Trees for Food-A 3000 Year Record of Subarctic Plant Use

Article excerpt

Introduction

Native peoples collected the inner bark of trees for diverse purposes across the northern hemisphere up until the late nineteenth century (see e.g. Eidlitz 1969; Erichsen-Brown 1979; Stewart 1984; Turner 1997; Zackrisson et al. 2000). Raw or processed inner bark was used primarily as a vegetable food. Inner bark was critical as a nutritional source in northern areas with long winter seasons and helped to protect from scurvy, caused by vitamin C deficiency (Urbye 1937:975-979; Ericsen-Brown 1979:8-11). Ethnographic evidence show the widespread use of different trees, primarily Pine species, across the northern hemisphere (Eidlitz 1969; Prince 2001; Kay & Swetnam 1999; Turner 1997; Sandgathe & Hayden 2003) (Figure 1).

[FIGURE 1 OMITTED]

Ethnographic data related to native peoples, collected from the seventeenth century onwards, reveal that unique and specialised techniques were involved in the process of bark peeling and the preparation of bark for food. Compared with other plant foods, the use of the inner bark of trees has several unique characteristics. The plant food substance was taken from long-lived species (trees typically with life-spans of 400-1000 years). Bark was peeled off from part of the tree in spring when sap is running, but leaving a strip of undamaged cambium so the tree would survive. The soft nutritious inner bark was separated from the coarse outer bark and then eaten fresh, or prepared for winter storage. Such non-lethal harvesting of bark left a characteristic scar on the surviving tree, which can be precisely measured and dated by counting tree rings (Zackrisson et al. 2000). The imprint of each specific bark-peeling was left in situ, allowing the spatial pattern of resource extraction over time to be analysed in undisturbed forests. Furthermore, woody material stays more or less intact for centuries after the death of the tree in subarctic environments (Ostlund et al. 2002: 56). Woody material preserved under anaerobic conditions in peatlands or lakes may persist even longer, tip to several millennia (Eronen et al. 1999: 570-75). Bark-peeling scars therefore constitute a unique biological artefact since they cross-cut the archaeological and palacoecological records.

Bark peelings help us to understand the full scale of subsistence strategies of native peoples living in areas with long winter seasons, in which the availability of nutritious plant food was severely restricted. In general, few details are known about the exploitation of non-cultivated plants as food resources over longer historical perspectives, despite being frequently mentioned in ethnographic literature covering many regions in recent centuries. One of the main reasons for this is that the practice of plant collection has left little archaeological and palaeoecological imprint, especially in subarctic areas, resulting in disproportionate estimates of the relative contributions of plant and animal sources to the diet in non-agricultural societies of the past (Clarke 1976; Zvelebil 1994; Mithen et al. 2001).

Aim of the study

The aim of this study is to analyse and interpret the use of a specific plant-food, Scots pine inner bark, by the native Sami people in northern Sweden over a long time perspective. We also discuss how the use of inner bark may have influenced Sami subsistence strategies and mobility patterns in a subarctic landscape.

Materials and methods

Study area

We have surveyed old forests and archaeological sites in an area in northern Sweden around the town of Arjeplog (Figure 1) in the northernmost part of Sweden in search of live and subfossil trees with bark-peeling scars. The selection of the study area was based on four factors: it has a number of well-defined archaeological sites covering the time-period from the earliest documented Sami settlements to the present time; there are historical records from this specific area describing Sami bark-peeling from the seventeenth century; there is a concentration of sites with live bark-peeled trees old enough to verify the oldest written information, and there are several sites with favourable conditions for preserving woody material and subfossil pine trees close to key archaeological areas.

Sami geography and history

Sami ethnicity developed in a context where northern hunter-gatherer communities amalgamated through a process of interaction with neighbouring agricultural and iron-producing societies. The Sami of north Europe formed a distinct ethnic group during the second millennium BC, as shown by characteristic artefacts, such as asbestos-tempered pottery (Mulk 1994: 7). They are described in historical records as early as 98 AD by Tacitus (Fjellstrom 1985: 52). Prehistoric Sami societies primarily relied on gathering, hunting and fishing until approximately 1500 BP, by which time reindeer pastoralism had emerged (Aronsson 1991: 10-11). Today, Sapmi, i.e. the Sami nation, cross-cuts the borders of four national states extending over the northern parts of Norway, Sweden and Finland and the Kola peninsula in Russia. In the 1600s, when the Sami were subject to Christian mission, numerous sources described their subsistence basis, including the use of Scots pine inner bark as a regular food (Schefferus 1674: 245-46; Leem 1767: 127). However, by the end of the nineteenth century the older traditions were successively phased out as the Sami people became increasingly incorporated into industrial society (Fjellstrom 1985: 283-89).

Sampling of trees with bark-peeling scars

We have sampled live and subfossil trees with typical bark-peeling scars in old growth forests near ancient Sami dwelling sites. Trees with bark-peeling scars have been identified by the following criteria: scar-size, shape of healing-lobes, presence of tool cuts and, for live and dead standing trees, scar direction (Zackrisson et al. 2000: 102) (Figure 2). Each tree with a bark-peeling scar was positioned using a hand-held GPS, and scar characteristics were measured. Scars on live trees were cored with a 12 mm increment corer and dated with traditional dendrochronological methods, using within-tree cross-dating and/or analysis of typical growth patterns associated with scar formation (Barret & Arno 1988; Ericsson et al. 2003). Subfossil logs with bark-peeling scars and with sufficient amount of non-degraded wood were sampled by extracting a small amount of wood from the scar margin (the nearest five annual rings) to facilitate AMS [sup.14]C dating. All bark peelings identified in submerged logs were found less than 150 metres from one specific archaeological site, Rappasundet, where subfossil pine trees annually emerge due to peat erosion caused by raised water levels of an hydro-electric power dam. Rappasundet is a key archaeological site in Sami prehistory where a large amount of artefacts and asbestos-tempered pottery, in addition to structures such as hearths and cooking pits have been discovered through archaeological excavations (Bergman 1995: 143-157). The main part of the objects consisted of scrapers, flakes, cores, and other knapping debris of local rocks. Pottery associated with ancient Sami culture (cf Jorgensen & Olsen 1988: 5-39) was produced on the site. Radiocarbon dating shows that the settlement was established about 3000 years ago (Bergman 1995: 145). Numerous cooking pits were also found at the site which may indicate that roasting or baking of plant food took place.

[FIGURE 2 OMITTED]

Large scale preparation of inner bark in cooking pits is well described in the earliest literature from this region (Schefferus 1674: 246; Lundius 1905: 31). Sheets of bark were wrapped in packages of birch bark and placed at the bottom of a pit. The pit was covered with soil, on top of which a fire was lit. The fire was maintained until the bark turned a reddish colour. The soil cover served as a medium through which the heat from the fire was transmitted to the bark without burning it. Moisture and heat were controlled and the process could easily be terminated when appropriate. Long-term moderate heat may have transformed complex polysaccharides into more digestible di- or monosaecharide and reduced polyphenol and resin content in the bark (cf Wandsnider 1997: 1-48).

Results

129 examples of bark-peeling scars on live trees were studied. The scars had a mean (standard) length of 91 cm (91.4 cm +/-1.7 SE) and bark had been taken from growing trees when they were on average slightly more than one hundred years old. Bark was also mostly taken from the north side of the trees. The spatial patterns of bark-peeling sites indicate typical concentrations of bark-peeled trees around Sami settlements (cf Ostlund et al. 2003). The dendrochronological datings also reveal that the Sami in this region have peeled trees continuously during the last c. 600 years (Figure 3). The data from the thirteen [sup.14]C-dated subfossil logs with peeling scars extends the record to c. 2800 BP (2805 [+ or -] 60 BP, 870 [+ or -] 80 BP, 850 [+ or -] 70 BP, 830 [+ or -] 70 BP, 805 [+ or -] 55 BP, 610 [+ or -] 70, 415 [+ or -] 70 BP, 415 [+ or -] 75 BP, 375 [+ or -] 40, 320 [+ or -] 55 BP, 275 [+ or -] 85 BP, 195 [+ or -] 60 BP and 185 [+ or -] 70 BP) (Figure 3). The older dates correspond to different periods of settlement at the archaeological sites, as confirmed by archaeological records. For example, we found subfossil bark peelings at the site Rappasundet that were dated roughly to the same time period (2805 [+ or -] 60 BP-185 [+ or -] 70 BP) as the Sami settlement period at that site (2695 [+ or -] 70 BP-540 [+ or -] 65 BP) (Bergman 1995: 145). The temporal data furthermore indicate that bark-peeling diminished rapidly in the early nineteenth century.

[FIGURE 3 OMITTED]

Discussion

The period when bark was used as food spans a time of fundamental changes in Sami society: the transition from hunting/gathering to the emerging Sami reindeer pastoralism, followed by incorporation of the Sami people into Nordic society from late medieval times onwards. In view of the long history of contact between the Sami and surrounding societies it is conspicuous that the use of inner bark for food remained invariable and exclusive to the Sami for thousands of years. Clearly, the use of bark formed an essential part of the diet and was not easily replaced by other food. However, the practice did not survive the secondary effects of the industrial revolution on Sami society, such as the availability of alternative carbohydrate and vitamin sources, the strong prohibition against using trees for purposes other than lumber, and changes in the traditional reindeer pastoralism of the late nineteenth and early twentieth centuries.

In our study we were able to confirm the Sami use of Scots pine inner bark for a period of almost 3000 years. This is the oldest and longest record of any specific non-agricultural plant use in the subarctic region. The reasons behind the persistence of this tradition are an adaptation to the long winter season in the subarctic, during which the availability of alternative nutritious plant food was severely restricted. The long winter season is problematic for agricultural societies relying on annual crop plants at these northern latitudes. Periods of harsh climate that destroy crop production and cause famine hit farmers especially hard, but had limited effect on Sami societies relying on reindeer herding, fishing, hunting and inner bark as the main plant food resource (Fellman 1906: 145-146). In contrast to cereals, availability of inner bark does not vary significantly due to annual variation in climate. Bark resources may therefore have been a stable and predictable part of a subsistence strategy that included many other uncertain elements. The quantities used probably depended on the size of the household. According to one of the written sources, rich people (implying large households) who produced a lot of reindeer milk would collect large quantities of bark (Drake 1918:154). The annual supply of bark flour, (i.e. crushed flakes) of one household could amount to 20-30 kg. Additional supplies of unprepared, but dried strips or sheets of bark were stored for later use during the winter by each household (Vorren 1964:8). Bark was also eaten fresh during the summer and may have been used in amounts similar to that of the winter supply. A conservative estimate indicate that a forest Sami family in N. Fenno scandia may have used at least 75 kg (dry weight) inner bark annually. Judging from the size of the registered bark peelings and empirically-based estimates of the dry weight of inner bark sheets, this implies that a minimum of 260 trees were peeled annually. However, figures on bark consumption are built on estimates from the nineteenth century when the use of inner bark already had started to decline (Zackrisson et al. 2000). It is reasonable to assume that bark consumption was much larger before trading of alternative food stuffs such as cereals became common in these northern regions. There are few comparable data available from other subarctic regions. From eastern Siberia however there are reports from the nineteenth century that a family used 160-260 kg of pine inner bark annually (Middendorff 1875: 1565).

The sophisticated technique of bark harvesting that allowed trees to survive and be used for later harvest and the uniform size of bark-peelings has been in practice at least for 3000 years. This veneration for older trees that had given food have had the further benefit that bark-peeled trees were not cut for firewood by the Sami, but remain over centuries around ancient Sami dwelling sites (Ostlund et al. 2003:85). While some of these practices may have had practical reasons, it is important to point out that other motives, such as rituals, also must be considered (cf. Boyd 1988). Our conclusion is that they may reflect common religious beliefs of trees being holy, which is often found among native people in the circumpolar region. The consistency in peeling direction, and the practice of leaving a string of living cambium on the southern (sun exposed) side of the tree, may also reflect ritual practices connected to the Sami sun goddess, Biejvve (Bergman et al. in press).

The continuity of bark peeling traditions over time gives considerable scope for analysing aspects of Sami life and their interaction with the subarctic environment. Peeling scars remaining on old-growth trees give precise spatial and temporal information on procurement logistics and settlement patterns of the nomadic Sami. For example, the clustering, size, age and number of scars at a certain Sami settlement show in detail the use of this food item in the local Sami economy. This is in sharp contrast to all other types of plant food used by subarctic peoples, which can only be studied indirectly and never strictly in situ by archaeological or palaeoecological methods. Scots Pine inner bark was of special importance since it was one of the few available vitamin C sources that could prevent scurvy during the long winter season and therefore probably had strong selective influences on the subsistence strategies of subarctic economies that developed over time (Eidlitz 1969:155-168). Stored dried or roasted bark was mixed into various dishes with blood, fat, meat or fish. The high protein content relative to carbohydrate content in meat based diets could cause several health problems for people, both with regard to uptake of nutrients and metabolism (Speth & Spielmann 1983: 5-31; Gottesfeld 1995:155-166). Plant foods such as inner bark contain carbohydrates, vitamins, food fibres, and antioxidants (Airaksinen et al 1986: 380-384) that could reduce such negative effects of a large meat consumption in hunter-gatherer societies (Cordain et al. 2002:42-52). Plant lignans in Scots pine inner bark may also have positive health effects by reducing risks fur cardiovascular and cancer diseases (Vanharanta et al 2002:952-957). The discovery of Palaeolithic tools that may have been used by European Neanderthals for collection of inner bark (Sandgathe & Hayden 2003) raises questions whether bark is an extremely early plant food source among hominids. As bark also is a common food among primates (especially the greater apes), Watanabe (1985:12) suggested that it may have been a food used by the first Homo sapiens that spread (from Africa) into temperate regions. It is therefore tempting to speculate that Scots pine bark could have been used by the first hominids that populated the northern temperate region. Scots pine had a wide distribution in temperate Eurasia in the Pleistocene when the first Neanderthals occurred.

It is probable that the spatial distribution of Scots pine forest with trees of the right quality (age, bark structure, taste and branchiness) shaped subsistence strategies and settlement patterns developed over millennia, just as much as factors traditionally regarded as important, such as the location of good fishing and hunting sites, and pasture for grazing reindeer. The continuous use of Scots pine inner bark over time strengthens the interpretation that inner bark was used as a common food source and not only as temporary food during periods of famine as has been reported among Nordic farmers (Eidlitz 1969: 57; Niklasson et al. 1994: 188). The cessation of inner bark use among the Sami in the nineteenth century coincided with the cessation of similar food practices among most native peoples within the circumpolar area (Eidlitz 1969; Gottesfeld 1992).

Today, both in North America and northern Eurasia, culturally modified trees are associated with old-growth forest stands, principally in national parks and forest reserves (Mobley & Eldridge 1992; Prince 2001; Ostlund et al. 2003). In commercial forests such trees have been cut down during the twentieth century. These areas are currently set aside to protect "natural forest". However, they are as much "tree museums" as natural systems, protecting relict evidence of native peoples' relationships to forest ecosystems. Therefore, old and ancient culturally modified trees, such as trees with peeling scars, should be included in preservation programs (Zackrisson et al. 2000:107). They comprise unique biological archives that help the interpretation of long-term relationships between people and northern ecosystems in areas that have been subjected to millennia of spatially broad but low intensity land-use. Northern forests containing both culturally modified trees and archaeological sites constitute unique environments where the archaeological and palaeoecological records cross-cut, and where spatial patterns of ancient land-use can be interpreted centuries and even millennia back in time.

Acknowledgements

This work was supported by FORMAS, Sweden, the Bank of Sweden Tercentenary Foundation and by the European Unions structural funds. We wish to thank Oliver Rackham and Bill Boyd for constructive comments on the manuscript, Rikard Andersson for help with maps and John Blackwell for improving the language.

References

ARONSSON, K-A., 1991. Forest reindeer herding A.D. 1-1800. Archaeol Environ 10. Umea: Umea University.

AIRAKSINEN, M.M., P. PEURA, L. ALA-FOSSI-SALOKANGAS, S. AUTERE, M. LUKKARINEN, M. SAIKKONEN, F. STENBACK. 1986. Toxicity of plant material used as emergency food during famines in Finland. Journal of Ethnopharmacology 18:273-296

BARRET, S. W. & S. F. ARNO. 1988. Increment-borer methods for determining fire history in coniferous Forests. General Technical Report INT-244. Missoula: USDA Forest Service.

BERGMAN, I. 1995. From Doudden to Varghalsen--A study of continuity and change in hunter-gatherer society in the interior of northern Sweden, 5200 BC-400 AD. Stud Archaeol Umensis 7. Umea: Umea. University.

BERGMAN, I., L. OSTLUND & O. ZACKRISSON. The use of plants as regular food in ancient subarctic economies: A case study based on Sami use of Scots pine inner bark. Arctic Anthropology, in press.

CLARKE, D. L. 1976. Mesolithic Europe: The economic basis, in Sieveking, G., Longworth, H & Wilson, K. E. (ed.), Problems in Economic and Social Archaeology: 449-82. London: Ducksworth.

CORDAIN, L., S.B. EATON, J.B. MILLER, N. MANN & K. HILL. 2002. The paradoxical nature of hunter-gatherer diets: meat based, yet non-atherogenic. European Journal of Clinical Nutrition 56: 42-52.

DRAKE, S. 1918. Vasterbottenlapparna under forra halften av 1800-talet. Uppsala: Wahlstrom & Wistrand.

EIDLITZ, K. 1969. Food and emergency food in the circumpolar area. Studia Ethnographica Upsaliensia 32. Uppsala: Almkvist & Wiksell.

ERICHSEN-BROWN, C. 1979. Use of plants for the past 500 years. Toronto: Breezy Creeks Press.

ERICSSON, S., L. OSTLUND, R. ANDERSSON. 2003. Destroying a path to the past, culturally modified trees along Allmunvagen, N Sweden. Silva Fennica, 37 (2): 283-298.

ERONEN M., H. HYVARINEN & P. ZETTERBERG. 1999. Holocene humidity changes in northern Finnish Lapland inferred from lake sediments and submerged Scots pines dated by tree-rings. Holoc. 9: 569-580.

FELLMAN, J. 1906. Anteckningar under min vistelse i Lappmarken. Helsingfors: Finska Litteratursallskapet.

FJELLSTROM, P. 1985. Samernas samhalle i tradition och nutid. Stockholm: Nordstedt.

GOTTESFELD, L.M.J. 1992. The importance of bark products in the aboriginal economies of northwestern British Columbia, Canada. Econ. Bot. 46: 148-157.

--1995. The role of plant foods in traditional Wetsuweten nutrition. Ecology of Food and Nutrition 34:149-169.

JORGENSEN, R. & B. OLSEN. 1988. Asbestkeramikk i Nord Norge. Finskt Museum 94: 5-39.

KAYE, M. W. & T. W. SWETNAM. 1999. An assessment of fire, climate, and Apache history in the Sacramento Mountains, New Mexico. Phys. Geogr. 20: 305-330.

LEEM, K. 1767. Beskrivelse over Finnmarkens Lapper. Kobenhavn: Rosenkilde og Bagger.

LUNDIUS, N. 1905. Nicolai Lundii Lappi Descriptio Lapponiae. Svenska Landsmal 17:5. Uppsala: Wretmans.

MIDDENDORFF, A.T. 1875. Reise in den aussersten Norden und Osten Sibiriens wahrend der Jahre 1843 und 1844. Bd. 5:2. St. Petersburg.

MITHEN, S., N. FINLAY, W. CARRUTHERS, S. CARTER, & P. ASHMORE. 2001. Plant use in the Mesolithic: Evidence from Staosnaig, Isle of Colonsay, Scotland. Journal of Archaeological Science 28: 223-234.

MOBLEY, C. M. & M. ELDRIDGE. 1992. Culturally modified trees in the Pacific Northwest. Arct. Anthrop. 29:91-110.

MULK, I-M. 1994. Sirkas a Sami hunting society in transition AD 1-1600. Stud. Archaeol. Umensis 6. Umea: Umea University.

NIKLASSON, M., O. ZACKRISSON & L. OSTLUND. 1994. A dendroecological reconstruction of use by Sami of Scots pine (Pinus sylvestris L.) inner bark over the last 350 years at Sadvajaur, N. Sweden. Veg. Hist. Archaeobot. 3:183-190.

OSTLUND, L., O. ZACKRISSON & G. HORNBERG. 2002. Trees on the border between nature and culture. Env. Hist. 7: 48-68.

OSTLUND, L., T.S. ERICSON. 2003. Traces of past Sami forest use: an ecological study of culturally modified trees and earlier land use within a boreal forest reserve. Scand. J. Fox Res 18: 78-98.

PRINCE, P. 2001. Dating and interpreting pine cambium collection scars From two parts of the Nechako River drainage, British Columbia. J. Arch. Sci. 28: 253-263.

SANDGATHE, D & B. HAYDEN. 2003. Did Neanderthals eat bark? Antiquity 77:709-718.

SCHEFFERUS, J. 1674. The history of Lapland wherein are shewed the original, manners, habits, merriages, conjurations of that people. Oxford: George Best.

SPETH, J. D., K.A. SPIELMANN. 1983. Energy source, protein metabolism and hunther-gatherer subsistence strategies. J. Anthrop. Arch. 2:1-31.

STEWART, H. 1984. Cedar. Tree of life to the northwest coast Indians. Seattle: Univ. Washington Press.

TURNER, N.J. 1997. Food plants of interior first peoples. Victoria: Univ British Columbia Press.

URBYE, J.G. 1937. Barkemel som antiscorbuticum. Tidskrift for den Norske Laegerforeningen 57: 975-979.

VANHARANTA, M., J. MURSU, T. NURMI, S. VOUTILAINEN, T. RISSANEN, R. SALONEN, H. ADLERCREUTZ & J.T. SALONEN. 2002. Phloem fortification in rye bread elevates serum entetolactone level. European Journal of Clinical Nutrition 56: 952-957.

VORREN, O. 1964. Barkebrod--hungersnod? Ottar 41:7-9.

WANDSNIDER, L. 1997. The roasted and the boiled: Food composition and heat treatment with special emphasis on pit-hearth cooking. J Anthropol Archaeol 16: 1-48.

WATANABE, H. 1985. The chopper-chopping tool complex of eastern Asia. An ethnographical--ecological re-examination. J Anthropol Archaeol 4:1-8.

ZACKRISSON, O. L. OSTLUND, O. KORHONEN & I. BERGMAN, I. 2000. Ancient use of Scots pine inner bark by Sami in N. Sweden related to cultural and ecological factors. Veg hist & Archaeobot. 9: 99-109.

ZVELEBIL, M. 1994. Plant use in the mesolithic and its role in the transition to farming. Proc. Prehist. Soc. 60: 35-74.

Lars Ostlund (1,2), Ingela Bergman (3) & Olle Zackrisson (1)

(1) Department of Vegetation Ecology, Swedish University of Agricultural Science, S-90183 Umea, Sweden

(2) (Email: Lars.Ostlund@svek.slu.se)

(3) The Silvermuseum of Arjeplog, S-930 90 Arjeplog, Sweden

Received: 20 March 2003: Accepted: October 2003; Revised: 3 December 2003