Long‐term dynamics of the East European forest‐steppe ecotone

Abstract

Question The European forest‐steppe ecotone extends over 6,000 km from the Carpathian to the Ural Mountains. It is extensively used for agriculture with very few patches of semi‐natural vegetation. Little is known about the history of the forest‐steppe ecotone in Eastern Europe and here we examine its Holocene dynamics and stability and investigate when it was transformed to the modern agro‐pastoral landscapes. Location Mid‐Russian Upland. Methods We summarize the information from five pollen diagrams for the last 7,000 years and estimate forest cover using the best modern analogue technique. We use the PCA and principal curve analysis to evaluate compositional changes. Results The pollen data suggest that the East European forest‐steppe boundary was located 50–70 km further northwest from the presumed present position during the period 7,000–4,500 cal yr BP. After 4,500 cal year BP, it moved approximately 100–130 km to the southeast. Since 2,000 cal year BP land use affected the boundary, while a total forest clearance and transformation to agricultural landscapes took place in the last 400 years. Pollen data indicate a NW–SE direction of the forest‐steppe vegetation gradient. Prior to clearance, open lime–pedunculate oak forests existed in the NW, while the south was characterized by pine woodlands with an admixture of oak and lime with 20%–40% forest cover. Conclusions The East European forest‐steppe ecotone is sensitive to climate change. The Late Holocene expansion of forest cover is in agreement with evidence suggesting an increase in moisture availability during this time. The rapid recovery to a similar composition after human disturbance indicates a high resilience of woodland in the ecotone, which may be connected to a naturally high disturbance regime, possibly through fire. The information revealed on the position of the gradient and natural composition of the forest is currently not depicted in maps of the potential natural vegetation.

Insights into the late Holocene vegetation history of the East European forest-steppe: case study Sudzha (Kursk region, Russia)

“…Compilation of the records from the forest-steppe region shows that Sudzha was located in the forest-steppe ecotone, close to the southern border of closed deciduous forests (Shumilovskikh et al 2017). Located in the south, Sudzha has the highest values of broadleaf tree taxa in comparison to the northern records but a comparable forest cover between 50% in…”

“…The Holocene changes in forest coverage in the area of 20 km around the site Sudzha were reconstructed using the Best Modern Analogue (BMA) technique (Overpeck et al 1985;Nakagawa et al 2002). The details of this approach are described in our previous publications (Novenko et al, 2014;Shumilovskikh et al, 2017). In this study we used squared-chord distances (SCD) as the index of dissimilarity between modern and fossil pollen spectra with a threshold T=0.4 and use 8 best analogues to calculate an average value of reconstructed forest coverage.…”

“…A charcoal peak suggests the presence of local fires or possibly a settlement in the close vicinity of the site. Khotinsky 1993, Shumilovskikh et al 2017.…”

“…Timing of this transformation is unclear due to difficulties to find appropriate pollen archives, the vegetation history of this large zone is very fragmentary studied (e.g. Shumilovskikh et al 2017).…”

Millennial to centennial vegetation change

“…Correcting for pollen production biases and comparing the vegetation reconstructions to charcoal data reveals that fire is more strongly associated with vegetation structure of Exmoor moorlands than is evident from pollen percentage–charcoal associations (Fyfe et al., ). Shumilovskikh, Novenko, and Giesecke () evaluate the degree of forest cover based on modern analogues documenting changes in location and composition of the East European forest‐steppe ecotone over the last 7,000 years. Although single‐site studies are the building block of all palaeoecological investigations, this special feature contains only two high‐resolution single‐site studies.…”