Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, 75007, Uppsala, Sweden.
Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, 51003, Tartu, Estonia.
Oecologia. 2021 Nov;197(3):807-816. doi: 10.1007/s00442-021-05061-z. Epub 2021 Oct 17.
In production forests, a common silvicultural objective is enhancing tree growth rates. The growth rate influences both mechanical and biochemical properties of wood, which may have an impact on dead wood inhabiting (i.e. saproxylic) species. In this study, we tested for the first time whether tree growth rates affect dead-wood associated assemblages in general and the occurrence of red-listed species in particular. We sampled saproxylic beetles (eclector traps) and fungi (DNA metabarcoding of wood samples) in dead trunks of Norway spruce (Picea abies), which had different growth rates within the same hemiboreal forests in Sweden. A high proportion of fungi showed a positive association to increasing tree growth. This resulted in higher fungal richness in fast-grown trees both at the trunk scale and across multiple studied trunks. Such patterns were not observed for saproxylic beetles. However, a set of species (both beetles and fungi) preferred slow-grown wood. Moreover, the total number of red-listed species was highest in slow-grown trunks. We conclude that dead wood from slow-grown trees hosts relatively fewer saproxylic species, but a part of these may be vulnerable to production forestry. It implies that slow-grown trees should be a target in nature conservation. However, where slow-grown trees are absent, for instance in forests managed for a high biomass production, increasing the volumes of dead wood from fast-grown trees may support many species.
在人工林中，一个常见的造林目标是提高树木生长速度。生长速度会影响木材的机械和生化特性，这可能会对栖息在枯木上的（即腐生性的）物种产生影响。在这项研究中，我们首次测试了树木生长速度是否会影响一般的枯木相关生物群落，特别是受威胁物种的出现。我们在瑞典同一半湿润森林中，对不同生长速度的挪威云杉（Picea abies）枯干进行了采样，包括采集腐生性甲虫（生态诱捕器）和真菌（木材样本的 DNA 宏条形码）。结果发现，相当一部分真菌与树木生长速度呈正相关。这导致在快速生长的树木中，无论是在树干尺度还是在多个研究树干中，真菌的丰富度都更高。这种模式在腐生性甲虫中并未观察到。然而，有一组物种（包括甲虫和真菌）更喜欢生长缓慢的木材。此外，生长缓慢的树干中受威胁物种的总数最高。我们得出的结论是，生长缓慢的树木产生的枯木上栖息的腐生性物种相对较少，但其中一部分可能容易受到人工林的影响。这意味着生长缓慢的树木应该成为自然保护的目标。然而，在没有生长缓慢的树木的情况下，例如在以高生物量生产为目标的森林中，增加快速生长的树木的枯木量可能会支持许多物种。
