Wood-pastures are special types of agroforestry systems that integrate trees with livestock grazing. Wood pastures can be hotspots for large old tree abundance and have exceptional natural values; but they are declining all over Europe. While presence of large old trees in wood-pastures can provide arguments for their maintenance, actual data on their distribution and abundance are sparse. Our study is the first to survey large old trees in Eastern Europe over such a large area. We surveyed 97 wood-pastures in Transylvania (Romania) in order to (i) provide a descriptive overview of the large old tree abundance; and (ii) to explore the environmental determinants of the abundance and persistence of large old trees in wood-pastures. We identified 2520 large old trees belonging to 16 taxonomic groups. Oak was present in 66% of the wood-pastures, followed by beech (33%), hornbeam (24%) and pear (22%). For each of these four species we constructed a generalized linear model with quasi-Poisson error distribution to explain individual tree abundance. Oak trees were most abundant in large wood-pastures and in wood-pastures from the Saxon cultural region of Transylvania. Beech abundance related positively to elevation and to proximity of human settlements. Abundance of hornbeam was highest in large wood-pastures, in wood-pastures from the Saxon cultural region, and in places with high cover of adjacent forest and a low human population density. Large old pear trees were most abundant in large wood-pastures that were close to paved roads. The maintenance of large old trees in production landscapes is a challenge for science, policy and local people, but it also can serve as an impetus for integrating economic, ecological and social goals within a landscape.

中文翻译：

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特兰西瓦尼亚（罗马尼亚）的木栈道里有很多大树

木材牧场是将树木与牲畜放牧结合在一起的特殊类型的农林业系统。木制牧场可能是大型老树丰产的热点，并具有非凡的自然价值。但是整个欧洲都在下降。虽然树木大的老树可以为它们的维护提供依据，但有关其分布和丰度的实际数据却很少。我们的研究是第一个在如此大的范围内对东欧的大型老树进行调查的研究。我们调查了特兰西瓦尼亚（罗马尼亚）的97个木草场，以便（i）对大型老树的丰度进行描述性概述；（ii）探索影响环境的因素，这些环境因素决定了树木大老树的丰度和持久性。我们鉴定出属于16个分类组的2520棵大树。橡木出现在66％的木本植物中，其次是山毛榉（33％），角树（24％）和梨（22％）。对于这四个物种中的每一个，我们构建了具有拟泊松误差分布的广义线性模型来解释单个树的丰度。橡树在大型木本植物和特兰西瓦尼亚撒克逊文化地区的木本植物中含量最高。山毛榉的丰度与人类住区的海拔高度和邻近程度成正相关。大型木本植物，撒克逊文化地区的木本植物以及邻近森林覆盖率高且人口密度低的地方，角树的丰度最高。大型老梨树在靠近铺路的大型木草丛中最为丰富。在生产景观中维护大型大树对科学，政策和当地人民都是一项挑战，