The dark side of the “redundancy hypothesis” and ecosystem assessment (2023)

Terrestrial plants act as ecosystem engineers modifying the flow of energy and matter and creating new habitats for other organisms. This vital concept also encompasses plants' effects on landforms and soils, crucial components of forested landscapes worldwide. In the present study, we investigate how trees through their roots and symbiotic organisms influence soil-weathering processes. The aim of the study was to answer one of the big questions in Earth sciences: how do biological agents, including fungi, acting at the critical interface between the biosphere and the abiotic environment, shape soil and landscape evolution? Within the present study we ask what is the level of fungal activity within root systems of trees and how can it influence biological weathering. The area of interest is in the Poprad River gorge in the southern part of the Sącz Beskidy Mountains, the Outer Western Carpathians. We applied the following analyses: 1) determination of the structural diversity of fungi (ITS1) and 2) assessment of the metabolic profile of soils (Biolog FFPlates). The highest average number of classified genera were fungi which simultaneously carried out pathotrophic, saprotrophic and symbiotrophic functions. Boletales, Agaricales, Cantharellales and Archaeorhizomycetales were the most abundant orders, but in one sample we also found a particularly high proportion of the order Mortierellales. The order Boletales and its family Boletaceae were significantly enriched in rock crack samples, whereas the highest number of differentially abundant taxa was observed in reference samples. The most frequently utilised substrates by fungi were: glycyl-L-glutamic acids, L-ornithine, L-phenylalanine, L-proline, D-galacturonic acid, fumaric acids, D-saccharic acids, succinic acids and N-acetyl-D-glucosamine. Our study demonstrates that the fungal community in the root zone is geochemically active and the organic acids secreted by plant roots in oligotrophic conditions and nutrient limitations significantly affect soil weathering.

Automated and reproducible methodology for assessing the ecological condition of lakes is essential for effective monitoring and facilitating the decision-making process aimed at achieving the stated environmental goals. At the same time, multidimensional measurement datasets are often an obstacle to drawing insightful conclusions, thus becoming an incentive for overly simplified analyzes. In this article, a set of measurements and ecological status assessment results for a collection of 499 lakes in Poland was used. Expert assessment process was recreated using the supervised kernel Support Vector Machine algorithm on dataset with reduced dimensionality, thus a model that automates the ecological assessment process was obtained. The use of the explanatory skill of latent variables made it possible to present the assessed objects along with their position in individual classes. The visualization of the results in reduced dimensionality increased, without interfering with the size of the classes, the informative evaluation potential, which should be considered as an acompanying assessment parameter in the future. The primary target of this paper is the ecological expert coping with automatization of assessment process and obtaining latent information for sense-making visual comprehension during consultations regarding ecosystem-oriented ecological decision making.

Acknowledging complexity within relationships between fundamental ecology and societal research is critical in improving our current understanding of how natural ecosystems work and how they could be managed to achieve set management goals. Specifically, this challenge is linked to the multifunctional nature of ecosystems. We develop the Bayesian Belief Multifunctionality Framework to studying nature-people links that allows a holistic and transparent analysis of the relationships between species, their functional traits, multiple ecosystem functions and multiple nature's contributions to people (NCPs). We assess seven ecosystem functions common in marine soft-sediments (secondary production, metal sequestration, denitrification, N-release, sediment stability, primary production and sediment formation) and nine NCPs (food and feed, supporting services, climate regulation, regulation of coastal water quality, physical and psychological experience, habitat creation, learning, materials and erosion control). We use a case study based on an extensive and diverse intertidal sandflat macrofaunal community within Kaipara Harbour, New Zealand. By testing different scenarios in which we identify the set of traits responsible for the highest function performance for every function, we show that functional redundancy (i.e., the presence of multiple species that deliver the maximum performance for a specific function) was high for some functions but low for others. In our model, functional redundancy was the lowest for denitrification and secondary production, while primary production exhibited high functional redundancy. The network analysis also allowed us to gain insight into functional synergies and trade-offs, resulting from maximising individual function to a trait set. The trait set that maximised secondary production contributes to higher sediment stability; the trait set that maximised metal sequestration contributes to higher N-release; and the trait set that maximised denitrification contributes to high rates of metal sequestration and N-release. Negative effects were also apparent, e.g., the trait set that maximised metal sequestration resulted in a lower probability in sediment stability and secondary production. Finally, the scenario testing feature of the framework allowed for exploration of the changes in NCPs from changes in macrofauna density. High density of species with a trait set identified as important to individual functions generated an increase in the provision of the majority of considered NCPs. Thanks to its clear and transparent result presentation and flexible analysis, the BN Multifunctionality Framework can deliver insightful messages into multifunctionality links helping to reveal the multifunctional nature of diverse and complex natural ecosystems.

The Habitats Directive (HD) and the Natura 2000 network establish a common framework for maintaining European natural habitats in a favourable conservation status and represent the main instrument used by conservation decision makers in the European Union. Habitat conservation status depends on the sum of the influences acting upon the habitat and its typical species that may affect its long-term natural distribution, structure and functions. Thus, ecosystem functioning is influenced by the diversity, number and functional traits of the species occurring in a habitat. Although the HD establishes that representative species should be selected to reflect favourable structure and functioning of the habitat type, it would not be realistic to associate species with all aspects of structure and functioning given the variability of Annex I habitats. This constraint led us to seek new approaches that allow a more direct assessment of the ecosystem functioning for natural habitats in space and time. We propose a remote sensing-based approach to characterize and assess the ecosystem functioning of habitats. As a case study, we applied our approach to three Mediterranean natural habitat types from the Iberian Peninsula included in Annex I of the Habitats Directive, i.e., Mediterranean sclerophyllous forest, Mediterranean deciduous forest and Sub-Mediterranean and temperate scrub. First, we estimated two key descriptors of ecosystem functioning derived from the Enhanced Vegetation Index and related them to primary production dynamics by using satellite images captured by the MODIS sensor for each year between 2001 and 2012. Second, we arranged these functional descriptors in two-dimensional space and calculated the distances from the habitats assessed to the reference sites, i.e., habitat patches that showed an optimal conservation status of composition and structure. Then, the distances were averaged over the period, and the habitats were categorized according to their mean distances as favourable or unfavourable-inadequate or unfavourable-bad, as outlined in the reporting guidelines under Article 17 of the Directive. Our approach provides new procedures to assess ecosystem functions across space and time, while complying with reporting obligations derived from the HD.

Ecological Complexity, Volume 28, 2016, pp. 62-68

In previous work by the authors about dynamic system modeling, basic ecosystems concepts and their application to ecological modeling theory were formalized. Measuring how a variable effects certain processes leads to improvements in dynamic systems modelling and facilitates the author’s study of system diversity in which model sensitivity is a key theme. Initially, some variables and their numeric data are used for modeling. Predictions from the constructed models depend on these data. Generic study of sensitivity aims to show to what degree model behavior is altered by modification of some specific data. If small variations cause important modifications in the model’s global behavior then the model is very sensitive in relation to the variables used. If uncertain systems are considered, then it is important to submit the system to extreme situations and analyze its behavior. In this article, some indexes of uncertainty will be defined in order to determine the variables' influence in the case of extreme changes. This will permit analysis of the system’s sensitivity in relation to several simulations.

Microchemical Journal, Volume 124, 2016, pp. 111-115

The occurrence and mobility of natural radioactive elements such as polonium, uranium and thorium isotopes in six pharmaceutical clays for internal use (as found on the Italian market) were determined because the effects on human health must take into account the availability of these elements. The simulation of gastrointestinal digestion was divided into two stages and was accomplished using two different solutions: a synthetic stomach solution and a synthetic bile–pancreas solution. The same sample was treated in two different ways: (a) only gastric digestion and (b) gastrointestinal digestion (stomach solution+bile–pancreas solution). Very significant differences were found for uranium with respect to those found for thorium, and for polonium with regard to either gastric or gastrointestinal digestion. On the contrary, the differences between the polonium mobility and that of thorium are not very pronounced for either gastric or gastrointestinal digestion. Gastric digestions present no differences with respect to complete gastrointestinal digestion for uranium, thorium and polonium mobility.

Engineering Applications of Artificial Intelligence, Volume 50, 2016, pp. 168-176

In this letter, the authors propose a new embedding scheme for image-based continuous face pose estimation. The main contributions are as follows. First, it is shown that the concept of label-sensitive Locality Preserving Projections, proposed for age estimation, can be used for model-less face pose estimation. Second, the authors propose a linear embedding by exploiting the connections between facial features and pose labels via a sparse coding scheme. The resulting technique is called Sparse Label sensitive Locality Preserving Projections (Sp-LsLPP). Third, for enhancing the discrimination between poses, the projections obtained by Sp-LsLPP are fed to a Discriminant Embedding that exploits the continuous labels. The resulting framework has less parameters compared to related works. It has been applied to the problem of model-less face yaw angle estimation (person independent 3D face pose estimation). It was tested on three databases: FacePix, Taiwan, and Columbia. It was conveniently compared with other linear and non-linear techniques. The experimental results confirm that the proposed framework can outperform, in general, the existing ones.

Ecological Complexity, Volume 28, 2016, pp. 212-217

The existence, or not, of cyclic dynamics is one of the pivotal aspects of ecological populations. This work considers a consumer resource model found in ecology that can describe both cyclic and non-cyclic dynamics depending on parameter conditions. A threshold consumption number C₀ is introduced, similar to the basic reproduction ${\mathcal{R}}_0$ in epidemiological models. It is shown that consumer survival requires C₀>1 and that a Hopf bifurcation occurs at $C_0=C_0^{*}$, where $C_0^{*}$ is defined here and is greater than 1. This result is discussed with an example and extensions to other more complicated models.

Ecological Complexity, Volume 28, 2016, pp. 218-221

Because they are intuitive and mathematically straight-forward, colonization rules are often used to model spatial patterns in ecology. Colonization rules assign individuals to categories according to the locations of previous colonists. In this note, a compact introduction to colonization rules in ecology is presented with implications for autocorrelation and spatial distributions. I use the colonization rule approach to unify a diverse set of spatial and species diversity analyses, exploring future extensions to incorporate greater realism.

Ecological Complexity, Volume 28, 2016, pp. 158-162

Studies on trophic interactions permits the use of community-wide network analyses to evaluate the consequences of human interventions in natural communities. In this paper, we aimed to get insights into the underlying mechanism of prey selection for four piscivorous species, and evaluate behavioral responses to prey selection after an impoundment. We assemble six food web models to search for the hypothesis that best predict observed prey selection pattern of piscivorous fishes combining the following assumptions: (i) predation window, defined as the size range of prey species consumed by a piscivorous fish; (ii) prey strategies to avoid predation (iii) and prey abundance. We tested the probability of each hypothesis to reproduce two empirical data, one before and one after an impoundment with minimum assumptions. Before impoundment, we found that predators presented switching behavior, preying preferably on abundant prey; while after impoundment, predators consumed prey within its predation window. Those results explained better than the null hypotesis and all other assumptions; and corroborate with both theoretical and empirical studies. We conclude that different assumptions drives piscivorous fish behavior in different environments; and modelling procedures can be used to assess gaps in trophic interactions of fish communities.