Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, 75007, Uppsala, Sweden.
Ecol Appl. 2018 Jun;28(4):1011-1019. doi: 10.1002/eap.1705. Epub 2018 May 21.
In many managed landscapes, low-productivity land comprises most of the remaining relatively untouched areas, and is often over-represented within protected areas. The relationship between the productivity and conservational value of a site is poorly known; however, it has been hypothesized that biodiversity increases with productivity due to higher resource abundance or heterogeneity, and that the species communities of low-productivity land are a nested subset of communities from more productive land. We tested these hypotheses for dead-wood-dependent beetles by comparing their species richness and composition, as well as the amount and diversity of dead wood, between low-productivity (potential forest growth <1 m ·ha ·yr ) and high-productivity Scots pine-dominated stands in Sweden. We included four stand types: stands situated on (1) thin soils and (2) mires (both low-productivity), (3) managed stands, and (4) unmanaged stands set aside for conservation purposes (both high-productivity). Beetle species richness and number of red-listed species were highest in the high-productivity set-asides. Species richness was positively correlated with the volume and diversity of dead wood, but volume appeared to be a better predictor than diversity for the higher species richness in set-asides. Beetle species composition was similar among stand types, and the assemblages in low-productivity stands were largely subsets of those in high-productivity set-asides. However, 11% of all species and 40% of red-listed species only occurred in high-productivity stands, while no species were unique to low-productivity stands. We conclude that low-productivity forests are less valuable for conservation than high-productivity forest land. Given the generally similar species composition among stand types, a comparable conservational effect could be obtained by setting aside a larger area of low-productivity forest in comparison to the high-productivity. In terms of dead wood volumes, 1.8-3.6 ha of low-productivity forest has the same value as 1 ha of unmanaged high-productivity forest. This figure can be used to estimate the conservation value of low-productivity forests; however, as high-productivity forests harbored some unique species, they are not completely exchangeable.
在许多管理良好的景观中，低生产力土地构成了大部分剩余的相对未受干扰的区域，并且在保护区内经常过度代表。站点生产力和保护价值之间的关系知之甚少；然而，据推测，由于资源丰富度或异质性较高，生物多样性随生产力的提高而增加，并且低生产力土地的物种群落是来自生产力更高土地的嵌套子集。我们通过比较瑞典低生产力（潜在森林生长<1 m·ha·yr）和高生产力苏格兰松主导林分之间的死木依赖甲虫的物种丰富度和组成，以及死木的数量和多样性，检验了这些假设。我们包括四种林分类型：（1）薄土和（2）沼泽地上的林分（两者都是低生产力），（3）管理林分和（4）为保护目的留出的未管理林分（都是高生产力）。高生产力保护区的红皮书中列出的物种丰富度和物种数量最高。物种丰富度与死木的体积和多样性呈正相关，但体积似乎比多样性更能预测保护区较高的物种丰富度。林分类型之间的物种组成相似，低生产力林分的组合在很大程度上是高生产力保护区的子集。然而，11%的所有物种和 40%的红皮书物种仅出现在高生产力林分中，而低生产力林分中没有独特的物种。我们得出的结论是，低生产力森林的保护价值低于高生产力林地。考虑到林分类型之间通常相似的物种组成，与高生产力相比，通过留出更大面积的低生产力森林可以获得相当的保护效果。就死木体积而言，1.8-3.6 公顷的低生产力森林与 1 公顷未管理的高生产力森林具有相同的价值。这个数字可以用来估计低生产力森林的保护价值；然而，由于高生产力森林拥有一些独特的物种，它们并不是完全可以互换的。
