Forest Residue Management Impact on Rodent (Rodentia: Murinae, Arvicolinae) Damage in Pedunculate Oak (Quercus robur L.) Forests in Croatia

Abstract

Small rodents (Rodentia, subfam. Murinae: real mice, Arvicoline voles) greatly affect natural regeneration, stability and dynamics of forest communities worldwide. Every 3–4 years rodent damage in Croatian state forests is the most severe in forest regeneration stands, especially in pedunculate oak (Quercus robur L.) and narrow-leaved ash (Fraxinus angustifolia Vahl.) forests, where rodents can seriously impede natural regeneration by damaging seeds, stems and roots of saplings. These negative interactions are an even bigger challenge nowdays as pedunculate oak and narrow-leaved ash have become more vunerable in the last decades and are known as the most sensitive species of lowland forests in Croatia due to microclimatic and macroclimatic changes and the unfavourable interaction of a whole series of anthropogenic, abiotic and biotic factors. In the last 40 years, in Croatian state forests, rodent management consisted of monitoring and mainly rodenticide use. Trying to implement IPM (Integrated Pest Management) postulates into practice over the years, different prevention methods against small rodents were tested, but not many came to use. The aim of this research was to look into different logging residue management approaches and their effect on the rodent damage in two pedunculate oak forest regeneration stands in central Posavina in Croatia. Rodent damage on stem and root of tree saplings was recorded by visual inspection on three plots (5x5 m) with scattered logging residue, and one plot (5x5 m) with no residue at one micro-depression site (95 m a.s.l.), and on one micro-elevation (99 m a.s.l.) site. Plots with scattered logging residue represented a type of forest residue management in which logging debris (branches) is cut to smaller lengths and distributed evenly at the forest regeneration stand. Plot with no logging debris represented a residue management method in which wood mass is completely removed from the regeneration stand after felling. We counted, determined and inspected tree saplings found at chosen plots for rodent damage (on stem and roots) and also determined the average weight and moisture content of logging residue (branches around 5–7 cm in diameter) found at the site. In spring 2017, 3380 tree saplings (2978; 81% pedunculate oak, 7; 0.2% narrow-leaved ash and 395; 11.7% other deciduous species) were inspected for rodent damage. At micro-depression site, on a plot with no logging residue, only 13.4% of the saplings were damaged, while the average share of damaged saplings on three plots with scattered residue was more than six times higher; 87.8%. The average mass of the logging residue weighed at site with scattered residue was 10.14 kg kg/m2 and moisture content was 19.2%. At micro-elevation site, 25.4% of the saplings were damaged on a plot with no logging residue, while the average share of damaged saplings on three plots with scattered residue was two times higher; 51.4%. The average mass of the logging residue weighed at SRP 1–3 was 5.1 kg/m2. We also determined moderately strong positive correlation (R=0.69133) between the mass of logging residue and rodent damage and strong negative correlation (R=–0.89598) between wood moisture content of the logging residue and rodent damage. In years ahead, with unpredictable climate effects and potentially very variable small rodent dynamics, removing the logging residue after the felling could represent a residue management that contributes to a more effective and ecologically based rodent management. It could also become a usable preventive method within IPM and help prevent sever rodent damage, even during the outbreaks in pedunculate oak regeneration stands.

Altitudinal Distribution, Seasonal Dynamics and Borrelia burgdorferi Sensu Lato Infections in Hard Ticks (Acari: Ixodidae) in Different Forest Communities in Inland Croatia

“…At the same time, our data correspond to a high share of subadults (88%) sampled in a forest habitat within Croatia's capital, the city of Zagreb [43]. In floodplain forests of the Posavina region in Central Croatia, only adult Ixodes ricinus were sampled from 2011 to 2013 [45]. On the Medvednica mountain, Ixodes ricinus nymphs were prevalent at all altitudinal limits (200, 400, 600, 800 and 1000 m asl.…”

“…There were also previous records of Haemaphysalis concinna sampled near the Croatian northwestern border, on the island of Krk in the Croatian Littoral [20] and in the eastern parts of the country, where it was present in small numbers, representing only 2.6% of the collected specimens [47]. Even though the genus Dermacentor is the second most abundant ixodid taxon in the Western Palaearctic region [69,70], we have collected no representatives in our three-year research, which corresponds to its lowland habitat preferences and its absence from higher mountain regions [45,71]. However, we expected ticks from this genus at low-altitude hill sampling sites or in climatically favorable valleys at higher altitudes [72].…”

“…Our results also differ from previous studies performed in pedunculate oak floodplain forests (Genisto elatae-Quercetum roboris Ht. 1938) in the Posavina region in Central Croatia [45], where Ixodes ricinus was determined in only 3.5% of collected specimens. On the mountain sites of Papuk and Medvednica, besides Ixodes ricinus, Ixodes frontalis and Haemaphysalis concinna were also recorded, but with very small percentages-0.08% and 1.0%, respectively (Table 4).…”

“…Croatian northwestern and western regions were only partly included [26,43,44]. Novel studies, carried out during the last two decades, have mainly been made at lower altitudes in central and eastern parts of inland Croatia [45][46][47]. A total of 23 hard tick species, belonging to five genera (Ixodes, Haemaphysalis, Rhipicephalus, Dermacentor and Hyalomma) have been recorded in Croatia so far [20,48].…”

The Effect of Knife Wear and Sharpening Mode on Chipper Productivity and Delays

“…In the period of chipping, the average temperature was 22.5 • C, average monthly precipitation was 71 mm, and average humidity was 70%. At both chipping sites, the raw material consisted of air-dried tops stacked at a roadside landing as a result of a common practice in Croatian lowland forests in which forwarders are used for primary transport [21,22] and a management method in which logging residue is completely removed from the regeneration stand after felling [23] to be chipped after seasoning at the roadside, as is common in most supply chains in European countries [24] and stated as the most cost-efficient [25]. The tops had been forwarded to the roadside after roundwood transport in two preparatory cuts conducted in hardwood stands in the last quarter of 2018 (chipping site B) and between the end of 2018 and the first quarter of 2019 (chipping site A).…”