Research Scotland’s native wild apple – Malus sylvestris: ecology and management By Rick Worrell, Markus Ruhsam, James Renny, Will Jessop and Graeme Findlay Summary Foresters and ecologists appear to have dismissed wild apple (Malus sylvestris (L.) Mill.) as unworthy of professional attention and as a result we know virtually nothing about the ecology and management of the species. This paper provides a basic account of the characteristics of wild apple based on a survey of 209 trees across Scotland and northern England. It is widely distributed, except on the most acid lithologies, and occurs infrequently as single trees or small groups, and never in stands. It grows in ancient woodland, usually near woodland edges and reaches Figure 1. Wild apple in ancient wood pasture near St Johns Town of Dalry, Galloway. its highest densities in wood pasture. It can grow to be a more substantial tree Introduction and aims paper to this (Worrell et al., 2019) points than previously reported: i.e. heights Foresters and ecologists have made out that we have been unsure even up to 14m and stem diameters up to good progress in the last few decades whether it is a native species, unclear 1m. The current generation is 60-120 on increasing our understanding of which of the apple trees growing in the years old and natural regeneration is Scotland’s rather limited palette of countryside are actually Malus sylvestris scarce, and there is a need to establish native trees and shrubs, but some species and uncertain how to identify it. The a new generation of trees. Cattle, have missed the spotlight altogether, main aim of the work described in this and presumably therefore formerly and none more so than wild apple. paper was to carry out an ecological auroch, appear to be heavily involved in Somehow both foresters and ecologists survey of wild apple in Scotland to try to promoting regeneration. It is a tree with have dismissed the tree as unworthy remedy this lack of knowledge. The main considerable potential as a spectacular of professional attention. As a result objectives were to determine: landscape tree, as a prolific producer we know virtually nothing about the • The distribution of the wild apple of a ‘non-wood forest product’ and as woodland types in which wild apple (M. sylvestris) and its ecological an important species for threatened trees grow; their site requirements and characteristics and requirements pollinator insects. Outline guidance their regeneration biology; and their • Basic information about its on conservation and management is distribution in Scotland has never been flowering, fruiting and regeneration. provided. properly described. The companion On the basis of the results we propose basic management and conservation guidance for wild apple, and propose how the species might be used in the THE AUTHORS future. Wild apple clearly needs to Rick Worrell* has been a self-employed forestry consultant since 1987, specialising in native be incorporated as a component of woodland and growing broadleaves for quality timber native woodlands and has potential as a Markus Ruhsam is a plant molecular ecologist at the Royal Botanic Gardens Edinburgh (RBGE) with spectacular landscape tree, as a prolific a particular interest in how plant populations change over time producer of a ‘non-wood forest product’, James Renny is a naturalist based in Grandtully, Perthshire and as a food source for threatened Will Jessop was an MSc student at the RBGE and is now studying for a PhD at the University of pollinator insects (Scottish Government, York 2017). In addition, our fieldwork revealed Graham Findlay is Planning and Conservation Forester at Forestry and Land Scotland, Dunkeld signs of past management and use of Office wild apples and their hybrids, and so *Corresponding author: [email protected], Upper Park, Aberfeldy, Perthshire PH15 2EH this paper briefly touches on evidence of Volume 74 No. 1 Spring 2020 | 21 Research the common history of people and wild trees). Ecological information was form stands. It occurs at highest density apples in Scotland. recorded for up to 209 of these covering: in wood pastures (up to ten mature Rather more is known about the • Tree size and structure: Height trees/ha), and makes a very startling ecology of the species in continental (m), crown diameter (m), stem contribution to the landscape in spring Europe, i.e. that it is a tree of woodland diameter (cm) at ground level, and (Figure 1). edges, growing as single individuals number of stems (183 trees). Trees This project produced the first or small groups, widely distributed thought to have been pollarded were map which unambiguously shows but never common, tolerating a range noted occurrences of wild apple (Figure 2 of soil types, often found on river • Site characteristics: Elevation, left). However this is an incomplete floodplains, and relatively intolerant of topographic position, habitat picture due to the limited number of shade (Stephan et al., 2003, Schnitzler (ancient woodland, native samples and varying sampling effort et al., 2014). Interestingly it is listed in woodland, other woodland, wood in different parts of the country. The Europe as a noble hardwood, capable pasture, hedgerow, or field); Botanical Society of Britain and Ireland of small-scale decorative timber National Vegetation Classification (BSBI) map for Malus sylvestris (Figure 2 production (Karen Russel, pers comm.). (NVC) woodland community middle) and a map we produced (Figure The ultimate aim of this paper is to (Rodwell, 1991); associated ground 2 right) using data from the Native encourage forestry and conservation flora species (209 trees) Woodland Survey of Scotland (Forestry professionals in Scotland to take the • Location: National Grid Reference Commission Scotland, 2014) give better species seriously and address some of and other information describing coverage, but do not distinguish between the symptoms of our collective neglect. the location. wild, hybrid and domestic apple. Whilst none of these maps is wholly adequate Methods Germination studies on its own, together they build up a A total of 342 apple trees were located in Apple seeds were collected from 24 wild fairly clear overall picture. Details of Scotland and parts of northern England apple trees and sown in the autumn in identification using both morphological (as described in Worrell et al., 2019), potting compost. Their germination and characteristics and DNA analysis are focusing primarily on wild apples (M. the growth of seedlings were recorded. given in the companion paper (Worrell sylvestris) and probable hybrids (M. et al., 2019). sylvestris × domestica), but also including Results Wild apple has strongholds in Loch a few feral domestic apple trees. These Species distribution Lomond and the Trossachs, Highland trees were identified to species, initially Wild apple occurs as single trees or Perthshire, and Dumfries and Galloway. in the field based on morphology, with occasionally in small groups, scattered It is apparently largely absent in many emphasis on leaf hairiness, crown through native woodland, wood pastures, parts of Deeside and Strathspey. Oddly, structure and, if available, fruit size as hedgerows, pastures and low-lying it also appears scarce in much of the described in Worrell et al. (2019), and moorland. As with other tree species of Western Highlands, but not wholly confirmed later via DNA analysis (342 the Rosaceae (cherries, rowan) it does not absent. Possibly the most interesting Figure 2. Distribution of Malus sylvestris: Left – wild apple verified by DNA in this study, with darker red dots reflecting greater numbers of samples at a location. The distribution partly reflects natural factors and partly surveying effort.Middle – according to the BSBI New Atlas but including M. domestica and hybrids (www.brc.ac.uk/plantatlas/plant/malus-sylvestris-sl). Right – woods containing ‘crab apple’ from the Native Woodland Survey of Scotland, though actually the data points include domestic and hybrid apple and some that were misidentified as apple. 22 | SCOTTISH FORESTRY Research human dispersal; these are mainly hybrids and domestic apples. Elevation The highest elevation trees were at about 300m asl in both Scotland and northern England. The highest tree in the Lake District is at 305m in Patterdale, on an Above: Figure 3. The most north-western wild apple tree recorded in Scotland, at 200m asl, near exposed ridge (see Figure 4); and this Dundonnell, south of Ullapool. Below: Figure 4. The highest apple (a hybrid) located at 300m in hybrid tree had grown to 10m tall and Patterdale, Lake District. It had its top 8m blown out (lying to right), but is regrowing vigorously. over 70cm stem diameter, had its top 8m blown out, but is now re-growing vigorously – suggesting that apple may be capable of growing at higher elevations than this. Anecdotally, a wild apple seedling planted accidentally in the southern uplands at 650m appears to be growing adequately (Philip Ashmole, pers comm.), which is rather startling, though its long term survival is obviously uncertain. Climatic conditions Wild apples occur in a very wide range of climatic conditions (see Figure 5) i.e. in areas with: • annual rainfall ranging between 600mm (Lothians) to over 3000mm (Lake District) location at which wild apple was found (Argyll), to apparent absence just a little • annual temperature ranging from in the west was on the valley slopes further west. It is common in northern over 1500 degree days (above above Dundonnell, near Ullapool, where Perthshire but apparently absent in 6oC) in lowland Dumfries and the seven trees occur in ancient woodland nearby Strathspey and Deeside. The Galloway coast, to 1100 degree days and wood pasture. These were only incidence of wild apple reduces markedly in Shetland, and down to 700–800 recorded because the estate owner and on acid lithology such as Moine schist degree days on some upland sites. gardener had a special interest in the and granites, in the same way as for Some of the finest woods for wild trees; they would otherwise not have elm and ash.