Perennial crops such as Christmas trees have increasingly been cultivated throughout Europe. However, knowledge on the influence of Christmas-tree plantations (CTP) on biodiversity is still scarce. We examined phytodiversity and soil and habitat-structure characteristics within young (CTP-YOUNG, tree age ≤ 6 years) and old (CTP-OLD, tree age > 6 years) conventionally managed CTP in comparison with the three most dominant habitat types within the study area: (1) intensively managed grasslands (GRASS), (2) windthrows (WIND) and (3) non-native spruce forests (FOREST) (n_{per sample type} = 18). Our study revealed clear differences in soil characteristics, habitat structure and plant-species richness between the five sample types. These differences were most pronounced between three groups of habitats: (1) CTP, (2) GRASS and (3) WIND/FOREST. CTP were characterized by a typical habitat structure composed of a distinct shrub layer, an intermediate herb layer and a low litter cover. In contrast to the other sample types CTP had a comparably high cover of bare ground and stones/gravel. Due to the practiced management CTP were characterized by a unique plant species community composed of a high number of ruderal species and some neophytes. The differences between CTP-YOUNG and CTP-OLD were generally small. Next to management, phytodiversity in CTP was influenced by the size of CTP. Small-scale CTP generally had a higher phytodiversity. For the cultivation of Christmas trees, we recommend the reduction of herbicide use as far as possible. New plantations should be implemented preferentially within homogeneous landscapes composed of habitats with low importance for biodiversity.

中文翻译：

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圣诞树人工林对植物多样性的影响：对保护的意义

遍及欧洲的多年生作物，例如圣诞树。但是，关于圣诞树种植园（CTP）对生物多样性影响的知识仍然匮乏。我们比较了传统管理的CTP的年轻（CTP-YOUNG，树龄≤6岁）和老龄（CTP-OLD，树龄> 6年）内植物多样性和土壤及生境结构特征，并与该区域内三种最主要的生境类型进行了比较。研究区域：（1）集约经营草地（GRASS），（2）抛草（WIND）和（3）非本地云杉林（FOREST）（_{每个样本类型}n = 18）。我们的研究揭示了五种样品类型在土壤特征，生境结构和植物物种丰富度方面的明显差异。这些差异在三类生境之间最为明显：（1）CTP，（2）GRASS和（3）WIND / FOREST。CTP的特征是典型的栖息地结构，包括独特的灌木层，中间草本层和低凋落物覆盖层。与其他样本类型相比，CTP的裸露地面和石头/砾石覆盖率较高。由于实行了有效的管理，CTP的特点是独特的植物物种群落，该群落由大量的杂种和一些新植物组成。CTP-YOUNG和CTP-OLD之间的差异通常很小。除了管理，CTP的植物多样性还受CTP大小的影响。小型CTP通常具有较高的植物多样性。对于圣诞树的种植，我们建议尽可能减少使用除草剂。应优先在由对生物多样性重要性不高的栖息地组成的同质景观中优先实施新的人工林。