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Changes in carbon storage of Masson Pine Forests along a latitudinal gradient with different stand structures in Southern China

100%

Wu Q. , Ma H. , Peng Y. , Yan W. , Pan D.

Polish Journal of Ecology

2021

tom Vol. 69, nr 3-4

137--155

The spatial patterns of carbon pool in landscape vary greatly with variation of forest structures and climate conditions. In this field study, the carbon storage in overstory, understory, litter layer of plants and soil carbon in forests was investigated in 26-28 year-old Masson pine (Pinus massoniana) pure and mixed forests along a latitudinal gradient (20–30 °N) crossing Hunan and Guangxi provinces of China, during the period of May 2015–August 2017. We found that the total carbon storage in Masson pine forests ranged 88.92–149.41 Mg/ha, of which 54.03% occurred in aboveground compound and 45.97% occurred belowground. The overall total carbon storage distribution was 34.62–68.72 Mg/ha, 3.82–10.19 Mg/ha, 2.37–3.96 Mg/ha, and 6.06–12.08 Mg/ha in stems, branches, leaves, and roots, respectively. The carbon storage in the overstory of forest stands and forest soils significantly decreased with increasing latitude, while the carbon storage in the understory and litter of the forest stands significantly increased as the latitude increased. The overall carbon storage significantly decreases by 8.26 Mg/ha in Masson pine forests as the latitude increased by one degree. The carbon storage increased by 8.43% in Masson pine mixed forests compared to the pure forest stands after the transformation from the pure forest stands into the mixed forest stands ∼ 15 years later. The results of changes in carbon storage in the studied forests with the latitudinal gradient could be attributed to variations in hydrothermal conditions with changing latitudes. The forest structure with different tree species composition was another important factor regulating carbon storage in forest ecosystems at the same latitude. The results provided a scientific basis for better understanding of latitudinal variation and spatial distribution of carbon storage in Masson pine forest stands with optimal forest stand structures in subtropical region of China.

Quantification of Individual Tree Competition Index Taking Chinese-Fir Plantations in Subtropical Low Hilly Area as an Example

86%

Zhang Y. , Deng X. , Huang Y. , Li Y. , Xiang W. , Yan W.

Polish Journal of Ecology

2019

tom Vol. 67, nr 1

1--16

Competition among trees is a fundamental interaction process within plant community, which is the theoretical basis of thinning. Plant competitive intensity is generally measured using a competition index (CI) that can be classified into two major categories: distance-independent and distance-dependent. The current study used Cunninghamia lanceolata (Lamb.) Hook as the test subject and used Hegyi's CI (distance-dependent), to quantify individual CI and their relationship with tree diameter at breast height (DBH). Five different criteria were used to select potential competitors for the calculation of CI. Seven basic linear and nonlinear mathematical functions were used to test and quantify the relationships between DBH of the target tree and the individual CI. Results showed that individual CI was negatively correlated with target tree DBH: as DBH increased, competition intensity weakened. The adjusted R2 with five different criteria of selection competitors simulated by seven functions ranged from 0.30 to 0.82. Considering the root mean square error (RMSE), P-value, and adjusted-R2, our results suggested that the best model to simulate the relationship between individual CI and focal tree DBH was power function (CI = 43.98 × DBH-1.08, adjusted R2 = 0.81) and with the Voronoi diagram method as the criteria for selecting competitors. These results can demonstrate a clearer understanding of the spatial structure of forests, and can be used to guide the selection of thinning trees in the process of thinning practice.