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Independent variations of plant and soil mixtures reveal soil feedback effects on plant community overyielding
No full text* Recent studies have shown that the positive relationship between plant diversity and plant biomass (‘overyielding’) can be explained by soil pathogens depressing productivity more in low than in high diverse plant communities. However, tests of such soil effects in field studies were constrained by experimental limitations to manipulate soil community composition independent of plant community composition. Here, we report of an experiment where feedback effects to plants were tested for both plant and soil monocultures and mixtures. * Our results demonstrate that overyielding is the result of plant species in mixture being more growth-limited by ‘own’ soil biota than by soil biota of other plant species. This effect disappeared when the soils had been sterilized by gamma-irradiation. Mixing plants themselves did not result in overyielding except when grown in the soil of one of the species (Leucanthemum vulgare), where growth of one species disproportionally increased in mixture compared to monoculture. * Soil nutrient availability could not explain differences in growth between the non-sterilized soils. Therefore, our results suggest that plant species–specific soil biota rather than the plants have contributed to the plant community overyielding. * Species biomass ranking in mixtures highly differed between non-sterilized soils of different histories of soil conditioning, whilst the ranking was more consistent in sterilized soil. Sterilized soils of different origin differed significantly in nutrient availability. These results suggest that shifts in competitive hierarchies depend on plant species–specific interactions influenced by soil biota and cannot be induced by mineral nitrogen. * Synthesis. Our results show that overyielding in four plant species mixtures can be due to species-specific interactions between plants and their specific soil biota. Neither mixing the plant species alone nor the differential responses of species to mineral nitrogen influenced community productivity, but mixing soil biota did. [KEYWORDS: Anthoxanthum odoratum biodiversity experiment biodiversity–productivity relationship competitive hierarchy determinants of plant community diversity and structure grasslands Leucanthemum vulgare micro-organisms pathogens plant–soil feedback]
Boekrecensie: Avondschot. Hoe Nederland zich terugtrok uit zijn Aziatisch imperium, J.J.P. de Jong
No full textHoe komt de folchoarder yn de tiidwurdkloft mei 3 tiidwurden yn Ynterferinsjefrysk ta stân?
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Delfts blauwe dood: de gevolgen van de cholera in de negentiende eeuw
No full textCholera-epidemieën waren in de 19de eeuw verantwoordelijk voor vele dodelijke slachtoffers. De ziekte maakte bovendien geen onderscheid tussen arm en rijk. Normaal gesproken relatief minder kwetsbare groepen in die tijd, zoals wat oudere kinderen en jongere volwassenen, liepen juist een groter risico om aan cholera te overlijden. Dat blijkt, bij voorbeeld, uit het verloop van de cholera-epidemie van 1866 in Delft.
Amazon poison frogs (Ranitomeya amazonica) use different phytotelm characteristics to determine their suitability for egg and tadpole deposition
No full textSustaining ecosystem functions in a changing world: a call for an integrated approach
No full textWith ever-increasing human pressure on ecosystems, it is critically important to predict how ecosystem functions will respond to such human-induced perturbations. We define perturbations as either changes to abiotic environment (e.g. eutrophication, climate change) that indirectly affects biota, or direct changes to biota (e.g. species introductions). While two lines of research in ecology, biodiversity–ecosystem function (BDEF) and ecological resilience (ER) research, have addressed this issue, both fields of research have nontrivial shortcomings in their abilities to address a wide range of realistic scenarios.
We outline how an integrated research framework may foster a deeper understanding of the functional consequences of perturbations via simultaneous application of (i) process-based mechanistic predictions using trait-based approaches and (ii) detection of empirical patterns of functional changes along real perturbation gradients. In this context, the complexities of ecological interactions and evolutionary perspectives should be integrated into future research.
Synthesis and applications. Management of human-impacted ecosystems can be guided most directly by understanding the response of ecosystem functions to controllable perturbations. In particular, we need to characterize the form of a wide range of perturbation–function relationships and to draw connections between those patterns and the underlying ecological processes. We anticipate that the integrated perspectives will also be helpful for managers to derive practical implications for management from academic literature.