Dataset on Woody Aboveground Biomass, Disturbance Losses, and Wood Density from an African Savanna Ecosystem

This dataset comprises raw and processed data from two tree inventories in savanna and savanna woodland vegetation along elephant disturbance gradients in Zambezi Region, Namibia. The recorded individuals represent all age classes and damage levels (including gullivers) and were classified accordingly into six growth classes. The raw data contains allometric/dendrometric proxies (height, canopy diameters, and (where applicable) stem circumferences for stems >15cm at the base) which were recorded for n = 6,179 woody individuals in 60 plots (each 0.1 ha). Wood samples were taken to measure specific wood density (SWD) for each recorded species.

SWD measurements and raw data have been used to estimate aboveground biomass (AGB) per individual via allometric models. Existing methodologies and workflows had to be improved to account for damages and diverse vegetation structure as shaped by disturbance impacts. In addition to standing biomass, our proposed method also delivered data on biomass losses to respective disturbance agents (elephants, fire, and others) for each individual.

The processed data comprises estimates of living AGB on individual and unit per area basis as determined with our proposed methodology, see:
Kindermann L, Dobler M, Niedeggen D, Linstädter A (2022). A new protocol for estimation of woody aboveground biomass in disturbance-prone ecosystems. Ecol. Indic. 135, 108466, https://doi.org/10.1016/j.ecolind.2021.108466.
Our proposed approach further delivered data on pre-disturbance AGB and AGB losses to major disturbance agents. For a description of biomass partitions also see detailed legend within the Data file.

Our research hypothesis was that increasing elephant densities decrease woody aboveground biomass (AGB) and increase elephant-mediated AGB losses along the disturbance gradient. Findings from the data presented here support this hypothesis. Furthermore, increasing elephant densities seem to decrease fire disturbance impacts along the same gradient. These trends can be demonstrated for two different vegetation types (savanna & savanna woodland). A comparison between the conventional standard method and our improved proposed methodology highlights the importance of suitable sampling strategies and protocols for determining biomass and carbon storage in highly disturbed dryland ecosystems. The conventional method over-estimated biomass in large but disturbed trees, while simultaneously under-estimating total biomass on a unit per area basis through omission of all smaller trees, shrubs, and highly damaged woody individuals (gullivers); see Kindermann L, Dobler M, Niedeggen D, Linstädter A (2022). A new protocol for estimation of woody aboveground biomass in disturbance-prone ecosystems. Ecol. Indic. 135, 108466, https://doi.org/10.1016/j.ecolind.2021.108466.

本数据集包含了纳米比亚赞比西地区草原及其林缘植被中，两个树木清单的原始和加工数据。这些数据记录了不同年龄段和受损程度的树木个体（包括巨树），并根据生长等级分为六类。原始数据包括异速生长/树木测量指标（树高、树冠直径和（适用时）树干基径大于15厘米的树干周长），这些指标在60个样地（每个样地0.1公顷）中针对6,179个木质个体进行了记录。对每个记录的物种进行了木材样本采集，以测量其特定木材密度（SWD）。通过异速生长模型，利用SWD测量值和原始数据估算每个个体的地上生物量（AGB）。为了考虑到受损和由干扰影响形成的多样化植被结构，现有的方法和工作流程必须得到改进。除了地上生物量外，我们提出的方法还提供了每个个体的生物量损失数据，针对相应的干扰因素（如象群、火灾等）。加工数据包括根据我们提出的方法在个体和单位面积基础上估算的存活AGB，具体参见：Kindermann L, Dobler M, Niedeggen D, Linstädter A (2022). 一种用于估算易受损生态系统木质地上生物量的新协议。生态指标，135，108466，https://doi.org/10.1016/j.ecolind.2021.108466。我们提出的方法进一步提供了干扰前AGB以及主要干扰因素造成的AGB损失数据。关于生物量分区的详细描述，请参阅数据文件中的详细图例。我们的研究假设是，随着象群密度的增加，木质地上生物量（AGB）将减少，并通过象群介导的AGB损失在干扰梯度上增加。本数据呈现的研究结果支持了这一假设。此外，随着象群密度的增加，火灾干扰的影响似乎在同一梯度上减少。这些趋势可以在两种不同的植被类型（草原和草原林）中得到证实。将传统标准方法与我们改进的提出的方法进行比较，凸显了在高度干扰的干旱生态系统中确定生物量和碳储存时，合适的采样策略和协议的重要性。传统方法高估了大而受损的树木的生物量，同时由于忽略了所有较小的树木、灌木和高度受损的木质个体（巨树），在单位面积基础上低估了总生物量；详见Kindermann L, Dobler M, Niedeggen D, Linstädter A (2022). 一种用于估算易受损生态系统木质地上生物量的新协议。生态指标，135，108466，https://doi.org/10.1016/j.ecolind.2021.108466。