Terrestrial biosphere changes over the last 120 kyr

A new global synthesis and biomization of long (> 40 kyr) pollen-data records is presented and used with simulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial–interglacial cycle. Simulated biome distributions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those inferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large-scale increases during the Last Glacial Maximum, between ca. 64 and 74 ka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are reflected in BIOME4 simulations of global net primary productivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composition of seawater as terrestrial carbon is depleted in 13C

Modelling silicon supply during the Last Interglacial (MIS 5e) at Lake Baikal

Limnological reconstructions of primary productivity have demonstrated its response over Quaternary timescales to drivers such as climate change, landscape evolution and lake ontogeny. In particular, sediments from Lake Baikal, Siberia, provide a valuable uninterrupted and continuous sequence of biogenic silica (BSi) records, which document orbital and sub-orbital frequencies of regional climate change. We here extend these records via the application of stable isotope analysis of silica in diatom opal (δ30Sidiatom) from sediments covering the Last Interglacial cycle (Marine Isotope Stage [MIS] 5e; c. 130 to 115 ka BP) as a means to test the hypothesis that it was more productive than the Holocene. δ30Sidiatom data for the Last Interglacial range between +1.29 to +1.78‰, with highest values between c. 127 to 124 ka BP (+1.57 to +1.78‰). Results show that diatom dissolved silicon (DSi) utilisation, was significantly higher (p=0.001) during MIS 5e than the current interglacial, which reflects increased diatom productivity over this time (concomitant with high diatom biovolume accumulation rates [BVAR] and warmer pollen-inferred vegetation reconstructions). Diatom BVAR are used, in tandem with δ30Sidiatom data, to model DSi supply to Lake Baikal surface waters, which shows that highest delivery was between c. 123 to 120 ka BP (reaching peak supply at c. 120 ka BP). When constrained by sedimentary mineralogical archives of catchment weathering indices (e.g. the Hydrolysis Index), data highlight the small degree of weathering intensity and therefore representation that catchment-weathering DSi sources had, over the duration of MIS 5e. Changes to DSi supply are therefore attributed to variations in within-lake conditions (e.g. turbulent mixing) over the period, where periods of both high productivity and modelled-DSi supply (e.g. strong convective mixing) account for the decreasing trend in δ30Sidiatom compositions (after c. 124 ka BP)

Vegetation and climate variability during the Last Interglacial evidenced in the pollen record from Lake Baikal

A high-resolution pollen record from the core sediments collected in the northern part of Lake Baikal represents the latest stage of the Taz (Saale) Glaciation, Kazantsevo (Eemian) Interglacial (namely the Last Interglacial), and the earliest stage of the Zyryanka (Weichselian) Glaciation. According to the palaeomagnetic-based age model applied to the core, the Last Interglacial in the Lake Baikal record lasted about 10.6 kyrs from 128 kyr to 117.4 kyr BP, being more or less synchronous with the Marine Isotope Stage 5e. The reconstructed changes in the south Siberian vegetation and climate are following. A major spread of shrub alder (Duschekia fruticosa = Alnus fruticosa) and shrub birches (Betula sect. Nanae/Fruticosae) in the study area was a characteristic feature during the late glacial phase of the Taz Glaciation. Boreal trees e.g. spruce (Picea obovata) and birch (Betula sect. Albae) started to play an important role in the regional vegetation with the onset of the interglacial conditions. Optimal conditions for Abies sibirica-Picea obovata taiga development occurred ca. 126.3 kyr BP. The maximum spread of birch forest-steppe communities took place at the low altitudes ca. 126.5-125.5 kyr BP and Pinus sylvestris started to form forests in the northern Baikal area after ca. 124.4 kyr BP. Re-expansion of the steppe communities, as well as shrubby alder and willow communities and the disappearance of forest vegetation occurred at about 117.4 kyr BP, suggesting the end of the interglacial succession. The changes in the pollen assemblages recorded in the sediments from northern Baikal point to a certain instability of the interglacial climate. Three phases of climate deterioration have been distinguished: 126-125.5, 121.5-120, and 119.5-119 kyr BP. The penultimate cooling signal may be correlated with the cool oscillation recorded in European pollen records. However, such far distant correlation requires more careful investigation

Vertragliche Zusammenarbeit bei der energetischen Biomasselieferung: Einstellungen und Bindungsbereitschaften von deutschen Landwirten

Im Zuge der Energiewende treten immer mehr Bioenergieanlagenbetreiber an Landwirte heran, um ihren Biomassebedarf langfristig vertraglich abzusichern. Sie verfügen jedoch nur über wenig Erfahrung bezüglich Vertragsmotivationen von Landwirten. Vor diesem Hintergrund wird auf Basis einer Befragung von 209 Landwirten eine Segmentierung von Betriebsleitern anhand ihrer unternehmerischen Einstellungen durchgeführt. Die identifizierten Unternehmersegmente unterscheiden sich hinsichtlich wahrgenommenem Vertragsnutzen und Bindungsbereitschaft. Langfristig bindungsbereite Vertragsbefürworter zeichnen sich durch eine geringe Autonomiepräferenz aus. Die in der Literatur häufig bestätigte Motivation, aus Risikogesichtspunkten Verträge einzugehen, kann dagegen nicht nachgewiesen werden. Auf Basis der Ergebnisse werden Managementempfehlungen hinsichtlich der Akquise von Vertragslieferanten sowie Schlussfolgerungen für die Vertragsforschung gegeben

Langfristige Rohstoffsicherung in der Supply Chain Biogas: Status Quo und Potenziale vertraglicher Zusammenarbeit

Im Zuge des Ausbaus der Biogaserzeugung steigt die Nachfrage nach landwirtschaftlicher Biomasse. Besonders die vermehrt auf den Biogasmarkt tretenden außerlandwirtschaftlichen Biogasbetreiber stehen vor der Herausforderung, ihren Substratbedarf abzusichern. Eine Ana- lyse der Struktur und Entwicklungen entlang der Supply Chain Biogas verdeutlicht die Notwendigkeit zur vertraglichen Zusammenarbeit als Form der koordinierten Rohstoffbe- schaffung. Da Biomasseabnehmer i. d. R. nur über wenige Erfahrungen mit Landwirten als Vertragspartnern verfügen, wurden sowohl deren generelle vertragliche Einstellungen als auch deren spezielle Präferenzen hinsichtlich konkreter Inhalte von Biomasselieferverträgen analysiert. Eine Befragung von 209 landwirtschaftlichen Betriebsleitern gibt über beides Auf- schluss. Landwirte beurteilen vertragliche Kooperationen infolge differenzierter Freiheits- und Risikopräferenz unterschiedlich. Vertragslieferanten zeichnen sich durch eine geringe Freiheitspräferenz, hohe Risikoaversion und vertikale Orientierung aus. Hinsichtlich der Vertragsinhalte favorisieren sie überwiegend kurzfristige Verträge mit marktorientierter Preisanpassung. Für potenzielle Biomasseerzeuger sind neben einem hohen Preisniveau ferner die landwirtschaftliche und regionale Orientierung des Abnehmers bei Vertragsüberlegungen relevant. Es werden sowohl theoretische Implikationen als auch Empfehlungen hinsichtlich der Akquise von Biomasselieferanten und der Ausgestaltung von Vertragsangeboten gegeben

Pleistocene climate changes based on palynological data

The paper presents general climate changes during the last 2.6 Ma in the Northern Hemisphere. Plant formations of warm intervals (interglacials and interstadials) are briefly described. Disappearance of some more climate-sensitive tree taxa as well as climate changes during the Pleistocene in Northern Europe are also portrayed