ALBERT

Description: The concentration–carbon feedback (β), also called the CO2 fertilization effect, is a key unknown in climate–carbon-cycle projections. A better understanding of model mechanisms that govern terrestrial ecosystem responses to elevated CO2 is urgently needed to enable a more accurate prediction of future terrestrial carbon sink. We conducted C-only, carbon–nitrogen (C–N) and carbon–nitrogen–phosphorus (C–N–P) simulations of the Community Atmosphere Biosphere Land Exchange model (CABLE) from 1901 to 2100 with fixed climate to identify the most critical model process that causes divergence in β. We calculated CO2 fertilization effects at various hierarchical levels from leaf biochemical reaction and leaf photosynthesis to canopy gross primary production (GPP), net primary production (NPP), and ecosystem carbon storage (cpool) for seven C3 plant functional types (PFTs) in response to increasing CO2 under the RCP 8.5 scenario. Our results show that β values at biochemical and leaf photosynthesis levels vary little across the seven PFTs, but greatly diverge at canopy and ecosystem levels in all simulations. The low variation of the leaf-level β is consistent with a theoretical analysis that leaf photosynthetic sensitivity to increasing CO2 concentration is almost an invariant function. In the CABLE model, the major jump in variation of β values from leaf levels to canopy and ecosystem levels results from divergence in modeled leaf area index (LAI) within and among PFTs. The correlation of βGPP, βNPP, or βcpool each with βLAI is very high in all simulations. Overall, our results indicate that modeled LAI is a key factor causing the divergence in β in the CABLE model. It is therefore urgent to constrain processes that regulate LAI dynamics in order to better represent the response of ecosystem productivity to increasing CO2 in Earth system models.

Description: Specimens of Cassigerinelloita amekiensis Stolk from the type collections and DSDP/ODP holes are found to possess a microperforate and pustulate wall and a triserial, pseudoplanispiral coiling mode. These characters prompt its affinity with the contemporaneous Guembelitria triseriata (Terquem). An amended description of Cassigerinelloita amekiensis is given, and the peculiar coiling mode discussed.

Description: The concentration-carbon feedback factor (β), also called the CO2 fertilization effect, is a key unknown in climate-carbon cycle projections. A better understanding of model mechanisms that govern terrestrial ecosystem responses to elevated CO2 is urgently needed to enable a more accurate prediction of future terrestrial carbon sink. We calculated CO2 fertilization effects at various hierarchical levels from leaf biochemical reaction, leaf photosynthesis, canopy gross primary production (GPP), net primary production (NPP), to ecosystem carbon storage (cpool), for seven C3 vegetation types in response to increasing CO2 under RCP 8.5 scenario, using the Community Atmosphere Biosphere Land Exchange model (CABLE). Our results show that coefficient of variation (CV) for the CABLE model among the seven vegetation types is 0.15–0.13 for the biochemical level β, 0.13–0.16 for the leaf-level β, 0.48 for the βGPP, 0.45 for the βNPP, and 0.58 for the βcpool. The low variation of the leaf-level β is consistent with a theoretical analysis that leaf photosynthetic sensitivity to increasing CO2 concentration is almost an invariant function. In CABLE, the major jump in CV of β values from leaf- to canopy- and ecosystem-levels results from divergence in modelled leaf area index (LAI) within and among the vegetation types. The correlations of βGPP, βNPP, or βcpool with βLAI are very high in CABLE. Overall, our results indicate that modelled LAI is a key factor causing the divergence in β values in CABLE model. It is therefore urgent to constrain processes that regulate LAI dynamics in order to better represent the response of ecosystem productivity to increasing CO2 in Earth System Models.

Description: The species of the earliest Palaeocene planktonic foraminiferal genus Parvularugoglobigerina are characterized by a small test with a smooth, microperforate wall and an elongate aperture. Pore-mound structures may occur on some specimens, while the coiling mode varies from high- to low-trochospiral. Four morphotypes are distinct enough to be recognized as species: P. eugubina (Luterbacher & Premoli Silva) is low spiral and multichambered and P. perexigua n. sp. is four-chambered; P. fodina (Blow) has a Globigerina bulloides-type morphology and P. alticonusa n. sp. has a high trochospire. With the exception of the high spire, this general morphology is repeated in late Eocene forms classified as Praetenuitella: P. insolita (Jenkins), P. patefacta Li, and other associated forms.The two groups acquired their strong similarities – highly distinctive, peculiarly elongated aperture and microperforate walls – through evolutionary convergence, not by being directly related. Stratigraphically they each have a brief occurrence in a geologically significant slice of Palaeogene time: the one during the recovery of ecosystems in the earliest Palaeocene; the other immediately prior to the great cooling and in the time of rapid change known as the Terminal Eocene Event. This study shows that Praetenuitella flourished in eutrophic conditions and that their evolution might have been nutrient-driven. We suggest by morphological pattern analogy that forms of Praetenuitella and Parvulorugoglobigerina reflect similar habitat in their similar form and especially in their aperture.

Description: The Cenozoic in southern Australia contains many foraminifera endemic to the region in neritic (intermediate- to shallow-water) facies. They were mostly epifaunal and inhabited waters to some 300 m deep. This endemism is first obvious in the later Eocene when Maslinella, Crespinina and Wadella, among others, evolved. More than half of the Eocene endemic species disappeared in the Eocene or Oligocene. There followed in the Oligocene the evolution of such species as Parrellina imperatrix and Astrononion centroplax. The Miocene was a time of slightly reduced endemism and is characterized by migration into the region of many larger (sub)tropical taxa such as Lepidocyclina and Cycloclypeus. The long-ranging genus Notorotalia emerged about 50 Ma ago and is still common in modern southern mid-latitude waters. The youngest common extant species which made their first appearance in the Pliocene–Quaternary include Discorbis dimidiatus and Parredicta porifera, both with a test up to 1.5 mm in diameter. A similar pattern has been recorded in New Zealand.Four phases of endemism can be recognized: later Eocene, Oligocene, Miocene and Pliocene–Quaternary. It appears that the four phases were all stimulated in response to major marine transgressions, respectively the Wilson Bluff ( = Khirthar), Aldingan, Clifton–Longfordian and Hallet Cove–Glanville transgressions. Probably they signal four important stages in the transformation of water masses along the southern continental margin.