Graminoid basal cover and biomass estimations in the Brotherton burning trial

The contribution of grass basal cover is an important measurement in rangeland science and is known as a proximate for grassland functional health and general range condition. Increased basal cover of grasses contributes to improved infiltration and reduces sediment losses. The importance of the Maloti-Drakensberg mountain range for water production has been emphasized and interest into the factors that influence basal cover and associated water delivery have followed. Measurements of basal cover in the Drakensberg have however, been constrained by timeous and inaccurate measurements (esp. the Hardy & Tainton (1993) method) associated with common techniques. This basal cover data was collected using a quadrat based technique which may be conveniently coupled to estimating herbaceous biomass. The method was tested on the Brotherton fire trial.
The method is straight forward. A quadrat of 0.500x0.500 m with 10 cm divisions along horizontal and vertical axes gives 25 sub quadrats each representing 4 % of the area covered by the quadrat. Therefore, basal cover in the 25 sub quadrats can be scored from 0 – 4 % in increments of one then, the total summed to give percentage basal cover. To improve the visibility of basal cover quadrats should be clipped before estimating basal cover. Furthermore, clippings may be weighed for estimation of herbaceous biomass. A CyberTraker application for recording the data has been developed for field use. Photos were taken of each quadrat making data verifiable by viewing photos. For the purposes of this verification, sub quadrats were consistently recorded from left to right, beginning at row one to five in the quadrats (see labelling in fig. 1).
A pilot study indicated that between six to eight quadrats per sample area (or treatment) are required. By placing six quadrats per plot at Brotherton, basal cover was estimated in the Brotherton field trial. Clippings were collected so that herbaceous biomass could be estimated. Sampling was done in winter after the autumn and winter burns, in these plots clipping was not necessary and biomass could not be collected.

草本基盖度（basal cover）的贡献率是草地科学中的重要衡量指标，被视为草地功能健康与整体牧场状况的替代表征。草本基盖度的提升有助于增强土壤入渗能力并减少泥沙流失。马洛蒂-德拉肯斯堡山脉（Maloti-Drakensberg mountain range）的产水重要性已得到学界重视，围绕影响基盖度及相关输水过程的因素展开的研究也随之增多。然而，德拉肯斯堡地区的基盖度测量常受限于传统方法耗时且精度不足的问题（尤以Hardy & Tainton 1993年提出的方法为甚）。本数据集的基盖度数据采用基于样方（quadrat）的技术采集，该方法可便捷地与草本生物量估算结合。该方法已在布拉瑟顿火烧试验（Brotherton fire trial）中得到验证。

该方法操作简便：取0.500m×0.500m的样方，在横竖轴上设置10cm刻度，可将样方划分为25个小样方，每个小样方对应总样方面积的4%。因此，可对25个小样方的基盖度以1%为增量从0至4%进行评分，最终求和得到总基盖度百分比。为提升基盖度估算的可视性，应在估算前对样方内植被进行剪割。此外，剪割下来的植被可称重以估算草本生物量。我们已开发一款用于野外数据记录的CyberTraker应用程序。同时为每个样方拍摄照片，以便通过回看照片验证数据。为统一验证流程，小样方的记录始终遵循从左至右、从样方第1行至第5行的顺序（详见图1标注）。

一项预试验表明，每个采样区（或处理组）需设置6至8个样方。本次在布拉瑟顿试验样地中，每块样方放置6个样方以估算基盖度，并收集剪割的植被以估算草本生物量。采样于秋冬火烧后的冬季进行，在此类样地中无需剪割植被，因此无法采集生物量。