If you’re fortunate enough to live within reach of farmland where stubbles have been left over the winter, now is a good time to survey them for arable bryophytes. Do be sure to survey before the farmers plough the ground in the spring though!
Overwintered stubble is an ideal habitat for many bryophytes, allowing them complete their life-cycles with little competition from other plants. The BBS Survey of Bryophytes of Arable Land (SBAL), undertaken for 3 years from 2002, found that they form six distinct assemblages, related to soil pH, crop type and geographical location.
Choose your field(s) carefully. Intensively managed fields are seldom very interesting – frequent fertiliser drenches only favour a few nutrient-demanding species – such as Bryum rubens, Barbula unguiculata, Tortula acaulon and Oxyrrhynchium hians. Then look for slight variations in the ground topography. Helpfully, you’ll often find these at the edges and in field corners, which is good news as you are less likely to be challenged by farmers when you are walking the margins!
Slight depressions where the ground stays damp throughout the year are particularly good places to look for hornworts and liverworts. If you are lucky, you might find hornworts, Anthoceros and Phaeoceros species, Fossombronia species and Riccia species. On neutral loams, there is always a chance of finding one of the two scarce balloonworts, Sphaerocarpos michelii or S. europaeus. Slightly raised ground may support Ephemerum serratum, or on heavy, calcareous clay, E. recurvifolium.
Tiny pottiaceous mosses with capsules are often present and can set the pulse racing. Tortula truncata is common on neutral or acid soil, but calcareous clays might also produce a diverse range of other capsule-bearing mosses, including Microbryum davallianum, M. rectum, and, in the autumn, M. floerkeanum. Weissia species are often supported by neutral to moderately acidic soils: W. longifolia, W. brachycarpa and if you get very lucky, W. squarrosa or W. wilsonii.
Of course, no visit to any arable land is complete without collecting plenty of small tuber-bearing mosses to check back home. Inevitably you’ll collect at least one tuberous Bryum – perhaps one of the less common ones such as Bryum sauteri, with its distinctive slightly compressed brown tubers, or B. klinggraeffii, which has numerous small raspberry-like tubers. Dicranella staphylina and D. schreberiana are frequent species with plenty of rhizoidal tubers.
If you are really lucky, you might even find Didymodon tomaculosus, a rare moss with remarkable-looking rhizoidal tubers which resemble miniature sausages.
In reality, arable land supports many different species of bryophyte. Here are a few photos to (hopefully) enthuse you:
Sharon Pilkington, January 2023