Overvåking av insekter i hule eiker 2023

One hundred oak trees were selected from a set of 600 veteran oaks registered in the national oak survey. These oaks were divided into two sets of 50 oaks, where insects can be sampled every second year in each oak. For practical reasons, these two sets represent two different geographical regions; region East (Oslo, Akershus, Buskerud, Østfold, Telemark & Vestfold) and region West (Agder, Rogaland og Vestland). The oaks for each set were selected at random, with the exception of a doubled likelihood of selecting oaks with a visible cavity in addition to diameter at breast height larger than 200 cm, and a few criteria relating to the number of trees in each plot. The distribution of oaks between counties and with-in/outside of forest was controlled after the selection was made and was considered adequately balanced.

Insects were sampled from the 50 selected oaks in region East in June and July in 2023. Two window traps were mounted at each tree, one in the canopy and one at the trunk, next to a cavity if the tree had any. Beetles were identified.

从全国橡树调查中登记的600棵老橡树中，选取了100棵橡树。这些橡树被划分为两组，每组50棵，每棵橡树每两年可以进行一次昆虫采样。鉴于实际因素，这两组分别代表了两个不同的地理区域；即东部区域（包括奥斯陆、阿克斯胡斯、布斯克鲁德、东福尔、特伦马克和韦斯特福尔德）以及西部区域（包括阿格德尔、罗加兰和韦斯特兰）。每组中的橡树均随机选取，但选取具有明显树洞且胸径超过200厘米的橡树的概率加倍，同时考虑了每个地块树木数量的若干标准。在选取后，对橡树在各县及森林内外分布的控制，确保了分布的均衡性。

2023年6月和7月，对东部区域选取的50棵橡树进行了昆虫采样。在每棵树上安装了两个窗口陷阱，一个位于树冠，另一个位于树干，若树木有树洞，则位于树洞旁边。对采集到的甲虫进行了鉴定。