Construction of fine root biomass estimation models of dominant tree species in a north tropic karst forest

doi:10.17521/cjpe.2023.0087

Abstract

Abstract:

Aims Fine root biomass is the basis for quantifying fine root dynamic characteristics, such as fine root turnover and nutrient return. The special karst habitat with high-rock outcrops and gravel soil indicates that the traditional root drilling method for measuring fine root biomass is time-consuming, labor-intensive, destructive, and difficult to achieve site-specific sampling, and the sample heterogeneity is large. Therefore, it is necessary to establish fine root biomass estimation models based on morphological characteristics to accurately estimate fine root biomass and its turnover rate.

Methods Five dominant tree species, Vitex kwangsiensis, Garcinia paucinervis, Streblus tonkinensis, Diospyros siderophylla, and Excentrodendron tonkinense in Nonggang National Nature Reserve, Guangxi, were selected to establish fine root biomass estimation models. Two types of fine root classification were defined as 1-3 orders and diameters ≤2 mm. Quantitative correlations between length and diameter, root surface area, and fine root biomass were established based on the collected data. Subsequently, the robustness and accuracy of different models were tested, and optimal fine root biomass estimation models were selected.

Important findings The results showed that: (1) fine root diameter, length, and surface area were significantly positively correlated with fine root biomass; thus, the fine root morphological characteristics can be used to construct the correlation equation with fine root biomass; and (2) the bivariate fine root biomass estimation model based on diameter and length is more accurate than that based on fine root surface area; (3) the optimal estimation models of fine root biomass are different among tree species, due to the differences in fine root diameter, specific root length, and root tissue density among tree species. The construction of a fine root biomass estimation model based on fine root morphological indicators is beneficial for converting the obtained fine root morphological data using visualization technology, such as micro-root canal in a fixed location, into biomass data. Moreover, it is also helpful to estimate the fine root turnover rate and nutrient return of special rock mountain habitats more accurately.

Key words: fine root, biomass estimation model, karst, tropical seasonal forest

PANG Yu, HE Tong-Xin, SUN Jian-Fei, NING Wen-Cai, PEI Guang-Ting, HU Bao-Qing, Wang Bin. Construction of fine root biomass estimation models of dominant tree species in a north tropic karst forest[J]. Chin J Plant Ecol, 2024, 48(10): 1312-1325.

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https://www.plant-ecology.com/EN/Y2024/V48/I10/1312

Figures/Tables 7

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土壤性质 Soil properties		土壤性质 Soil properties
pH	7.35 ± 0.02	有效磷含量 Available phosphorus content (mg·kg^-1)	6.60 ± 0.46
土壤有机碳含量 SOC content (g·kg^-1)	34.16 ± 1.20	交换性钾含量 Exchangeable K⁺content (mg·kg^-1)	76.21 ± 1.60
总氮含量 TN content (g·kg^-1)	3.71 ± 0.07	交换性钙含量 Exchangeable Ca²⁺ content (g·kg^-1)	15.85 ± 0.07
铵态氮含量 NH₄⁺-N content (mg·kg^-1)	12.42 ± 0.62	交换性钠含量 Exchangeable Na⁺ content (mg·kg^-1)	14.18 ± 0.08
硝态氮含量 NO₃^--N content (mg·kg^-1)	9.40 ± 0.67	交换性镁含量 Exchangeable Mg²⁺content (g·kg^-1)	1.21 ± 0.01

土壤性质 Soil properties		土壤性质 Soil properties
pH	7.35 ± 0.02	有效磷含量 Available phosphorus content (mg·kg^-1)	6.60 ± 0.46
土壤有机碳含量 SOC content (g·kg^-1)	34.16 ± 1.20	交换性钾含量 Exchangeable K⁺content (mg·kg^-1)	76.21 ± 1.60
总氮含量 TN content (g·kg^-1)	3.71 ± 0.07	交换性钙含量 Exchangeable Ca²⁺ content (g·kg^-1)	15.85 ± 0.07
铵态氮含量 NH₄⁺-N content (mg·kg^-1)	12.42 ± 0.62	交换性钠含量 Exchangeable Na⁺ content (mg·kg^-1)	14.18 ± 0.08
硝态氮含量 NO₃^--N content (mg·kg^-1)	9.40 ± 0.67	交换性镁含量 Exchangeable Mg²⁺content (g·kg^-1)	1.21 ± 0.01

树种 Tree species	立木密度 Stand density (plant·hm^-2)	胸径 Diameter at breast height (cm)		树高 Height of tree (m)
树种 Tree species	立木密度 Stand density (plant·hm^-2)	平均 Mean	范围 Range	平均 Mean	范围 Range
广西牡荆 Vitex kwangsiensis	2.22	14.9	1.9-20.0	7.0	3.0-13.1
金丝李 Garcinia paucinervis	2.19	8.5	3.0-18.5	11.0	5.2-21.4
米扬噎 Streblus tonkinensis	3.81	6.9	1.5-12.2	9.3	3.6-17.8
山榄叶柿 Diospyros siderophylla	6.61	9.0	2.3-18.4	11.8	3.2-23.7
蚬木 Excentrodendron tonkinense	3.69	7.9	1.5-23.5	11.0	4.6-21.8

树种 Tree species	立木密度 Stand density (plant·hm^-2)	胸径 Diameter at breast height (cm)		树高 Height of tree (m)
树种 Tree species	立木密度 Stand density (plant·hm^-2)	平均 Mean	范围 Range	平均 Mean	范围 Range
广西牡荆 Vitex kwangsiensis	2.22	14.9	1.9-20.0	7.0	3.0-13.1
金丝李 Garcinia paucinervis	2.19	8.5	3.0-18.5	11.0	5.2-21.4
米扬噎 Streblus tonkinensis	3.81	6.9	1.5-12.2	9.3	3.6-17.8
山榄叶柿 Diospyros siderophylla	6.61	9.0	2.3-18.4	11.8	3.2-23.7
蚬木 Excentrodendron tonkinense	3.69	7.9	1.5-23.5	11.0	4.6-21.8

	比根长 Specific root length (m·g^-1)	直径 Diameter (mm)	长度 Length (cm)	表面积 Surface area (cm²)	组织密度 Tissue density (g·cm^-3)
GXMJ	-0.20^**	0.67^**	0.67^**	0.83^**	0.20^**
JSL	-0.52^**	0.88^**	0.53^**	0.91^**	-0.09
MYY	-0.24^**	0.80^**	0.32^**	0.81^**	0.32^**
SLYS	-0.50^**	0.85^**	0.38^**	0.84^**	0.26^**
XM	-0.23^**	0.73^**	0.60^**	0.93^**	-0.03
Total	-0.19^**	0.76^**	0.50^**	0.85^**	0.15^**