Data for developing allometric models and evaluating carbon stocks of the Zambezi Teak Forests in Zambia

This paper presents data on carbon stocks of tropical tree species along a rainfall gradient. The data was generated from the Sesheke, Namwala, and Kabompo sites in Zambia. Though above-ground data was generated for all these three sites, we uprooted trees to determine below-ground biomass from the Sesheke site only. The vegetation was assessed in all three sites. The data includes tree diameter at breast height (DBH), total tree height, wood density, wood dry weight and root dry weight for large (≥ 5 cm DBH) and small (< 5 cm DBH) trees. We further presented Root-to-Shoot Ratios of uprooted trees. Data on the importance-value indices of various species for large and small trees are also determined. Below and above-ground carbon stocks of the surveyed tree species are presented per site. This data were used by Ngoma et al. (2018) [1] to develop above and below-ground biomass models and the reader is referred to this study for additional information, interpretation, and reflection on applying this data.

and the reader is referred to this study for additional information, interpretation, and reflection on applying this data.
& 2018 Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Subject area Ecology
More specific subject area Carbon stocks of the Zambezi Teak Forests.

Type of data Tables and Figures. How data was acquired
We generated data to develop above-ground and below-ground biomass models by respectively cutting down trees and uprooting trees. We assessed vegetation characteristics by generating data to determine carbon stocks. We determined the carbon fractions in leaves, branches, stems, and roots from all cut and uprooted trees. These carbon fractions were measured in the laboratory using a Fisons EA1108 CHN-0 elemental analyser (See Ngoma et al. [1] for details). Data format Analyzed and Raw.

Experimental factors
Root and wood samples were immediately weighed whilst in the field. Samples taken to develop allometric models were then oven dried for 24 h at 105°C to obtain their dry weight after determining their volume through the water-displacement approach in the 'as received condition' [1,2]. Stem, branches, roots, and leaves were ground into fine powder before analyzing them for their C fraction. Wood volume was not measured for the disk samples that were taken to determine their carbon fraction. Experimental features Data were collected along a rainfall gradient covering high, intermediate and low rainfall areas (See Ngoma et al. [1] for details).

Value of the data
The data can be used to understand carbon-stock distributions for a tropical precipitation gradient.
This gives insights on how climate change likely affects these distributions.
The data provide information on the carbon-storage potential of various species, thereby giving insight on the carbon-sequestration potential of individual species.
The average root-to-shoot ratio presented can be applied in similar forests to determine the belowground biomass stocks from the above-ground biomass values; and The data can be used to develop allometric models of similar tropical forests types and species.

Data
We present data on various tree parameters (e.g. diameter at breast height (DBH), total tree height, wood density, and dry weight). The data presented in Section 1.1 were used to determine carbon fraction in leaves, stem, branches, and roots, and to develop above and below-ground biomass  models. Root-to-Shoot ratios of the uprooted trees were also calculated. Section 1.2 provides the species-importance-value (SIV) indices of all surveyed trees, which are categorized as large (Z 5 cm DBH) or small (o 5 cm DBH) trees. In Section 1.3, data on carbon stocks of various surveyed tree species per study site are presented.

Parameters of trees used to develop allometric models
See Tables 1-3 here.

Species importance value indices of large ( Z 5 cm DBH) and small (o 5 cm DBH) trees
This section provides the SIV indices of all surveyed trees and tree species [1] (see Tables 4 and 5). Indices were calculated following the Cottam and Curtis [3] method. Supplementary information 1 (small trees) and 2 (large trees) provide a list of all trees and tree species surveyed. The information are excel files and available in electronic format.

Carbon stock per species per site
See Table 6 and Supplementary information 1 and 2.

Experimental design, materials and methods
Our sampling strategy and methods are fully described in Ngoma et al. [1] and its cited references. This section only presents the pictorial processes that we followed to collect our samples to develop below-ground (Section 2.1) and above-ground biomass (Section 2.2) models.

Sample collection process for developing below-ground biomass models
Before felling a tree, we first measured total tree height, bole height, DBH, and crown diameters. The uprooting process started by first exposing all roots connecting directly to the taproot ( Fig. 1A and B). We followed both lateral and taproots till they tapered to r 5 mm in diameter (Fig. 1C). We recorded rooting distance and depth for each recorded root. Big root mid-diameters ( Z 5 cm diameter) and their lengths were also measured (Fig. 1D). All roots were weighed immediately after excavation to get their green weight (Fig. 1E).

Sample collection process for developing above-ground biomass models
The felled tree was then cross cut (Fig. 2B) into small billets (Fig. 2C) to unable lifting (Fig. 2D) of the pieces for weighing. However, before weighing, the scale had to be calibrated (Fig. 2E). Large pieces ( Z 10 cm mid diameter) were weighed individually (Fig. 2F) while small pieces ( o 10 cm middiameter) were weighed as batches together with their twigs and leaves (Fig. 2G).