Recent progress in systems ecology

Metabolic ecology in aquatic ecosystems: Viewed from trophic compartments and communities in food webs

A different perspective in metabolic ecology is presented using food web data, based on trophic compartments and communities in aquatic ecosystems (coastal areas, shelves and estuaries in marine ecosystems, and lake ecosystems), including primary producers (phytoplankton and aquatic plants). The relationships among the metabolic traits (biomass, respiration and production) in aquatic communities are expressed through power laws, hence, the value of one of the three metabolic traits provides the values of the other two. Noteworthily, these metabolic traits (biomass, respiration, production) are related to those of primary producers according to various power laws. That is: the metabolic traits of communities can be estimated from those of primary producers alone. These power laws appear to be universal in marine ecosystems but vary among different lake ecosystems.

Fusing multidimensional hierarchical information into finer spatial landscape metrics

One of the core issues of ecology is to understand the effects of landscape patterns on ecological processes. For this, we need to accurately capture changes in the fine landscape structures to avoid losing information about spatial heterogeneity. The landscape pattern indicators (LPIs) can characterize the spatial structures and give some information about landscape patterns. However, researches on LPIs had mainly focused on the horizontal structure of landscape patterns, while few studies addressed vertical relationships between the levels of hierarchical landscape structures. Thus, the ignorance of the vertical hierarchical relationships may cause serious biases and reduce LPIs' representational ability and accuracy. The hierarchy theory about the landscape pattern structures could notably reduce the loss of hierarchical information, and the information entropy could quantitatively describe the vertical status of landscape units. Therefore, we established a new multidimensional fusion method of LPIs based on hierarchy theory and information entropy. Here, we created a general fusion formula for commonly used simple LPIs based on two-grade land use data (whose land use classification system contains two grades/levels) and derived 3 fusion landscape pattern indicators (FLIs) with a case study. The results show that the information about fine spatial structure is captured by the fusion method. The regions with the most differences between the FLIs and the traditional LPIs are those with the largest vertical structure such as the ecological ecotones, where vertical structure was ignored before. The FLIs have a finer spatial representational ability and accuracy, not only retaining the main trend information of first-grade land use data, but also containing the internal detail information of second-grade land use data. Capturing finer spatial information of landscape patterns should encourage the application of fusion method, which should be suitable for more LPIs or more dimensional data. And the increased accuracy of FLIs will improve ecological models that rely on finer spatial information.

Invasive potential of tropical fruit flies in temperate regions under climate change

Tropical fruit flies are considered among the most economically important invasive species detected in temperate areas of the United States and the European Union. Detections often trigger quarantine and eradication programs that are conducted without a holistic understanding of the threat posed. Weather-driven physiologically-based demographic models are used to estimate the geographic range, relative abundance, and threat posed by four tropical tephritid fruit flies (Mediterranean fruit fly, melon fly, oriental fruit fly, and Mexican fruit fly) in North and Central America, and the European-Mediterranean region under extant and climate change weather (RCP8.5 and A1B scenarios). Most temperate areas under tropical fruit fly propagule pressure have not been suitable for establishment, but suitability is predicted to increase in some areas with climate change. To meet this ongoing challenge, investments are needed to collect sound biological data to develop mechanistic models to predict the geographic range and relative abundance of these and other invasive species, and to put eradication policies on a scientific basis.

Application of Systems Thinking to the assessment of an institutional development project of river restoration at a campus university in Southern Brazil

Rapid urban growth and high population density have become a problem for urban water resources, especially in developing countries. In general, the pollution of rivers and degradation of ecosystems are the result of both management failures and lack of sewage treatment. River restoration appears as a solution to improve this scenario, but it is common for there to be an absence of a systemic vision in these projects. Thus, this work analysed one of these projects as an initial approach to create coherent (qualitative) shared perspectives on the same problem. This project was developed in a Brazilian university territory in response to a Public Civil Action. Rivers within the university surroundings are degraded due to sewage disposal and wastewater pollution from external and internal sources within the university, but the programme actions contemplate only interventions within the perimeter of the university while excluding the other parts of its watershed. We analyse this problem under a Systems Thinking approach by using causal loop diagrams, being clear that ecosystems cannot be reduced to territorial limits only. The systemic map shows many actions that contribute to the water quality degradation, with emphasis on illegal dumping of wastewater (sewage) and land use change in the upstream areas prior to the university. Point measures are palliative and do not guarantee the quality of river water. Regulation of impervious surfaces and correct disposal of wastewater can improve the current panorama, but greater integration between stakeholders and other key actors is required.

Linking biodiversity to ecosystem services supply: Patterns across aquatic ecosystems

Global initiatives have been increasingly focusing on mainstreaming the values of biodiversity and ecosystem services into decision-making at all levels. Due to the accelerated rate at which biodiversity is declining and its consequences for the functioning of ecosystems and subsequently, the services they provide, there is need to develop comprehensive assessments of the services and the benefits nature delivers to society. Based on expert evaluation, we identified relevant flow linkages in the supply-side of the socio-ecological system, i.e. from biodiversity to ecosystem services supply for eight case studies across European aquatic ecosystems covering freshwater, transitional, coastal and marine waters realms. Biological mediated services were considered, as well as those reliant on purely physical aspects of the ecosystem, i.e. abiotic outputs, since both have implications for spatial planning, management and decision-making. Due to the multidimensional nature of ecosystems and their biodiversity, our approach used ecosystem components such as habitats and biota as proxies for biodiversity and as the focal point for linkage identification. Statistical analysis revealed the importance of considering mobile biota in the spatial assessment of habitats. Contrary to literature evidences so far, our results showed significantly different and complementary ecosystem services supply patterns across the continuum of aquatic realms. The implemented score of ecosystem services supply has a high potential for integrated aquatic ecosystem service supply assessments in the context of ecosystem-based management.

Multilevel analysis of dendroclimatic series with the R-package BIOdry

The R-package BIOdry allows to model and compare fluctuations of Tree-ring Width (TRW) and climate, or dendroclimatic fluctuations, while accounting for source variability. The package eases multilevel modeling and multivariate comparison in dendroclimatic analysis using the nlme and ecodist packages, respectively. For implementing such libraries, the in-package algorithms transform the dendroclimatic fluctuations into Multilevel Dendroclimatic Data Series and maintain categorical variables and time units in the outputs. The dendroclimatic modeling is developed with two functions: modelFrame and muleMan. The first function binds core-level cumulative TRWs to the processed data sets and subtracts trends in TRWs by fitting multilevel log-linear growth formulas or multilevel linear formulas. modelFrame can also model within-group fluctuations in dendroclimatic variables other than tree-radial increments such as aridity indices or allometric components of tree growth: e.g. diameters at breast height over bark, tree basal areas, total tree biomass, among other. The second function compares fluctuations in modelFrame objects that share outermost categorical variable and annual records. Here, we use BIOdry to model dendroclimatic relationships in northern and east-central Spain to illustrate future users in the implementation of the package for modeling ecological relationships in space and time.

The robustness of ecosystems to the species loss of community

To study the robustness of ecosystems is crucial to promote the sustainable development of human society. This paper aims to analyze the robustness of ecosystems from an interesting viewpoint of the species loss of community. Unlike the existing definitions, we first introduce the notion of a community as a population of species belonging to the same trophic level. We then put forward a novel multiobjective optimization model which can be utilized to discover community structures from arbitrary unipartite networks. Because an ecosystem is commonly represented as a multipartite network, we further introduce a mechanism of competition among species whereby a multipartite network is transformed into a unipartite signed network without loss of species interaction information. Finally, we examine three strategies to test the robustness of an ecosystem. Our experiments indicate that ecosystems are robust to random species loss of community but fragile to target ones. We also investigate the relationships between the robustness of an ecosystem and that of its community composed network both to species loss. Our experiments indicate that the robustness analysis of a large-scale ecosystem to species loss may be akin to that of its community composed network which is usually small in size.