The Land Use History (1278–1990) of a Mixed Hardwood Forest in Western Belgium and Its Relationship with Chemical Soil Characteristics K

Journal of Biogeography, 26, 1115–1128

The land use history (1278–1990) of a mixed hardwood forest in western Belgium and its relationship with chemical soil characteristics K. Verheyen, B. Bossuyt, M. Hermy and G. Tack1 Laboratory for Forest, Nature and Landscape Research, Catholic University of Leuven, V. Decosterstraat 102, B–3000 Leuven and 1Ministerie van de Vlaamse Gemeenschap, Administratie voor Ruimtelijke Ordening en Huisvesting, Monumenten en landschappen, Gebr. Van Eyckstraat 2–6, B–9000 Gent, Belgium

Abstract Aim During the last decades, an increasing number of studies have stressed the importance of historical human influence on the ecology of forests and on the characteristics of forest soils. Therefore, the objectives of this study are (1) the quantification of the land use history of Ename Wood from 1278 to 1990 and (2) to find out whether the former land use of the forest has long-lasting effects on present-day chemical soil properties. Location The 62-ha present-day Ename Wood is situated in western Belgium and is the remainder of the 145-ha historical Ename Wood. Methods We disposed of eighteen land-use maps for the period between 1278 and 1990 which were digitized using a geographic information system (GIS). Transition between the different land uses and Shannon–Wiener diversity indices were calculated to quantify the history of changing land use. Mixed soil samples were taken in lots delimited on the basis of the historical data. Next, the soil properties were combined with the land-use variables using redundancy analysis and ANOVA. Results The quantification of the land use changes showed that the present Ename Wood is the result of several forest regression and progression phases, with a complete clearance in the nineteenth century. Diversity in land use was maximal between the fourteenth and the sixteenth century due a variety of transitional forms between forest and pasture. A positive correlation between the duration of arable land use since the 19th century clearance and soil pH, calcium and phosphate content was observed and a negative correlation was found with the carbon content, the total nitrogen content and the C:N ratio. These correlations are probably caused by a combination of acidification processes and the accumulation of organic matter under forest in combination with manuring practices in the twentieth century. Present-day forest lots which have been pastured for some time between 1278 and nineteenth-century clearance still had a significantly lower pH and degree of base saturation, which is probably caused by the export of nutrient rich plant material at that time. Discussion and conclusions The results demonstrate that the developed methodology is successful and confirm that historical land use, even in the distant past, can still influence present-day soil characteristics. For this reason, long-term historical land use should always be considered in forest ecological research.

Keywords Forest history, land use history, historical ecology, soil characteristics, GIS, redundancy analysis.

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INTRODUCTION research as a case study for the large-scale historical ecological research of Flemish forests (Tack et al., 1993). This historical Some decades ago, ecologists in several European countries research has resulted in the reconstruction of eighteen land- started to recognize the importance of long-term human use maps of Ename Wood between 1278 and 1990 which disturbances in forests (Peterken, 1974; Rackham, 1980; Dubois, enabled us to assess the effects of this long-lasting land-use 1989; Pounds, 1990; Vos & Stortelder, 1992; Tack et al., history on the present-day forest. Therefore, the aim of this 1993; Willis, 1993; Fritzbøger, 1994; Ellenberg, 1995; Kirby & paper is: Watkins, 1998). These days, the extreme impact of land use history on both the ecology and present-day nature conservation • to quantify the land-use history changes of Ename Wood value of forests is widely accepted (Peterken, 1993, 1996). It from 1278 to 1990; has been proven that the historical human activity still has • to develop a methodology to relate these changes to profound effects on the present-day distribution of woodland ecological characteristics of the forest, in particular with species, the so-called ‘ancient woodland species’ (e.g. Hermy present-day soil characteristics; and et al., 1993) and on present-day chemical forest soil properties • to determine whether the former land use, reconstructed such as pH, degree of base saturation, soil organic matter and back to 1278, has had long-lasting effects on present-day phosphate content (e.g. Froment & Tanghe, 1967; Goovaerts chemical soil properties of the forest. et al., 1990; Catt, 1994; Koerner et al., 1997; Wilson et al., 1997). While the data reported are speciﬁc to Ename Wood and In this respect, North American forests offer opportunities the soils it contains, it is believed that the forest is representative which are denied to European ecologists. The pre-settlement for many other forests in Belgium and elsewhere in temperate forests are still present as remnants, which enables scientists Europe. to make direct comparisons between these forests and the post- settlement ones (e.g. Foster, 1992a, 1992b; Orwig & Abrams, STUDY AREA 1994; Motzkin et al., 1996; and Matlack, 1997a, 1997b). Furthermore, since land-use changes have taken place relatively recently and have involved only one or two land-use changes Physical setting on each patch of land, effects can often be securely related to The present-day Ename Wood, which consists of two disjunct causes (Peterken, 1996). parts, occupies 62 ha in the province of Eastern Flanders, about In most of Europe however, it is much more complicated 25 km south of Ghent. It is the remainder of the 145-ha to assess the effects of former land use since almost no primary historical Ename Wood (Fig. 1). or old growth forest is left as a reference and the observed The annual precipitation is 775 mm and the mean annual effects of a particular land use history might be obscured by temperature 9.5°C. On average, the vegetation growing period the effects of an even earlier land use. Despite this drawback, lasts about 170 days. The forest itself is located on the eastern most of the research assessing the impact of historical land use side of the River Scheldt and the altitude ranges from 14 m to only covered relatively short time periods (Wilson et al., 1997) 62 m above sea level. The northern part (25%) lies on humic and early agricultural and forestry practices have been lumped alluvial and colluvial sediments. The remainder of the forest by ecologists into broad categories and discussed with little is situated on the relatively steep slopes of the river valley on regard to spatial precision (Foster, 1992b). This is all in sharp sandy–loam soils of Quarternary niveo-eolian origin with a contrast with the long-term and complex human disturbance clayey or stony sandy layer of Tertiary marine origin at variable in European forests. depth. Some soils are derived from this Tertiary material. Therefore, to assess the effects of former land use in Europe on present-day forest ecosystems, it is extremely important to reconstruct the land-use history in as detailed a manner as Biological setting possible and to maximize the temporal scale. This also Ename Wood used to be managed as a coppice with standards encompasses the development of a methodology to quantify for hundreds of years. However, during the last century the historical land-use changes and to relate these changes to forest was gradually transformed into a highwood: 32% of the present-day ecological data. area was planted with homogeneous Populus × canadensis The former county of Flanders (western Belgium and (Moench) (nomenclature follows De Langhe et al., 1988); 39% northern France) has been subjected to extreme human impact. of the area has a mixture of broadleaved trees of which Populus As early as the thirteenth century Flanders was, and still is, one × canadensis (Moench) is the dominant tree species and 29% of the most densely populated areas of Europe. Additionally, the of the area has a mixture of Fraxinus excelsior (L.) and Quercus former county of Flanders has an extensively documented robur (L.). Underneath the tree canopy a neglected coppice layer history. Therefore, this region offers unique opportunities to is still found, consisting mainly of Alnus glutinosa (Gaertn.), assess the long-lasting effects of historical land use. Within the Fraxinus excelsior (L)., Acer pseudoplatanus (L) and Corylus county, Ename Wood has been the subject of a detailed historical avellana (L.) (Verheyen & Vackier, 1997). The 75% of the forest which is situated on sandy–loam soils Correspondence: K. Verheyen, Fax: ++32 16 329760; e-mail: kris. belongs to the Endymio-Carpinetum forest plant community [email protected] (Noirfalize, 1984). This plant community is characterized by

 Blackwell Science Ltd 1999, Journal of Biogeography, 26, 1115–1128 Land use history of a mixed hardwood forest 1117

Figure 1 Map of the historical and the present-day Ename Wood and the location of the seventy-four lots used for the soil sampling.

Hyacinthoides non-scripta (Chouard ex Rothm.). On the following the deforestation movement in the eleventh to alluvial and colluvial sediments (25%), the forest belongs to twelfth century. By 1300, forest covered only 9% of the the Pruno-Fraxinetum forest plant community (Oberdorfer, total area. However, some large forest areas remained 1953) with Filipendula ulmaria (Maxim.), Primula elatior (Hill), and they were connected by smaller forest patches and Cardamine pratensis ssp. picra (De Langhe et D’Hose) as many hedges. All forests were used intensively for differential species. pasturing, resulting in a variety of transitional forms between forest and pasture. The abbeys, which developed from the eleventh century onwards, had a large inﬂuence Historical setting of the former county of Flanders on the land use history of the region. The increasing The forests of the former county of Flanders have undergone demand for fuel wood led to an extensive new four major periods of forest progression and regression (Tack reforestation, raising the area of forest to about 15% in et al., 1993): the eighteenth century. • 1880–1990: increasing forest area, mainly by planting, • Prehistory (4000–50 BC): spontaneous afforestation after deforestation in the nineteenth century. The forests following forest regression in the New Stone, Bronze were transformed from coppice-dominated systems into and Iron Age. Settlements in that period were often highwood. concentrated in present-day forests. • During Roman times (50 BC–300 AC), the extreme human interference in both forest and agricultural land involving Historical setting of Ename Wood considerable forest fragmentation was characteristic for the whole county of Flanders and neighbouring parts of Ename Wood is situated in the centre of the former county of the county of Hainaut and the Duchy of Brabant. After Flanders (Fig. 1). The earliest traces of occupation near Ename the Gallo-Roman period, in the so-called ‘Dark Ages’ Wood date from prehistory (Middle and New Stone Ages): (300–600 AC), forest recovered more or less naturally. three sites on the upper parts and two sites in the valley. Since • Fourteenth to nineteenth century: increasing forest area one of these sites is situated within the forest, it is very likely

 Blackwell Science Ltd 1999, Journal of Biogeography, 26, 1115–1128 1118 K. Verheyen et al. that a part of the forest was already transformed into arable area at a certain point in time was assigned to grassland and land, and that other parts were pastured and degraded. No the other half to forest. systematic archaeological research has been carried out for the Next, the area changes of the three main land uses between Bronze and early Iron Ages. However, toponymic research two consecutive maps were calculated. indicates that the area was inhabited at that time. More data Diversity in land use in Ename Wood has been expressed are available for the Roman period. Traces of habitation were for every point in time by computing a Shannon–Wiener found in sixteen sites, of which five settlements are situated in diversity index (Magurran, 1988): a radius of 1 km around Ename Wood (Tack & Hermy, 1998). S This high population density suggests that the forest was Diversity=−PilnPi extensively pastured and wood was cut, probably resulting in i=1 a kind of open forest. Hardly any information exists about the Dark Ages. In 1063 the Abbey of Ename was founded and with: S: the number of land-use categories at a certain point between its foundation and 1278 the abbey gradually acquired in time; PI: the proportion of a land-use category. the historical Ename Wood (145 ha; Fig. 1). The abbey possessed This widely used diversity index, originally designed for the forest until 1795 when the abbey was dismantled by the ecological research, has already proved to be successful in French occupier and the forest became state property. From totally different areas of research: psychology (e.g. Laming, 1845 onwards the forest has been private property. In the 1996), genetics (e.g. Barral et al., 1996), etnobotany (e.g. Begossi, middle of the nineteenth century, due to an economic crisis, 1996), etc. Therefore, the use of this index as a measure to the forest was totally cleared and used as arable land. By the describe the diversity of a landscape seems legitimate. end of the nineteenth century most fields were abandoned and The index was also calculated separately within the land- reforested, which gave birth to the smaller present-day Ename use classes ‘forest’ and ‘grassland’. This gave an idea of the Wood (62 ha; Fig. 1). diversity of transitional forms of land use, and probably also of the correlated species diversity (Rosenzweig, 1995). MATERIALS AND METHODS Chemical soil properties Since the archives (charters, tenant and tax books, return books, inventories of goods, tree and coppice sales, memoirs For the soil analyses, the present-day Ename Wood (62 ha) was of the abbot, rules for the abbey staff and several maps) of the divided in seventy-four lots based on differences in land use Abbey of Ename have been preserved to a large extent and since the beginning of the nineteenth-century clearance of the contain detailed information about the use and management forest (Fig. 1). This date was chosen (1) for practical reasons of the forest, land-use maps for eleven different points in time since the lots were too small if they were based on differences between 1278 and 1795 could be reconstructed. Another seven in land use since 1278 and (2) because the nineteenth-century land-use maps were reconstructed for the period 1795–1990 clearance and subsequent agricultural use probably have based on topographical maps, the primitive land register and important bearings on the present-day chemical soil properties. historical works. Ultimately, a total of eighteen land-use maps In each of the seventy-four lots soil samples with a depth for the period between 1278 and 1990 were available. During of 15 cm were taken, using a systematic sampling scheme: this period, eleven different kinds of land use were transects, 30 m apart and parallel with the border of the lot, distinguished, with several transitional forms between forest were followed and every 20 m a sample was taken. In this and pasture (Table 1). way, a constant sampling density of approximately seventeen The changes in historical land use between 1278 and 1990 samples/ha was achieved. Afterwards the samples of each lot were quantified, based on the eighteen land-use maps. This were bulked and mixed thoroughly. The chemical analysis of result was used for the delimitation of seventy-four lots, in the samples was performed by the Belgian Soil Service using which the soil samples were taken. Finally, land-use variables the analytical methods listed in Table 2. In Belgium, these were extracted and linked with the chemical soil properties. methods are used widely to assess the chemical soil fertility (e.g. Hendrickx et al., 1992). From an ecological point of view, determination of the chemical soil fertility seemed the most Quantification of the changes in the historical land use relevant since it reflects the available amounts of nutrients for The eighteen land-use maps were digitized and the area of each plants. land-use category at every point in time was determined using Since differences between soil types were expected to obscure a geographical information system (GIS) (ESRI, 1996). the effects of land use history (e.g. Connell et al., 1995), an For further analysis, the eleven different land-use categories overlay of the published soil map (Louis & Sanders, 1986) with (Table 1) were classified into three major classes based on the the seventy-four lots was made. This allowed the studied lots dominant land use in a category: the categories 1–4 and half to be assigned to one of the three following soil types: colluvial/ of the area of category 5 were considered as grassland, the alluvial soils, soils on sandy–loam with clay-accumulation categories 6–8 and half of the area of category 5 were considered horizon and soils on a clay substrate from Tertiary origin. as forest and the categories 9 and 10 were considered as arable Only lots with more than 75% of their area covered with one land. Since in land-use category 5 (private wood pasture) of these types (sixty-four lots) were used for further analysis grazing and wood use were of equal importance, half of its (Fig. 1). To check for the differences between the three soil

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Table 1 Distinguished land use categories in Ename Wood between 1278 and 1990. No Land use category Description 1 Meadows (Dutch: hooiland Grassland for hay making, in general on less drained soils or meers) 2 Intensive pasture Pasture without trees or shrubs on dry soils, very (Dutch: intensief grasland) intensively grazed, small parcels (< 1 ha), enclosed with fences 3 Semi-intensive pasture Pasture on same type of soil as the intensive pasture, larger (Dutch: halfintensief parcels (> 1 ha), transitional form grasland) between intensive pasture and wood-pasture or pastured forest. Grazing pressure is smaller than on the intensive pasture, which resulted locally in the emergence of trees or shrubs 4 Wood pasture (or Commonly used pasture on dry or moist soils, with trees commons) and shrubs. Extensive grazing is more (Dutch: bosweide) important than wood use, not enclosed 5 Private wood pasture (or Private and enclosed wood-pasture; grazing and wood use park) are of equal importance (Dutch: broek) 6 Pastured forest Forest where both grazing and wood use occurred in an (Dutch: beweid bos) extensive way. Conditions for this type of land use are a low grazing pressure and a limited and selected wood logging 7 Forest with pasturing Forest for wood production that was grazed in the last (Dutch: bos met period of the exploitation cycle when influence nabeweiding) on the growth of the new shoots was negligible 8 Forest Coppice, coppice with standards or high wood, forest only (Dutch: middelhoutbos and for wood production. Grazing was hooghoutbos) forbidden, but occurred illegally on a small scale until the first half of the nineteenth century. Before ca. 1930, the forest consisted mainly of coppice wood, but since then the forest was gradually transformed into highwood 9 Fallow (Dutch: vaag): Abandoned arable land 10 Arable land (Dutch: akker) Arable land 11 Other Tree nursery, orchard, wicker (Dutch: griend), buildings and gardens

Table 2 Overview of analytical methods of the chemical soil properties (Belgian Soil Chemical soil property Analytical method

Service, not published; Hendrickx et al., 2+ 1992). Calcium (Ca ); Magnesium Extraction with ammonium-lactate (pH 3.70–3.80); (Mg2+); Potassium (K+) Determination with atomic absorption (mg/100 g air-dried soil) spectrophotometer (A.A.S.) Phosphate (mg/100 g air-dried Extraction with ammonium-lactate (pH 3.70–3.80); soil) Determination with spectrophotometer Carbon-content (C; % of Walkley & Black soil-weight) pH (KCl) KCl-1N-solution; glass electrode

pH (H2O) Demineralized water; glass electrode Total nitrogen (Total-N; mg/ Kjeldahl (organic and ammonia nitrogen) 100 g air-dried soil)

types, an explorative redundancy analysis (RDA; CANOCO 4, Land use and chemical soil properties Ter Braak & Smilauer, 1998) was performed with the soil properties as response and the soil types as explanatory Given the almost complete deforestation of the Ename Wood variables. Next, a single-factor ANOVA (SPSS 8.0, 1998) was and the subsequent transformation in arable land in the middle performed on a subset of lots of the three soil types which of the 19th century, the long-term impact of land use on the had a similar land use history. present-day soil properties was analysed in two steps.

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Table 3 Overview of the assumed transition dates and calculated factor levels for a single-factor ANOVA (SPSS 8.0, 1998) on periods of constant land use before the nineteenth-century clearance. the soil properties. Point in time for which a land Assumed transition date(s)/the use map was reconstructed calculated period of constant land RESULTS use (years) Quantification of the changes in historical land use 1278 1296.5/18.5† 1315 1296.5, 1337.5/41‡ As a result of a preceding period of intensive forest pasturing, 1360 1337.5, 1385/47.5 in 1278 some 60% of the forest area was wood pasture and 1410 1385, 1438.5/53.5 only 30% of the area was occupied by forest for wood 1467 1438.5, 1492/53.5 production (Fig. 2). By the end of the thirteenth century, due 1517 1492, 1543.5/51.5 1570 1543.5, 1596.5/53 to the increasing demand for wood as fuel, the abbey decided 1623 1596.5, 1649.5/53 to regularize the forest management (e.g. by making exclosures). 1676 1649.5, 1703.5/54 In addition, 49 ha of former pasture and degraded forest was 1731 1703.5, 1753/49.5 afforested. The area taken in by forest increased up to 1775 1775 1753, 1804.5/51.5 (Fig. 2). Due to an increasing population density in the region 1834 1804.5, 1851–1868/46.5–63.5§ (in 1570 around 100 inhabitants/km2) and the consequent larger food and energy demand, pasture was almost completely = + = †(1315–1278)/2 18.5 years. ‡ (1315–1278)/2 (1360–1315)/2 transformed into forest or arable land (Fig. 3). The second half 41 years. § Varies since the lots were cleared between 1851 and 1868. of the eighteenth century showed an increasing polarization between forest and arable land use due to continued population growth (about 250–340 people/km2) with consequently larger First, for each of the remaining sixty-four lots, the time that food and energy demands (Fig. 2). a lot had been under cultivation since this nineteenth-century In 1845 the forest was sold and became private property. clearance was determined. It was possible to assign all the lots The unstable equilibrium between arable land and forest was to one of the following classes: 18, 27, 36 and more than severely disturbed by the increasing use of coal as an energy 36 years under cultivation. Using these classes as factor levels, source and the consequent decline in the use of coppice for a single-factor ANOVA (SPSS 8.0, 1998) on the soil properties fuelwood. Furthermore, a population explosion, together with was performed. an economic crisis, caused the last major famine in Flanders Since the results of this analysis might have been obscured during the winter of 1845–46. This resulted in a complete by the effects of land use before the nineteenth-century transformation of Ename Wood to subsistence agriculture clearance, the next step was therefore to account for possible (Fig. 3). The fields covered an average area of only 1275 m2. effects of the land use between 1278 and the nineteenth- Most of these fields were used by people who practised century clearance. agriculture only as an additional occupation. They had no or For each lot the total number of years that a lot has been hardly any cattle and used no manure. Artificial fertilizers only under cultivation and the total number of years that a came into use at the end of the nineteenth century. Therefore lot has been under grassland use between 1278 and the possibly exhausted soils, together with erosion, the import of nineteenth-century deforestation was determined. This was cereals from the United States and Australia and an increasing achieved by making overlays by means of a GIS (ESRI demand for wood for the mining industry, resulted in the ArcView, 1996) between the lots and the twelve land-use abandonment of the arable land and the resurrection of the maps which preceded the nineteenth-century clearance. In forest at the end of the nineteenth century (Fig. 3). During the order to calculate the above-mentioned variables, it was twentieth century, apart from a small decrease in forest area assumed that the date of the land-use changes in two between 1910 and 1937, the forest area remained stable. In subsequent maps was equal to the mean of the dates of 1990 some 40% of the area was covered with forest (the these two maps. The assumed transition dates and the present-day Ename Wood), 30% with arable land and 30% calculated periods of assumed constant land use are given with intensive pasture (Fig. 2). in Table 3. The total number of years that a lot has been The changes in the area occupied by forest, grassland and under cultivation or under grassland use were obtained by arable land between 1278 and 1990 are clearly reflected in the summing the periods when one of these land-use types was Shannon–Wiener diversity index of the land use categories present. If more than one land-use type occurred on one (Fig. 4). This index is maximal in the period between 1410 lot, a period for each type weighted by its respective area and 1517. This time period is characterized by a variety of in the lot was calculated. transitional land uses between forest and pasture (Fig. 2). Next, a redundancy analysis (RDA; CANOCO 4,Ter Braak Before 1410, the diversity was smaller, because a larger area & Smilauer, 1998) was performed with the soil properties was occupied by the same transitional land use (wood pasture), as response and the log-transformed land-use variables as and the real grassland forms (half-intensive and intensive explanatory variables. This RDA allowed us to distinguish pasture) were less represented. After 1517 the index decreased a number of lot types based on differences in their land use and reached an absolute minimum in 1775, because of gradual history from 1278 onwards. These types were then used as reforestation of the whole area. In 1834 it increased again due

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Figure 2 Evolution of the land-use history in Ename Wood between 1278 and 1990.

Figure 3 Transition between the three main land uses in Ename Wood between 1278 and 1990.

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Figure 4 Shannon–Wiener diversity index for different types of land use in Ename Wood between 1278 and 1990. to deforestation and the replacement of forest by an increasing Land use and chemical soil properties pasture area. In 1990, a value comparable to that of 1278 was achieved but, nevertheless, it was lower than the diversity in Since no clear results were found for lots on the colluvial/ 1517. The index for the grassland categories reached a alluvial soils and on a Tertiary clay substrate, only results maximum in 1517, started to decline in 1676 and fell to zero for the lots on sandy–loam with clay-accumulation horizon in 1775. Almost the same pattern is observed for the forest (twenty-three lots) are reported. As mentioned before, erosion diversity index, with a maximum in 1570. This means that the was one of the causes for the abandonment of the arable land increase in the total diversity index after 1775 was not caused at the end of the nineteenth century. Since the colluvial soils by the transitional forms between forest and pasture, but by a and the soils on a Tertiary clay substrate probably originated more equal area distribution of forest, intensive pasture and as a consequence of erosion, this might be the reason why no arable land in Ename Wood. clear effects of former land use on the chemical soil properties were found. Lots which have been cultivated for more than 36 years Chemical soil properties since the nineteenth-century deforestation still have a

In Fig. 5, the two RDA axes account for 100% of the ‘soil significantly higher pH(H2O), pH(KCl) and calcium content properties–soil type relations’, while 16% of the total variance than lots which have been cultivated for 18 or 27 years (Table 5). in the soil properties is explained. The soil properties clearly For the carbon content (and, to a lesser extent, also for the separate out along the three soil types. Total nitrogen, the total nitrogen content and the C:N ratio), a more gradual carbon content, C:N and the potassium content are positively decrease with increasing period of cultivation is observed. No correlated with the soils on a clay substrate, which is probably clear effects were found for the potassium and magnesium caused by the accumulation of organic material on these poorly content. The phosphate content was (not significantly) higher drained soils and the presence of glauconite (Louis & Sanders, in the lots with a prolonged period of cultivation. 1986). The positive correlation between pH, calcium and The RDA indicates that the land use between 1278 and the magnesium content and the colluvial/alluvial soils might be mid-nineteenth century still affects present-day soil chemical due to the less weathered character of this soil. However, the properties (Fig. 6). The biplot displays 36% of the total variance strong positive correlation of the phosphate content with soils of the chemical soil properties and 88% of ‘the soil properties on sandy loam with clay-accumulation horizon is less clear. – land use relations’. The first axis accounts for 27% of the The results of the single-factor ANOVA (Table 4) consolidated total variance, the second for 9%. Due to (1) the strong positive former correlations and consequently it was necessary to correlation between the number of years a lot has been under use the lots grouped by soil type for further analysis. grassland and the number of years a lot has been under

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Figure 5 RDA of the chemical soil properties and the three soil types. cultivation and (2) the orthogonal character of the variables • lots which have had a grassland (mean: 37 years) and/or that describe the land use before and after the nineteenth- arable (mean: 47 years) use between 1278 and the nineteenth- century clearance, it was possible to distinguish four classes of century clearance and which have only shortly been lots based on differences in their land-use history from 1278 cultivated (mean: 22.5 years) since the nineteenth-century onwards: clearance (quadrant II, n=9); • lots which have always been forested between 1278 and • lots which have always been forested between 1278 and the nineteenth century clearance and which have only shortly the nineteenth-century clearance and which have had a been cultivated (mean: 19.5 years) since the nineteenth- prolonged arable use (mean: 66 years on average) since the century clearance (quadrant I, n=6); clearance (quadrant III, n=5);

Table 4 Single factor ANOVA between parcels with different soil types and similar land-use Soil property Main effect† Soil series‡ history. Soils on a tertiary Sandy–loam soils Colluvial soils and substrate (n=6) (n=8) alluvial soils (n= 13)

C(%) ∗∗∗ 4.7a 3.4b 3.6b Ca2+ (mg/100 g) ∗∗∗ 167.5a 98.0b 184.4a K+ (mg/100 g) NS 29.3a 25.6a 24.7a Mg2+ (mg/100 g) ∗∗∗ 19.5a 10.8b 24.3a Phosphate (mg/100 g) ∗∗ 4.0ab 5.1b 3.0a ∗∗∗ pH(H2O) 4.7a 4.7a 5.7b pH(KCl) ∗∗∗ 3.7a 3.7a 4.7b Total-N (mg/100 g) ∗∗ 288.1a 223.8b 227.9b C:N ratio NS 16.6a 15.2a 15.8a

†Two-sided P-value of the F-test for main effects: NS not signiﬁcant; ∗∗0.01 > P≥0.001; ∗∗∗P < 0.001. ‡Tukey HSD multiple comparisons (level of signiﬁcance=0.05).

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Table 5 Single factor ANOVA on the chemical soil properties of sandy–loam soils with clay Soil property Main effect† Duration of cultivation‡§ accumulation horizon. The factor levels are 18 years (n=10) 27 years (n=5) More than 36 years the number of years a lot has been under (n=6) cultivation since the nineteenth-century clearance. C(%) ∗∗ 4.1a 3.3ab 2.9b Ca2+ (mg/100 g) ∗ 120.0a 89.6a 219.0b K+ (mg/100 g) NS 25.8a 23.2a 22.0a Mg2+ (mg/100 g) NS 13.5a 9.0a 13.0a Phosphate (mg/100 g) NS 5.3a 5.2a 6.7a ∗∗∗ pH(H2O) 4.7a 4.7a 6.0b pH(KCl) ∗∗∗ 3.7a 3.8a 5.3b Total-N (mg/100 g) ∗ 252.3a 208.8a 206.0a C:N ratio NS 16.3a 15.9a 13.9a

†Two-sided P-value of the F-test for main effects: NS not signiﬁcant; ∗0.05 > P≥0.01; ∗∗0.01; > P≥0.001; ∗∗∗P < 0.001. ‡We omitted 36 years because there were only two lots. §Tukey HSD multiple comparisons (level of signiﬁcance=0.05).

Figure 6 RDA between the chemical soil properties of the sandy-loam soils with clay accumulation horizon and the land-use variables.

• lots which have had a long grassland (mean: 270 years) The ANOVA between these four land-use classes (Table 6) and/or arable (mean: 77 years) use between 1278 and the reveals that the incorporation of the pre-clearance land use nineteenth-century clearance and which have had a can reﬁne the results of the ﬁrst ANOVA (Table 5). It appears prolonged arable use (mean: 62 years) since the clearance that the agricultural use between 1278 and the nineteenth- (quadrant IV, n=3). century clearance still causes a lower pH and calcium

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Table 6 Single factor ANOVA on the chemical soil properties of sandy-loam soils with clay Soil property Main effect† Land-use history class‡ accumulation horizon. The four different –/– (n=6) –/+(n=9) +/– (n=5) +/+(n=3) classes of land-use history between 1278 and 1990 are used as factor levels. ∗∗∗ pH(H2O) 5.0b§ 4.5a 6.0c 6.3c pH(KCl) ∗∗∗ 4.0a 3.6a 5.4b 5.5b Ca2+ (mg/100 g) ∗∗ 164.2ab 73.6a 244.0b 218.0b K+ (mg/100 g) ∗ 29.9b 21.6a 23.6ab 22.7ab Mg2+ (mg/100 g) ∗ 16.4a 9.1a 15.8a 15.0a Phosphate (mg/100 g) ∗ 4.9a 5.4a 4.2a 9.0b C(%) (∗) 3.9a 3.8a 2.9a 2.6a Total-N (mg/100 g) NS 249.2b 230.2ab 218.9ab 182.6a C:N ratio NS 15.5a 16.6a 13.5a 14.3a

†Two-sided P-value of the F-test for main effects: NS not signiﬁcant; (∗)0.1 > P≥0.05; ∗0.05 > P≥ 0.01; ∗∗0.01 > P≥0.001; ∗∗∗P < 0.001. ‡–/–: Lots which have always been forested between 1278 and the nineteenth-century clearance and which have only shortly been cultivated (19.5 years on average) since the clearance; –/+: lots which have had grassland (37 years on average) and/or arable (47 years on average) use between 1278 and the nineteenth-century clearance and which have only shortly been cultivated (22.5 years on average) since the clearance; +/–: lots which have always been forested between 1278 and the nineteenth-century clearance and which have had prolonged arable use (66 years on average) since the clearance; +/+:lots which have had grassland (270 years on average) and/or arable (77 years on average) use between 1278 and the nineteenth-century clearance and which have had prolonged arable use (62 years on average) since the clearance. §Tukey HSD multiple comparisons (level of signiﬁcance=0.05).

content. This effect is eliminated by a more recent prolonged Flanders (see historical setting). However, former forest history period of cultivation. In these lots the highest pH and is different from the forest history of Great Britain. Until calcium content are noticed. the thirteenth century both were comparable: due to shifting On the contrary, the highest magnesium and potassium cultivation in the Neolithic and Bronze Age and more intensive levels are found in the lots without agricultural use between agriculture in the Roman Period, the prehistoric and the Roman 1278 and the nineteenth century and with only a short period were the most active periods of forest destruction in agricultural use after the clearance. It appears that the the history of England (Rackham, 1980). The forests that agricultural land use between 1278 and the nineteenth- survived had also undergone modification from felling, grazing century clearance has depleted these elements. or burning activities. After that time, forest cover in England Only recent cultivation has raised the phosphate level, decreased continually from 30% in 586 to 15% in 1086 and while agricultural land use between 1278 and the nineteenth- 10% in 1350 (Rackham, 1980). However, there was no large- century clearance has not affected it significantly. scale re-afforestation after 1300. This contrasts strongly with Although no significant effects were found for the C:N the forest history of the former county of Flanders, where the ratio, the carbon and the total nitrogen content, the same forest area increased constantly until 1775, then declined and trends as in the former analyses can be seen: it is mainly increased again between 1884 and 1990. the prolonged post-clearance cultivation period that causes For Ename Wood it appears that only 30% of the area the lower levels. forested in 1775, the threshold date for ancient woodland in Belgium, was also forested in 1278. In western Europe, ancient woodland is defined as forest that has existed continuously DISCUSSION since at least a date in the seventeenth, eighteenth or nineteenth centuries, depending on the local availability of historical site Quantification of the changes in the historical land use information (Hermy et al., 1999). The figures for Ename Wood The great number of transitional land uses between forest and confirm that ancient woodland in the former county of Flanders pasture in Ename Wood is not unique. A similar variety is is by no means synonymous with primary forest. This statement known in the forest history of Great Britain and elsewhere in also holds for the rest of Europe, an area where hardly any Europe (Rackham, 1980). In general, there was a conflict virgin forest can now be found due to its long history of between grazing and trees: the more trees, the less abundant settlement, cultivation and industrialization (Pounds, 1990). the pasture and the worse its condition, while the more animals Even in the most remote areas (mountains, boreal areas), grazed the pasture, the more difficult it became to replace the grazing and charcoal burning has occurred (Peterken, 1996). trees. Since a high diversity index (thus the presence of many, The observed land-use history of Ename Wood correlates more or less equally abundant, land-use categories) also well with the general forest history of the former county of encompasses a high structural diversity in Ename Wood, the

 Blackwell Science Ltd 1999, Journal of Biogeography, 26, 1115–1128 1126 K. Verheyen et al. possibilities for increased diversity in plant and animal species and Ihori et al. (1995) on different soil types. The higher were probably larger in the past than at present. Moreover, mineralization rate of soil organic matter in arable land because of the agricultural intensification with its scale compared with forests is to be explained by a lower input of enlargement and its massive use of barbed wire (only since organic matter, a higher insolation, aeration and World War II), the borders between different land use types homogenization (Bridges, 1978). Again, the observed became sharper. As a result, the habitat for forest edge species correlations can also be interpreted as a positive correlation decreased and many of these species became vulnerable or are between the accumulation of organic matter and the duration in danger (Cortenraad & Mulder, 1989; Tack et al., 1993). of reforestation (e.g. Wilson et al., 1997). The lower C:N ratio (however, not significant) in the lots with a prolonged arable use is probably due to the application The impact of the post-clearance land-use history on of fertilizers and manure on these lots, as was also observed present-day chemical soil properties by Koerner et al. (1997). The increased phosphate content in The positive correlation between pH and duration of the lots with the longest post-clearance agricultural land use agricultural use has already been reported in several other was already observed by Honnay et al. (1999). Again, this studies. On a forest–arable–forest chronosequence in the reflects the intensified agriculture in the twentieth century. Belgian Ardennes, Goovaerts et al. (1990) found a higher pH, a higher exchangeable cation content and a higher degree of base saturation compared with permanently forested plots. The impact of the pre-clearance land use on present- This study covered soils on a Tertiary clay substrate and day chemical soil properties shallow loess soils developed on a schist substrate. Koerner et al. (1997), who studied the impact of nineteenth-century Hardly any effects of pre-clearance land use are found on lots land use on the soils of present-day forests in the Vosges which have known a prolonged (60 years on average), more mountains, also found that former arable land had higher pH intensive (application of manure, artificial fertilizer and lime) values independent of the soil type. Dudal & Livens (1954) period of cultivation after the nineteenth-century clearance. compared soils in the Belgian loess belt which were still under Modern agricultural practices are able to eliminate these effects forest cover and soils for which the time since clearing is completely (e.g. Dudal & Livens, 1954). approximately known. For soils under cultivation, they noticed However, the effects of land use that took place several a higher pH and degree of base saturation and concluded that hundreds of years ago are still reflected in the pH and degree liming and manuring may completely resaturate acidified forest of base saturation of lots that have not known a more recent soils. period of intensive cultivation. The depletion of potassium, Since historical documents have revealed that farming during magnesium and calcium (both to a lesser extent) is probably the nineteenth century clearance of Ename Wood consisted caused by pasturing since all the lots have been pastured, while mainly of subsistence farming by local nonfarmers, it is rather only few have known a period of cultivation between 1278 doubtful that liming was applied at that time. Therefore, the and the nineteenth-century clearance. This was also found by higher pH and calcium content in the forest lots that have been Glatzel (1991), who stated that pasturing lowers the base under cultivation for more than 36 years since the nineteenth- saturation of forest soils due to the export of nutrient rich century clearance may result from liming practices that took plant material (foliage, herb layer). Glatzel also mentions that place during the twentieth century. especially potassium, and to some extent magnesium, is depleted However, the positive correlation between the pH values because the herbaceous layer is rich in potassium. and the duration of arable use can also be interpreted as The indifference of the C:N ratio, the carbon and the total a negative correlation with the period of reforestation, as nitrogen content for the pre-clearance land use suggests that acidification and cation loss in aggrading forest ecosystems are this land use (mainly pasturing) has not caused a significant well-known phenomena (Knoepp & Swank, 1994; Richter et al., decrease of the organic matter content. The alternative 1994; Hu¨ttl & Schaaf, 1995). For instance, Catt (1994) mentions hypothesis, namely that some 100 years after the abandonment a decrease of the soil pH by three units (from 7.1 in 1886 to of the fields the organic matter content has reached an 4.2 in 1986) on a site that had been under cultivation until equilibrium, is less probable (e.g. Froment & Tanghe, 1967; 1886 and was forested afterwards. The decrease of the calcium Wilson et al., 1997). and magnesium content in aggrading forests is attributed to The absence of relations between pre-clearance land use leaching and to the sequestration of nutrients in the forest and available phosphate-content might be caused by (1) the biomass. Potassium, on the other hand, is well buffered in dominance of pasturing as pre-clearance land use and hence most soils. This can be explained by a combination of biological the consequent absence of manuring, or (2) by the use of the recycling via leaching of canopies and forest floor on one hand available phosphate content instead of the total (or organic) and mineral weathering release on the other hand (Knoepp & phosphate content. Wilson et al. (1997) observed higher total Swank, 1994; Richter et al., 1994). and organic phosphate contents under ancient woodland The negative relation between the carbon and the total compared to recent woodland independent of the soil type. nitrogen content, two constituents related to the soil organic Moreover, in archaeology the total phosphate content is well matter, and the duration of arable use was also observed by known for the identification of historical land use (Provan, Froment & Tanghe (1967), Elliot (1986), Goovaerts et al. (1990) 1971; Gebhardt, 1982; Davidson & Simpson, 1994).

 Blackwell Science Ltd 1999, Journal of Biogeography, 26, 1115–1128 Land use history of a mixed hardwood forest 1127

CONCLUSIONS Begossi, A. (1996) Use of ecological methods in ethnobotany: diversity indices. Econ. Bot. 50, 208–289. The results presented here demonstrate the following. Bridges, E.M. (1978) Interaction of soil and mankind in Britain. J. Soil Sci. 29, 125–139. • The long-term human influence on forest ecosystems and Catt, J.A. (1994) Long-term consequences of using artificial and organic the rejection of the myth of the assumed stability of forests. fertilizers: the Rothamsted experiments. The history of soils and Forests, especially in Europe, are no more permanent than field systems (ed. by S. Foster and T. C. Smout), pp. 119–134. Scottish any other community. Cultural Press, Aberdeen. • That it is extremely important to reconstruct the land use Connell, M.J., Raison, R.J. & Khanna, P.K. (1995) Nitrogen min- history in as detailed a manner as possible and to maximize eralization in relation to site history and soil properties for a Range the temporal scale. This encompasses co-operation between of Australian forest soils. Biol. Fertil. Soils 20, 213–220. ecologists, historians, historical geographers and soil Cortenraad, J. & Mulder, T. (1989) De achteruitgang van een aantal scientists. Zuidlimburgse bosplanten nader beschouwd. Natuurhistorisch • That the developed methodology is successful in relating Maandblad. 78, 80–85. Davidson, D.A. & Simpson, I.A. (1994) Soils and landscape history: land-use history with present-day ecological data. More case studies from the Northern Isles of Scotland. The history of soils detailed results can be obtained if the exact dates of land and field systems (ed. by S. Foster and T. C. Smout), pp. 66–74. use-changes are known. However, when these dates are Scottish Cultural Press, Aberdeen. lacking, the average of the dates of two consequent land- De Langhe, J. E., Delvosalle, L., Duvigneaud, J. & Vanden Berghen, use maps can be used as an approximation. Furthermore, C. (1988) Flora van Belgie¨, het Groothertogdom Luxemburg, Noord- the presence of historical land-use boundaries within the lots Frankrijk en de aangrenzende gebieden (Pteridofyten en Sperm- should be minimized, although this might result in too small atofyten). Nationale Plantentuin van Belgie¨, Meise. lots when the temporal scale is increased. When working Dubois, J.J. (1989) Espaces et milieux forestiers dans le Nord de la with mixed soil samples the presence of too small lots can France, e´tude de biogeógraphie historique, p. 1023. The`se de doctorat, be countered successfully using the developed methodology University of de Paris. Dudal, R. & Livens, P.J. (1954) De l’influence de la mise en culture in which the contribution of the different land uses before sur le degre´ de saturation et la morphologie de sols sur limon a certain date is calculated by weighting their relative area loessique. Gene`se Du Sol, Classification et Cartographie, IV. 368–373. in the lot. Cinquie`me Congre`s International De La Science Du Sol, Actes Et • That the impact of a pastoral land use which took place Comptes Rendus Transactions, Leópoldville. hundreds of years ago is still reflected in the present-day pH Ellenberg, H. (1995) Vegetation Mitteleuropas Mit Den Alpen, 5° and degree of base saturation of the forest soil, when this Auflage. Ulmer, Stuttgart. pastoral use was not followed by a more recent, intensive ESRI (1996) Arcview 3.0. Environmental Systems Research Institute agricultural use. Inc, Redlands. • Concerning the ecological consequences, the dual impact of Elliott, E.T. (1986) Aggregate structure and carbon, nitrogen, and historical land use on the vegetation must be stressed: not phosphorus in native and cultivated soils. Soil. Sci. Soc. Am. J. 50, 627–633. only the historical transformation of forest into agricultural Foster, D.R. (1992a) Land-use history (1730–1990) and vegetation land has important effects on present-day forest vegetation, dynamics in central New England, USA. J. Ecol. 80, 753–772. but also the modified soil properties due to this agricultural Foster, D.R. (1992b) Post-settlement history of human land-use and use. This confirms Foster’s (1992a) statement that ‘the vegetation dynamics of a Tsuga canadensis (hemlock) woodlot in ramifications of the land use history in terms of contemporary central New England. J. Ecol. 80, 773–786. ecological processes are too great to be dismissed by modern- Fritzbøger, B. (1994) Kulturskoven. Dansk Skovbrug Fra Oldtid Til day ecologists’. Nutid. Ministry of Environment, Gyldedal. Froment, A. & Tanghe, M. (1967) Re´percussion des formes anciennes d’agriculture sur les sols et la composition floristique. Bull. Socie´te´ ACKNOWLEDGMENTS Royale Bot. Belg. 100, 335–351. Gebhardt, V.H. (1982) Phosphatkartierung Und Bodenkundliche Ge- The authors thank Anne Verheyen for improvement of the la¨ndeuntersuchungen Zur Eingrenzung Historischer Siedlungs- Und English language and Prof. R. Dudal and O. Honnay for their Wirtschaftsfla¨chen Der Geestinsel Flo¨geln, Kreis Cuxhaven. Probleme useful comments on the manuscript. The paper was written Kustenforschung Sudlichen Nordseegebiet, 14, 1–9. while the first author held a grant from the Flemish Institute Glatzel, G. (1991) The impact of historic land use and modern forestry for the encouragement of Scientific and Technological Research on nutrient relations of central European forest ecosystems. Fert. (IWT) and the second author benefited from a grant from the Res. 27, 1–8. Foundation for Scientific Research (FWO). We are grateful to Goovaerts, P., Frankart, R. & Ge´rard, G. 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