A 2500-yr late holocenemulti-proxy record of vegetation and hydrologic changes from a cave guano-clay sequence in SW Romania

We provide sedimentological, geochemical, mineral magnetic, stable carbon isotope, charcoal, and pollen-based evidence froma guano/clay sequence in Gaura cuMuscă Cave (SWRomania), fromwhichwe deduced that from ~1230 BC to ~AD 1240 climate oscillated betweenwet and dry. From ~1230 BC to AD 1000 the climate was wetter than the present, prompting flooding of the cave, preventing bats fromroosting, and resulting in a slowrate of clay accumulation. The second half of the MedievalWarm Period (MWP) was generally drier; the cave experienced occasional flash flooding in between which maternity bat roosts established in the cave. One extremely wet event occurred around AD 1170, when Fe/Mn and Ti/Zr ratios show the highest values coincident with a substantial increase of sediment load in the underground stream. The mineral magnetic characteristics for the second part of the MWP indicate the partial input of surface-sourced sediments reflecting agricultural development and forest clearance in the area. Pollen and microcharcoal studies confirm that the overall vegetation cover and human land use have not changed much in this region since the medieval times

Palaeoenvironmental information from the palynology of an 800 year old bat guano deposit from Măgurici Cave, NW Transylvania (Romania)

Pollen analysis of a 270 cm deep guano deposit from Măgurici Cave (NW Romania) was performed to understand the vegetation dynamics and the influence of deforestation and farming activities that unfolded in the Transylvania area over the past 800 years. The study discusses the value of cave guano as a source of palaeoclimate data and tests if guano sequences record the same signals as other proxies (tree rings, speleothems, lakes or peat). The pollen record extracted from Măgurici Cave guano is consistent with the known vegetation history during the Late Subatlantic period, exhibiting two climate events: the Medieval Climate Anomaly and the Little Ice Age. Human influence on vegetation is also revealed, especially in modern times, by the decrease of arboreal pollen, the increase of herbaceous taxa related to grazing and the occurrences of cereals. Cave bat guano is emphasized as a source of valuable palaeoclimate data, especially in areas where no conventional archives are available

Macrocharcoal analysis of a 4200 year old lake sediment profile from Northern Romania - fire regimes and climate implications

Macroscopic charcoal particles, magnetic susceptibility and AMS C14 dates were performed on a sediment sequence from a small subalpine lake (Buhaescu Mare), Rodnei Mts. in order to reconstruct fire regimes in the area.  Specifically we aim to distinguish between natural fire activity and human driven fires. Buhaescu Mare lake, also known as Rebra lake (0.4 ha; 1920 m a.s.l.,) is today surrounded by mire vegetation, Ericaceae, Carex and Pinus mugo patches further away, being situated just above the current tree line. The sedimentary profile, with a total length of 98 cm is composed of clayey silt (98-80 cm) and gyttja (80-0 cm). Magnetic susceptibility was used to support the charcoal results, this parameter being expected to rise during episodes of intense fire and subsequent erosive events.The results from the charcoal record indicate periods of high charcoal activity at about 4200 cal. BP, 3000 cal. BP, 2700 cal BP, 2000 cal BP and 1350 cal BP. and point to a succession of warm/dry and cold/wet periods. The increase in charcoal particles over the last 2000 years was probably related to human impact, but this remains to be documented through the analysis of pollen and coprophilous fungi record.</p

Alpine treeline and timberline dynamics during the Holocene in the Northern Romanian Carpathians

High altitude environments (treeline and alpine communities) are particularly sensitive to climate changes, disturbances and land-use changes due to their limited tolerance and adaptability range, habitat fragmentation and habitat restriction. The current and future climate warming is anticipated to shift the tree- and timberlines upwards thus affecting alpine plant communities and causing land-cover change and fragmentation of alpine habitats. An upslope movement of some trees, shrubs and cold adapted alpine herbs as a response to the current climate warming has already been noted in many montane and subalpine regions.Four Holocene peat and lacustrine sediment sequences located between 1670 and 1918 m a.s.l. (Fig.1), in the Rodna Mountains (Northern Romania, Eastern Carpathians) are used with the aim to determine: i) the sensitivity of high mountain habitats to climate, fire and land use changes; ii) tree- and timberline shifts: and iii) the influence of landscape topography on trees and shrubs.</p