England’s Important Arable Plants Introduction England has a diverse arable flora. Rather than being ‘arable deserts’ the annual plants associated with this habitat are unique and some of our most threatened flora. Twenty-three vascular plants associated with cultivated and disturbed habitat are noted as being of conservation concern on Section 41 of the Natural Environment and Communities Act 2006. As such, the UK government created the England Biodiversity 2020 pledge, which includes increasing the amount of arable habitat. The decline of arable plants can be attributed to many changes in the agricultural sector. The use of broad-spectrum herbicides introduced in the 1950s increased towards the end of the 20th century and are still a major factor influencing our landscape. Seed cleaning became more efficient, and fertiliser use increased along with the development of modern crop varieties that can take-up large quantities of nutrients growing faster than the arable plants that lived alongside them. In addition, farming systems have changed considerably resulting in a greater proportion of autumn-sown cereals compared with the historical spring-sown cereals, changes from conventional ploughing to minimum tillage, and there has been a decline in the ‘traditional’ rotation of crops resulting in the grass ley break in cultivation being replaced with a break crop. This has resulted in the fields being continuously cropped, and there is no low- intensity period when arable plants could establish and fulfil their short lifecycle. Across parts of England, particularly the smaller farms in the southwest of England, there is thought to be a decline of arable land, from one of mixed farming including growing cereals for livestock feed to more pastoral based livestock businesses with a reliance on grass silage. Meanwhile the costs of arable farming have increased; making it uneconomical for smaller farms to cultivate land, and the increasing size and costs of machinery has made it more difficult to cultivate smaller fields. More recently the tariffs offered for solar energy production have established a new land use of fields filled with arrays. Many of the fields used for this business were low-intensity arable fields. Solar arrays hinder any arable cultivation, as they panels are too close together for cultivation in between, and the housing is too delicate to be disturbed. There is the option of cultivating around the perimeter of the arrays, but few farmers are advised of this management through the Environmental Impact Assessment. However, the arable fields that are still cultivated and managed with low-inputs retain impressive arable plant assemblages. Arable plants also survive along the edges of more intensely-managed cropped fields in annually cultivated uncropped margins, conservation headlands and low-input cereals and whole crop. These measures also benefit farmland birds, small mammals and insects, including providing a food source at an early period of the year when resources are short for pollinators. Arable plants provide food and shelter for a huge variety of wildlife, many of which have also declined. During the spring and summer, flowers provide an essential nectar and pollen source for bumblebees, butterflies and other insects. Amongst many others, poppies Papaver sp., dead- nettles Lamium sp., field pansies Viola arvensis and corn marigolds Glebionis segetum are visited by bumblebees and provide pollen which is an essential part of their diet. Winter seeds from plants such as black mustard Brassica nigra, chickweed Stellaria media, fat hen Chenopodium album and annual meadow-grass Poa annua provide food for a wide range of farmland birds, small mammals and insects. In turn predators that feed on these insects, small mammals and birds will also benefit. Rather than being evenly distributed across cultivated land, arable plants have a complex relationship with historical land use, soil type, crop and rotation, climate and topography. The amount of arable land that has been surveyed is very low as this land use had a low conservation profile until the ‘Fields of Vision’ conference held in 2000i, and there are difficulties obtaining access to cultivated fields to undertake surveys. In addition, arable plants do not necessarily germinate every year, and can remain dormant and undetected in the soil seed bank for many years until conditions are suitable. Further survey work is desperately needed to establish whether historical populations of arable plants are still surviving and locate new populations of arable plants. This arable plant mapping exercise has been undertaken to identify the location of threatened arable plants across National Character Areas in England. It can be used to refine the targeting of conservation measures for arable plants and inform locations where further surveys should be targeted. Important Arable Plant Areasii Important Arable Plant Areas (IAPAs) are a method of assessing arable sites based on the presence of threatened species and/or exceptional assemblages: Criterion A – threatened species. IAPAs selected under threatened species are based on the occurrence of arable plants recognised in National, European or Global red lists. Currently no arable plants present in Wales are considered to be threatened at a European level, thus there is no present qualification of European or Global level under criterion A. However, at the National level (UK and Wales) there is allowance of key sites of threatened or protected species, particularly those considered of conservation concern and stated on the Section 42 list of species on the Natural Environment and Rural Communities Act 2006 or as Biodiversity Action Plan species. Up to 30 ‘best’ sites from across Britain can be selected for threatened species (Critically Endangered, Endangered and Vulnerable species). Populations of threatened species and county rarities not selected under criteria A as being of National Importance should be selected as being of County Importance. Criteria B – outstanding assemblages. IAPAs are selected based on a weighted scoring system regarding each species individual rarity (table 1). A basic list of plants was drawn together using PLANTATTiii and supplemented with a selection of additional plants considered to occur occasionally on arable land. Individual species scores range from 0 for no concern and 1-3 for degrees of least concern to 9 for critically endangered or extinct species (appendix A). The plant scores have recently been updated in January 2015 taking into account recent distribution information. In addition, cumulative score thresholds have been set accounting for County, National and European levels of significance based on soil qualities (table 2). This allows the relative comparison of different sites. The thresholds are considered to be provisional as they were based on the best available information in 2005 and further refinement work may be undertaken in the future. Table 1: IAPA weighted scores based on the rarity of an individual species at a UK level. Score Status 9 Critically Endangered (CR) or Extinct (EX) 8 Endangered (EN) 7 Vulnerable (VU) 6 Near threatened (NT) OR additional Nationally Rare (i.e. 1-15 10-km squares) 5 Additional Nationally scarce: 16 to 50 10-km squares OR 51 to 100 10-km squares and change index of –1.0 or less 4 Additional Nationally scarce: other Nationally scarce species not covered by the above category 3 Species of local concern: 101 to 500 10-km squares 2 Species of local concern: 501 to 1000 10-km squares 1 Species of local concern: 1001 to 1500 10-km squares and change index less than 0.0 (i.e. negative) Table 2: threshold scores for assessing the conservation status of IAPAs Sands and freely Clays Chalk and limestone draining acid soils derived soils County importance 20-34 20-29 30-44 National importance 35-69 30-69 45-89 European importance 70+ 70+ 90+ To ascertain the IAPA score for each tetrad the dominant soil type has been determined using NapMapiv soils data. The three soil categories are very broad and many different soil classifications fall within each category. There are also soils that straddle the boundary between the soil broad categories, and soils that do not fall into any of the broad categories. Table 3 provides examples of the soil types that fall into the three broad categories ‘sands’, ‘clays’ and ‘chalk/limestone’ soils and an ‘other’ category. Table 3: Examples of soil types included in each broad soil category. Sands and freely Typical sand-pararendzinas draining acid soils Typical sandy-gley soils Typical argillic brown earths (all other types) Clays Cambic stagnogley soils Typical alluvial gley soils Pelo-stagnogley soils Chalk and limestone Humic, brown, gley and colluvial rendzinas derived soils Brown earths over limestone bedrock Other Disturbed soils (i.e. from disused mining operations) Raw oligo-amorphous peat soils Humus-ironpan stagnopodzols Figure 1: IAPA score for each National Character Area. Darker reds are higher scores, indicating that there are a higher number of rare and threatened plants present. Map created using information collated in 2005. Conservation measures for arable plants in England Agri-environment measures are the primary conservation mechanism delivering management for arable plants, and will continue to play a major role in their conservation for the foreseeable future. Cultivated land has long been the target for conservation measures. The first agri- environment scheme in 1987 did not include measures