Continent wide response of mountain vegetation to climate change

Climate impact studies have indicated ecological fingerprints of recent global warming across a wide range of habitats. Whereas these studies have shown responses from various local case studies, a coherent large-scale account on temperature-driven changes of biotic communities has been lacking. Here we use 867 vegetation samples above the treeline from 60 summit sites in all major European mountain systems to show that ongoing climate change gradually transforms mountain plant communities. We provide evidence that the more cold-adapted species decline and the more warm-adapted species increase, a process described here as thermophilisation. At the scale of individual mountains this general trend may not be apparent, but at the¦larger, continental scale we observed a significantly higher abundance of thermophilic species in 2008, compared with 2001. Thermophilisation of mountain plant communities mirrors the degree of recent warming and is more pronounced in areas where the temperature increase has been higher. In view of the projected climate change the observed transformation suggests a progressive decline of cold mountain habitats and their biota.

Morphological, hydrological, biogeochemical and ecological changes and challenges in river restoration - the Thur River case study

River restoration can enhance river dynamics, environmental heterogeneity and biodiversity, but the underlying processes governing the dynamic changes need to be understood to ensure that restoration projects meet their goals, and adverse effects are prevented. In particular, we need to comprehend how hydromorphological variability quantitatively relates to ecosystem functioning and services, biodiversity as well as ground-and surface water quality in restored river corridors. This involves (i) physical processes and structural properties, determining erosion and sedimentation, as well as solute and heat transport behavior in surface water and within the subsurface; (ii) biogeochemical processes and characteristics, including the turnover of nutrients and natural water constituents; and (iii) ecological processes and indicators related to biodiversity and ecological functioning. All these aspects are interlinked, requiring an interdisciplinary investigation approach. Here, we present an overview of the recently completed RECORD (REstored CORridor Dynamics) project in which we combined physical, chemical, and biological observations with modeling at a restored river corridor of the perialpine Thur River in Switzerland. Our results show that river restoration, beyond inducing morphologic changes that reshape the river bed and banks, triggered complex spatial patterns of bank infiltration, and affected habitat type, biotic communities and biogeochemical processes. We adopted an interdisciplinary approach of monitoring the continuing changes due to restoration measures to address the following questions: How stable is the morphological variability established by restoration? Does morphological variability guarantee an improvement in biodiversity? How does morphological variability affect biogeochemical transformations in the river corridor? What are some potential adverse effects of river restoration? How is river restoration influenced by catchment-scale hydraulics [GRAPHICS] and which feedbacks exist on the large scale? Beyond summarizing the major results of individual studies within the project, we show that these overarching questions could only be addressed in an interdisciplinary framework.

The Mediterranean benthic herbivores show diverse responses to extreme storm disturbances

Catastrophic storms have been observed to be one of the major elements in shaping the standing structure of marine benthic ecosystems. Yet, little is known about the effect of catastrophic storms on ecosystem processes. Specifically, herbivory is the main control mechanism of macrophyte communities in the Mediterranean, with two main key herbivores: the sea urchin Paracentrotus lividus and the fish Sarpa salpa. Consequently, the effects of extreme storm events on these two herbivores (at the population level and on their behaviour) may be critical for the functioning of the ecosystem. With the aim of filling this gap, we took advantage of two parallel studies that were conducted before, during and after an unexpected catastrophic storm event. Specifically, fish and sea urchin abundance were assessed before and after the storm in monitored fixed areas (one site for sea urchin assessment and 3 sites for fish visual transects). Additionally, we investigated the behavioural response to the disturbance of S. salpa fishes that had been tagged with acoustic transmitters. Given their low mobility, sea urchins were severely affected by the storm (ca. 50% losses) with higher losses in those patches with a higher density of sea urchins. This may be due to a limited availability of refuges within each patch. In contrast, fish abundance was not affected, as fish were able to move to protected areas (i.e. deeper) as a result of the high mobility of this species. Our results highlight that catastrophic storms differentially affect the two dominant macroherbivores of rocky macroalgal and seagrass systems due to differences in mobility and escaping strategies. This study emphasises that under catastrophic disturbances, the presence of different responses among the key herbivores of the system may be critical for the maintenance of the herbivory function.

How to introduce connectance in a frame of an expression for diversity

Systems made of parts that are totally connected do not work, neither ecosys- tems nor artifacts. Relative connectance is inversely related to diversity, and both magnitudes can find a common frame of expression, in which some constant expressing the constraints of any organization might be embodied. If S is Simp- son's index, the expression (1 - S)IS as a measure of diversity offers some advantages or, at least, helps further reasoning. Such expression is the ratio between total interspecific possible interactions and possible intraspecific inter- actions.

Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past

The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs.

Small but powerful: Top predator local extinction affects ecosystem structure and function in an intermittent stream.

Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the topdown effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire.We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore ecosystem structure and function.

Macroalgae across environmental gradients : tools for managing rocky coastal areas of the northern Baltic Sea

Macroalgae are the main primary producers of the temperate rocky shores providing a three-dimensional habitat, food and nursery grounds for many other species. During the past decades, the state of the coastal waters has deteriorated due to increasing human pressures, resulting in dramatic changes in coastal ecosystems, including macroalgal communities. To reverse the deterioration of the European seas, the EU has adopted the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD), aiming at improved status of the coastal waters and the marine environment. Further, the Habitats Directive (HD) calls for the protection of important habitats and species (many of which are marine) and the Maritime Spatial Planning Directive for sustainability in the use of resources and human activities at sea and by the coasts. To efficiently protect important marine habitats and communities, we need knowledge on their spatial distribution. Ecological knowledge is also needed to assess the status of the marine areas by involving biological indicators, as required by the WFD and the MSFD; knowledge on how biota changes with human-induced pressures is essential, but to reliably assess change, we need also to know how biotic communities vary over natural environmental gradients. This is especially important in sea areas such as the Baltic Sea, where the natural environmental gradients create substantial differences in biota between areas. In this thesis, I studied the variation occurring in macroalgal communities across the environmental gradients of the northern Baltic Sea, including eutrophication induced changes. The aim was to produce knowledge to support the reliable use of macroalgae as indicators of ecological status of the marine areas and to test practical metrics that could potentially be used in status assessments. Further, the aim was to develop a methodology for mapping the HD Annex I habitat reefs, using the best available data on geology and bathymetry. The results showed that the large-scale variation in the macroalgal community composition of the northern Baltic Sea is largely driven by salinity and exposure. Exposure is important also on smaller spatial scales, affecting species occurrence, community structure and depth penetration of algae. Consequently, the natural variability complicates the use of macroalgae as indicators of human-induced changes. Of the studied indicators, the number of perennial algal species, the perennial cover, the fraction of annual algae, and the lower limit of occurrence of red and brown perennial algae showed potential as usable indicators of ecological status. However, the cumulated cover of algae, commonly used as an indicator in the fully marine environments, showed low responses to eutrophication in the area. Although the mere occurrence of perennial algae did not show clear indicator potential, a distinct discrepancy in the occurrence of bladderwrack, Fucus vesiculosus, was found between two areas with differing eutrophication history, the Bothnian Sea and the Archipelago Sea. The absence of Fucus from many potential sites in the outer Archipelago Sea is likely due to its inability to recover from its disappearance from the area 30-40 years ago, highlighting the importance of past events in macroalgal occurrence. The methodology presented for mapping the potential distribution and the ecological value of reefs showed, that relatively high accuracy in mapping can be achieved by combining existing available data, and the maps produced serve as valuable background information for more detailed surveys. Taken together, the results of the theses contribute significantly to the knowledge on macroalgal communities of the northern Baltic Sea that can be directly applied in various management contexts.

Introduced taxa in disturbed ecosystems

In the literature, introduced taxa are assumed to be present, more abundant, and occupy greater physical space in portions of ecosystems disturbed by human activity. This study tested this principle in two sites, Short Hills provincial Park ("SHU) and Backus Woods ("B~l"). spatial distribution of introduced taxa of vegetation, isopods, and earthworms was determined with the runs test along 300m transects encompassing gradients of anthropogenic disturbance severity. The hypothesis was that introduced taxa would be aggregated along these transects; the null hypothesis was that they would not be aggregated. The null hypothesis was rejected for the introduced taxa as a unit, and vegetation and earthworms individually. Introduced taxa were aggregated along 53.33% (N~30) and 57.14% (N~21) of the transects in SH and BW (respectively). Introduced vegetation (90.00%, N~10 and 100.00%, N~7) and earthworms (50.00%, N~10 and 50.00%, N~8) were also significantly aggregated within the sites. Introduced isopods, however, were not significantly aggregated at either place (20. 00%, N-=10 and 16. 67%, ~J~6). This study demonstrated that introduced taxa are aggregated within ecosystems disturbed by human activity. However, since introduced isopods were not significantly aggregated it was also shown that taxa respond differently.

Qu’est-ce que le bien des écosystèmes? Fondements philosophiques des notions de fonction écologique et de santé écosystémique

L’objectif de cette thèse est de proposer une caractérisation du bien propre des touts écologiques, comme les communautés biotiques et les écosystèmes, dont peut être dérivée une notion de ce qui est bon pour eux. Ceci vise à défendre les deux principales approches holistes en éthique de l’environnement, c’est-à-dire l’approche pragmatiste défendue par Bryan G. Norton et l’approche écocentriste défendue par J. Baird Callicott, contre certaines objections ayant été soulevées contre elles, faisant valoir l’impossibilité pour les écosystèmes d’avoir un bien propre. Cette thèse répond à ces objections en mobilisant plusieurs ressources théoriques issues de la philosophie de la biologie et de la méta-éthique. Ces ressources sont notamment celles fournies par les discussions sur les notions de fonction et de santé en philosophie de la biologie, celles fournies par les conceptions néo-aristotéliciennes de la normativité en méta-éthique, et celles offertes par les discussions de philosophie de l’écologie sur le holisme et le réductionnisme, sur l’idée d’équilibre de la nature, et sur le concept de santé écosystémique. Cette thèse mobilise ces ressources afin d’élaborer les fondements philosophiques des notions de fonction écologique et de santé écosystémique, desquelles est dérivée une caractérisation du bien propre des écosystèmes.

Retting Of Coconut Husk - A Unique Case Of Water Pollution On The South West Coast Of India

The extensive backwaters of Kerala are the sites for a flourishing cottage industry - the coir industry. This enterprise almost exclusively located along the 590 km coastal belt of Kerala, provides direct employment to over half a million people in the state and produces nearly 90% of the total coir goods in the world. The shallow bays and lagoons of the 30 backwater systems of the state are traditional areas for the retting of coconut husk for the production of the coir fibre. The paper examines the environmental status of the retting grounds in Kerala, in relation to the biotic communities. The study revealed that retting activity has caused large scale organic pollution along with the mass destruction of the flora and fauna, converting sizeable sections of the backwaters into virtual cesspools of foul smelling stagnant waters. High values of hydrogen sulphide, ammonia, BOD5 associated with anoxic conditions and low community diversity of plankton, benthic fauna, fish, shell fish, wood boring and fouling organisms were the outstanding feature of the retting zones.

Earth's Changing Land

Entre el 14 i el 18 de març de 1998 es va celebrar a Barcelona la conferència Earth’s Changing Land sota la tutela dels programes internacionals Global Change in Terrestrial Ecosystems (GCTE) i Land Use and Land Cover Change (LUCC). L’objectiu principal de la trobada era presentar les darreres aportacions científiques sobre els efectes presents i previsibles del canvi global sobre els ecosistemes terrestres i la societat. Al mateix temps, es volia afavorir l’establiment de ponts de diàleg entre els professionals implicats en el canvi global

Desequilibri en el desordre

De banda a banda del Mediterrani, diferents amenaces tiben l’equilibri dels ecosistemes submarins. En la major part dels casos han estat problemes locals que ara corren el risc d’estendre’s i esdevenir globals. Emma Cebrian, investigadora de la UdG, treballa per caracteritzar-los

Emissions de N2O i desnitrificació en sòls agrícoles i d'ecosistemes naturals. Factors de regulació

La major conscienciació actual dels problemes de pol·lució que acompanyen les pèrdues de N del sòl cap a l'atmosfera ha reorientat les investigacions cap a un coneixement més profund dels processos implicats en les emissions dels compostos nitrogenats que comporten un major perjudici des d'un punt de vista ecològic així com els seus principals factors reguladors. La creixent preocupació per l'increment de la concentració atmosfèrica de N2O és deguda a les seves interaccions amb la fotoquímica atmosfèrica i el balanç de radiació de la Terra ja que intervé en la destrucció de la capa estratosfèrica d'ozó, contribueix a l'efecte hivernacle i participa de la pluja àcida. Es considera que els sòls són la principal font de N2O atmosfèric. Al voltant del 90% d'aquestes emissions són d'origen biòtic; els principals processos implicats són la desnitrificació i la nitrificació. L'emissió del N2O produït a través d'aquests dos processos es caracteritza pels diferents nivells de regulació que presenta ja que depèn de la taxa dels processos, de la proporció de N canalitzada per cada procés cap a la producció de N2O i del seu consum dins el mateix sòl el qual està relacionat amb les dificultats en el transport cap a l'atmosfera. Això comporta una gran dificultat a l'hora d'aprofundir en el coneixement de les emissions de N2O del sòl cap a l'atmosfera i de la seva regulació. El desconeixement dels nivells d'emissió de N2O i de la importància de la desnitrificació així com de la seva regulació tant en sòls agrícoles com naturals de les nostres contrades és el principal punt de partida dels objectius d'aquest treball.

Relation between green spaces and bird community structure in an urban area in Southeast Brazil

Increased urbanization typically leads to an increase in abundance of a few species and a reduction in bird species richness. Understanding the structure of biotic communities in urban areas will allow us to propose management techniques and to decrease conflicts between wild species and human beings. The objective of this study was to describe the structure of the bird community in an urban ecosystem. The study was carried out in the city of Taubaté in southeastern Brazil. Point-counts were established in areas with different levels of tree density ranging from urban green spaces to predominantly built-up areas. We looked for a correlation between the richness/abundance of birds and the size of the area surveyed, the number of houses, the number of tree species and the number of individual trees. The results of multiple regression showed that bird richness had a direct relationship with vegetation complexity. The abundance and diversity of tree species were better predictors of bird species than the number of houses and size of the area surveyed. We discuss implications of this study for conservation and management of bird diversity in urban areas, such as the need to increase green areas containing a large diversity of native plant species. © 2011 Springer Science+Business Media, LLC.

Four year multitrophic food web: source food web description, methodology accuracy and species diversity

Food webs have been used in order to understand the trophic relationship among organisms within an ecosystem, however the extension by which sampling efficiency could affect food web responses remain poorly understood. Still, there is a lack of long-term sampling data for many insect groups, mainly related to the interactions between herbivores and their host plants. In the first chapter, I describe a source food web based on the Senegalia tenuifolia plant by identifying the associated insect species and the interactions among them and with this host plant. Furthermore, I check for the data robustness from each trophic level and propose a cost-efficiently methodology. The results from this chapter show that the collected dataset and the methodology presented are a good tool for sample most insect richness of a source food web. In total the food web comprises 27 species belonging to four trophic levels. In the second chapter, I demonstrate the temporal variation in the species richness and abundance from each trophic level, as well as the relationship among distinct trophic levels. Moreover, I investigate the diversity patterns of the second and third trophic level by assessing the contribution of alfa and beta-diversity components along the years. This chapter shows that in our system the parasitoid abundance is regulated by the herbivore abundances. Besides, the species richness and abundances of the trophic levels vary temporally. It also shows that alfa-diversity was the diversity component that most contribute to the herbivore species diversity (2nd trophic level), while the contribution of alfa- and beta-diversity changed along the years for parasitoid diversity (3rd level). Overall, this dissertation describes a source food web and bring insights into some food web challenges related to the sampling effort to gather enough species from all trophic levels. It also discuss the relation among communities associated with distinct trophic levels and their temporal variation and diversity patterns. Finally, this dissertation contributes for the world food web database and in understanding the interactions among its trophic levels and each trophic level pattern along time and space