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Sci*vA>f«c (W^cavv, l. n before; elm and linden never re- .r the strength they had in the ^„„■val forest. 1 \ll this seems to mean that men •Jr ircd large areas of the original forest .iih axes, burned over the clearings, -Jjiitcd small fields of cereals and used •.»x- rest for pasturing animals. Their col-*u/.itKm was of short duration: when •.!«- forest grew back, they moved on to .ir.ir a suitable new area. According to •he pollen record, some of their settlements can scarcely have lasted more ttuti 50 years. Now this is a neat, tidy theory, but there are troublesome questions, (inikl Neolithic man really have cleared Uf^c areas of the thick primeval forest «tth his crude flint axes? Could he have burned off the felled trees and shrubs ..i his clearings? Our team of ecologists mh! .archaeologists decided to put these •(tH'stions to the test of field experiment. Wr obtained the needed funds and permission to clear a two-acre area in the Dravi'd Forest of Denmark, which is a »ucel oak forest like that of Neolithic tones. Two archaeologists, Jörgen Troels-Swith and Svend Jörgensen, took charge «< the axe tests. They were able to ob-Wn a number of Neolithic flint axe U«lcs from the National Museum in Copenhagen, and a model for the wood-« naft was available in the form of the •«nous Sigerslev hafted axe excavated '""n a Danish bog. In Neolithic axes, **»se hafts were of ash wood, the blade **J inserted in a rectangular hole in the *■» [see drawing on opposite page]. Jfrgcnsen and Troels-Smith demon-**'ed that if the haft was not to be jj*t. 't must not hold the blade too ■P*'!)' but must leave room for a little "dcwise play of the blade when it *uek. After making a number of hafted axes ^ with Stone Age man's blades, the archaeologists, together with two Passional lumberjacks, went forth into ■ tou>Ksi in SePtember> 1952-When the ! ^y attacked the trees, it soon became TREES WERE BURNED by covering them with brushwood and igniting a 30-foot strip. When the strip was almost burned out, the larger logs were used to light the next one. SEED WAS SOWN by hand in the still-warm ash {left). Then the seed bed was raked with a forked stick {right). The plants sown were barley and two primitive varieties of wheat. EŠ&KI-- BARLEY HAD GROWN to this height six weeks after it had been sown in the ash of the burned brushwood and trees. Barley sown in plots not covered with ash grew very poorly. 37 apparent that the usual tree-chopping technique, in which one puts his shoulders and weight into long, powerful blows, would not do. It often shattered the edge of the delicate flint blade or broke the blade in two. The lumberjacks, unable to change their habits, damaged several axes. The archaeologists soon' discovered that the proper way to use the flint axe was to chip at the tree with short, quick strokes, using mainly the elbow and wrist. Troels-Smith, working with an axe blade which had not been sharpened since the Stone Age, employed it effectively throughout the whole clearing operation without damaging it. When the two archaeologists reached peak form, they were able to fell oak trees more than a foot in diameter within half an hour. Small trees they dropped by cutting all around the trunk; on substantial-sized ones they used the slower method of hewing through notches on the opposite sides, in order to control the direction of fall. We realized that for clearing purposes it would be advantageous to have all the trunks lying in the north-south direction; for example, the wood would dry more quickly. In this manner we cleared the two acres of forest, letting the largest trees stand but killing them by cutting rings through the sapwood. Troels-Smith and Jörgensen concluded that Neolithic men could have cut large clearings in the forests with their flint axes without great difficulty. T^he next problem was to learn how •*- they might have burned off their clearings. For help in this phase of the experiment we called on Kustaa Vilkuna of the University of Helsinki, who is an expert on primitive burning techniques which were still being used quite recently by farmers in the spruce forests of Finland. Without waiting for the wood to dry, we first tested two burning methods, one modern,.the other primitive. The modern method, though effective in forests of conifers, failed completely in our deciduous forest. The primitive method, how- REGENERATED FOREST PRIMEVAL FOREST Z. mm* T-:-: ■ P ISfec^. ••& ELM LINDEN ASH OAK BIRCH HAZELNUT POLLEN DIAGRAM shows the effect of forest clearance on the vegetation of Denmark between about 2500 B.C. and 2300 B.C. The diagram is based on many samples of pollen taken by boring down into bogs. The width of each colored area on the diagram reP sents the proportion of pollen from one species in compariso" that from all others. The scale of the proportions is given at 38 O use was successful, and we proceeded it in the clearing in May of 1954, j r the felled trees had had more than ,.„• to dry. Brushwood and branches from the trees were spread over the to be burned. Then this material s jmiited along a 30-foot-wide belt by a„'s of torches of burning birch bark iticlu'd to stakes. When the belt was •H clcrtied, we pushed its still burning iy.s forward with long poles to set fire "the adjacent area. In this way we burned off the tangle of felled vegetation Krll bv belt. The fire was controlled care- iullv dav and night, to achieve an even tI«j thorough burning of the ground. It „ (s rather hard work, as oak wood burns Jowlv. but there were no serious diffi- culties, and in three or four days the job was finished. We burned only half of the two-acre clearing, because we wished to compare the subsequent growth on burned and unburned ground. Immediately after the burning we sowed part of the area with primitive varieties of wheat (einkorn and emmer) and naked barley. That these cereals were grown in Denmark by Neolithic man is shown by grain impressions on excavated pottery. Axel Steensberg, an expert on agricultural methods, old and new, obtained seeds of the cereals from botanical collections and directed our agriculture. We spread the seeds on the ground, raked them in with a forked branch, and waited for the harvest. For comparison we sowed two sets of plots—one burned and one unburned but hoed and weeded. The contrast in results was remarkable. On the unburned ground the grain scarcely grew at all. Evidently the rather acid forest soil was not suited to cereal growing. But the burned ground produced a luxuriant crop (which Steensberg harvested, in Neolithic fashion, with a flint knife and a flint sickle). The success of the cereals in this ground was due in part to sweetening of the soil by the wood-ash and the absence of competition from other vegetation, but the burning may also have created other beneficial factors, and we are now investigating this matter. In any case, COMMON LANCET BRACKEN GRASSES PLANTAIN PLANTAIN OTHER COMPOSITES ô CEREALS . ■ ' a WEEDS ! Ieft. In the primeval forest (colored areas below the bottom ontal line) the distribution of pollens was 30 per cent elm, an" a8h; 30 per cent oak; 5 per cent birch; 10 per cent hazel, and so on. During the three stages of forest clearance (1,2 and 3) the distribution of pollens changed. The distribution of herb pollens is shown at the right of the break in the horizontal lines. 39 NEW COMMUNITY OF WILD PLANTS grew up in the parts of the clearing that had been burned over. At the left is a species of fern called bracken. Second from the left is hazel. Both of the« plants had been present in the original forest. They grew up again whatever the factors are, they are shortlived, for the second year the burned plots yielded much smaller crops. Now, two years after the clearing and burning, we are in the process of watching developments in the early recovery of natural plant growth. The burned and unburned areas are developing quite differently. In the area cleared of trees but unburned, events are following an unsurprising and unexciting course. The ground vegetation consists mainly of the species that grew there before the clear- ing, though it is growing more luxuriously because it has more sunlight. Bracken (ferns), always abundant in this part of the world, is flourishing far more richly than when it was shaded. Grasses anil sedges have increased. The burned ground, on the other 50 40 30 20 10 it 1 1 .1 B BRACKEN GRASSES SEDGES MOSSES COMPOSITES BOG MOSS NETTLE TUBULIFLORAE ISPHAGNUMl LIGULIFLORAE NEOLITHIC COMMUNITY OF WILD PLANTS that followed clearance and cultivation is analyzed in this pollen diagram. The 40 colored bars indicate the amount of pollen from each plant be clearance. The black bars indicate the amount of pollen aft«r c j from relatively deep roots. Third from the left are dandelions, members of a family which grows in profusion under such condi- tions. Fourth are mosses, which had never been seen in this forest before. Their spores were blown into the clearing on the wind. hand, is a scene of botanical revolution, liiacken is coming back here too, but most of the other old plants, having shallower roots, were killed off by the fire. In their stead we have a whole garden of new plants. Plantain has made its appearance, just as it does in the ancient PARSLEY COMMON FAMILY PLANTAIN LANCET PLANTAIN ™ce- The scale at the left is based on grains Pollen per 1,000 grains of tree pollen. pollen record after forest clearance. There is a profusion of members of the family Compositae, including dandelions, daisies, sow thistle and so forth. (These plants do not bulk large in the fossil pollen record, but that is understandable because they are pollinated by insects rather than by the wind.) A particularly interesting development is the sudden appearance of mosses and their spread over large patches of the burned area. The main species have never been seen in this forest before. Their spores have flown into the clearing on the wind, and no doubt mosses came the same way to the areas burned by Neolithic man. What makes them especially significant is that certain mosses seem to be definite indicators of fire; three species have been so identified in America, and sure enough the same three appeared in our burned clearing. Since the moss phase in a burned forest must be ephemeral, moss spores in the fossil record should enable us to pinpoint the dates of forest clearance by Neolithic man and to learn whether they burned the same clearing more than once during the existence of a continuous settlement. Unfortunately the small moss spores are difficult to recognize, and analysts of the ancient pollen deposits have not counted them hitherto. We made a small test count at the site of a Neolithic forest clearing in Denmark, analyzing the layers representing the time of the clearance and the period just before. According to our fragmentary count, there was a sharp rise in general moss growth (we made no attempt to distinguish individual species) immediately after the clearance of the area [see chart at the left]. Our experimental clearing in the Danish forest is just beginning to pass into the second phase, when pioneer trees appear and the regeneration of the forest commences. Birch seedlings are starting to spring up in profusion; willow seedlings have appeared; and hazel, aspen and linden shoots are rising from roots that were not killed by the fire. We are looking forward to studying this gradual regeneration in the years to come, as well as to reliving the stage in Neolithic farming when men grazed their cattle on the re-emerging ground vegetation. ]\/Teanwhile we can say that so far our -"-'-*■ experiment has confirmed the archaeological interpretation of the pollen record on several important counts. It has been demonstrated that the forest could indeed have been cleared by the primitive tools of Neolithic man, and that in the first stage at least the reviving vegetation follows a course very like that deduced from the ancient pollen layers. Of course man's transition from hunting to farming may well have taken other paths besides the one we have traced in the Danish clearings. More than one type of agriculture may have existed simultaneously in Denmark. As a matter ; of fact, Troels-Smith has found evidences of a more primitive agriculture during the same period on the Danish coast, where the Middle Stone Age men apparently cleared no forests but practiced a little crude farming along with/ their hunting and fishing. The Neolithic farming culture de-> scribed in this article is so much more-advanced, and begins so suddenly, that it seems to signal the arrival and invasion of a vigorous new people from another region.