Data for "Analyzing long-term impacts of ungulate herbivory on forest-recruitment dynamics at community and species level contrasting tree densities versus maximum heights"

<b>Study area</b><br>Regeneration dynamics were monitored on the forest area (90 km²) of the mountain massif “Höllengebirge” (highest elevation 1862 m), being part of the northern Limestone Alps in Upper Austria, Central Europe (47°49’N, 13°30’E). The forest is located around a central plateau that lays above the forest line. Geological substrates are dominated by limestone and dolomite, typical soils are Rendzinas and relictic loams. The climate of the region is submaritime, with long winter periods and cool, wet and short summer periods. Mean annual temperature of the area is about 6-8°C (depending on altitude) and mean annual precipitation reaches approx. 1800 mm. Annual precipitation is characterized by a bimodal temporal pattern, with one maximum occurring at July and another one between November and January. The area is typically covered by snow on approx. 170 days per year, with large inter-annual variation (ZAMG 2013). Typical forest communities are montane mixed forests comprising of Norway spruce (<i>Picea abies</i>), silver fir (<i>Abies alba</i>), European beech (<i>Fagus sylvatica</i>), ash (<i>Fraxinus excelsior</i>), and sycamore maple (<i>Acer pseudoplatanus</i>). They are classified as Helleboro nigri-Fagetum and Adenostylo glabrea-Fagetum (Mucina et al. 1993). The silvicultural system is permanent forest (shelterwood and strip-selection cutting) with natural forest regeneration and additionally strip clear-cuts with supplementary afforestation. During the investigation period no serious climatic events (e.g. drought, wind throw, snow break) or insect calamities occurred.<br>The mean ungulate density on the forested area in spring (without newborn calves, fawns and kids) is in total about 20 animals per km2, consisting of approximately four red deer (<i>Cervus elaphus</i>, counted at winter-feeding stations), five to ten roe deer (<i>Capreolus capreolus</i>, estimated by local hunters), and six to ten chamois (<i>Rupicapra rupicapra</i>, estimated by local hunters) per km2; the hunting season runs from May to December. Hunting bags were 1 to 2 red deer, 1 to 4 roe deer, and 1 to 2 chamois per km2 and year, on a constant level over the observation period.<br><br><b>Data acquisition</b><br>We established pairs of ungulate exclosures (excluding the occurring red deer, roe deer and chamois) and unfenced control plots at altitudes between 500-1100 a.s.l. and investigated them for 18 years. Minimum distance between plot pairs is 200 meters. Plots were installed at forest sites where tree regeneration was potentially possible (i.e. mature forests providing seed trees), and where initial stages of regeneration already existed in the majority of cases or were expected to occur in the near future (Reimoser et al. 1999; Reimoser et al. 2014). In choosing sites we also considered that light conditions would enable further development of seedlings (maximum canopy density by seed trees about 80%) and that a subsequent dense canopy closure was unlikely. Smaller mammals like hares (<i>Lepus europaeus</i>) or herbivore voles and mice were able to enter the exclosures. The type of treatment (fencing vs. control) was randomly attributed with a coin toss. Exclosures were constructed with a 2.0 m tall, galvanized fence outlining an area of 6 x 6 m. Distances between exclosures and corresponding control plots ranged from 5 m up to max. 20 m with largest possible congruence of site and stand conditions between exclosures and control plots. Within the 6 x 6 m area of each fence and control plot, we recorded plant data within the central 5 x 5 m square (i.e. survey area without “edge effects”), which was permanently marked with metal rods. Data were first recorded in the year of establishment of exclosure/control pairs and afterwards in a three-year cycle. Thereby, the height of the tallest tree of all species per sampling plot (25 m2, each fenced and unfenced) was recorded using the following height classes: ≤ 10 cm, 11-25 cm, 26-40 cm, 41-70 cm, 71-100 cm, 101-130 cm, 131-160 cm, 161-200 cm, 201-250 cm, 251- 300 cm, ... (continuing 50 cm classes). For the 18-year period, we further recorded stem numbers and height classes of all trees. <br>No animal experiments were carried out. The ungulates were neither caught nor influenced by medication. They were only denied access to small patches within forests by means of a fence. The fencing was carried out in accordance with all relevant guidelines and regulations. The entire sampling design was optimized to capture effects of ungulate herbivory and to keep other driving factors as constant as possible.<br><b><br>File description</b><br>- The file "heightclass.xlsx" contains a data frame including the ID of the plot pair, information about the treatment (fencing), the year of record and the maximum height value for occurring tree species (maximum height value per tree species = the mid-point height per height class interval; e.g. 85 cm for the 71-100 cm height class).<br>- The file "stemnr_incl_seedlings.xlsx" contains a data frame including the ID of the plot pair, information about the treatment (fencing), the year of record and the total stem number of occurring tree species per hectare.<br>- The file "stemnr_excl_seedlings.xlsx" contains a data frame including the ID of the plot pair, information about the treatment (fencing), the year of record and the stem number of occurring tree species, higher than 10 cm, per hectare.<br><br>Each data frame is formatted in a wide data format. Each file consists of two spreadsheets including the data ("data"-spreadsheet) and corresponding description of the variables ("code"-spreadsheet).<br><b>References</b><br><br>Mucina L, Grabherr G, Wallnöfer S (1993) Die Pflanzengesellschaften Österreichs. Teil III - Wälder und Gebüsche. Gustav Fischer Verlag Jena, Stuttgart, New York<br>Reimoser F, Armstrong H, Suchant R (1999) Measuring forest damage of ungulates: what should be considered. For Ecol Manage 120:47–58. https://doi.org/10.1016/S0378-1127(98)00542-8<br>Reimoser F, Schodterer H, Reimoser S (2014) Beurteilung des Schalenwildeinflusses auf die Waldverjüngung – Vergleich verschiedener Methoden des Wildeinfluss‐Monitorings („WEM ‐ Methodenvergleich”). BFW-Dokumentation Vol. 17. Bundesforschungszentrum für Wald, Vienna, Austria<br>ZAMG (2013) Klimadaten von Österreich 1971–2000. http://www.zamg.ac.at/fix/klima/oe71-00/klima2000/klimadaten_oesterreich_1971_frame1.htm. Accessed 30 March 2019<br>