A challenge of phenological research is to integrate remotely sensed observations obtained at different spatial and temporal scales to provide information that contains both a high temporal density and fine spatial scale observations. This study aims to improve the level of spatial detail and the temporal density required for efficient monitoring of vegetation phenology by applying two remote sensing techniques, MODIS and digital camera images. Based on the vegetation indices extracted from each measurement, we analyzed phenological changes of vegetation and deduced phenophases transition dates, such as start dates of green-up and senescence by applying different two methods, the rate of change of curvature, K and HMV. The start and end of the growing season of Mongolian oak expressed in ExG-DC, which were extracted from digital camera image, were agreed well with that of visual assessment. EVI among three vegetation indices (EVI, NDVI and ExG-MI) showed the high correlation with ExG-DC and visual assessment. Based on RMSE, the transition dates assessed by visual observation were agreed better with the dates, which were estimated based on curvature K than with the dates estimated from HMV in all vegetation indices. Sap flow time-series estimates for the phenological transition dates were closely accorded with the estimates derived from near-surface time-series, and coincided better with the dates estimated based on curvature K than that based on HMV. In conclusion, based on the result of this study, we suggest that it is effective to use EXG-DC obtained from digital camera and EVI from MODIS when these two instrument are integrated as the vegetation indices and that curvature K is an effective method for extracting the phenological event dates of vegetation.

This study aims to monitor spatiotemporal changes of spring phenology using the green-up start dates based on the accumulated growing degree days (AGDD) and the enhanced vegetation index (EVI), which were deducted from moderate resolution imaging spectroradiometer (MODIS) land surface temperature (LST) data. The green-up start dates were extracted from the MODIS-derived AGDD and EVI for 30 Mongolian oak (Quercus mongolica Fisch.) stands throughout South Korea. The relationship between green-up day of year needed to reach the AGDD threshold (DoYAGDD) and air temperature was closely maintained in data in both MODIS image interpretation and from 93 meteorological stations. Leaf green-up dates of Mongolian oak based on the AGDD threshold obtained from the records measured at five meteorological stations during the last century showed the same trend as the result of cherry observed visibly. Extrapolating the results, the spring onset of Mongolian oak and cherry has become earlier (14.5 ± 4.3 and 10.7 ± 3.6 days, respectively) with the rise of air temperature over the last century. The temperature in urban areas was consistently higher than that in the forest and the rural areas and the result was reflected on the vegetation phenology. Our study expanded the scale of the study on spring vegetation phenology spatiotemporally by combining satellite images with meteorological data. We expect our findings could be used to predict long-term changes in ecosystems due to climate change.

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The Changwon and Nam streams that run through the Changwon city were evaluated based on longitudinal and horizontal configurations and vegetation state in order to prepare a restoration plan. Riparian vegetation of the Changwon and Nam streams are normally dominated by herbaceous plants. However, the woody plants, Salix pseudolasiogyne, Rubus parvifolius, Salix koreensis, Robinia pseudoacacia, and Amorpha fruticosa have appeared. Planting to introduce various types of plants for landscape architecture has also been observed. Evaluation of naturalness based on the vegetation state of both Changwon and Nam streams showed very low naturalness of degree 1 or 2, with the exception of a few reaches of the upstream sector. In these few reaches of the upstream sector, Salix koreensis and Salix chaenomeloides showed heights at the subtree level, however, they were located at the position of shrubland close to the waterway. These reaches were, therefore, evaluated as degree 3 rather than degree 4 in naturalness. The result of diagnostic evaluation classified by reach indicated the requirement for active restoration, such as transformation of the channelized stream into a meandering one and a step-type cross section into a pool-type one, introduction of vegetation suitable to the region and site, and creation of an ecological network between the stream and the surrounding terrestrial ecosystems.

This study was conducted to clarify the changes in vegetation that occurred due to changing environmental factors, especially climate, at Korean fir (Abies koreana) stands with different climatic conditions established on Mt. Halla, which is located on a southern island of South Korea. The difference of species composition between sites was large and depended on elevation and slope aspect at lower elevations, whereas not as much among stands or between sites at the highest elevations of each slope aspect. It was interpreted that differences and similarities among sites were dominated by the microclimate determined by the topographic conditions of each site. The result of vegetation dynamics analysis predicted that the Korean fir forests would be replaced by temperate forests such as Mongolian oak (Quercus mongolica) forests or shade intolerant forests composed of early successional species such as Korean cherry (Prunus maximowiczii) and Spreading yew (Taxus cuspidata) at lower elevations, while would continuously persist at the highest elevations. We interpreted the vegetation changes appeared at the lower elevations as an allogenic succession, as the recent rapid climate changes directly and indirectly dominated the change. The species distribution modeling predicted that the distributional range of Korean fir would decrease to 13.4 and 10.1% of the current distribution in 2050 and 2070, respectively. Further, the distribution modeling showed that the sites located at lower elevations would no longer be within the distributional range of Korean fir forest, and those at the highest elevations would be sparsely scattered in fragmented states.