic

grassland/hay meadows and pastures

– 3.3 Antropogenic coastal heathland (Calluna)

• Habitat status:– Decrease in area 21-50% /

50 years– Due to change of land use

• Red list status_– DC (declining/ care

demanding

Caraway, Carum carvi, spice in Norwegian ”Akevitt”

• Genotypes from wild populations used for harvesting / cultivation

• Dependant on lightopen fields

• Decline in grazed pastures, increase in mowed fields.

• Not red-listed or threatened at the moment

Mountain Everlasting, Antennaria dioica, indicator for species which need to be widespread?

• Previous findings investigated in 2002

• Mountain (not so) Everlasting disappeared from a number of locations, due to cease of agriculture

• Male individuals dominate in some populations

• Populations more isolated, reintroducing more unlikely

• Some species get problems when they no longer are as numerous and widespread as they used to be

Species connected to permanent grasslands, cont.

• Fruits, berries and ornamentals• Fragaria vesca• Ribes sp.• Rubus sp.• Rosa pimpinellifolia• Rosa rubiginosa • Crataegus monogyna• Prunus avium• Malus sylvestris• Tulipa sylvestris

Effects of cease of agriculture:

• Depends on type of field; mowed/pastured, when/time period etc

• Inscreased level of organic matter and N in soil• Increased humidity Often increase in number and size of many

flowering species/nice view Small and light demanding plants with a short life

cycle disappear fast/not visible New species establish

Species rich mowed field with autumn grazing by sheeps

Abandonned meadow, dominated by Deschampsia caespitosa. Experiment with reintroduced sheep.

Same field, after some weeks of grazing.

A pasture grassland can be restored, only when the time without grazing is limited.

Diversity increases productivity

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5 11 13 25 brakklagt (15) Antall plantearter

Biomasse (g/m2) 1997

1998

Dry matter production in a grassland increase when number of species is high, also higher levels of N and P in soil and higher levels of microbial C and N. (S.S.Dhillion)

Activities in the National PGR-program

Registration and evaluation of grasslands in three counties:

•Species present, edaphic/climatic conditions

•Agricultural history and future plans for the fields

•Evaluate how existing grants/subsidies can be used to encourage continued farming

Recommendations

• Maintain habitats in different regions (altitude, climate etc.) to conserve the diversity within species

• Necessary to continue the agricultural practices that has created the genotypes

• Use grants and regulations to encourage farmers to continue traditional farming methods

• Establish ex-situ seed collections as security means• Develop farming methods which combine new

technology/economic conditions with the aim of maintaining genetic diversity in grasslands

• Chose a limited number of valuable grasslands for continued farming in the National Program

Use of fields near museums etc. to maintain traditional farming methods and genetic variation within species

Acheivements and further work:

1. Handbook in evaluation of grasslands, recommendations for further farming and use of subsidies.

2. Recommendations to the ministry to adapt subsidies and regulations to the aim of maintenance of Plant Genetic Resources.

3. Extended registration/evaluation of grasslands to the entire country in cooperation with regional/local agricultural authorities.