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Biogeochemical theory emphasizes nitrogen (N) limitation and the many factors that can restrict N accumulation in temperate forests, yet lacks a working model of conditions that can promote naturally high N accumulation. We used a dynamic simulation model of ecosystem N and δ15N to evaluate which combination of N input and loss pathways could produce a range of high ecosystem N contents characteristic...
Plant–soil interactions have been proposed as a causative mechanism explaining how invasive plant species impact ecosystem processes. We evaluate whether an invasive plant influences plant and soil-microbe acquisition of nitrogen to elucidate the mechanistic pathways by which invaders might alter N availability. Using a 15N tracer, we quantify differences in nitrogen uptake and allocation in communities...
Epizootics of nucleopolyhedrovirus characterize declines of cyclic populations of western tent caterpillars, Malacosoma pluviale californicum. In field populations, infection can be apparently lacking in one generation and high in the next. This may suggest an increase in the susceptibility to infection of larvae at peak density or the triggering of a vertically transmitted virus. Here, we test the...
Carbon, nitrogen, and phosphorus (C, N, P) stoichiometry influences the growth of plants and nutrient cycling within ecosystems. Indeed, elemental ratios are used as an index for functional differences between plants and their responses to natural or anthropogenic variations in nutrient supply. We investigated the variation in growth and elemental content of the rootless terrestrial bromeliad Tillandsia landbeckii...
Infection-induced changes in a host’s thermal physiology can represent (1) a generalized host response to infection, (2) a pathological side-effect of infection, or (3), provided the parasite’s development is temperature-dependent, a subtle case of host manipulation. This study investigates parasite-induced changes in the thermal biology of a first intermediate host infected by two castrating trematodes...
A general prediction of the specialist/generalist paradigm indicates that plant responses to insect herbivores may depend on the degree of ecological specialization of the insect attacker. However, results from a single greenhouse experiment evaluating the responses of the model plant Arabidopsis thaliana to three specialist (Plutella xylostella, Pieris rapae, and Brevicoryne brassicae) and three...
Crassulacean acid metabolism (CAM) and the capacity to store large quantities of water are thought to confer high water use efficiency (WUE) and survival of succulent plants in warm desert environments. Yet the highly variable precipitation, temperature and humidity conditions in these environments likely have unique impacts on underlying processes regulating photosynthetic gas exchange and WUE, limiting...
Indirect resource competition and interference are widely occurring mechanisms of interspecific interactions. We have studied the seasonal expression of these two interaction types within a two-species, boreal small mammal system. Seasons differ by resource availability, individual breeding state and intraspecific social system. Live-trapping methods were used to monitor space use and reproduction...
Micro-arthropods in moss patches have been used as a model system to investigate the effects of habitat destruction and fragmentation on population viability and ecosystem functioning. Previous assessments of the sensitivity to fragmentation and the effectiveness of mitigating landscape structures have to some extent been contradictory, one possible reason being a lack of knowledge of the realised...
The impact of parasites on population dynamics is well documented, but less is known on how host population density affects parasite spread. This relationship is difficult to assess because of confounding effects of social structure, population density, and environmental conditions that lead to biased among-population comparisons. Here, we analyzed the infestation by two groups of nematodes (gastro-intestinal...
Data assimilation, or the fusion of a mathematical model with ecological data, is rapidly expanding knowledge of ecological systems across multiple spatial and temporal scales. As the amount of ecological data available to a broader audience increases, quantitative proficiency with data assimilation tools and techniques will be an essential skill for ecological analysis in this data-rich era. We provide...
Within-range effects of climatic change on tree growth at the sub-regional scale remain poorly understood. The aim of this research was to use climate and radial-growth data to explain how long-term climatic trends affect tree growth patterns along the southern limit of the range of Pinus nigra ssp. salzmannii (Eastern Baetic Range, southern Spain). We used regional temperature and precipitation data...
Model–data fusion is a powerful framework by which to combine models with various data streams (including observations at different spatial or temporal scales), and account for associated uncertainties. The approach can be used to constrain estimates of model states, rate constants, and driver sensitivities. The number of applications of model–data fusion in environmental biology and ecology has been...
The island syndrome predicts directional changes in the morphology and demography of insular vertebrates, due to changes in trophic complexity and migration rates caused by island size and isolation. However, the high rate of human-mediated species introductions to some islands also increases trophic complexity, and this will reduce the perceived insularity on any such island. We test four hypotheses...
We treated Norway spruce (Picea abies) stems with methyl jasmonate (MeJA) to determine possible quantitative and qualitative effects of induced tree defenses on pheromone emission by the spruce bark beetle Ips typographus. We measured the amounts of 2-methyl-3-buten-2-ol and (S)-cis-verbenol, the two main components of the beetle’s aggregation pheromone, released from beetle entrance holes, along...
A positive effect of (meta)population density on emigration has been predicted by many theoretical models and confirmed empirically in various organisms. However, in butterflies, the most popular species for dispersal studies, the evidence for its existence has so far been equivocal, with negative relationships between density and emigration being reported more frequently. We analysed dispersal in...
Dominance of invasive species is often assumed to be due to a superior ability to acquire resources. However, dominance in plant communities can arise through multiple interacting mechanisms, including disturbance. Inter-specific competition can be strongly affected by abiotic conditions, which can determine the outcome of competitive interactions. We evaluated competition and disturbance as mechanisms...
We examined how the galling aphid Pemphigus batae manipulates resource translocation patterns of resistant and susceptible narrowleaf cottonwood Populus angustifolia. Using carbon-14 (14C)-labeling experiments in common garden trials, five patterns emerged. First, although aphid galls on resistant and susceptible genotypes did not differ in their capacity to intercept assimilates exported from the...
Because nutrient enrichment can increase ecosystem productivity, it may enhance resource flows to adjacent ecosystems as organisms cross ecosystem boundaries and subsidize predators in recipient ecosystems. Here, we quantified the biomass and abundance of aquatic emergence and terrestrial spiders in a reference and treatment stream that had been continuously enriched with nitrogen and phosphorus for...
Mature forest canopies sustain an enormous diversity of herbivorous arthropods; however, with the exception of species that exhibit large-scale outbreaks, canopy arthropods are thought to have relatively little influence on overall forest productivity. Diminutive gall-inducing mites (Acari; Eriophyoidae) are ubiquitous in forest canopies and are almost always highly host specific, but despite their...
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