Demographic strategies of a dominant tree species in response to logging in a degraded subtropical forest in Southeast China

International audienceAbstractKey messageThe demography of pioneer tree species (Pinus massonianaLamb.) is significantly affected by logging in Southeast China. Logging negatively affects the population growth rate ofP. massoniana, which facilitates the growth of individual trees but has no effect on reproduction probability. The survival and growth of seedlings contribute the most to population growth.ContextSubtropical forest degradation caused by unreasonable disturbances is closely related to anthropogenic activities in Southeast China, and the frequent small-scale logging activity by local people was the dominated disturbance regime in forests in this region over the past several decades.AimsThe objective of this study is to evaluate the demographic consequences of logging on Pinus massoniana, a pioneer tree species, at individual level (survival, growth, and fecundity) and population level (the population growth rate and size distribution) over short-term period.MethodsThe size of tree individuals was combined with vital rates using various modeling approaches based on demographic data from three annual censuses. The integral projection model (IPM) was constructed and used to conduct comparative demographic analyses.ResultsLogging negatively affected the population growth rate: from a slight expansion before logging to a moderate decline after logging. This study found a significant reduction in seedling recruitment after logging, and plant growth and mortality were slightly enhanced. The survival of seedlings greatly contributes to population growth rate compared to other life stages for both periods (before and after logging) while its relative importance decreases after logging. Seedling growth is also important to population growth, and its relative importance increased after logging. Shrinkage and fecundity have a minimal contribution effect on the population growth rate.ConclusionGrowing plants in a nursery with a similar demography to P. massoniana could be beneficial for pioneer species regeneration in that this will improve the survival rate and growth of small individuals after logging

Plant demography data of Pinus massoniana measured from 2011-2013 in a degraded subtropical forest in Southeast China

Subtropical forest degradation induced by unreasonable disturbance is closely related to human activities in Southeast China, frequent small-scale logging by local people was the dominated disturbance regime in the forest over the past decades. The objective of this research is to evaluate the demographic consequences of logging for Pinus massoniana, a pioneer species, at the individual scales (survival, growth and fecundity) and the population scales (population growth rate and size distribution) in short-term period. Individual's size was combined with vital rates using various modeling approaches based on demographic data from three annual censuses (2011-2013). Integral projection model (IPM) was constructed and used to conduct comparative demographic analyses. The study was performed at Changting County (25°18′40″-26°02′05′N, 116°00′45′-116°39′20′E) located in the southern Wuyi Mountain in Southeast China. In 2011, one permanent plot (25°36′48″N, 116°26′18′E) approximately 30 × 30 m size was established, in which P. massoniana was the main dominant tree species. To ease data collection, the plot was subdivided into 36 subplots of 5 × 5 m. Measurements took place in the entire plot in July 2011, 2012 and 2013. For each individuals of P. massoniana, basal diameter, total height were measured and labelled during the first census. For those individuals with heights more than 1.5m, diameter at breast height (DBH) was also measured and recorded. In subsequent years, all labelled individuals were checked and re-measured, new recruits (seedlings that germination and establishment between census periods) within the plot were searched, labelled and measured. The number of produced pinecones over the studied periods were also recorded. For each individual, plant growth was calculated via subtracting the plant size in current year by the plant size in the previous year. The sample plot was logged in October 2012 after the second census. The meteorological data of Changting County (measurement site 58911 located in 25°38′20″N，116°27′28″E) was also recorded