Reliable quantification of savanna vegetation structure is critical for accurate carbon accounting and biodiversity assessment under changing climate and land-use conditions. Inventories of fine-scale vegetation structural attributes are typically conducted from field-based plots or transects, while large-area monitoring relies on a combination of airborne and satellite remote sensing. Both of these approaches have their strengths and limitations, but terrestrial laser scanning (TLS) has emerged as the benchmark for vegetation structural parameterization – recording and quantifying 3D structural detail that is not possible from manual field-based or airborne/spaceborne methods. However, traditional TLS approaches suffer from similar spatial constraints as field-based inventories. Given their small areal coverage, standard TLS plots may fail to capture the heterogeneity of landscapes in which they are embedded. Here we test the potential of long-range (>2000 m) terrestrial laser scanning (LR-TLS) to provide rapid and robust assessment of savanna vegetation 3D structure at hillslope scales. We used LR-TLS to sample entire savanna hillslopes from topographic vantage points and collected coincident plot-scale (1 ha) TLS scans at increasing distances from the LR-TLS station. We merged multiple TLS scans at the plot scale to provide the reference structure, and evaluated how 3D metrics derived from LR-TLS deviated from this baseline with increasing distance. Our results show that despite diluted point density and increased beam divergence with distance, LR-TLS can reliably characterize tree height (RMSE = 0.25–1.45 m) and canopy cover (RMSE = 5.67–15.91%) at distances of up to 500 m in open savanna woodlands. When aggregated to the same sampling grain as leading spaceborne vegetation products (10–30 m), our findings show potential for LR-TLS to play a key role in constraining satellite-based structural estimates in savannas over larger areas than traditional TLS sampling can provide.

在变化的气候和土地利用条件下，对热带稀树草原植被结构进行可靠的量化对于准确进行碳核算和生物多样性评估至关重要。精细植被结构属性的清单通常是从基于野外的地块或样地进行的，而大面积监视则依赖于机载和卫星遥感的结合。这两种方法都有其优势和局限性，但陆上激光扫描（TLS）已成为植被结构参数化的基准-记录和量化3D结构细节，这是基于手动场或机载/空载方法无法实现的。但是，传统的TLS方法与基于字段的清单存在类似的空间限制。鉴于他们的区域覆盖面很小，标准TLS图可能无法捕获嵌入它们的景观的异质性。在这里，我们测试了远距离（> 2000 m）地面激光扫描（LR-TLS）的潜力，以便在山坡尺度上对热带稀树草原植被3D结构提供快速而可靠的评估。我们使用LR-TLS从地形优势点对整个热带稀树草原坡度进行了采样，并在距LR-TLS站越来越远的距离上收集了一致的样地比例（1 ha）TLS扫描。我们以绘图比例合并了多个TLS扫描以提供参考结构，并评估了从LR-TLS导出的3D度量如何随着距离的增加而偏离此基线。我们的结果表明，尽管稀释了点密度并且随着距离增加了光束发散度，LR-TLS仍可以可靠地表征树的高度（RMSE = 0.25–1.45 m）和树冠覆盖（RMSE = 5.67–15）。91％）在稀疏的热带稀树草原林地中，最远可达500 m。当汇总到与主要星载植被产品相同的采样谷物（10–30 m）时，我们的发现表明，LR-TLS可能在限制热带稀树草原中基于卫星的结构估计中发挥关键作用，而传统TLS采样无法提供。