Data from: Taxonomic and functional diversity in Mediterranean pastures: Insights on the biodiversity-productivity trade-off

Agricultural intensification is one of the main causes of biodiversity loss world-wide. The inclusion of semi-natural features in agricultural landscapes is suggested as a means of enhancing farm biodiversity, but this practice may have potential negative effects on yield production. Moreover, little evidence exists for effects of semi-natural features on other components of biodiversity, such as functional diversity. Yet this could provide a more comprehensive understanding of biodiversity–productivity trade-offs.
Here, we report the effects of semi-natural woody vegetation on taxonomic and functional diversity, and biomass production of herbaceous species at the field and farm scales by sampling 50 fields, ranging from 0 to 90% woody vegetation cover, on nine similarly managed farms in central-western Spain.
We found significant differences in herbaceous species richness among farms. Both taxonomic and functional β-diversity exhibited significant negative relationships with herbage production, highlighting the trade-off between biodiversity and productivity in these agroecosystems.
Woody vegetation cover had a significant negative relationship with biomass production and a unimodal relationship with species richness at the field scale. At high values of woody vegetation cover, species richness and functional diversity indices were decoupled, suggesting that at this extreme of the woody vegetation gradient, only herbaceous species with contrasting trait values were present. Our results showed both convergent and divergent patterns of trait values, suggesting that different assembly processes are acting concurrently along the gradient of woody vegetation.
Synthesis and applications. Our result indicates that management of woody vegetation may indeed increase both taxonomic and functional diversity, but this may come at the expense of key ecosystem services or other management goals, namely herbage production. Optimization of the trade-off between herbage diversity and productivity can be reached with a woody vegetation cover of c. 30% at the field scale.

农业集约化是全球范围内生物多样性丧失（biodiversity loss）的主要诱因之一。将半自然生境（semi-natural features）融入农田景观被认为是提升农田生物多样性（farm biodiversity）的有效手段，但该举措或对作物产量带来潜在负面影响。此外，目前关于半自然生境对生物多样性其他组分（如功能多样性（functional diversity））的影响的研究证据仍较为匮乏，而此类研究或可帮助我们更全面地理解生物多样性-生产力权衡（biodiversity–productivity trade-offs）关系。

本研究通过对西班牙中西部9个管理模式相近的农场的50块样地进行采样（样地的木本植被覆盖度介于0至90%之间），解析了半自然木本植被对田间与农场尺度下草本物种的分类学多样性、功能多样性以及生物量生产的影响。

研究发现不同农场间的草本物种丰富度（herbaceous species richness）存在显著差异。分类学β多样性与功能β多样性均与草本生物量产出呈显著负相关关系，凸显了此类农业生态系统（agroecosystems）中生物多样性与生产力之间的权衡关系。

在田间尺度下，木本植被覆盖度与生物量生产呈显著负相关，与物种丰富度呈单峰关系（unimodal relationship）。当木本植被覆盖度较高时，物种丰富度与功能多样性指数呈现解耦状态，表明在木本植被梯度的这一极端区间内，仅存具有差异化性状值的草本物种。本研究结果同时显示了性状值的趋同与分异模式，表明不同的群落组装过程（assembly processes）沿木本植被梯度同步发挥作用。

结论与应用。本研究结果表明，调控木本植被或可同时提升分类学多样性与功能多样性，但此举可能以牺牲关键生态系统服务（ecosystem services）或其他管理目标为代价，具体而言即为草本生物量生产。在田间尺度下，当木本植被覆盖度约为30%时，可实现草本多样性与生产力之间权衡关系的最优解。