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Query: "keywords" (Quercus) .

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Contrasting resource dynamics in mast years for European Beech and Oak - a continental scale analysis
Anita Nussbaumer, Arthur Gessler, Sue Benham, B. De Cinti, Sophia Etzold, Morten Ingerslev, Frank Jacob, François Lebourgeois, Tom Levanič, Hrvoje Marjanović, 2021, original scientific article

Abstract: Resource allocation to different plant tissues is likely to be affected by high investment into fruit production during mast years. However, there is a large knowledge gap concerning species-specific differences in resource dynamics. We investigated the influence of mast years on stem growth, leaf production, and leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations and contents in Fagus sylvatica, Quercus petraea, and Q. robur at continental and climate region scales using long-term data from the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and similar datasets. We discussed the results in the light of opposing resource dynamics hypotheses: (i) resource accumulation before mast years and exhaustion after mast years (resource storage hypothesis), (ii) shifting resources from vegetative to generative compartments (resource switching hypothesis), and (iii) investing resources concurrently in both vegetative and generative compartments (resource matching hypothesis). Linear mixed-effects modelling (LMM) showed that both stem growth and leaf production were negatively influenced by weather conditions which simultaneously lead to high fruit production. Thus, the impact of generative on vegetative growth is intermixed with effects of environmental factors. Superposed epoch analyses and LMM showed that for mast behaviour in F. sylvatica, there are indicators supporting the resource storage and the resource switching hypotheses. Before mast years, resources were accumulated, while during mast years resources switched from vegetative to generative tissues with reduced stem and leaf growth. For the Quercus species, stem growth was reduced after mast years, which supports the resource storage hypothesis. LMM showed that leaf C concentrations did not change with increasing fruit production in neither species. Leaf N and P concentrations increased in F. sylvatica, but not in Quercus species. Leaf N and P contents decreased with increasing fruit production in all species, as did leaf C content in F. sylvatica. Overall, our findings suggest different resource dynamics strategies in F. sylvatica and Quercus species, which might lead to differences in their adaptive capacity to a changing climate.
Keywords: climate change, Fagus sylvatica, long-term monitoring, mast fruiting, Quercus petraea, Quercus robur, resource dynamics
Published in DiRROS: 15.07.2021; Views: 853; Downloads: 627
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19.
First report of European truffle ectomycorrhiza in the semi%arid climate of Saudi Arabia
Seema R. Bajaj, Sandesh J. Marathe, Tine Grebenc, Alessandra Zambonelli, Salem Shamekh, 2021, original scientific article

Abstract: Tuber melanosporum Vittad. (Black or Périgord truffle) is a truffle native to the Mediterranean Southern Europe, popular for its unique flavor, and has great economic importance. The present work focused on assessing the possibility of cultivating T. melanosporum associated with Quercus robur L. in the desert climate of Saudi Arabia. The plantation was initiated in November 2018 by planting 271 oak seedlings in the Al-Qassim desert area and checked for survival and ectomycorrhiza development after 1.5 years of plantation maintenance. Amongst the 271 seedlings planted, 243 plants survived two harsh seasons (2019 and 2020), and the randomly selected and tested seedlings were still mycorrhized with T. melanosporum. The mycorrhization level with T. melanosporum was between 5 and 35% of all fine roots, and the share of contaminant ectomycorrhiza was low. In comparison to other areas where T. melanosporum is successfully cultivated, the Al-Qassim desert area has 10%15 °C higher average summer temperatures and a low total annual precipitation, which necessitates regular irrigation of the plantation. This work opens the avenue for an adapted, yet sustainable cultivation of T. melanosporum-inoculated oak tree in a desert climatic condition and introduces new opportunities of the agro-forest business in Saudi Arabia and GCC region.
Keywords: Tuber melanosporum, Quercus robur, Desert climate, Truffle cultivation, Ectomycorrhiza
Published in DiRROS: 26.01.2021; Views: 1053; Downloads: 277
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20.
The effect of bedrock and species mixture on wood density and radial wood increment in pubescent oak and black pine
Luka Krajnc, Polona Hafner, Jožica Gričar, 2020, original scientific article

Abstract: Wood density and radial wood increment were examined in trees of pubescent oak (Quercus pubescens Willd.) and black pine (Pinus nigra Arnold., subsp. nigra) in relation to stand mixture and underlying bedrock. Trees of both species from pure and mixed stands were sampled across two types of bedrock, limestone and flysch. Trees from each species were similar in age. Wood density was estimated in standing trees using resistance drilling and increment cores were taken from a smaller subsample of trees of both species. Tree-ring, earlywood and latewood widths were measured and compared to radial profiles of wood density. The influence of stand mixture, diameter at breast height and bedrock on wood density was examined using a Bayesian general linear model. Wood density was significantly higher in pubescent oak than in black pine. Stand mixture was found to affect wood density positively, although the magnitude of the effect was relatively small when compared to other influencing factors also included in the current study. The effect of diameter on wood density was positive on both bedrocks in pubescent oak and negative or neutral in black pine. The size of the effect varied by bedrock and species. On flysch bedrock, the influence of diameter on wood density was stronger than it was on limestone. These indirect bedrock effects on wood density are probably a result of different soil fertility rather than the bedrock itself. There was a notable difference in radial wood increment in both species across the two bedrocks, whereas the differences in densities were smaller. Higher wood densities found on flysch in the subsample of pubescent oaks are likely an effect of higher proportions of latewood, while the opposite trend was observed in black pine. Higher wood density was found on limestone in black pine despite higher latewood percentages on flysch. In the context of forest management, the species composition of the naturally occurring mixtures in the sub-Mediterranean region should be adjusted slightly to favor pubescent oak, since it is a climax species and will bind more carbon for longer than black pine due to higher wood densities. Future forest management should also promote the overall development of pubescent oak trees in sub-Mediterranean stands. The results are especially important in the European context, because the share of sub-Mediterranean stands is expected to rise with global warming.
Keywords: Karst, wood structure, resistograph, resistance drilling, Quercus pubescens, Pinus nigra, limestone, flysch
Published in DiRROS: 14.01.2021; Views: 1084; Downloads: 362
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