Comparison of vegetation patch dynamics after the eruptions of the volcano Mount Usu, northern Japan, in 1977-1978 and 2000, detected by imagery chronosequence

Vegetation patch dynamics were analyzed to detect vegetation development patterns after eruptions on two sites (summit destroyed in 1977-1978, and a foothill, Konpira destroyed in 2000) on the volcano Mount Usu, in northern Japan. Aerial photos and satellite images taken in 2000, 2006, and 2014 were used to develop an imagery chronosequence of vegetation patch dynamics. Vegetation patches were identified by the Normalized Difference Vegetation Index (NDVI) for satellite images, and by the Normalized Green-Red Difference Index (NGRDI) for aerial photos. We categorized the vegetation patch types based on whether the patches overlapped (touching) or not (isolated) with the future vegetation patches and whether their area increased (growing) or decreased (shrinking). Afterwards, patch dynamics were compared between the two sites through changes in patch types, dense vegetation, and patch growth with slope degree, elevation, and time. Isolated patches were established more at the summit and showed high mortality, while at Konpira most isolated patches survived until 2006 and merged into touching patches by 2014. Moreover, the vegetation density of patches was higher at Konpira than at the summit. Patch growth was associated with patch types at both sites. However, the time was more important for the patch dynamics at the summit, and the vegetation density affected the dynamics more at Konpira. Therefore, the two sites had different vegetation patch dynamics, which were related to the characteristics of topography and eruptions. In conclusion, the imagery chronosequence proposed in this study monitored patch dynamics well, and patches developed faster at Konpira

Remote sensing of forest diversities : the effect of image resolution and spectral plot extent

Detecting field diversities via remote sensing is becoming important to monitor vegetation dynamics at large scale. The characteristics of the remotely sensed image, depending on the study organism and habitat, affect the efficiency of measuring alpha-and beta-diversities. Therefore, we examined the impact of image resolutions and spectral plot extents on the accuracy of estimating forest alpha-diversities and compositional variances on the active volcano Mount Usu, northern Japan. Low- (3.2 m) and high-resolution (0.8 m) IKONOS multispectral images were used to create spectral indicators from pixels covering the field plots (narrow extent) and from pixels including neighbouring area (wide extent). Six forest diversity indices were obtained for canopy and for canopy-herb layer (total diversity): species richness (S), Shannon (H'), evenness (J'), Gini-Simpson (D), and true diversity of order 1 (N (1) = expH') and order 2 (N (2) = 1/D). Changes in species composition were assessed by dissimilarity matrices. The spectral diversity indicators were calculated from the combination of image resolutions and spectral plot extents, and then compared with field diversities. The low-resolution-narrow extent based spectral indicators showed the highest correlations with canopy and total diversities. The best spectral indicators were derived from the scores of the first axis of principal component analysis and from the near infrared band, reaching high correlations with both canopy and total field diversity indices. Of the six field diversities, J' showed the highest correlations with single spectral indicators, and N (1, 2) showed the highest correlations with pairs of spectral indicators. The correlations between spectral and field dissimilarities were lower than the correlations between alpha-diversities and spectral indicators, and were unaffected by the resolution and extent. In conclusion, the best spectral indicators were obtained from the low-resolution-narrow extent combination, and the indicators estimated canopy and total field diversity indices of temperate forests equally

Differences in canopy and understorey diversities after the eruptions of Mount Usu, northern Japan-Impacts of early forest management

Evaluating the effects of management on successional trajectories, plant composition, and diversity has been difficult due to the scarcity of long-term studies. This study examined the composition and diversity of species in natural and artificially regenerated forests at two eruption sites of Mount Usu, northern Japan, during 2015-2019, to compare the effects of active and passive management. The two sites are Yosomi, damaged by the 1910 eruptions, and the summit, damaged by the 1977-78 eruptions. Various natural and artificial forests developed at both sites, whose species composition was analyzed by non-metric multidimensional scaling to measure similarity between the forest types, and whose diversity was compared by the true diversity index, showing the effective number of species, from order 0 (presence-absence) to order 2 (weighted species) for two layers: the canopy (woody species with DBH > 3 cm) and understorey (< 2 m high plants). Canopy diversity was measured by stem density in five 10 m x 10 m plots in each forest type, and understory diversity was measured by shoot density in four 1 m x 1 m quadrats in each plot. The canopy and understorey species compositions were distinct between the forest types, but the canopy was more affected by management than the understorey, indicating that early forest management had long-term effects on species composition. Species composition of the plantations resembled those of the natural forests when the plantations had patchy spatial structure. The naturally regenerated forests showed the highest diversities at both eruption sites, while the plantations dis -played low diversities, except in one case, when the plantation showed heterogeneous forest structure. The plantations changed their species composition slowly and did not transform into natural forests. In conclusion, we suggest using a patchy plantation design with some space between patches instead of dense planting, to create resilient, diverse, and native forests after disturbances

Egy útfejlesztés várható hatásai - Az M44-es autóút várható gazdaságfejlesztési hatása Békés megyére 2041-ig

INST: Szakdolgozatok (Közgazdaságtudományi Intézet