Temporal Effects of Thinning on the Leaf C:N:P Stoichiometry of Regenerated Broadleaved Trees in Larch Plantations

Abstract

The shift from natural mixed broadleaved forests to pure coniferous plantations results in soil degradation and the unsustainable development of plantations due to the simple stand structure and low species diversity. Thinning can practically sustain the forest structure and promote the regeneration and growth of broadleaved trees in these pure coniferous plantations. The growth of regenerated broadleaved trees is closely related to leaf ecological stoichiometry, which is strongly restricted by environmental factors such as light, soil moisture, and nutrients after thinning. However, the temporal effects of thinning on leaf C:N:P stoichiometry are still not well understood, which constrains our understanding of implementing thinning in coniferous plantations to promote the regeneration and growth of broadleaved species, and further forming the mixed larch-broadleaf forests. Here, we compared canopy openness (i.e., light availability) and the soil and leaf stoichiometry for regenerated broadleaved trees in larch (Larix keampferi) plantations in short-term (1–3 years), medium-term (4–9 years), and long-term (≥10 years) periods after thinning, taking natural mixed broadleaved forests as a control in Northeast China. The results showed that the temporal effects of thinning were not significant with respect to soil C concentrations, but significant with respect to soil C:P and N:P ratios. The regenerated broadleaved trees adjusted their leaf N concentrations and C:N ratios in response to the changed environmental conditions after thinning over time. The responses of soil and leaf stoichiometry to thinning and their significant correlation indicated a strong interaction between the soil and understory regeneration following thinning. Thus, thinning affects the soil and leaf stoichiometry of regenerated trees over time. These findings provide new insights into the conversion of pure coniferous plantations into mixed larch-broadleaf forests by controlling thinning intervals.

Early Growth Characterization and C:N:P Stoichiometry in Firmiana simplex Seedlings in Response to Shade and Soil Types

“…Our results were consistent with earlier reports, and further supported our findings to some extent. Moreover, lower C:N and C:P ratios in stems and leaves showed that the lowest nutrient use efficiency and growth rate may occur under shading conditions [18]. The higher C:N and C:P ratios were observed in leaves under moderate shading conditions, indicating that a higher C:N or C:P ratio accumulated in seedlings [2].…”

“…Although plants may adapt to many soil types, the growth, biomass allocation, root architecture, nutrient absorption, and physiological characteristics are directly or indirectly affected by the differences in soil types [16,17]. Earlier studies showed that under low nitrogen (N) and low phosphorus (P) conditions, the ratios of C:N and C:P in leaves of plants are lower, resulting in more efficient nutrient utilization efficiency [18]. Moreover, nutrients are more easily absorbed in fertile, moist, and well-drained loam, which improves seedlings growth and development in some plants [19,20].…”

Cascading effect of source limitation on the granivore-mediated seed dispersal of Korean pine (Pinus koraiensis) in secondary forest ecosystems

“…Photographs were taken with Canon 6D and Canon 8-15 mm f/4L USM hemispherical lens. Images were processed by the Gap Light Analyzer Software (Sun et al 2016;Xie et al 2020). The relevant results are shown in Additional file 1: Fig.…”

Nutrient stoichiometric and resorption characteristics of the petals of four common urban greening Rosaceae tree species

“…In the long-term evolution process, plants have formed a series of mechanisms and strategies to adapt to the changing environment. One of the important, nutrient resorption is important for nutrient recycling and reuse under the pressures of resource crisis caused by environmental changes and the need for a stable balance of nutrients to maintain the normal physiological activities of plants (Sterner and Elser, 2002;Fan et al, 2015;Xie et al, 2020;Li et al, 2021), thus increasing the chances of plant survival and species continuation (Zhao et al, 2006). Nutrient resorption is the transfer and transport of nutrients to other tissues of plants before senescence and litterfall (Killingbeck, 1986;Aerts, 1996;Lu et al, 2018); it provides energy and nutrients for new tissues and prolongs the retention time of nutrients in plants, thereby reducing the process of plant dependence on external nutrients (Covelo et al, 2008;Zhao et al, 2010;Vergutz et al, 2012).…”