How do trees respond to species mixing in experimental compared to observational studies?

For decades, ecologists have investigated the effects of tree species diversity on tree productivity at different scales and with different approaches ranging from observational to experimental study designs. Using data from five European national forest inventories (16,773 plots), six tree species diversity experiments (584 plots), and six networks of comparative plots (169 plots), we tested whether tree species growth responses to species mixing are consistent and therefore transferrable between those different research approaches. Our results confirm the general positive effect of tree species mixing on species growth (16% on average) but we found no consistency in species‐specific responses to mixing between any of the three approaches, even after restricting comparisons to only those plots that shared similar mixtures compositions and forest types. These findings highlight the necessity to consider results from different research approaches when selecting species mixtures that should maximize positive forest biodiversity and functioning relationships.     

Behavioural responses to predation may explain shifts in community structure

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Competition is the mechanism of biocontrol of brown rot in stone fruit by <Emphasis Type="Italic">Penicillium frequentans</Emphasis>

The mechanism of biocontrol of brown rot in stone fruit by Penicillium frequentans Westling (Pf909) was investigated using in vitro and in vivo growth assays and a benomyl-resistant strain of Monilinia fructicola (G Winter) Honey (Mf3C). For the in vitro assays, Pf909 and Mf3C conidia were suspended in Czapek-Dox broth, which was amended or not amended with a skin extract of mature peaches. The growth and germination of Pf909 and Mf3C conidia were determined by counting the number of colony-forming units on potato dextrose agar plates, which were amended or not amended with 0.5 g ml^?1 benomyl. In some of the assays, germinated Pf909 conidia were used before their exposure to Mf3C conidia. For the in vivo assays, healthy cherries were inoculated with Mf3C conidia before and after applying Pf909 conidia on the cherry surface and the incidence of brown rot was recorded for seven days. Since we found that Pf909 conidia compete with Mf3C conidia for space and nutrients in the different assays, we concluded that competition is the probable primary mechanism of biocontrol of Pf909.     

Identification and characterization of microsatellite loci in the spiny spider crab <Emphasis Type="Italic">Maja brachydactyla</Emphasis>

The spiny spider crab Maja brachydactyla in an important fishery resource throughout its distribution range (Northeast Atlantic). Here we describe the isolation of nine microsatellite loci for this species. These new markers were tested in 20 crabs from NW Spain. The number of alleles ranged from 3 to 20 and expected heterozigosity from 0.57 to 0.95. All loci followed Hardy–Weinberg expectations except mMb33 and mMb307, which could be affected by null alleles. Some of these loci seem to be better fitted by a multi-step substitution process.     

Integrated archaeobotanical research into vegetation management and land use in El Llano de la Horca (Santorcaz, Madrid, central Spain)

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Micropropagation of adult Stone Pine (Pinus pinea L.)

This paper describes a micropropagation protocol for in vitro propagation of mature Stone Pine trees. Axillary bud development was achieved by culturing bud explants in media containing various cytokinins. Experiments were conducted to test the effect of asepsis conditions, type and concentration of cytokinin and rooting protocol. Four cytokinins were tested, namely, benzyladenine, meta-topolin, N-benzyl-9-(2-tetrahydropyranyl)-adenine and thidiazuron (TDZ) of which TDZ gave the best results, as 59% shoot development was obtained following the application of 1 μM TDZ to the culture medium. The shoot development was significantly influenced by the genotype of the tree, but was effective in explants from all 20 genotypes used in the trial. In vitro rooting was, however, difficult to achieve and could only be induced at low rates. This protocol represents the first successful biotechnological approach to the micropropagation of adult Pinus pinea trees. Paloma Moncaleán and Ricardo Javier Ordás contributed equally.