Fire history and tree population dynamics in Białowieża Forest, Poland and Belarus

Fire history and fire regime parameters in relation to the long-term tree population dynamics were studied with dendroecological methods across coniferous habitats of Białowieża Forest (E Poland and W Belarus), a semi-natural European temperate woodland ecosystem. In four different studies various aspects of fire dynamics were explored by using nearly 1500 tree ring samples of Pinus sylvestris and Picea abies. By applying tree diameter at the first fire scar and post-fire growth response as proxies for fire intensity, the fire regime of Białowieża Forest was proven to have been dominated by low-intensity surface fires. However, occasional occurrence of high-intensity stand-replacing fires that were causing substantial successional changes at the stand scale was also recorded (I). Using a multiple-site fire history reconstruction combined with historical maps, eye-witness accounts and information on the abundance of light-demanding flora the omnipresence of fire throughout the coniferous sections of Białowieża and its role in shaping landscape-scale Scots pine dominance was revealed (II), as well as massive spruce encroachment following the fire cessation across those habitats (III). By reconstructing the extent of historical fires in a 9 km2 part of the study area, exploring the spatial dimension of fire disturbance in Białowieża Forest was proven to be possible and documented the occurrence of large-scale fires exceeding 500 ha (IV). The conclusion from these studies is that fire was the main driver of tree population dynamics across the coniferous portions of the Białowieża landscape until relatively recently, i.e. 100–150 yrs ago, with substantial influence on the tree species composition, habitat openness and the following biological diversity, especially of the light-demanding taxa. In that respect, the common opinion that fire is less important in shaping forest dynamics of both, Białowieża Forest, and temperate Europe, was challenged

First Spatial Reconstruction of Past Fires in Temperate Europe Suggests Large Variability of Fire Sizes and an Important Role of Human-Related Ignitions

The spatial component of past forest fires in temperate Europe has been little studied, despite the value of such data in quantifying human and natural factors driving fire activity and associated forest dynamics. Changes in fire regimes reported across a range of ecosystems call for a better understanding of variability in historic fires and may help define reference points that can be relied upon when discussing climate change effects. We provide the first dendrochronological reconstruction of historical fire sizes in Central Europe and analyze the minimum extent of fires during the last four centuries in a 9.2 km(2) (920 ha) conifer-dominated section of Bialowieza Forest, one of the largest continuous lowland forests of the subcontinent. We recorded 82 fires between 1666 and 1946, using 275 sample trees, while 92% of fires (76 out of 82) spread beyond the studied area. Fires varied considerably in size, from events recorded at only one site (1-200 ha) to fires recorded in more than half of the studied area, thus exceeding 500 ha in size. The fire cycle was 11 years over the whole study period, with three distinct periods revealed by the regime shift analysis. In the years 1670-1750, the fire cycle averaged 12 years. It shortened to 7 years between 1755-1840 and increased to 22 years over the 1845-1955 period. In comparison with present day data, the reconstructed fire density of 3.2 fires per 100 km(2) (10 000 ha) and year exceeded lightning ignition density by one to two orders of magnitude, suggesting a significant contribution of human-related ignitions. Our results highlight the important role of fire disturbance in Bialowieza Forest and provide critical baseline information to design biological conservation strategies for European forests

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Publisher Copyright: © 2022, The Author(s).Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.Peer reviewe

Are natural disturbances represented in strictly protected areas in Germany?

Natural disturbances are largely suppressed in Central European landscapes due to economic and human safety concerns. European goals to increase the extent of secondary wilderness areas have the potential to support the restoration of threatened habitats associated with natural disturbances. Germany is among the Central European countries with the most advanced wilderness goals. This study aimed to investigate whether habitat types shaped by natural disturbances are mostly red-listed as threatened and require special consideration within systematic conservation planning (SCP). First, we reviewed literature and the German Red List of Threatened Habitat Types to identify the conservation status of habitat types associated with three natural abiotic disturbance types in Germany: floods, forest fires and landslides. Second, we mapped the potential area coverage of these disturbance types and identified gaps in the current network of strictly protected areas (PA) to inform SCP. Fifty-two per cent of the habitat types associated with the three disturbance types floods, forest fires and landslides were listed as & ldquo;critically endangered & rdquo; (n = 1) or & ldquo;endangered to critically endangered & rdquo; (n = 9). The potential area for river dynamics accounted for 4.3% of German terrestrial territory, areas potentially subject to forest fires accounted for 0.9% and areas with a very high susceptibility to landslides for 1.1%. Areas potentially subject to forest fires (0.15% strict PA coverage) and river dynamics (0.81%) were underrepresented in German National Parks and the core zones of Biosphere Reserve, whereas strict PA coverage of areas with a very high susceptibility to landslides was higher (6.8%). European and German wilderness goals can support the restoration of threatened habitat types associated with natural disturbances if spatial information on those areas is integrated into SCP concepts. Yet, sophisticated management regimes will be required to resolve conflicts between wilderness areas subject to natural disturbances and the surrounding cultural landscape and infrastructure.(c) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Mesophication in temperate Europe: A dendrochronological reconstruction of tree succession and fires in a mixed deciduous stand in Białowieża Forest

Abstract The shift from shade‐intolerant species to shade‐tolerant mesophytic species in deciduous and mixed forests of the temperate zone is well described in studies from North America. This process has been termed mesophication and it has been linked to changes in fire regime. Fire suppression results in the cessation of establishment of heliophytic, fire‐dependent tree species such as oak (Quercus) and pine (Pinus). Due to the scarcity of old‐growth forests in Europe, data on long‐term compositional changes in mixed forests are very limited, as is the number of studies exploring whether fire played a role in shaping the dynamics. The aim of this study was to reconstruct tree succession in a 43‐ha natural mixed deciduous forest stand in Białowieża Forest (BF), Poland using dendrochronological methods. In addition, the presence of aboveground fire legacies (charred and fire‐scarred deadwood) enabled the fire history reconstruction. Dendrochronological data revealed tree establishment (Quercus) back to the end of the 1500s and fires back to 1659. Under a regime of frequent fires until the end of the 18th century, only oak and pine regenerated, sporadically. A shift in the fire regime in the first half of the 19th century triggered oak and pine cohort regeneration, then gradually spruce (Picea) encroached. Under an increasingly dense canopy and less flammable conditions, regeneration of shade‐tolerant Carpinus, Tilia, and Acer began simultaneously with the cessation of oak and pine recruitment. Synthesis. The study reports the first evidence of mesophication in temperate Europe and proves that fire was involved in shaping the long‐term dynamics of mixed deciduous forest ecosystems. Our data suggest that fire exclusion promoted a gradual recruitment of fire‐sensitive, shade‐tolerant species that inhibited the regeneration of oak and pine in BF

Long-term results from the multicentric European randomized phase 3 trial CWS/RMS-96 for localized high-risk soft tissue sarcoma in children, adolescents, and young adults

Background: CWS/RMS-96 was an international multicenter trial with randomization between two therapy arms of the standard four-drug therapy (vincristine, ifosfamide, adriamycin, dactinomycin [VAIA]) versus an intensified six-drug regimen (carboplatin, epirubicin, vincristine, dactinomycin, ifosfamide, and etoposide [CEVAIE]) for high-risk rhabdomyosarcoma (RMS), extraskeletal Ewing sarcoma (EES), and undifferentiated sarcoma (UDS) in children, adolescents, and young adults aiming to improve their survival. Intensified chemotherapy with CEVAIE did not improve outcome. Methods: Patients younger than 21 years with a previously untreated localized HR-RMS, EES, and UDS were enrolled from Cooperative Weichteilsarkom Studiengruppe (CWS) centers in Germany, Austria, Poland, Switzerland, and from Italian Soft Tissue Sarcoma Committee (STSC) centers. Randomization (1:1) to receive either 9 x 21 days cycles of VAIA or CEVAIE was performed separately in CWS and STSC. Hyperfractionated accelerated radiotherapy (32-44.8 Gy) was added at week 9-12 according to histology and response to chemotherapy. A secondary microscopically complete nonmutilating resection was performed if possible. Primary endpoints were response to chemotherapy, event-free (EFS) and overall survival (OS). Results: Five hundred fifty-seven patients (HR-RMS: n = 416, EES and UDS: n = 141) underwent randomization: VAIA (n = 273) or CEVAIE (n = 284). Radiotherapy was given to 70% of patients in both groups. A secondary resection was performed in 47% and 48% patients, respectively. The 5-year EFS and OS for the VAIA and CEVAIE treatment arms were 59.8% and 60.8% (p = .89), and 74.2% and 68.3% (p = .16), respectively. No differences in response, toxicity, or second malignancies emerged in the two groups. Conclusion: The use of an intensified regimen failed to show a significant improvement in tumor response and outcome of patients with localized HR-RMS, EES, and UDS

The tale of TILs in breast cancer: A report from The International Immuno-Oncology Biomarker Working Group

International audienceAbstract The advent of immune-checkpoint inhibitors (ICI) in modern oncology has significantly improved survival in several cancer settings. A subgroup of women with breast cancer (BC) has immunogenic infiltration of lymphocytes with expression of programmed death-ligand 1 (PD-L1). These patients may potentially benefit from ICI targeting the programmed death 1 (PD-1)/PD-L1 signaling axis. The use of tumor-infiltrating lymphocytes (TILs) as predictive and prognostic biomarkers has been under intense examination. Emerging data suggest that TILs are associated with response to both cytotoxic treatments and immunotherapy, particularly for patients with triple-negative BC. In this review from The International Immuno-Oncology Biomarker Working Group , we discuss (a) the biological understanding of TILs, (b) their analytical and clinical validity and efforts toward the clinical utility in BC, and (c) the current status of PD-L1 and TIL testing across different continents, including experiences from low-to-middle-income countries, incorporating also the view of a patient advocate. This information will help set the stage for future approaches to optimize the understanding and clinical utilization of TIL analysis in patients with BC