Finished: Grassland restoration perspective and knowledge

Introduction
This first webinar focused on enhancing biodiversity on Dutch levees (dikes) while ensuring water safety. Prof. de Kroon shared insights from a decade of collaboration with water boards, exploring seed mixtures, soil improvement, and management strategies to create species-rich grasslands that are both ecologically valuable and structurally resilient.

Key Speaker Highlights

Prof. de Kroon discussed:

• Current status and goals: Dike vegetation must resist erosion while supporting biodiversity; species-rich grasslands can achieve both.
• Experimental findings:
  • Diverse plant communities increase root biomass, improving erosion resistance.
  • Safety tests showed flower-rich dikes withstand extreme flooding as effectively as traditional clay-based dikes.
• Seed mixtures and soil factors:
  • Developed grass and herb mixtures (9 grasses, 22 herbs including legumes) tailored to soil types from sandy to clay.
  • Optimal conditions found on loamy soils with moderate organic matter.
• Climate resilience:
  • Diversity improves drought recovery; combined grass-herb mixtures performed best in stress tests.
• Biodiversity benefits: Flower-rich dikes support half of all Dutch wild bee species, including many on the Red List.

Key Takeaways

• Species-rich dikes are safe, enhance biodiversity, and can become a new standard for water boards.
• Restoration requires patience: vegetation establishment and soil development take years.
• Management matters—mowing (not year-round grazing) and adaptive strategies are essential for success.

Participant Insights and Key Questions

The Q&A addressed critical topics such as:

• Erosion risk during establishment: Use fast-growing pioneer species and phased succession to strengthen cover early.
• Inspection and burrowing concerns: Maintain mowable vegetation for visibility; tall swards require adapted inspection protocols.
• Techniques and practices:
  • Hay transfer for seed dispersal—remove hay after seeds drop.
  • Start from bare soil or cut existing vegetation very low before sowing.
  • Collect mowings to prevent nutrient buildup and encourage diversity.
• Other issues:
  • Mycorrhizal inoculation not seen as limiting; living soil recommended.
  • Sheep grazing reduces diversity; mowing or mixed regimes preferred.
  • Soil improvement with compost tested on sandy dikes; phosphorus generally not limiting.
  • Future research: simulate flood after drought, optimize mixtures for climate extremes.

Introduction
This second webinar explored why species-rich grasslands in Belgium are in poor conservation status and presented practical strategies for reversing biodiversity loss. Dr. De Schrijver shared insights from long-term research and field experiments, offering actionable guidance for nature managers and farmers.

Key Speaker Highlights

Dr. De Schrijver discussed:

• Current challenges: High nitrogen and phosphorus levels, fragmentation, and drought stress reduce species richness.
• Experimental findings:
  • Early mowing (before May 15) significantly reduces grass dominance and improves forage quality.
  • Introduction of Rhinanthus angustifolius (yellow rattle) suppresses grasses but requires bare soil.
  • Reintroduction of species via hay transfer and seed addition accelerates recovery; seed addition proved most effective.
• Long-term results: Some plots achieved favorable conservation status within six years, showing that restoration is possible even on nutrient-rich soils.

Key Takeaways

• Continuous management is essential; nutrient-poor sites should be strictly protected.
• Combining mowing strategies with species reintroduction offers the best outcomes.
• More herbs do not compromise forage quality and can even enhance calcium and protein levels.

Participant Insights and Key Questions

The Q&A addressed critical topics such as:

• Timing of interventions:
  • Best period for early cuts (flexible, based on first grass flowering).
  • Hay and seed introduction typically in autumn after hay collection.
• Practical constraints:
  • Need for bare soil before sowing; methods include sod cutting.
  • Management after sowing—continue mowing regimes (two or three cuts).
• Ecological considerations:
  • How to maintain flowering diversity across the season—alternate early and late mowing.
  • Challenges with high phosphorus soils and fluctuating groundwater levels.
• Future directions:
  • Testing drought-resistant species and plug planting.
  • Monitoring nitrogen in roots and long-term hydrology impacts. 

Introduction
This third webinar explored how fire and herbivory shape temperate open habitats and prevent biodiversity loss caused by forest encroachment. Dr. Amsten presented findings from long-term experiments in Swedish wood-pastures, highlighting the ecological roles of these processes and their potential as conservation tools.

Key Speaker Highlights

Dr. Amsten discussed:

• Historical context: Europe lost 95% of large mammal biomass since the Ice Age, removing natural herbivory and fire regimes.
• Experimental design: 24 plots tested four treatments—fire only, herbivory only, both, and control—using cattle grazing and prescribed burns.
• Vegetation responses:
  • Tree saplings showed species-specific strategies: oak re-sprouted after fire, pine aimed for rapid growth beyond the “fire trap.”
  • Forbs needed herbivory for establishment but reduced grazing for flowering; fire strongly promoted inflorescence.
• Pyric herbivory: Cattle preferred burned areas, reducing fuel and altering future fire patterns, creating landscape heterogeneity.
• Key insight: Absence of fire and grazing leads to tree dominance and loss of open habitats.

Key Takeaways

• Fire and herbivory are essential for maintaining open ecosystems and biodiversity in Northern Europe.
• Prescribed burning and variable grazing can mimic natural processes, but optimal fire frequency remains uncertain.
• Combining these tools creates structural diversity and supports species adapted to disturbance.

Participant Insights and Key Questions

The Q&A addressed critical topics including:

• Implementation barriers: Legal restrictions, safety concerns, and cultural norms limit fire use in many European countries.
• Ecological impacts:
  • Effects on insects and birds—low-intensity burns minimize harm; long-term benefits outweigh short-term risks.
  • Influence of ash on soil fertility—acknowledged but not yet studied.
• Management strategies:
  • Differences between cattle, sheep, and other herbivores; breed choice affects landscape impact.
  • Fire frequency—annual burns reduce fuel but may not mimic natural regimes; likely longer intervals needed.
  • Year-round low-intensity grazing vs. seasonal grazing—future research planned.
• Future directions: Growth ring analysis for fire effects, inclusion of drought-tolerant species, and multi-herbivore trials.

Introduction

The EXPBIO webinar, held on November 27, featured Dr. Sandrine Godefroid from Meise Botanic Garden, focusing on “Contribution to grassland restoration through the translocation of rare plant species: why and how to implement it?”. The session explored why translocation is sometimes necessary for biodiversity conservation, practical techniques for implementation, and lessons from large-scale restoration projects in Belgium.

Key Speaker Highlights

Dr. Godefroid presented insights from years of research and practice, emphasizing:

• Why translocation matters: Rare species often fail to return naturally due to short-lived soil seed banks, limited dispersal capacity, and minimum viable population size requirements.
• Techniques for success: 
  • Use seeds from stable populations to maintain genetic diversity.
  • Propagate plants ex situ for rare species with limited seed availability.
  • Mix multiple seed origins to enhance resilience and genetic exchange.
• Implementation essentials: 
  • Prepare habitats thoroughly (e.g., soil cutting, removal of competing species).
  • Plant large founder populations (hundreds of individuals) for viability.
  • Monitor demographic, genetic, and ecological parameters – preferably for at least 10 years.
• Collaboration benefits: Partnerships between botanic gardens and field practitioners enable ambitious, habitat-based restoration strategies.

Key takeaway: Translocation can significantly improve restoration success when combined with proper site preparation, genetic considerations, and long-term monitoring.

Participant Insights and Key Questions

The Q&A addressed critical topics such as:

• Seed sourcing dilemmas: 
  • “Is it better to use stable non-local populations over declining local ones?”
    → Ecological similarity matters more than geographic proximity; avoid outbreeding depression.
• Long-term success:  
  • Monitoring should last 10+ years to confirm population dynamics and habitat functioning.
• Practical challenges:  
  • Managing soil seed banks of weeds requires patience and repeated interventions.
  • Climate change raises questions about assisted migration and future habitat suitability.
• Technical considerations: 
  • Growing plants in standard potting soil is sufficient for short propagation periods.
  • Orchid restoration via direct sowing works but requires patience due to slow growth.

Introduction

The fifth webinar, “Restoration of Species-Rich Grassland – Practice and Monitoring”, was presented by M.Sc. Franziska Breit from the nature conservation syndicate SICONA in Luxembourg. SICONA has over 25 years of experience in restoring species-rich grasslands and shared practical insights into restoration techniques, planning, and long-term monitoring.

Key Speaker Highlights

Franziska Breit discussed:

• Restoration Techniques: Four main approaches—fresh hay transfer, directly harvested seed mixtures, locally produced certified seed mixtures, and translocation of rare species.
• Planning Essentials: Early financing, authorizations, and agreements with landowners are critical for success.
• Site Selection: Nutrient-poor soils and matching donor-recipient site conditions are key.
• Monitoring: Standardized long-term monitoring (up to 10 years) is indispensable for evaluating success.
• Lessons Learned: Cooperation with farmers and contractual nature conservation ensures sustainable outcomes.

A key takeaway: Restoration is a slow but successful process when combined with systematic planning and monitoring.

Participant Insights and Key Questions

The Q&A session addressed critical topics, including:

• Seed Distribution Accuracy: How to ensure correct sowing rates when hand-seeding (approx. 10 g/m² for mixed material).
• Nutrient Management: Why phosphorus is the limiting factor compared to nitrogen.
• Hay Handling: Whether inoculated hay should be removed (answer: no, it aids moisture retention).
• Design Choices: Stripes vs. patches for restoration aesthetics and practicality.
• Post-Restoration Use: Experiences with mowing height (10 cm recommended) and grazing—generally avoided in early years.
• Monitoring Challenges: Dispersion rates of species from restored stripes remain an area for future research.
• Main Future Challenge: Finding suitable recipient sites given nutrient loads and farmer acceptance.