Project name: External expert services for the LIFE CONTRA AILANTHUS project: Monitoring of Tufa Barriers (Lot1) and Monitoring of Biodiversity and Soil Quality Impacts (Lot2)
Period: 3/2022 – 4/2025
Location: Krka National Park, Croatia
As part of the LIFE CONTRA AILANTHUS project, Oikon provided external expert services under two distinct lots aimed at supporting the removal of the invasive alien species Ailanthus altissima (tree of heaven) and assessing its ecological impacts:
Lot 1 – Development of Monitoring Protocol and Impact Assessment on Tufa Habitats
A tailored monitoring protocol was developed to track the condition and recovery of tufa barriers (Natura 2000 habitat type 32A0) after the removal of Ailanthus altissima. Monitoring was conducted at four key sites: Roški slap, Manojlovac, Skradinski buk, and HPP Miljacka, with a focus on:
- Physical water parameters: temperature, pH, conductivity, dissolved oxygen, oxygen saturation
- Chemical parameters: nitrates, nitrites, orthophosphates
- Tufa composition: ratio of organic to inorganic matter
Sampling took place over seven field visits: in spring and autumn of 2022, 2023, and 2024, and spring 2025. The spring 2022 campaign served as the baseline before removal, with subsequent monitoring assessing habitat recovery.
Lot 2 – Development of Monitoring Protocol and Impact Assessment on Biodiversity
This three-year study examined the effects of Ailanthus altissima on soil biodiversity and soil properties. A total of 20 permanent plots were established across 10 locations, each including a plot with Ailanthus infestation (P) and a reference plot without Ailanthus (NP). Monitoring activities included:
- Soil invertebrate sampling: earthworms, aboveground macrofauna (pitfall traps), and mesofauna (Berlese extraction)
- Soil and microbial indicators: pH, conductivity, organic matter content, and microbial activity via the Tea Bag Index
- Taxonomic analysis: identification to family/genus level, functional group categorisation, and biodiversity indices (e.g., Shannon index)
A total of 400 soil samples and 60 pitfall traps were collected and analysed. Data were processed using advanced statistical methods (LMM, NMDS, PERMANOVA) in R software, allowing for detailed comparisons between P and NP plots and over time (2022–2024).
The results provided a comprehensive insight into the effectiveness of Ailanthus altissima removal measures and their ecological impact on sensitive habitats and biodiversity.
Implementation of this Project contributes to the following Sustainable Development Goals:
