Botanical macro-remains of vascular plants of the Heveskesklooster terp (the Netherlands) as tools to characterize the past environment

Abstract

The aim of this study is to present the archaeobotanical results of the Heveskesklooster terp located in the northeastern part of the Netherlands. The samples that have been analyzed are dated to one of the four habitationperiods: 1 ) c. 50 BC - c. 400 AD, 2) c. 800 - c. 1300, 3 ) c. 1300 - 1610 and 4) 1610 - 1975.

The samples yielded many plant remains, in which the species composition proved to be determined particularly by age (period), feature type and depth. Though distinguishable on a small scale, the species composition of samples of the first two habitation periods tumed out to be very much alike. Environmental changes, reflected by a shift in species composition of the samples, have been demonstrated for the transition of: 1) the second and third periods and 2) the third and last periods, though there was a limited number of samples of the last period.

The environment has been analyzed for the folIowing characteristics : 1) salinity, 2) moisture, 3) nutrient availability and 4) structure of vegetation and succession. During all four periods of habitation, both halophytic and glycophytic species are well represented. There is a slight decrease of halophytes in favour of glycophytes in the course of time. Salt-marsh vegetations of the first period have been treated in detail. All four periods are dominated by plants indicative of moist and wet conditions, whereas a clear increase of dry conditions can be demonstrated for the last period only. As to nutrient availability, all four periods are represented by species indicating poor, moderate and rich soils, and there was evidence of an increase of taxa indicating moderate soils from the first period onwards. Dominant vegetation types for all periods are grasslands and pioneer vegetation. The environmental characterization of the periods shows on the one hand a considerable overlap on the level of individual samples, but can be differentiated by external factors of samples, viz. location and feature type. If other Dutch terps are compared to the Heveskesklooster terp on the basis of indicator taxa, it shows that the environmental characterization fits in quite well with the overall picture, though indicator taxa for saline and dry conditions and for all three classes of moisture regimes are relatively well represented.

Important agricultural plants cultivated by the terp dwellers are: Hordeum vulgare (in the third period also ssp. distichum), Avena sativa, Linum usitatissimum, Camelina sativa, Vicia faba var. minor and probably also Brassica rapa and Cannabis sativa. Though written sources give the consumption of Hordeum vulgare, Avena sativa, Secale cereale and Triticum aestivum for the third habitation period, samples of this period yielded only quite large amounts of the first two species. But samples of the third and last periods yielded many other economically important plants as well, including rare species like Atropa belladonna and Aframomum melegueta. Compared with the subfossil records of other taps, this botanical richness is only found in medieval Leeuwarden and reflects the presence of a commandery of the Johanniter order in Heveskesklooster.