The role of human-induced fire and sweet chestnut (Castanea sativa Mill.) cultivation on the long-term landscape dynamics of the southern Swiss Alps

Changes in fire occurrence during the last decades in the southern Swiss Alps make knowledge on fire history essential to understand future evolution of the ecosystem composition and functioning. In this context, palaeoecology provides useful insights into processes operating at decadal-to-millennial time scales, such as the response of plant communities to intensified fire disturbances during periods of cultural change. We provide a high-resolution macroscopic charcoal and pollen series from Guèr, a well-dated peat sequence at mid-elevation (832 m.a.s.l.) in southern Switzerland, where the presence of local settlements is documented since the late Bronze Age and the Iron Age. Quantitative fire reconstruction shows that fire activity sharply increased from the Neolithic period (1–3 episodes/1000 year) to the late Bronze and Iron Age (7–9 episodes/1000 year), leading to extensive clearance of the former mixed deciduous forest (Alnus glutinosa, Betula, deciduous Quercus). The increase in anthropogenic pollen indicators (e.g. Cerealia-type, Plantago lanceolata) together with macroscopic charcoal suggests anthropogenic rather than climatic forcing as the main cause of the observed vegetation shift. Fire and controlled burning were extensively used during the late Roman Times and early Middle Ages to promote the introduction and establishment of chestnut (Castanea sativa) stands, which provided an important wood and food supply. Fire occurrence declined markedly (from 9 to 5–6 episodes/1000 year) during late Middle Ages because of fire suppression, biomass removal by human population, and landscape fragmentation. Land-abandonment during the last decades allowed forest to partly re-expand (mainly Alnus glutinosa, Betula) and fire frequency to increase.

Temperate Mountain Forest Biodiversity under Climate Change: Compensating Negative Effects by Increasing Structural Complexity

Species adapted to cold-climatic mountain environments are expected to face a high risk of range contractions, if not local extinctions under climate change. Yet, the populations of many endothermic species may not be primarily affected by physiological constraints, but indirectly by climate-induced changes of habitat characteristics. In mountain forests, where vertebrate species largely depend on vegetation composition and structure, deteriorating habitat suitability may thus be mitigated or even compensated by habitat management aiming at compositional and structural enhancement. We tested this possibility using four cold-adapted bird species with complementary habitat requirements as model organisms. Based on species data and environmental information collected in 300 1-km2 grid cells distributed across four mountain ranges in central Europe, we investigated (1) how species’ occurrence is explained by climate, landscape, and vegetation, (2) to what extent climate change and climate-induced vegetation changes will affect habitat suitability, and (3) whether these changes could be compensated by adaptive habitat management. Species presence was modelled as a function of climate, landscape and vegetation variables under current climate; moreover, vegetation-climate relationships were assessed. The models were extrapolated to the climatic conditions of 2050, assuming the moderate IPCC-scenario A1B, and changes in species’ occurrence probability were quantified. Finally, we assessed the maximum increase in occurrence probability that could be achieved by modifying one or multiple vegetation variables under altered climate conditions. Climate variables contributed significantly to explaining species occurrence, and expected climatic changes, as well as climate-induced vegetation trends, decreased the occurrence probability of all four species, particularly at the low-altitudinal margins of their distribution. These effects could be partly compensated by modifying single vegetation factors, but full compensation would only be achieved if several factors were changed in concert. The results illustrate the possibilities and limitations of adaptive species conservation management under climate change.

Revealing regional deforestation dynamics in north-eastern Madagascar - Insights from multi-temporal land cover change analysis

The north-eastern escarpment of Madagascar harbours the island’s last remaining large-scale humid forest massifs surrounded by a small-scale agricultural mosaic. There is high deforestation, commonly thought to be caused by shifting cultivation practiced by local land users to produce upland rice. However, little is known about the dynamics between forest and shifting cultivation systems at a regional level. Our study presents a first attempt to quantify changes in the extent of forest and different agricultural land cover classes, and to identify the main dynamics of land cover change for two intervals, 1995–2005 and 2005–2011. Over the 16-year study period, the speed of forest loss increased, the total area of upland rice production remained almost stable, and the area of irrigated rice fields slightly increased. While our findings seem to confirm a general trend of land use intensification, deforestation through shifting cultivation is still on the rise. Deforestation mostly affects the small forest fragments interspersed in the agricultural mosaic and is slowly leading to a homogenization of the landscape. These findings have important implications for future interventions to slow forest loss in the region, as the processes of agricultural expansion through shifting cultivation versus intensified land use cannot per se be considered mutually exclusive.

Alpine Common Property Institutions under Change: Conditions for Successful and Unsuccessful Collective Action by Alpine Farmers in the Canton of Grisons, Switzerland

The protection and sustainable management of alpine summer pastures has been stated as a goal in Swiss national law since 1996, and direct payments from the state for summer pasturing have been tied to sustainability criteria since 2000. This reflects the increasing value of the alpine cultural landscape as a public good. However, provision of this public good remains in the hands of local farmers and their local common pool resource (CPR) institutions for managing alpine pastures. These institutions are increasingly struggling to maintain their institutional arrangements, particularly regarding the work needed to maintain the pastures. This paper examines two cases of local CPR institutions for managing alpine pastures in the Swiss Canton of Grisons that manifest different institutional developments in light of changing conditions. The differences in how these institutions reacted to change and the impacts this has had on the provision of the CPR are explained by focusing on relative prices, bargaining power, and ideology as drivers of institutional change that are often neglected within common property research. Key words: summer pasture management, institutional change, bargaining power, ideology

Fair Access to Energy Resources, Market Transfers and Climate Change in the WTO

This paper addresses the issues of dual pricing and export restrictions in the energy sector, stressing the comparability of their economic and climate change impacts. It assesses whether WTO disciplines relevant and applicable to such practices are well-equipped to ensure fair access to energy resources. It finds that relevant GATT disciplines are overall deficient in the case of dual pricing and export taxes, while the landscape of WTO-plus obligations generally consisting of a network of narrowly tailored commitments. It discusses possible avenues to address such practices under the ASCM to the extent that they distort domestic energy prices and subsidize consumption of cheap fossil fuels

Overdeepened glacial basins as archives for the Quaternary landscape evolution of the Alps

The Alps and the Alpine foreland have been shaped by repeated glaciations during Quaternary glacial-interglacial cycles. Extent, timing and impact on landscape evolution of these glaciations are, however, poorly constrained due to the fragmentary character of terrestrial archives. In this context, the sedimentary infills of subglacially eroded, ‘overdeepened’, basins may serve as important archives to complement the Quaternary stratigraphy over several glacial-interglacial cycles. In this thesis, the infills of deep subglacial basins in the Lower Glatt valley (N Switzerland) are explored to better constrain the Middle- to Late Pleistocene environmental change. Five drill cores gave direct insight into to the up to ~200 m thick valley fill at the study site and allowed for detailed analysis of sedimentary facies, age and architecture of the basin fills. A first focus is set on the sedimentology of coarse-grained diamicts with sorted interbeds overlying bedrock in the trough center, which mark the onset of deposition in many glacial bedrock troughs. Evidence from macro- and microsedimentology suggests that these sediments are emplaced subglacially and reflect deposition, reworking and deformation in response to repeated coupling and decoupling of the ice-bed interface promoted by high basal water pressures. Overlying these subglacial sediments, large volumes of sandy glacio-deltaic, fine-grained glacio-lacustrine and lacustrine sediments document sedimentation during glacier retreat from the basins. On these thick valley fill sequences the applicability and reliability of luminescence dating is investigated in a second step on the basis of experiments with several different luminescence signals, protocols and experiments to assess the signal stability. The valley fill of the Lower Glatt valley is then grouped into nine depositional cycles (Formations A-I), which are related to the Birrfeld Glaciation (~MIS2), the Beringen Glaciation (~MIS6), and up to three earlier Middle Pleistocene glaciations, tentatively correlated to the Hagenholz, Habsburg, and Möhlin Glaciations, according to the regional glaciation history. The complex bedrock geometry and valley fill architecture are shown to be the result of multiple erosion and infilling cycles and reflect the interplay of subglacial erosion, glacial to lacustrine infilling of overdeepened basins, and fluvial down-cutting and aggradation in the non-overdeepened valley fill. Evidence suggests that in the study area deep bedrock incision, and/or partial re-excavation, occurred mainly during the Beringen and Hagenholz Glaciation, while older structures may have existed. Together with the observation of minor, ‘inlaid’ glacial basins, dynamic changes in the magnitude and focus of subglacial erosion over time are documented.