Intensive grassland management disrupts below-ground multi-trophic resource transfer in response to drought.

Modification of soil food webs by land management may alter the response of ecosystem processes to climate extremes, but empirical support is limited and the mechanisms involved remain unclear. Here we quantify how grassland management modifies the transfer of recent photosynthates and soil nitrogen through plants and soil food webs during a post-drought period in a controlled field experiment, using in situ C and N pulse-labelling in intensively and extensively managed fields. We show that intensive management decrease plant carbon (C) capture and its transfer through components of food webs and soil respiration compared to extensive management.

The ecological impacts of multiple environmental stressors on coastal biofilm bacteria.

Ecological communities are increasingly exposed to multiple interacting stressors. For example, warming directly affects the physiology of organisms, eutrophication stimulates the base of the food web, and harvesting larger organisms for human consumption dampens top-down control. These stressors often combine in the natural environment with unpredictable results.

Data quantity is more important than its spatial bias for predictive species distribution modelling.

Biological records are often the data of choice for training predictive species distribution models (SDMs), but spatial sampling bias is pervasive in biological records data at multiple spatial scales and is thought to impair the performance of SDMs. We simulated presences and absences of virtual species as well as the process of recording these species to evaluate the effect on species distribution model prediction performance of (1) spatial bias in training data, (2) sample size (the average number of observations per species), and (3) the choice of species distribution modelling method. Our approach is novel in quantifying and applying real-world spatial sampling biases to simulated data.

Quantifying large-scale ecosystem stability with remote sensing data.

To fully understand ecosystem functioning under global change, we need to be able to measure the stability of ecosystem functioning at multiple spatial scales. Although a number of stability components have been established at small spatial scales, there has been little progress in scaling these measures up to the landscape. Remote sensing data holds huge potential for studying processes at landscape scales but requires quantitative measures that are comparable from experimental field data to satellite remote sensing.

Individual species provide multifaceted contributions to the stability of ecosystems.

Exploration of the relationship between species diversity and ecological stability has occupied a prominent place in ecological research for decades. Yet, a key component of this puzzle-the contributions of individual species to the overall stability of ecosystems-remains largely unknown. Here, we show that individual species simultaneously stabilize and destabilize ecosystems along different dimensions of stability, and also that their contributions to functional (biomass) and compositional stability are largely independent.

Biomass encounter rates limit the size scaling of feeding interactions.

The rate that consumers encounter resources in space necessarily limits the strength of feeding interactions that shape ecosystems. To explore the link between encounters and feeding, we first compiled the largest available dataset of interactions in the marine benthos by extracting data from published studies and generating new data. These data indicate that the size-scaling of feeding interactions varies among consumer groups using different strategies (passive or active) to encounter different resource types (mobile or static), with filter feeders exhibiting the weakest feeding interactions.

Drought decreases incorporation of recent plant photosynthate into soil food webs regardless of their trophic complexity.

Theory suggests that more complex food webs promote stability and can buffer the effects of perturbations, such as drought, on soil organisms and ecosystem functions. Here, we tested experimentally how soil food web trophic complexity modulates the response to drought of soil functions related to carbon cycling and the capture and transfer below-ground of recent photosynthate by plants. We constructed experimental systems comprising soil communities with one, two or three trophic levels (microorganisms, detritivores and predators) and subjected them to drought.

Land cover drives large scale productivity-diversity relationships in Irish vascular plants.

The impact of productivity on species diversity is often studied at small spatial scales and without taking additional environmental factors into account. Focusing on small spatial scales removes important regional scale effects, such as the role of land cover heterogeneity. Here, we use a regional spatial scale (10 km square) to establish the relationship between productivity and vascular plant species richness across the island of Ireland that takes into account variation in land cover.

Combined effects of warming and nutrients on marine communities are moderated by predators and vary across functional groups.

Warming, nutrient enrichment and biodiversity modification are among the most pervasive components of human-induced global environmental change. We know little about their cumulative effects on ecosystems; however, even though this knowledge is fundamental to predicting and managing their consequences in a changing world. Here, we show that shifts in predator species composition can moderate both the individual and combined effects of warming and nutrient enrichment in marine systems.

Benthic assemblages associated with native and non-native oysters are similar.

Invasive species can impact native species and alter assemblage structure, which affects associated ecosystem functioning. The pervasive Pacific oyster, Crassostrea gigas, has been shown to affect the diversity and composition of many host ecosystems. We tested for effects of the presence of the invasive C.

On the context-dependent scaling of consumer feeding rates.

The stability of consumer-resource systems can depend on the form of feeding interactions (i.e. functional responses).

On the dimensionality of ecological stability.

Ecological stability is touted as a complex and multifaceted concept, including components such as variability, resistance, resilience, persistence and robustness. Even though a complete appreciation of the effects of perturbations on ecosystems requires the simultaneous measurement of these multiple components of stability, most ecological research has focused on one or a few of those components analysed in isolation. Here, we present a new view of ecological stability that recognises explicitly the non-independence of components of stability.

Distinguishing between direct and indirect effects of predators in complex ecosystems.

1. Global declines in biodiversity have stimulated much research into the consequences of species loss for ecosystems and the goods and services they provide. Species at higher trophic levels are at greater risk of human-induced extinction yet remarkably little is known about the effects of consumer species loss across multiple trophic levels in natural complex ecosystems.

Idiosyncratic species effects confound size-based predictions of responses to climate change.

Understanding and predicting the consequences of warming for complex ecosystems and indeed individual species remains a major ecological challenge. Here, we investigated the effect of increased seawater temperatures on the metabolic and consumption rates of five distinct marine species. The experimental species reflected different trophic positions within a typical benthic East Atlantic food web, and included a herbivorous gastropod, a scavenging decapod, a predatory echinoderm, a decapod and a benthic-feeding fish.

The predictive science of community ecology.

Body mass measures provide a tantalizing tool for explaining both variation in emergent community-level patterns and as a mechanistic basis for fundamental processes such as metabolism, consumption and competition. The unification of body mass, abundance and food web (ecological network) structure in community ecology is an effective way to explore future scenarios of environmental change. However, constraints over the availability of data against which to validate model predictions limit the application of size-based approaches.

Loss of functionally unique species may gradually undermine ecosystems.

Functionally unique species contribute to the functional diversity of natural systems, often enhancing ecosystem functioning. An abundance of weakly interacting species increases stability in natural systems, suggesting that loss of weakly linked species may reduce stability. Any link between the functional uniqueness of a species and the strength of its interactions in a food web could therefore have simultaneous effects on ecosystem functioning and stability.

Interaction strength, food web topology and the relative importance of species in food webs.

1. We established complex marine communities, consisting of over 100 species, in large subtidal experimental mesocosms. We measured the strength of direct interactions and the net strength of direct and indirect interactions between the species in those communities, using a combination of theoretical and empirical approaches.

Press perturbations and indirect effects in real food webs.

The prediction of the effects of disturbances in natural systems is limited by the general lack of knowledge on the strength of species interactions, i.e., the effect of one species on the population growth rate of another, and by the uncertainty of the effects that may be manifested via indirect pathways within the food web.

Perturbations to trophic interactions and the stability of complex food webs.

The pattern of predator-prey interactions is thought to be a key determinant of ecosystem processes and stability. Complex ecological networks are characterized by distributions of interaction strengths that are highly skewed, with many weak and few strong interactors present. Theory suggests that this pattern promotes stability as weak interactors dampen the destabilizing potential of strong interactors.

Predator diversity enhances secondary production and decreases the likelihood of trophic cascades.

We manipulated the diversity of top predators in a three trophic level marine food web. The food web included four top benthic marine fish predators (black goby, rock goby, sea scorpion and shore rockling), an intermediate trophic level of small fish, and a lower trophic level of benthic invertebrates. We kept predator density constant and monitored the response of the lower trophic levels.