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Globally there is increasing concern about the decline in the health of oak Quercus trees. The impact of a decline in oak trees on associated biodiversity, species that utilize oak trees, is unknown. Here we collate a database of all known birds, bryophytes, fungi, invertebrates, lichens and mammals that use oak (Quercus petraea and Q. robur) in the UK. In total 2300 species are listed in the database. For each species we provide a level of association with oak, ranging from obligate (only found on oak) to cosmopolitan (found on a wide range of other tree species). Data on the ecology of each oak associated species was collated: part of tree used, use made of tree (feeding, roosting, breeding), age of tree, woodland type, tree form (coppice, pollarded, or natural growth form) and season when the tree was used. Data on use or otherwise by each of the 2300 species of 30 other tree species was also collated. A complete list of data sources is provided. For further insights into how this data can be used see Collapsing foundations: The ecology of the British oak, implications of its decline and mitigation options [1]. Data can be found at EIDC https://doi.org/10.5285/22b3d41e-7c35-4c51-9e55-0f47bb845202.

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This study investigated changes in carbon-based plant secondary metabolite concentrations in the needles of Pinus sylvestris saplings, in response to long-term elevation of atmospheric CO2, at two rates of nutrient supply. Experimental trees were grown for 3 years in eight open-top chambers (OTCs), four of which were maintained at ambient (∼350 µmol mol-1) and four at elevated (700 µmol mol-1) CO2 concentrations, plus four open air control plots. Within each of these treatments, plants received either high (7.0 g N m-2 year-1 added) or low (no nutrients added) rates of nutrient supply for two years. Needles from lateral branches were analysed chemically for concentrations of condensed tannins and monoterpenes. Biochemical determinations of cellulase digestibility and protein precipitating capacity of their phenolic extracts were made because of their potential of importance in ecological interactions between pine and other organisms including herbivores and decomposers. Elevated CO2 concentration caused an increase (P<0.05) in dry mass per needle, tree height and the concentration of the monoterpene α-pinene, but there were no direct effects of CO2 concentration on any of the other chemical measurements made. High nutrient availability increased cellulase digestibility of pine needles. There was a significant negative effect of the OTCs on protein precipitating capacity of the needle extracts in comparison to the open-air controls. Results suggest that predicted changes in atmospheric CO2 concentration will be insufficient to produce large changes in the concentration of condensed tannins and monoterpenes in Scots pine. Processes which are influenced by these compounds, such as decomposition and herbivore food selection, along with their effects on ecosystem functioning, are therefore unlikely to be directly affected through changes in these secondary metabolites.

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Heather (Calluna vulgaris), a common dietary component of many mammalian herbivores, contains a broad range of tannin phenolics, flavonoids, and simple phenolic compounds. These may lead to a number of negative effects on herbivores as a result of toxicity or digestive inhibition. We assessed the effect of some simple phenolic compounds from heather on rumen microbial activity using thein vitro consecutive batch culture technique. The compounds tested were orcinol, quinol, and arbutin, a glucoside of quinol. At a concentration of 10 mM, both orcinol and quinol depressed production of gas and volatile fatty acids (VFAs). Orcinol and, to a lesser extent, quinol also reduced digestion of the substrate. In contrast to these negative effects on rumen microbial fermentation, arbutin stimulated both gas and VFA production, probably due to the presence of the fermentable sugar moiety. The presence of arbutin also resulted in different concentrations and proportions of VFAs compared to the presence of orcinol and quinol. Since many simple phenolic compounds are found in plants in the form of glycosides, the negative digestive effects of the phenolic moieties may be accompanied by the positive effect of the sugar moiety, which is liberated in the gastrointestinal tract on hydrolysis by glycosidase enzymes. This study suggests that when phenolics are present as glycosides, they do not necessarily adversely affect digestion by herbivores.

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Holcus lanatus, a temperate grass, was found to contain low but measurable concentrations of condensed tannins (CT), according to the vanillin-HCl and the butanol-HCl methods. The variation in CT concentrations between different types of tissue including leaf age and reproductive versus nonreproductive tissue was examined. There was no evidence that floral tissue contained more CT than nonreproductive tissue. A sequential extraction and analysis procedure showed a decreasing proportion of free-unbound CT and greater preponderance of protein-bound and fiber-bound CT with increasing leaf age and in dead matter. Samples collected from an agricultural pasture on two sampling dates, January 24 and March 5, 1993, showed short-term temporal variation in free-unbound CT.

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Mountain hares (Lepus timidus L.) commonly have high proportions of birch (Betula spp.) in their winter diets, whereas European hares (Lepus europaeus) do not. The effects of a birch extract added to laboratory diets offered to mountain hares and European hares on the digestibility and sodium balance were measured. The extract added contained total phenolics equivalent in amount to that occurring in diets containing 0, 40, 60 and 80% dry matter of birch twigs. Increasing dietary phenolic concentration led to reduced voluntary food intake and apparent protein digestibility in both hare species. No effects on apparent dry matter digestibility were observed. The highest concentration of birch extract caused severe sodium losses via the urine by European hares but not by mountain hares. The effects of the birch extract within the digestive system appear to be similar in the two hare species, whereas the mountain hare appears to be better adapted to the toxic effects that disrupted sodium balance in the European hare. These preliminary results suggest that detoxification rather than digestive abilityper se may contribute to different mammalian herbivores' feeding strategies.

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Seasonal differences in daily patterns of plasma melatonin concentration were investigated in both free-living and captive mountain hares, in relation to reproductive activity. There was a marked increase in plasma melatonin concentrations at night at all times of the year. The period of elevation of plasma melatonin above the daytime values was longer in winter than in summer, correlating with the longer duration of darkness. The magnitude of the nighttime rise in melatonin concentrations did not differ significantly between seasons. There was no change in the plasma melatonin profile under similar photoperiods before the summer solstice when hares are sexually active or after the summer solstice when gonadal regression occurs, indicating that melatonin is not directly pro- or antigonadal. These field and laboratory observations support the view that the daily rhythm of melatonin secretion plays a role in the transduction of photoperiodic information in the mountain hare. Furthermore, they favor the hypotheses that the circadian melatonin rhythm transduces photoperiod information by means of the duration of nocturnal melatonin secretion or by the coincidence of elevated melatonin with a particular sensitive period, rather than by the amplitude of the nocturnal rise.

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The abundance of the intestinal helminth Trichostrongylus retortaeformis in adult mountain hares (Lepus timidus) from a moor in northeastern Scotland was assessed monthly. Weight and fatness of each hare was measured and the reproductive output of females was estimated by sectioning ovaries. Abundance of the parasite was lower in December and January than at other times of year, and there was no difference in abundance between male and female hares. There was no correlation between intensity of infection with T. retortaeformis and weight or fatness of hares either at the onset of the reproductive period (February and March) or at its termination (August and September). We found no relationship between fecundity of female hares and parasite abundance.

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Parents will increase their fitness by varying the sex ratio of their progeny in response to differences in the costs and benefits of producing sons and daughters. Sex differences in energy requirements or viability during early growth, differences in the relative fitness of male and female offspring, and competition or cooperation between siblings or between siblings and parents might all be expected to affect the sex ratio. Although few trends have yet been shown to be consistent, growing numbers of studies have demonstrated significant variation in birth sex ratios in non-human mammals. These are commonly cited as evidence of adaptive manipulation of the sex ratio. However, several different mechanisms may affect the birth sex ratio, and not all of them are likely to be adaptive. Valid evidence that sex ratio trends are adaptive must be based either on the overall distribution of those trends or on cases in which the sex ratio can be shown to vary with the relative fitness of producing sons and daughters. The distribution of observed sex ratio trends does not conform closely to the predictions of any single adaptive theory. Some recent studies, however, indicate that, within species, the sex ratio varies with the costs or benefits of producing male or female offspring.

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