How reliable is my historical land-use reconstruction? Assessing uncertainties in old cadastral maps

Old maps are a fundamental source for land-use reconstruction frequently used in biodiversity conservation and environmental management. In particular, cadastral maps as one type of old maps, depict both land tenure (discrete category) and land-use (continuous category); thus resulting in uncertainties in determination of individual parcels and their use. These uncertainties pose fundamental questions that are addressed in this paper: (i) to what extent land-use determined the delimitation of parcels?; (ii) how significant did the contrast between two land-use classes have to be to in order to delineate a new boundary? Agroforestry land-use classes were chosen as an example to demonstrate the approaches in the delimitation of parcels among different land-use combinations. We used Franciscan Cadastre, created in the mid-19th century under the Habsburg Monarchy (Central Europe), which depicts up to 10 agroforestry classes, to analyse factors that could influence delimitation of borders between patches (parcels) in old cadastral maps. The study area was located in the rural landscape of N Czechia, where approximately 10% of the agroforestry land area was used. We based our analysis on a detailed database of parcels and their land use type and property information. The novel approach to patch contrast indicator for old map analyses is introduced. The approach is based on statistical testing of the differences between parcel boundaries, separating similar/different owner, similar/different land-use and considering the length of the boundaries. Total number of identified parcels for all districts was 4108. Half of the boundaries length and 60% of boundaries count separated land of different owners. The rest of them separated land of one owner with different owner or with distinct parcels geometry. Our results indicate variable contrast between pairs of neighbouring land use categories. In particular, the contrast between pastures, wood-pastures and forests proved to be very low. Various factors, including land ownership, land-use, as well as landscape patch geometry and configuration were important to delineate a single parcel. We have concluded that these factors have important implications on inaccuracies and uncertainties of land use reconstructions based on old cadastral maps and used as historical baselines for current considerations on land change and environmental management.