Limiting the spread and impacts of invasive alien species (IAS) on biodiversity and ecosystems has become a goal of global, regional and national biodiversity policies. Evidence based management of IAS requires support by risk assessments, which are often based on expert judgment. We developed a tool to prioritize potentially new IAS based on their ecological risks, socio-economic impact and feasibility of management using multidisciplinary expert panels.

Lessons learned from rapid environmental risk assessments for prioritization of alien species using expert panels

Worldwide, coastal freshwater wetlands arefacingsalinizationat anincreasingrate duetolarge-scaleland use change, freshwater extraction, climate-drivensea level rise, droughts and land subsidence. Although itis known that increased surface water salinity doesinfluence wetland functioning, effects on nutrientdynamics reported in literature are contradictory andevidence from controlled, long-term field experiments isscarce. We therefore tested the effects of 4 levels ofincreased surface water salinity, from oligohaline tomesohaline conditions (0.9, 2.25, 4.5, 9 PSU), onbiogeochemical and physicochemical processes in thesediment of a formerly brackish freshwater wetland.

Salinization lowers nutrient availability in formerlybrackish freshwater wetlands; unexpected resultsfrom a long-term field experiment

Mires and peatlands in general are heavilyinfluenced by anthropogenic stressors like acidification,eutrophication, desiccation and fragmentation.Groundwater-fed mires are, in contrast to rainwater-fedmires, often well protected against desiccation due toconstant groundwater discharge. Groundwater-fedmires can however be influenced by groundwater pol-lution such as groundwater nitrate enrichment, a threatwhich has received minor attention in literature. Thepresent case study demonstrates how groundwater ni-trate enrichment can affect the biogeochemical function-ing and vegetation composition of groundwater-fedmires through direct nitrogen enrichment and indirectnitrate-induced sulphate mobilisation from geologicaldeposits.

Effects of Groundwater Nitrate and Sulphate Enrichmenton Groundwater-Fed Mires: a Case Study

Zakkende veengronden worden een steeds groter probleem voor de bestaande huizen in veengebieden, maar ook de waterhuishouding voor de landbouw wordt problematisch. Bovendien komt veel CO2 vrij door ontwatering.
Om de zakking van de bodem te vertragen of te stoppen worden technische oplossingen bedacht die weliswaar duur zijn, maar waardoor het huidige landgebruik niet zou hoeven te wijzigen. Deze technische benadering wordt omarmt door vooral agrariërs en belangenorganisaties. In dit artikel wordt onderbouwd waarom de gepropageerde technische maatregelen -onderwaterdrainage en/of drukdrainage- geen oplossing zijn voor zowel de veenzakking als het beperken van de CO2 uitstoot van de veengebieden. Een discussie over een landgebruik waarbij de waterpeilen sterk worden verhoogd moet worden gevoerd!

Onderwaterdrainage in veenweidegebieden

Sod cutting is used as measure in heathlands affected by increased nitrogen deposition, but species recovery is often limited. This paper provides experimental evidence for barriers to successful restoration introduced by sod cutting: soil acidity and P limitation. Having important implications for managing ecosystems under high nitrogen load, this advocates a sound N emission reduction instead of N removal policy.

Barriers to restoration: Soil acidity and phosphorus limitation constrain recovery of heathland plant communities after sod cutting.

Acidification has led to a strong decline of species characteristic of shallow soft-water lakes. In spite of reductions in acidifying deposition, natural recovery of biodiversity is modest or even absent, suggesting that the impact of acidification is difficult to reverse. We compared recovery from acidification in non-restored and restored lakes using data from 1983 and 2004. In restored lakes, accumulated organic matter was removed and alkaline water was supplied, resulting in an increase in pH and alkalinity and a decrease in ammonium, sulphur and aluminium. For evaluation of biotic changes we selected chironomid larvae (Diptera). In non-restored lakes, chironomid response did not indicate a recovery, despite an improved water chemistry in terms of decreased acidity and sulphur (not ammonium and aluminium).

Natural recovery and restoration of acidified shallow soft-water lakes: Successes and bottlenecks revealed by assessing life-history strategies of chironomid larvae

De brede geelgerande waterroofkever wordt beschermd via de EU-Habitatrichtlijn Annex II en IV. Maar welke maatregelen zou je als terreinbeheerder kunnen treffen om de leefomstandigheden voor deze soort te behouden en te verbeteren? Die vraag is niet gemakkelijk te beantwoorden. De kever wordt namelijk onder zeer verschillende omstandigheden aangetroffen en de ecologische kennis over de soort bevat veel hiaten.

Habitateisen van brede geelgerande waterroofkever ontrafeld door af te dalen langs de voedselketen.