More frequently occurring droughts, related to climate change, lead to reduced growth and loss of vitality in trees. The recent drought of 2018 was extreme, long-lasting and resulted in high evaporative demands due to the concurrent high temperatures. The aim of this study was to compare the drought resilience of nine temperate tree species in the Netherlands, and to determine their responses to the severe drought of 2018 in comparison with five earlier drought events since 1970. To assess drought effects on tree species, we analysed tree-ring series of 678 trees in 45 plots throughout the Netherlands. Resilience indices were calculated based on growth reactions and growth recovery after drought. Furthermore, the impact of drought events on species productivity was quantified. We observed species-specific differences in growth responses to drought timing. All species in nearly all sites responded with growth reductions to drought, except sessile oak (Quercus petraea (Matt.) Liebl.). The most productive species in our study were found to be drought sensitive, with productivity losses of up to 30 % during drought in some sites. Productivity losses were highest on the driest soils. Resilience to the 2018 drought did not differ significantly from other drought years for six out of the nine studied species. However, 77.5 % of the individual trees of all studied species did not fully recover in growth within the following two years. Low post-drought growth remains poorly understood and should be taken into account in future studies to safeguard the health and productivity of the forest under climate change. We consider sessile oak a promising species for future forests in the Netherlands. Based on our results, we provide an outlook on future resilience and growth potential of the species studied under projected climate change for the Netherlands.
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Due to climate change, rising temperatures lead to more extreme heat stress in urban areas. Last summer, there were poignant images of people looking for shade in cities. Trees are effective measures to provide shade and decrease the perceived temperature. However, trees cannot grow in healthy conditions due to the conflicting interests of the many functions and infrastructure in cities. Also time is a limiting factor; before trees are fully grown and can fulfil its various functions (shade, biodiversity, appearance), it takes not only physical space but also time. Alternative interventions, such as a pergola, can help increase urban resilience by reducing the negative impacts of climate change.Pergolas are known, for example, in more southern Europe cities. However, despite the described promising effects of the pergola in documents to reduce heat stress and provide shade, we barely see these structures in the Dutch public space. We all know the pergola as an esthetical piece in the backyard where it provides shade, privacy and contributes to well-being, but they are not widely used in the public realm.Next to that, there are few or no known preconditions for an urban pergola. The functions that an urban pergola can offer go beyond providing shade. The pergola might help reduce noise and pollution, provide a meeting place in a neighbourhood and support biodiversity. Since space is scarce in cities where many different interests come together, we want to explore the potential contribution of an urban pergola to different problems. Therefore, at the Amsterdam University of Applied Sciences, we have worked on an urban pergola as a real 'boundary object' where we bring education, research, municipalities, and entrepreneurs across disciplines and sectors together to discuss the potential of such an object.For this workshop, we would like to show our first results of this interdisciplinary action research and continue answering the question: how can a pergola fit in the Dutch urban area? Therefore, we would like to explore the functions and forms of the urban pergola with stakeholders, such as municipalities, entrepreneurs, citizens, students, and researchers all from different disciplines. The desired outcome of this workshop is a joint proposal for implementing urban pergolas that can meet the versatile needs of cities and thereby make cities more liveable.
MULTIFILE
Worldwide, coral reefs are rapidly declining due to increased sea water temperatures and other environmental stresses (Figure 1). To counter the extinction of major coral reef building species on the island of Bonaire, the non-profit organization Reef Renewal Foundation Bonaire is restoring degraded reef sites using corals that are grown in local nurseries. In these nurseries, corals are propagated on artificial trees using fragmentation. After 6-8 months of growth in the nursery, the corals are transplanted to degraded reef sites around the island. Over the years more than 21.000 corals have been outplanted to reef restoration sites in this way. These corals show high survivorship under natural reef conditions but remain under threat by environmental disturbances, such as increased water temperatures, diseases, and competition with macroalgae. A promising intervention to increase reef persistence and resilience is to manipulate the coral-associated microbiome. At present, the composition of the microbiome in nursery-reared and outplanted corals on Bonaire is unknown. The aim of the current project is to identify and isolate naturally occurring beneficial bacteria that may stimulate the resilience of these corals. Our key objectives are: 1) to assess the presence of functionally beneficial bacteria in corals in nursery and restoration sites on Bonaire using metagenomic screening. 2) to design culture strategies to isolate these functionally beneficial bacteria. In the future, a selection of these beneficial bacteria can be applied to the corals to increase their resilience against environmental disturbances.
Gebouwen blijven lang (gemiddeld 50 jaar) in functie. Desondanks wordt circulariteit van gebouwen vaak gelijk gesteld aan herbruikbaarheid van de toegepaste materialen na sloop. Door de aanscherpende functionele eisen is het moeilijk om de bouwmaterialen die bij sloop of verbouwing vrijkomen één-op-één te hergebruiken. Deze materialen voldoen niet meer aan de huidige eisen en worden veelal gerecycled om de materialen/grondstoffen in de kringloop te houden. Als hergebruik van afzonderlijke bouwmaterialen moeilijk is dan wordt het interessant om te onderzoeken of de levensduur van een gebouw in z’n totaliteit kan worden opgerekt: door te streven naar bijvoorbeeld levensduren van 100 jaar en meer. In de leidraad Circulair Ontwerpen van CB’23, een platform dat onderzoek doet naar circulariteit in de gebouwde omgeving, worden onder meer overmaat en koestering als randvoorwaarden voor een langere levensduur genoemd. Door het gebouw te over-dimensioneren kan het gemakkelijker andere functies in zich opnemen. Koestering gaat over waardering van de gebruikers voor een gebouw. Uit het literatuuronderzoek dat met een KIEM-subsidie is uitgevoerd, blijken gebouwen met royale en aansprekende entrees en die uitgevoerd zijn in zorgvuldig gedetailleerde materialen die mooi verouderen hiervoor in aanmerking te komen: materialen als beton, natuursteen en baksteen – dure materialen met relatief hoge schaduwkosten. Het consortium, bestaande uit architectenbureaus, bouwfysische en constructieve adviesbureaus, opdrachtgevers, ontwikkelaars en koepelorganisatie/kennisplatform NEVAP wil het onderzoek naar gebouwen die lang in functie kunnen blijven, doorzetten. Het architectonische en theoretische onderzoek naar gebouwen met lange levensduren wordt uitgebreid, maar het onderzoek gaat zich vooral richten op de vraag hoe deze gebouwen technisch en financieel gerealiseerd kunnen worden. De onderzoeksvraag is hierbij : ‘Op welke manieren kan de levensduur van gebouwen worden verlengd om waardeverlies van gebouw en gebruikte materialen te voorkomen waarbij niet alleen rekening wordt gehouden met architectonische en (gebruiks-)technische, maar ook met financiële en milieutechnische randvoorwaarden?’
In the Netherlands, the theme of transitioning to circular food systems is high on the national agenda. The PBL Netherlands Environmental Assessment Agency has stressed that commuting to circular food chains requires a radical transformation of the food chain where (a) natural resources must be effectively used and managed (soil, water, biodiversity, minerals), (b) there must be an optimum use of food by reducing (food) waste . . ., (c) less environmental pressure, and (d) an optimum use of residue streams. The PBL also recognizes that there should be room for tailored solutions and that it is important to establish a benchmark, to be aware of impacts in the production chain and the added value of products. In the line of circular food systems, an integrated nature-inclusive circular farming approach is needed in order to develop a feasible resource-efficient and sustainable business models that brings shared value into the food chain while invigorating the rural areas including those where agricultural vacancy is occurring. Agroforestry is an example of an integrated nature-inclusive circular farming. It is a multifunctional system that diversifies and adapts the production while reducing the carbon footprint and minimizing the management efforts and input costs; where trees, crops and/or livestock open business opportunities in the food value chains as well as in the waste stream chains. To exploit the opportunities that agroforestry as an integrated resource-efficient farming system adds to the advancement towards (a) valuable circular short food chains, (b) nature-based entrepreneurship (nature-inclusive agriculture), and (c) and additionally, the re-use of abandoned agricultural spaces in the Overijssel province, this project mobilizes the private sector, provincial decision makers, financers and knowledge institutes into developing insights over the feasible implementation of agroforestry systems that can bring economic profit while enhancing and maintaining ecosystem services.
