Plant aboveground biomass (AGB) is a useful metric to assess ecosystem functioning, and its sensitivity to changing environmental conditions provides insight into potential global change impacts. Allometric estimates of AGB using vegetation characteristics such as plant cover or height provide nondestructive biomass proxies for repeated measurements but can introduce uncertainty to estimates. We estimated the relationship between both plant cover and a cover·height index and AGB for 15 plant species from six sites to identify the most reliable approach to estimate biomass nondestructively in semiarid eastern Australian rangelands. Estimates were made by grouping species at four different levels of specificity, to test whether generic estimates were more robust than grouping species based on life history and morphological characteristics. Estimates were then tested on a 1.5-m² plot at each site for validation. In all cases, models were highly significant (P < 0.001) with adjusted R² values ranging from 0.42 to 0.96 for cover models and 0.38 to 0.98 for cover·height index models. We found the addition of height improved model fits in four groups while reducing model fits in two groups. The error around AGB estimates for cover·height index−based models ranged from −66.8 to 4% (absolute mean 35%). Cover-based models had errors between −13.4% and 53% (absolute mean 14.2%). For cover-based estimates of AGB in validation plots, grouping plants by plant functional types (PFTs) increased accuracy (absolute mean error 17.3%) compared with estimates using data from all 15 species (absolute mean of 65.2%). Overall cover was a useful surrogate to estimate AGB (with the exception of one site, accuracy ranged from −2.3% to 11.5%), while height (thought to be a surrogate for canopy characteristics) provided benefit in a few circumstances. We suggest that future research should test additional nondestructive proxies and group species based on PFTs to improve AGB estimates using allometry.

植物地上生物量（AGB）是评估生态系统功能的有用指标，其对变化的环境条件的敏感性提供了对潜在的全球变化影响的洞察力。利用植被特征（例如植物覆盖度或高度）对AGB进行异速测量，可以为重复测量提供非破坏性的生物量代理，但会给估计带来不确定性。我们估算了植物覆盖率与覆盖率·高度指数之间的关系以及六个区域的15种植物的AGB，以确定最可靠的方法来无损估计澳大利亚东部半干旱牧场的生物量。通过将物种按四个不同的特异性级别进行分组来进行估计，以检验通用估计是否比根据生命历史和形态特征对物种进行分组更可靠。然后在每个站点的1.5 m ²地块上对估计值进行测试以进行验证。在所有情况下，模型都是高度显着的（P <0.001），调整后的R ²值对于覆盖物模型为0.42至0.96，对于覆盖物高度指数模型为0.38至0.98 。我们发现身高增加了改进了四组的模型拟合，同时减少了两组的模型拟合。基于覆盖物高度指数模型的AGB估计值周围的误差范围为-66.8至4％（绝对平均值为35％）。基于封面的模型的误差在-13.4％到53％之间（绝对平均值为14.2％）。对于盖验证区中基于AGB的估算，按植物功能类型（PFT）对植物进行分组，与使用所有15种物种的数据进行估算（绝对平均值为65.2％）相比，提高的准确性（绝对平均误差为17.3％）。总体覆盖率是评估AGB的有用替代方法（一个站点除外，准确度范围从-2.3％到11.5％），而高度（被认为是树冠特征的替代物）在某些情况下提供了好处。我们建议未来的研究应基于PFT测试其他无损代理和组物种，以使用异速测量法改善AGB估计。