Distribution patterns and associations of dominant tree species in a mixed coniferous-broadleaf forest in the Changbai Mountains

Abstract

In 2012 a plot was established with 1-ha area in a mixed coniferous-broadleaf forest in the Changbai Mountains, northeastern China for examining local forest processes, structure and succession. A method of O-ring statistics (paircorrelation function) was applied to analyze the spatial patterns and associations of the dominant species within different vertical layers. After the evaluation by their importance values, six tree species (or group) (i.e. Abies nephrolepis, Picea jezoensis, Pinus koraiensis, Tilia amurensis, and species group of Betula ssp. and species group of Acer ssp.) were determined as dominant trees species. It was found that some of these species exhibited closely clustered distributions at fine distances. As spatial distance increased, a random or even regular distribution gradually appeared with the exception of the upper layers of A. nephrolepis and P. koraiensis, and the lower layers of P. jezoensis, P. koraiensis and Betula ssp., which were substantially randomly distributed. Intra-and inter-species spatial associations varied in accordance with species, tree height and reciprocal distances. Positive associations were observed between the lower and upper height classes of trees of the same species (except for that of P. jezoensis) at fine distances. This may be owing to limited seed dispersal and geological heterogeneity. The aggregation intensity declines with increasing distances and this consistent with the predictions of self-thinning. Some coniferous trees (e.g. Pinus koraiensis) in the lower height class were positively associated with T. amurensis and group of Betula ssp. of the upper height class at some distances, suggesting that saplings of coniferous trees occupy a broader niche and can grow well under the canopy of the adult of broad-leaved trees. Negative associations were observed between upper coniferous trees and lower broad-leaved trees and between upper P. jezoensis and lower P. koraiensis, suggesting that a canopy of these trees might not provide suitable environment for the survival, establishment, and growth of lower individuals, corresponding well to Janzen-Connell hypothesis.

Niches and Interspecific Associations of Dominant Populations in Three Changed Stages of Natural Secondary Forests on Loess Plateau, P.R. China

“…The dominance of associated species, especially in community I, agreed well with studies at other sites 42 . Many of these species were also important in defining changed pathways.…”

“…Although many species were present on the Loess Plateau, our results showed that the interspecific association with an extremely significant level was low, and the results were consistent with the findings in the subtropical evergreen broadleaf forest 24 . The dominance of associated species, especially in community I, agreed well with studies at other sites 42 . Many of these species were also important in defining changed pathways.…”

“…Some researchers considered that the ratios of positive to negative associations were below 1 may be caused by the secondary nature and youth of the communities and artificial episodic changes 42 . This suggestion implied that secondary, young and artificially disturbed communities may have more negative interspecies associations.…”

“…In this changed series, the ratio of positive to negative associations in the Pinus tabulaeformis community was below 1, indicating a possible negative correlation among the majority of the species pairs, but the significance test showed that most species were in positive association, and an analysis on multi-species association showed that all tree species in each community had significant associations on the whole. Some researchers considered that the ratios of positive to negative associations were below 1 may be caused by the secondary nature and youth of the communities and artificial episodic changes 42 . This suggestion implied that secondary, young and artificially disturbed communities may have more negative interspecies associations.…”

Spatial association and optimum adjacent distribution of trees in a mixed coniferous-broadleaf forest in northeastern China

“…The landscape is hilly, with forests at altitudes between 300 and 1200 m. The mean monthly temperature is 3.9°C, and the cumulative temperature above 10°C is approximately 2473°C. The annual precipitation is 500-600 mm, and the annual number of frost-free days is 110-130 d. The region has 170 days of snowfall from November to April (Li et al, 2013;Zhang et al, 2015). The soil is brown podzol.…”