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1.
Ying Yong Sheng Tai Xue Bao ; 30(10): 3356-3366, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31621221

RESUMO

To reveal the seedlings dynamics of dominant trees and their response to canopy changes (as indicated by changes in leaf area index), we analyzed the seedlings dynamics of dominant trees and canopy structure during forest regeneration based on three-year (2014 to 2016) censuses and hemispherical photography in a 4 hm2 forest dynamics monitoring plot. The results showed that canopy LAI first decreased and then increased during the survey period, with significant interannual difference. The seedlings of 12 dominant tree species showed notable response to the change of canopy structure, with the response varying among different tree species. The relative abundance or frequency of seedlings for neutral tree species generally increased with the decreases of canopy LAI. The relative abundance or frequency of seedlings of light-demanding tree species generally decreased with the increases of canopy LAI. In multi-response permutation procedures by analyzing the numeric composition and distribution of dominant tree seedlings, there was significant difference among the three censuses. Such interannual difference gradually decreased from 2014 to 2016. Significant change occurred in the indicator species of dominant tree seedlings, reflecting their responses to the changes of canopy structure.


Assuntos
Plântula , Árvores , China , Florestas , Folhas de Planta
2.
Ying Yong Sheng Tai Xue Bao ; 29(1): 18-24, 2018 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-29692008

RESUMO

We established a 4 hm2(200 m×200 m) temperate secondary forest plot in the montane region of eastern Liaoning Province, China, and analyzed the spatial patterns and interspecific spatial associations of tree seedlings at scales of 0-50 m. The results showed that under complete spatial randomness null model, 95% of the species at the scale of 0-20 m showed a significant aggregation pattern, and 19 species at the scale of 0-16 m showed an aggregation pattern. The proportion of species exhibiting aggregated patterns decreased with the spatial scale. At the scale of 50 m, the random distribution pattern became the main form of tree species distribution. Underheterogeneous Poisson process null model, 5% of the species at the scale of 0-24 m showed a significant aggregation pattern, and 42% and 58% of the species at the scale of 26-50 m showed a random distribution and regularity patterns, respectively. Under complete spatial randomness null model, the proportion of species pairs of positive correlation was the highest, and at the scale of 50 m, the proportion of species pairs showed positive correlation, uncorrelated and negative correlation tended to be equal. Under heterogeneous Poisson process null model, species pairs mainly showed negative correlation, and the proportion of species pairs exhibiting negative correlation increased with spatial scale. The results implied that seed dispersal limitation and habitat heterogeneity could explain the aggregation pattern of tree seedlings. The strong aggregation of tree seedlings also contributed to close interspecific spatial associations and poor stability of the regeneration community.


Assuntos
Florestas , Plântula/crescimento & desenvolvimento , China , Ecossistema , Árvores
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