Picea abies | EPFL Graph Search

Picea abies, the Norway spruce or European spruce, is a species of spruce native to Northern, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, 9–17 cm long. It is very closely related to the Siberian spruce (Picea obovata), which replaces it east of the Ural Mountains, and with which it hybridizes freely. The Norway spruce has a wide distribution for it being planted for its wood, and is the species used as the main Christmas tree in several countries around the world. It was the first gymnosperm to have its genome sequenced. The Latin specific epithet abies means “like Abies, Fir tree” Description Norway spruce is a large, fast-growing evergreen coniferous tree growing tall and with a trunk diameter of 1 to 1.5 m. It can grow fast when young, up to 1 m per year for the first 25 years under good conditions, but becomes slower once over tall. The shoots are orange-brown

Spruce tree-ring proxy signals during cold and warm periods

The strength and temporal rigidity of climate signals are important characteristics of proxy data used to reconstruct climate variability over pre-instrumental periods. Here, we assess the performance of different tree-ring proxies, including ring width, maximum latewood density, delta C-13, and delta O-18, during exceptional cold (1800-1850) and warm periods (1946-2000). The analysis was conducted at a spruce (Picea abies) timberline site in the Swiss Alps in proximity to long homogenized instrumental records to support calibration tests against early temperature and precipitation data. In this cold environment, tree-ring width, maximum latewood density, and delta O-18 are mainly controlled by temperature variations. delta C-13 is influenced by various factors including temperature, precipitation, sunshine, and relative humidity. When comparing the response patterns during cold and warm periods, ring width and maximum latewood density revealed temporally stable temperature signals. In contrast, the association between the stable isotopes and climate changed considerably between the early 19th and late 20th centuries. The temperature signal in delta O-18 was stronger during the recent warm period, whereas the opposite is true for delta C-13. In delta C-13, the temperature signal weakened from the early 19th to the late 20th centuries, but an (inverse) precipitation signal evolved indicating that soil moisture conditions additionally limited recent carbon isotope ratios. An attempt to combine the tree-ring proxies in a multiple regression model did not substantially improve the strength of the dominating temperature signal retained in the latewood density data as this proxy already explained a significant fraction of summer temperature variability. Our findings underscore the importance of split calibration/verification approaches including cold and warm periods, and challenge transfer models based on only late 20th century observational data.

Bogucki Wydawnictwo Naukowe2017

Long-term dynamics of aboveground fungal communities in a subalpine Norway spruce forest under elevated nitrogen input

Rita Bütler Sauvain, Simon Egli, François Gillet

As anthropogenic N deposition has been suspected to be the main reason for the decline of macromycetous sporocarp production in forest ecosystems, various N-fertilization experiments were started in the mid 1990s. The dynamics of ectomycorrhizal (root-inhabiting) and terricolous saprobic (litter-inhabiting) fungal communities were studied by exhaustive sporocarp inventories in a substitution Norway spruce (Picea abies) forest in two 256-m(2) plots sampled for periods of 1 week at 1-m(2) resolution between 1994 and 2007. N was added to the soil twice per year in one plot from the fourth year onwards. The effects of N input and time on aboveground fungal communities were assessed using redundancy analysis, principal response curves and non-parametric multivariate ANOVA. Results of this long-term experiment revealed that both ectomycorrhizal and saprobic fungal communities responded to an increase in soil N input. The ectomycorrhizal community reacted by a fast decrease in sporocarp production and in species richness, whereas the saprobic community was less affected. The response was highly species specific, especially for the saprobic community. The difference in species composition between control and fertilized plots was significant after 1 year of N addition for ectomycorrhizal fungi and only after 3 years for saprobic fungi. An aging effect affected sporocarp production in the whole area. For both communities, this unidirectional drift in species composition was as important as the treatment effect. This result highlights the importance of considering the respective role of treatment and year effects in long-term field experiments on fungal communities.

Springer Verlag2010

Nurse plants, tree saplings and grazing pressure: decreasing facilitation along a biotic environmental gradient

Charlotte Vandenberghe

Current conceptual models predict that an increase in stress shifts interactions between plants from competitive to facilitative; hence, facilitation is expected to gain in ecological importance with increasing stress. Little is known about how facilitative interactions between plants change with increasing biotic stress, such as that incurred by consumer pressure or herbivory (i.e. disturbance sensu Grime). In grazed ecosystems, the presence of unpalatable plants is reported to protect tree saplings against cattle grazing and enhance tree establishment. In accordance with current conceptual facilitation-stress models, we hypothesised a positive relationship between facilitation and grazing pressure. We tested this hypothesis in a Weld experiment in which tree saplings of four diVerent species (deciduous Fagus sylvatica, Acer pseudoplatanus and coniferous Abies alba, Picea abies) were planted either inside or outside of the canopy of the spiny nurse shrub Rosa rubiginosa in enclosures diVering in grazing pressure (low and high) and in exclosures. During one grazing season we followed the survival of the diVerent tree saplings and the level of browsing on these; we also estimated browsing damage to the nurse shrubs. Shrub damage was highest at the higher grazing pressure. Correspondingly, browsing increased and survival decreased in saplings located inside the canopy of the shrubs at the high grazing pressure compared to the low grazing pressure. Saplings of both deciduous species showed a higher survival than the evergreens, while sapling browsing did not diVer between species. The relative facilitation of sapling browsing and sapling survival – i.e. the diVerence between saplings inside and outside the shrub canopy – decreased at high grazing pressure as the facilitative species became less protective. Interestingly, these Wndings do not agree with current conceptual facilitationstress models predicting increasing facilitation with abiotic stress. We used our results to design a conceptual model of facilitation along a biotic environmental gradient. Empirical studies are needed to test the applicability of this model. In conclusion, we suggest that current conceptual facilitation models should at least consider the possibility of decreasing facilitation at high levels of stress.

2007