Image_2_Arbuscular mycorrhizal and ectomycorrhizal plants together shape seedling diversity in a subtropical forest.TIFF

IntroductionBurgeoning mycorrhizal research has focused on identifying the various diverse mycorrhizal strategies of forest communities. Mounting evidence suggests that mycorrhizae play important roles in regulating forest community structure and composition. However, research into the manifestation of this influence in the seedling stage is lacking, especially in small-scale plots.MethodsOur research utilized structural equation models parameterized using data from a subtropical monsoon broad-leaved evergreen forest situated in Yunnan Province, China.ResultsWe noted that seedlings included plants that utilized both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. More seedling plots with the relatively higher species diversity were the product of the mixed mycorrhizal strategy, meaning the coexistence of AM and EM seedlings in a small-scale plot rather than the dominance of one type of strategies. These mixed communities were primarily found on slopes and mountain ridges. The abundance of AM or EM trees indirectly affected seedling diversity by influencing the abundance of different mycorrhizal seedlings. In this case, the diversity of the mixed mycorrhizal community was also restricted by the level of leaf thickness in the community, followed by abiotic factors such as elevation, convexity, soil pH and soil available phosphorus.DiscussionThe effect of leaf thickness on mycorrhizal seedling abundance reflected the importance of water conditions in shaping seedling communities. The effect of convexity on seedling diversity also reflected the limitation of seedling communities by the distribution of humidity and heat conditions during topographic change. The results suggested that it is crucial to preserve seedling diversity via the mixed mycorrhizal strategy of communities in the subtropical forest.</p

Image_1_Arbuscular mycorrhizal and ectomycorrhizal plants together shape seedling diversity in a subtropical forest.TIFF

IntroductionBurgeoning mycorrhizal research has focused on identifying the various diverse mycorrhizal strategies of forest communities. Mounting evidence suggests that mycorrhizae play important roles in regulating forest community structure and composition. However, research into the manifestation of this influence in the seedling stage is lacking, especially in small-scale plots.MethodsOur research utilized structural equation models parameterized using data from a subtropical monsoon broad-leaved evergreen forest situated in Yunnan Province, China.ResultsWe noted that seedlings included plants that utilized both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. More seedling plots with the relatively higher species diversity were the product of the mixed mycorrhizal strategy, meaning the coexistence of AM and EM seedlings in a small-scale plot rather than the dominance of one type of strategies. These mixed communities were primarily found on slopes and mountain ridges. The abundance of AM or EM trees indirectly affected seedling diversity by influencing the abundance of different mycorrhizal seedlings. In this case, the diversity of the mixed mycorrhizal community was also restricted by the level of leaf thickness in the community, followed by abiotic factors such as elevation, convexity, soil pH and soil available phosphorus.DiscussionThe effect of leaf thickness on mycorrhizal seedling abundance reflected the importance of water conditions in shaping seedling communities. The effect of convexity on seedling diversity also reflected the limitation of seedling communities by the distribution of humidity and heat conditions during topographic change. The results suggested that it is crucial to preserve seedling diversity via the mixed mycorrhizal strategy of communities in the subtropical forest.</p

Data_Sheet_1_Arbuscular mycorrhizal and ectomycorrhizal plants together shape seedling diversity in a subtropical forest.ZIP

IntroductionBurgeoning mycorrhizal research has focused on identifying the various diverse mycorrhizal strategies of forest communities. Mounting evidence suggests that mycorrhizae play important roles in regulating forest community structure and composition. However, research into the manifestation of this influence in the seedling stage is lacking, especially in small-scale plots.MethodsOur research utilized structural equation models parameterized using data from a subtropical monsoon broad-leaved evergreen forest situated in Yunnan Province, China.ResultsWe noted that seedlings included plants that utilized both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. More seedling plots with the relatively higher species diversity were the product of the mixed mycorrhizal strategy, meaning the coexistence of AM and EM seedlings in a small-scale plot rather than the dominance of one type of strategies. These mixed communities were primarily found on slopes and mountain ridges. The abundance of AM or EM trees indirectly affected seedling diversity by influencing the abundance of different mycorrhizal seedlings. In this case, the diversity of the mixed mycorrhizal community was also restricted by the level of leaf thickness in the community, followed by abiotic factors such as elevation, convexity, soil pH and soil available phosphorus.DiscussionThe effect of leaf thickness on mycorrhizal seedling abundance reflected the importance of water conditions in shaping seedling communities. The effect of convexity on seedling diversity also reflected the limitation of seedling communities by the distribution of humidity and heat conditions during topographic change. The results suggested that it is crucial to preserve seedling diversity via the mixed mycorrhizal strategy of communities in the subtropical forest.</p

Direct, indirect and total standardized effects on AGB based on structural equation models.

<p>Direct, indirect and total standardized effects on AGB based on structural equation models.</p

Summary of the general linear models (GLMs) for the relationships between the endogenous variables and predictor variables, each variable separately analyzed.

<p>Summary of the general linear models (GLMs) for the relationships between the endogenous variables and predictor variables, each variable separately analyzed.</p

The distribution of 112 plots inventoried in the <i>Pinus kesiya</i> primary forest by using ArcGIS 9.3(ESRI,Redlands,CA,USA;http://www.esri.com).

<p>The distribution of 112 plots inventoried in the <i>Pinus kesiya</i> primary forest by using ArcGIS 9.3(ESRI,Redlands,CA,USA;<a href="http://www.esri.com/" target="_blank">http://www.esri.com</a>).</p

Relationship between species richness and aboveground biomass in a primary <i>Pinus kesiya</i> forest.

<p>The red solid line is from multiple OLS regression by adding the cubic term. Gray shaded areas show 95% confidence interval of the fit.</p

Structural equation models linking aboveground biomass and species richness in the primary <i>Pinus kesiya</i> forest.

<p>(a) Effects of species richness, soil nutrient regime and stand age on aboveground biomass. (b) Effects of species richness, soil nutrient regime, stand age and climate moisture index on aboveground biomass. (c) and (d) The model with climate moisture index as the linking mechanism. The coefficients are standardized prediction coefficients indicate each path. Solid lines represent significant paths (<i>P</i><0.05) and dash lines indicate non-significant paths (<i>P</i>≥0.05).</p

Biomass allometric equations of each component of <i>Pinus kesiya</i> and other broadleaf species.

<p>Biomass allometric equations of each component of <i>Pinus kesiya</i> and other broadleaf species.</p

Changes in Biomass Carbon and Soil Organic Carbon Stocks following the Conversion from a Secondary Coniferous Forest to a Pine Plantation

<div><p>The objectives of this study were to estimate changes of tree carbon (C) and soil organic carbon (SOC) stock following a conversion in land use, an issue that has been only insufficiently addressed. For this study, we examined a chronosequence of 2 to 54-year-old <i>Pinus kesiya</i> var. <i>langbianensis</i> plantations that replaced the original secondary coniferous forest (SCF) in Southwest China due to clearing. C stocks considered here consisted of tree, understory, litter, and SOC (0–1 m). The results showed that tree C stocks ranged from 0.02±0.001 Mg C ha^-1 to 141.43±5.29 Mg C ha^-1, and increased gradually with the stand age. Accumulation of tree C stocks occurred in 20 years after reforestaion and C stock level recoverd to SCF. The maximum of understory C stock was found in a 5-year-old stand (6.74±0.7 Mg C ha^-1) with 5.8 times that of SCF, thereafter, understory C stock decreased with the growth of plantation. Litter C stock had no difference excluding effects of prescribed burning. Tree C stock exhibited a significant decline in the 2, 5-year-old stand following the conversion to plantation, but later, increased until a steady state-level in the 20, 26-year-old stand. The SOC stocks ranged from 81.08±10.13 Mg C ha^-1 to 160.38±17.96 Mg C ha^-1. Reforestation significantly decreased SOC stocks of plantation in the 2-year-old stand which lost 42.29 Mg C ha^-1 in the 1 m soil depth compared with SCF by reason of soil disturbance from sites preparation, but then subsequently recovered to SCF level. SOC stocks of SCF had no significant difference with other plantation. The surface profile (0–0.1 m) contained s higher SOC stocks than deeper soil depth. C stock associated with tree biomass represented a higher proportion than SOC stocks as stand development proceeded.</p></div