温带人工林林分发展 15 年中多样性-生产力关系方向的变化,Journal of Ecology

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温带人工林林分发展 15 年中多样性-生产力关系方向的变化
Journal of Ecology ( IF 5.3 ) Pub Date : 2022-02-05 , DOI: 10.1111/1365-2745.13855
Tanvir Ahmed Shovon ₁ , Stephanie Kang _{2,

3} , Michael Scherer‐Lorenzen ₃ , Charles A. Nock _{1,

3}

Affiliation

操纵森林和草原多样性的实验经常观察到积极的多样性-生产力关系（DPR），这种关系在植物群落发展过程中趋于加强。这种模式通常归因于生态位互补性或便利性的增加。大多数分析没有检查物种优势和密度，它们也会随着时间而变化。此外，树种之间的社区规模相互作用如何影响 DPR 尚不清楚。
我们分析了来自 Simplex 实验的生长和死亡率数据，这是 BIOTREE 树多样性实验的一部分。^{Simplex 由 36 个地块组成，每个地块种植四种常见且具有商业重要性的树种，以在两种树密度（6667 和 3556 棵树 ha -1}）下创建树种均匀度梯度。我们测试是否：（a）均匀度对地上总生物量生产力随林分发展（年）增加的影响，（b）均匀度对生产力的影响在密集地块中更强；(c) 与共优势物种相比，来自邻居的种内竞争对优势物种的生长产生更强烈的负面影响，以及这种负面影响是否在更密集的地块中更强。
DPR 的方向最初是负面的，因为快速生长的长寿先驱花旗松 ( Pseudotsuga menziesii [Mirb.] Franco) 占主导地位。然而，随着时间的推移，耐荫的挪威云杉（Picea abies [L.] Karst.）和欧洲山毛榉（Fagus sylvatica L.）的丰度增加（按生物量），均匀度与生物量增量之间的关系由负变为正在高密度地块。邻域分析显示，对于道格拉斯冷杉和挪威云杉，同种树降低了不同密度水平和年份的个体增长率。
合成。在我们的实验中，我们观察到 15 年来多样性-生产力关系的变化。随着时间的推移，增加的种内竞争限制了不平坦地块中丰富的花旗松的增量，并且在均匀地块中耐阴挪威云杉和欧洲山毛榉的丰度（生物量）持续增加导致更高的群落生物量增量，这导致积极的 DPR。在温带人工林中出现积极的 DPR 需要大量时间，并且重要的是通过邻里规模的多样性（亲密混合）以及更高密度的种植来促进。

"点击查看英文标题和摘要"

Changes in the direction of the diversity–productivity relationship over 15 years of stand development in a planted temperate forest

Experiments manipulating diversity in both forests and grasslands have often observed a positive diversity–productivity relationship (DPR) which tends to strengthen during plant community development. This pattern is generally attributed to an increase in niche complementarity or facilitation. Most analyses do not examine species dominance and density, which also change over time. Moreover, how neighbourhood-scale interactions among tree species affect the DPR is not well-understood.
We analysed growth and mortality data from the Simplex experiment, a part of the BIOTREE tree diversity experiment. Simplex consists of 36 plots each planted with four common and commercially important tree species to create a gradient of tree species evenness at two tree densities (6667 and 3556 trees ha⁻¹). We test whether: (a) the effect of evenness on total above-ground biomass productivity increase with stand development (year), (b) the effect of evenness on productivity is stronger in dense plots; and (c) intraspecific competition from neighbours negatively affect the growth of dominant species more strongly compared to co-dominant species, and whether this negative effect is stronger in denser plots.
The direction of DPR was initially negative because the fast-growing long-lived pioneer Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) dominated. However, with time, shade-tolerant Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) increased in abundance (by biomass), and the relationship between evenness and biomass increment changed from negative to positive in high-density plots. Neighbourhood analyses revealed that for Douglas fir and Norway spruce, conspecifics reduced individual growth rates across density levels and years.
Synthesis. We observed a shift in the diversity–productivity relationship over 15 years in our experiment. Over time, increasing intraspecific competition limited the increment of the abundant Douglas fir in uneven plots, and a persistent increase in the abundance (by biomass) of shade-tolerant Norway spruce and European beech in even plots led to a higher community biomass increment, which led to a positive DPR. Emergence of a positive DPR in temperate forest plantations requires significant time and is importantly promoted by diversity at the neighbourhood scale (intimate mixtures) as well as higher density planting.

更新日期：2022-02-05

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