Relationship between the Decomposition Process of Coarse Woody Debris and Fungal Community Structure as Detected by High-Throughput Sequencing in a Deciduous Broad-Leaved Forest in Japan

<div><p>We examined the relationship between the community structure of wood-decaying fungi, detected by high-throughput sequencing, and the decomposition rate using 13 years of data from a forest dynamics plot. For molecular analysis and wood density measurements, drill dust samples were collected from logs and stumps of <i>Fagus</i> and <i>Quercus</i> in the plot. Regression using a negative exponential model between wood density and time since death revealed that the decomposition rate of <i>Fagus</i> was greater than that of <i>Quercus</i>. The residual between the expected value obtained from the regression curve and the observed wood density was used as a decomposition rate index. Principal component analysis showed that the fungal community compositions of both <i>Fagus</i> and <i>Quercus</i> changed with time since death. Principal component analysis axis scores were used as an index of fungal community composition. A structural equation model for each wood genus was used to assess the effect of fungal community structure traits on the decomposition rate and how the fungal community structure was determined by the traits of coarse woody debris. Results of the structural equation model suggested that the decomposition rate of <i>Fagus</i> was affected by two fungal community composition components: one that was affected by time since death and another that was not affected by the traits of coarse woody debris. In contrast, the decomposition rate of <i>Quercus</i> was not affected by coarse woody debris traits or fungal community structure. These findings suggest that, in the case of <i>Fagus</i> coarse woody debris, the fungal community structure is related to the decomposition process of its host substrate. Because fungal community structure is affected partly by the decay stage and wood density of its substrate, these factors influence each other. Further research on interactive effects is needed to improve our understanding of the relationship between fungal community structure and the woody debris decomposition process.</p></div

SEM analysis results of the decomposition rate index of <i>Fagus</i> CWD.

<p>Numbers beside the arrows represent path coefficients. All paths included in the analysis are presented. Straight single-headed arrows represent causal pathways. Curved, double-headed arrows indicate covarying variables. Thick, straight, black arrows indicate significant causal pathways at the level of <i>p</i> < 0.05. Thick, gray, curved arrows indicate significant covarying relationships at the level of <i>p</i> < 0.05. Dashed, straight, curved arrows indicate non-significance (<i>p</i> > 0.05).</p

Results of the PCA ordination of individual pieces of <i>Fagus</i> CWD and fungal OTUs.

<p>Fungal OTUs are presented by subdivision or class to avoid redundancy.</p

Two-way cluster analysis of fungal OTUs and both <i>Fagus</i> and <i>Quercus</i> CWDs.

<p>Each row represents a CWD, and each column represents an OTU. Columns are clustered according to the abundance of OTUs on CWDs, whereas rows are clustered according to the composition of OTUs. Numbers in the heat map show the matrix coding values, which were relative percent abundance within the matrix.</p

Results of the SEM analysis of the decomposition rate index of <i>Quercus</i> CWD.

<p>See the legend of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0131510#pone.0131510.g005" target="_blank">Fig 5</a> for an explanation of the values and arrows.</p

Results of the PCA ordination of individual pieces of <i>Quercus</i> CWD and fungal OTUs.

<p>Fungal OTUs are presented by subdivision or class to avoid redundancy.</p

Succession Influences Wild Bees in a Temperate Forest Landscape: The Value of Early Successional Stages in Naturally Regenerated and Planted Forests

<div><p>In many temperate terrestrial forest ecosystems, both natural human disturbances drive the reestablishment of forests. Succession in plant communities, in addition to reforestation following the creation of open sites through harvesting or natural disturbances, can affect forest faunal assemblages. Wild bees perform an important ecosystem function in human-altered and natural or seminatural ecosystems, as they are essential pollinators for both crops and wild flowering plants. To maintain high abundance and species richness for pollination services, it is important to conserve and create seminatural and natural land cover with optimal successional stages for wild bees. We examined the effects of forest succession on wild bees. In particular, we evaluated the importance of early successional stages for bees, which has been suspected but not previously demonstrated. A range of successional stages, between 1 and 178 years old, were examined in naturally regenerated and planted forests. In total 4465 wild bee individuals, representing 113 species, were captured. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056678#s3">Results</a> for total bees, solitary bees, and cleptoparasitic bees in both naturally regenerated and planted conifer forests indicated a higher abundance and species richness in the early successional stages. However, higher abundance and species richness of social bees in naturally regenerated forest were observed as the successional stages progressed, whereas the abundance of social bees in conifer planted forest showed a concave-shaped relationship when plotted. The results suggest that early successional stages of both naturally regenerated and conifer planted forest maintain a high abundance and species richness of solitary bees and their cleptoparasitic bees, although social bees respond differently in the early successional stages. This may imply that, in some cases, active forest stand management policies, such as the clear-cutting of planted forests for timber production, would create early successional habitats, leading to significant positive effects for bees in general.</p> </div

Effects of different successional stages on the abundance and species richness of bees, showing total (A and B), social (C and D), solitary (E and E), and cleptoparasitic (G and H) assemblages, in naturally regenerated and conifer (<i>Cryptomeria japonica</i>) planted forests.

<p>Y axes indicate the numbers of collected individuals for abundance and the number of collected species for species richness, respectively. Solid circles represent naturally regenerated forest, and open circles represent planted conifer forest.</p

Model comparisons, for the abundance and species richness of bee groups (all, social bees, solitary bees, and cleptoparasitic assemblages) in natural regenerated forest.

<p>The table shows values of AIC and of ΔAIC calculated as the difference from AIC values of the null models.</p

Unmanned Aerial Survey of Fallen Trees in a Deciduous Broadleaved Forest in Eastern Japan

<div><p>Since fallen trees are a key factor in biodiversity and biogeochemical cycling, information about their spatial distribution is of use in determining species distribution and nutrient and carbon cycling in forest ecosystems. Ground-based surveys are both time consuming and labour intensive. Remote-sensing technology can reduce these costs. Here, we used high-spatial-resolution aerial photographs (0.5–1.0 cm per pixel) taken from an unmanned aerial vehicle (UAV) to survey fallen trees in a deciduous broadleaved forest in eastern Japan. In nine sub-plots we found a total of 44 fallen trees by ground survey. From the aerial photographs, we identified 80% to 90% of fallen trees that were >30 cm in diameter or >10 m in length, but missed many that were narrower or shorter. This failure may be due to the similarity of fallen trees to trunks and branches of standing trees or masking by standing trees. Views of the same point from different angles may improve the detection rate because they would provide more opportunity to detect fallen trees hidden by standing trees. Our results suggest that UAV surveys will make it possible to monitor the spatial and temporal variations in forest structure and function at lower cost.</p></div