Ambient atmospheric concentrations of isoprene and monoterpenes were measured at two forest sites, one deciduous and one coniferous, over the year 2022. Both sites in a regional area were sampled monthly between April and September. The samples were taken using sorbent tubes and analyzed with thermal desorption–gas chromatography–mass spectrometry. The highest concentrations were determined in August at both sites. While isoprene is the most abundant compound at the deciduous forest with an average concentration of 5.59 µg m⁻³ in August, α-pinene and β-pinene dominate throughout the year at the coniferous forest with the highest concentrations also in August (3.44 µg m⁻³ and 1.51 µg m⁻³). Because other monoterpenes (camphene, sabinene, 3-carene, p-cymene and limonene) are also emitted in significant amounts, the total concentration measured in the coniferous forest is higher (7.96 µg m⁻³ in August) in comparison to the deciduous forest (6.08 µg m⁻³). Regarding the detected monoterpenes in the deciduous forest, sabinene is the dominant monoterpene in addition to α-pinene and is sometimes present in higher (July) or equal (August) concentrations. The seasonal and diurnal concentrations of all monoterpenes correlate very well with each other at both sites. An exception is sabinene with a diurnal concentration profile similar to isoprene.

This study focused on elucidating the possibilities of improving current trapping methods for Ips typographus (Linnaeus, 1758). Three field experiments were conducted simultaneously in one study area in the German federal state of Saxony. A comparison of six different commercial attractants revealed a significant superiority of Typosan^®, especially for adult beetles after hibernation in the phase of their first swarming. It also attracted fewer individuals of Thanasimus spp. than the other highly attractive products Pheroprax^® and IT Ecolure Extra^®. Increasing the Pheroprax^® application rate by using four instead of one dispenser in a single trap increased the total catch of I. typographus only by 15.5%. In contrast, Thanasimus spp. catch increased by 195.5% when four dispensers were used. A test of different trap types showed a species-specific catching capability, with the 12-funnel WitaTrap^® being the most effective in catching I. typographus. The quantity of Thanasimus spp. bycatch in multiple-funnel traps demonstrated the necessity of a selective mechanism to minimize impacts on predator populations. Although we were not able to identify new milestones towards mass trapping, this study contributes to necessary improvements of current trapping methods. Especially in future stands with a smaller share of Norway spruce (Picea abies Karsten, 1881) the weakened beetle population in spring could be effectively reduced by properly conducted mass trapping.

The cultivation of fast-growing tree species in short rotation coppices has gained popularity in Germany in recent years. The resilience of these coppices to phyllophagous pest organisms is crucial for their profitable management, since the loss of a single annual increment can lead to uncompensable economic losses. To study the effects of leaf loss on the growth of poplar and willow varieties that are frequently cultivated under local conditions, three sample short rotation coppices including five poplar (Populus spp.) and three willow (Salix spp.) varieties were established in a randomized block design with four artificial defoliation variants and, on one site, with three different variants regarding the number of defoliation treatments. After up to three defoliation treatments within two growing seasons, the results show negative effects of leaf loss on the height growth and the fresh weight of the aboveground biomass of plants. Our data also suggests a lasting effect of defoliation on plant growth and re-growth after the end of the treatment. In general, defoliation had a greater impact on the growth of poplars than on willows. We conclude that even minor leaf loss can have an impact on plant growth but that the actual effects of defoliation clearly depend on the site, tree species, and variety as well as the extent and number of defoliations, which determine the ability of plants for compensatory growth.

Assessing the extent and magnitude of wildlife impact on forest regeneration (e.g., % browsed seedlings or reduction in regeneration density) remains a central challenge. This study explores the potential of unmanned aircraft systems (UAS) to quantify wildlife impact through the integration of drone-based thermal surveys and vegetation assessments. Specifically, it evaluates whether UAS-derived wildlife density estimates can be linked to browsing intensity and regeneration structure, thereby enabling an indirect assessment of silviculturally relevant forest dynamics. By combining remotely sensed wildlife data with field-based vegetation inventories, the study aims to identify measurable relationships between structural forest characteristics and browsing effects. This approach contributes to the development of spatially efficient, objective, and reproducible monitoring methods at the forest–wildlife interface. Ultimately, the study provides a novel framework for integrating modern remote sensing technologies into wildlife–ecological monitoring and for improving adaptive, evidence-based management in forest ecosystems increasingly affected by high ungulate densities and climate-related stressors. Two silviculturally contrasting study areas were selected: a broadleaf-dominated mixed forest in Hesse, where high ungulate densities were expected, and a pine-dominated site in Brandenburg, anticipated to experience lower browsing pressure. Thermal surveys were conducted using a DJI Matrice 30T drone equipped with a high-resolution infrared camera to detect and geolocate wildlife. In parallel, browsing impact was assessed using a modified circular transect method (“Neuzeller method”). Regeneration was recorded by tree species, height class, and browsing intensity. Statistical analyses and GIS-based spatial visualizations were used to examine the relationship between estimated ungulate densities and browsing levels. Results revealed clear differences in wildlife abundance and browsing intensity between the two sites. In the Heppenheim forest, roe deer densities exceeded 40 individuals per 100 ha, correlating with high browsing pressure—particularly on ecologically and silviculturally valuable species such as sycamore maple and sessile oak. In contrast, the Rochauer Heide exhibited lower densities and a comparatively moderate browsing impact, although certain tree species still showed signs of selective pressure. This study demonstrates that drone-based wildlife monitoring offers an innovative, non-invasive means to indirectly evaluate forest structural conditions in regeneration layers. The findings highlight the relevance of UAV-supported methods for evidence-based wildlife management and the adaptive planning of silvicultural measures. The method enhances transparency and spatial resolution in forest–wildlife management and supports evidence-based decision-making in times of ecological and climatic change.

Parasitoids are key natural antagonists of forest insect pests and are gaining importance in integrated forest protection under increasing climate-related disturbances. This study aimed to quantify the influence of vegetation diversity and canopy structure on the abundance and diversity of the overall insect community responses to vegetation structure and to provide an ecological context. Second, detailed analyses focused on three focal parasitoid families (Braconidae, Ichneumonidae, Tachinidae), which are of particular relevance for integrated forest protection due to their central role in integrated forest protection and in pesticide-free regulation approaches for risk mitigation in forest ecosystems. Malaise traps were deployed at eight randomly selected broadleaf and coniferous sites, and insect samples from six sampling dates in summer 2024 were analyzed. The sampling period coincided with the full development of woody and vascular plants, representing the phase of highest expected activity of phytophagous insects and associated parasitoids. Vegetation surveys (Braun–Blanquet), canopy closure, and canopy cover were recorded for each site. Across all samples, five arthropod classes, 13 insect orders, and 31 hymenopteran families were identified, with pronounced site-specific differences in community composition and abundance. Our results suggest that broadleaf-dominated sites, characterized by higher plant species richness and greater structural heterogeneity, support a more diverse assemblage of phytophagous insects, thereby increasing host availability and niche diversity for parasitoids. Parasitoid communities generally showed higher diversity at broadleaf sites. Spearman correlations and multiple linear regressions revealed a strong negative relationship between canopy cover and total insect abundance ρ (Spearman’s rank correlation coefficient (Spearman ρ = −0.72, p = 0.042; p = 0.012, R² = 0.70), R² (coefficient of determination), whereas parasitoid diversity (Shannon index) and the relative proportion of Ichneumonidae were positively associated with canopy cover (ρ = 0.85, p = 0.008). In addition, canopy cover had a significant positive effect on overall insect diversity (Shannon index; p = 0.015, R² = 0.63). Time-series analyses revealed a significant seasonal decline in parasitoid abundance (p < 0.001) and parasitoid diversity (p = 0.018). Time-series analyses revealed seasonal dynamics characterized by fluctuations in parasitoid abundance and diversity and a general decrease over the course of the sampling period. The findings demonstrate that structurally diverse mixed forests, particularly those with a high proportion of broadleaf trees mixed forests with heterogeneous canopy layers can enhance the diversity of specialized natural enemies, while dense canopy cover reduces overall insect abundance. These insights provide an ecological basis for silvicultural strategies that strengthen natural regulation processes within integrated forest protection.