Natuurherstel: van standplaats naar landschap

Contains fulltext : 75393.pdf (publisher's version ) (Open Access)6 p

Native and Non-Native Plants Provide Similar Refuge to Invertebrate Prey, but Less than Artificial Plants

Non-native species introductions are widespread and can affect ecosystem functioning by altering the structure of food webs. Invading plants often modify habitat structure, which may affect the suitability of vegetation as refuge and could thus impact predator-prey dynamics. Yet little is known about how the replacement of native by non-native vegetation affects predator-prey dynamics. We hypothesize that plant refuge provisioning depends on (1) the plant’s native status, (2) plant structural complexity and morphology, (3) predator identity, and (4) prey identity, as well as that (5) structurally similar living and artificial plants provide similar refuge. We used aquatic communities as a model system and compared the refuge provided by plants to macroinvertebrates (Daphnia pulex, Gammarus pulex and damselfly larvae) in three short-term laboratory predation experiments. Plant refuge provisioning differed between plant species, but was generally similar for native (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton perfoliatus) and non-native plants (Vallisneria spiralis, Myriophyllum heterophyllum, Cabomba caroliniana). However, plant refuge provisioning to macroinvertebrate prey depended primarily on predator (mirror carp: Cyprinus carpio carpio and dragonfly larvae: Anax imperator) and prey identity, while the effects of plant structural complexity were only minor. Contrary to living plants, artificial plant analogues did improve prey survival, particularly with increasing structural complexity and shoot density. As such, plant rigidity, which was high for artificial plants and one of the living plant species evaluated in this study (Ceratophyllum demersum), may interact with structural complexity to play a key role in refuge provisioning to specific prey (Gammarus pulex). Our results demonstrate that replacement of native by structurally similar non-native vegetation is unlikely to greatly affect predator-prey dynamics. We propose that modification of predator-prey interactions through plant invasions only occurs when invading plants radically differ in growth form, density and rigidity compared to native plants

Preadvies beekdallandschappen : knelpunten, kennislacunes en kennisvragen voor natuurherstel in beekdalen

Dit preadvies is onder begeleiding van het OBN deskundigenteam beekdallandschappen opgesteld door een groep deskundigen afkomstig van KWR, Alterra, B-WARE, Stichting Bargerveen en Vlinderstichting. Het rapport bevat tevens achtergronddocumentatie betreffende: hydrologie, processen in beken, stofstromen en stofregulatie, bodemvorming, dispersie van soorten en klimaatsverandering. Speciale aandacht wordt gegeven aan dagvlinders, libellen, beekvissen en beekdalmacrofaun

Milieu- en habitatpreferenties van Nederlandse zoetwatermacrofauna

Macrofauna speelt een belangrijke rol in het beoordelen van de ecologische kwaliteit van oppervlaktewateren, bijvoorbeeld voor de Europese Kaderrichtlijn Water. Daarnaast kan de samenstelling van de macrofauna informatie geven over kenmerken van of problemen met een water (diagnostische waarde). Na een rapport waarin van een groot aantal Nederlandse soorten de zeldzaamheid is aangegeven (Nijboer & Verdonschot red. 2001), was het achterhalen van de milieu- en habitateisen van de macrofaunasoorten een logisch vervolg. Deze milieu- en habitatkennis maakt het mogelijk om gegevens over macrofauna te gebruiken om de toestand van het oppervlaktewater te omschrijven. Dit biedt een belangrijke meerwaarde bij het gebruik van bestaande biologische parameters in het water- en natuurbeheer

The nursery function of artificial floodplain habitats in the lower Rhine and Meuse for riverine fish

Contains fulltext : 202317.pdf (publisher's version ) (Open Access)14th NCR-days 201

高効率なメモリ順序違反検出機構に関する研究

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 浅見 徹, 東京大学教授 坂井 修一, 東京大学准教授 田浦 健次朗, 東京大学准教授 豊田 正史, 国立情報学研究所教授 五島 正裕University of Tokyo(東京大学

Foundation species enhance food web complexity through non-trophic facilitation

Food webs are an integral part of every ecosystem on the planet, yet understanding the mechanisms shaping these complex networks remains a major challenge. Recently, several studies suggested that non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structure. However, it remains unclear whether these findings generalize across ecosystems, and whether non-trophic interactions affect food webs randomly, or affect specific trophic levels or functional groups. Here, we combine analyses of 58 food webs from seven terrestrial, freshwater and coastal systems to test (1) the general hypothesis that non-trophic facilitation by habitat-forming foundation species enhances food web complexity, and (2) whether these enhancements have either random or targeted effects on particular trophic levels, functional groups, and linkages throughout the food web. Our empirical results demonstrate that foundation species consistently enhance food web complexity in all seven ecosystems. Further analyses reveal that 15 out of 19 food web properties can be well-approximated by assuming that foundation species randomly facilitate species throughout the trophic network. However, basal species are less strongly, and carnivores are more strongly facilitated in foundation species' food webs than predicted based on random facilitation, resulting in a higher mean trophic level and a longer average chain length. Overall, we conclude that foundation species strongly enhance food web complexity through non-trophic facilitation of species across the entire trophic network. We therefore suggest that the structure and stability of food webs often depends critically on non-trophic facilitation by foundation species

Overlevingsstrategieen koppelen soorten aan hun landschap = Using life-history strategies to match species to their landscape

Contains fulltext : 75701.pdf (publisher's version ) (Open Access)8 p

Het gebruik van laaglandbeken door vissen

Contains fulltext : 176089.pdf (publisher's version ) (Open Access

Matching species to a changing landscape - Aquatic macroinvertebrates in a heterogeneous landscape

Contains fulltext : 32097_matcsptoa.pdf (publisher's version ) (Open Access)The goal of this thesis was the development, application and evaluation of a method by which relationships between aquatic macroinvertebrate species and their environment can be explained and aggregated to a manageable number of key relationships. The need for such a method is evident. From an applied point of view, knowledge on the impact of degradation is needed to derive sound possibilities to address the biodiversity crisis. From a fundamental point of view, knowledge on the causal mechanisms is needed to provide a predictive framework which explains how abiotic and biotic factors set limits to species occurrences, ultimately shaping ecosystems. Causal mechanisms explaining a species' environmental requirements are rooted in species traits (e.g., a chitinous exoskeleton, diapausing eggs, parental care, development time). By investigating interrelations between traits and interpreting their function, it was possible to define 'sets of co-adapted species traits designed by natural selection to solve particular ecological problems', which are termed life-history tactics. Species with alternative suites of traits that solved environmental problems in a similar way were assigned to the same tactic. This provided a functional classification spanning species from different systematic groups. Life-history tactics were successfully applied to a fundamental (abundance-occupancy relationship in macroecology) and an applied problem (effects of management in restoration ecology). Life-history tactics can aggregate information over many different species without sacrificing information on the causal mechanisms underlying a species' presence or absence. This makes life-history tactics ideally suited to fill the gap between a single species approach and a community approach. Environmental heterogeneity results from the interplay between abiotic conditions and the effect of interacting species. Life-history tactics can unravel the importance of abiotic boundary conditions and species interactions. Successful conservation of biodiversity will strongly depend on this ability to identify and subsequently strengthen the processes underlying landscape heterogeneityRadboud University, Animal Ecology & Ecophysiology / Environmental Science, 07 maart 2008Promotores : Siepel, H., Velde, G. van der150 p