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In order to understand the aerosol exchange dynamics between the atmosphere and a peri-urban forest ecosystem located in the Po Valley, a region characterized by high PM concentrations, eddy covariance (EC) aerosol fluxes were measured between September and December 2017. The aerosol sampling, performed with an Electrical Low Pressure Impactor (ELPI +, DEKATI), involved a wide range of particle sizes including both ultrafine and fine aerosol. The monitoring campaign comprised a period with leaves (PL) and a period without leaves (PNL) to assess their influence on the emission and deposition fluxes. The diurnal profiles of particle number (PN) fluxes associated to the geometric mean diameters (GMD) of 0.02 µm and 0.48 µm were chosen as representative of the behaviour of ultrafine and fine particles, respectively. Fluxes of ultrafine particles showed a net emission pattern both in PL and PNL assuming values up to 5.6 106 m−2 s−1 and 4.5·106 m−2 s−1, respectively. Instead, fine particles fluxes showed a net deposition pattern in PL, assuming values up to −1.1 · 106 m−2 s−1, while in PNL a slight emission up to 4.1 ·105 m−2 s−1 occurred. The behaviour of the fluxes of the cumulative classes PM0.1 and PM1 was similar to the one of the PN fluxes of ultrafine and fine aerosol, respectively. Deposition velocities were calculated for PL and PNL depending on the atmospheric stability class. The values emerged from this study (from −0.25 cm s−1 up to 0.12 cm s−1) evidenced that under stable and very stable atmospheric conditions all size classes presented negative or slightly positive deposition velocities both in PL and PNL. Instead under unstable conditions fine particles showed deposition velocities whose direction changed in the two periods (PL and PNL).

Structural complexity and local biodiversity of species-rich tropical forests can be characterized by their spatial patterns, which contribute to species intra- and interspecific interactions. Aiming to describe spatial patterns of species at fine spatial scales, we applied the quantitative analyses based on the relationships of nearest neighbors of conspecific and heterospecific trees. In a two-hectare plot of a tropical broadleaved forest stand in central Vietnam with minimal human influence, all tree individuals with diameter at breast height ≥ 2.5 cm were mapped and their characteristics were recorded. We applied two different types of analyses: (1) Intraspecific structural characteristics using nearest neighbor statistics; (2) overall interspecific associations through a classification scheme based on bivariate nearest neighbor distribution function D12(r) and Ripley’s K function K12(r). The findings showed that: (1) Most of studied species in the forest were highly mixed with other species, while conspecifics were regular to aggregated distribution at small spatial scales. Tree individuals with different diameter values were surrounded by heterospecific trees; (2) The majority of 306 species-species pairs showed spatial independence (66.7%), whereas 29.8% of all species showed an overall positive association and negative association consisted only a small percentage (3.5%) up to spatial scales of 50 m. We found significant evidences of the main ecological theories such as dispersal limitation, Neutral theory, Janzen-Connell hypothesis, and other effects like the stochastic dilution. We suggest using both the bivariate distribution of the structural parameters and the spatial point pattern analysis based on nearest neighbor distance as advantageous approaches for further understanding of population structure, as well as discovering and protecting biodiversity in the future.

While a large sum of timber stock in private forests, especially broadleaved forests, has been ignored by their owners, a rising global concern about climate change and ecosystems has led to a renewed interest in natural broadleaved forest management strategies. This study establishes the forest growth model for the natural broadleaved forest of Gangwon-do based on the matrix model developed by Buongiorno and Michie. The matrix model by Buongiorno and Michie has been widely applied to study forest population dynamics, especially for uneven-aged forests. To develop an existing matrix model, our approach applies transitional probabilities of forest stands which are calibrated using National Forest Inventory data. Both long and short-term predicted simulation results show that the predicted average tree density and diameter distribution from our model are very close to the stand density and diameter distribution from observed data. Although the model simplifies reality, the results from our study confirm that our models are valid enough to predict the average stand status of the broadleaved forests in Gangwon-do.

A 425 cm core has been collected from the Gantang subalpine peat bog, in Pingnan County, Fujian Province of Southern China. High-resolution pollen analysis of the core has allowed for the reconstruction of past vegetation and climate changes over the last 50,000 years. Today, Fujian province is located in the eastern part of middle subtropical zone where the dominant vegetation is evergreen broadleaved forest that receives its precipitation from the East Asian Monsoon. The pollen record testifies that the vegetation in Fujian varied between subtropical evergreen and warm temperate deciduous forests during the last glacial-interglacial cycle. It appears that during Marine Oxygen Isotope Stage 3, this area was covered with broadleaved forest suggesting warm and wet subtropical condition, whereas the flora was quite different with many ancient elements. The Last Glacial Maximum is distinguished by an increase in warm temperate deciduous taxa, particularly Fagus and Alnus accompanied by abundant Ericaceae, implying a spatial shift of zonal vegetation during this coldest episode in the world. Local swamp developed soon after the Younger Dryas event coinciding with the formation of peatlands in the Northern Hemisphere possibly linked with atmospheric carbon accumulation. A rapid increase in evergreen broadleaved taxa that dominated the local forest occurred at ~ ca. 8.2 cal ka BP, indicating the inception of the regional thermal maximum during the Holocene, which was generally characterised by more humid conditions. The middle to late Holocene sees a progressive decline in arboreal elements, and an increase in grasses and Ericaceae. These changes beginning from around 4 ka cal BP were concordant with the general weakening of the East Asian Monsoon during the Holocene, corresponding with an orbitally induced reduction of boreal summer insolation. This is the first terrestrial high-resolution record from eastern part of middle subtropical areas that evaluates the forest changes through the last glacial-interglacial cycle.