Botanical diversity has been linked to increased biomass production of grasslands, but these relationships have not been explored as extensively in silvopasture systems where shade impacts on forage mass are variable due to the unique structure and environment of each system. The objective of this study was to evaluate the impact of multiple artificial shade levels on the DM yield and botanical composition of three cool‐season forage mixtures near Blackstone, Virginia, USA. Mixtures were as follows: simple = tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] and white clover (Trifulium repens L.); intermediate = simple + orchardgrass (Dactylis glomerate L.) and red clover (Trifolium pretense L.); and complex = intermediate + Kentucky bluegrass (Poa pratensis L.), birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.). Slatted structures created conditions of 30%, 50% and 70% shade relative to a full sun control. Forages were harvested mechanically (no grazers present). Annual yield (DM kg/ha) did not differ among mixtures. As compared to full sun, annual yield was no different at 30% shade, but was reduced by 22 and 36% at 50 and 70% shade respectively. In contrast to other species in the mixtures, orchardgrass increased in proportion when grown beneath all shade levels and is recommended for silvopasture use. Orchardgrass is not particularly well‐adapted to the transition zone between the northern temperate and southern subtropical United States; therefore, these results indicate that silvopastures may be an effective way to integrate marginally adapted, shade‐tolerant cool‐season forages into transition zone grazing systems.

中文翻译：

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遮荫水平提高对多种草料林干物质产量和植物组成的影响

植物多样性与草地生物量的增加有联系，但是在草地牧草系统中尚未广泛探讨这些关系，因为每种系统的独特结构和环境，阴影对草料质量的影响是可变的。这项研究的目的是评估多种人工遮荫水平对美国弗吉尼亚州黑石附近三种冷季牧草混合物的干物质产量和植物组成的影响。混合物如下：简单=高羊茅[ Schedonorus arundinaceus（Schreb。）Dumort。，nom。缺点]和白三叶草（Trifulium repens L.）；中级=简单+果园（Dactylis glomerate L.）和红三叶草（Trifolium pretenseL.）; 复合物=中间体+肯塔基州蓝草（Poa pratensis L.），鸟足三叶草（Lotus corniculatus L.）和苜蓿（Medicago sativa）L.）。相对于全面的阳光控制，板条形结构创造了30％，50％和70％的阴影条件。机械收获草料（不存在放牧者）。混合物之间的年产量（DM kg / ha）没有差异。与全日照相比，在30％的阴影下年产量没有变化，但在50％和70％的阴影下年产量分别降低了22％和36％。与混合物中的其他物种相反，果园草在所有阴影等级以下生长时，其比例均增加，建议用于灌木林。乌节草不太适合美国北部温带和南部亚热带之间的过渡带。因此，这些结果表明，森林牧草可能是将略带适应性，耐荫性的冷季牧草整合到过渡带放牧系统中的有效方法。