16:33 〜 16:48
[U04-05] Geodiversity loss in the Anthropocene and its impact on biodiversity
★招待講演
キーワード：biodiversity、geodiversity、fossil landform、disaster prevention、disturbance-dependent species
Geodiversity encompasses a range of geological, geomorphological, soil, hydrological, and sometimes topoclimatic features. Of these, geomorphological features (landforms and geomorphic processes) play a crucial role in illustrating the relationship between biodiversity and geodiversity. In this paper, I discuss geodiversity while focusing on landforms.
Different aspects of the relationship between geodiversity and biodiversity are highlighted at different time scales when the two are considered based on the relationship between landforms and vegetation. For example, in the Kamikochi area of central Japan, uplift and igneous activity were crucial in the formation of the landforms at a scale of millions to tens of millions of years. These processes determined the arrangement of the main ridges and the valley through which the Azusa River flows, as well as the slope relief energy. The process of landform formation at this scale may have affected species dispersal and contributed to shaping the regional species’ characteristics and phylogeny. At the scale of thousands to hundreds of thousands of years, glacial and periglacial processes and the accompanying climatic changes are noteworthy; they shaped landforms in the high-elevation areas in the Kamikochi area. The current distribution of alpine plant communities and the location of forest limits correspond to the microlandforms created through these processes; the diversity of the landforms contributes to the diversity of the vegetation. At the scale of years to hundreds of years, volcanic processes, mass movements, and fluvial processes are important; they form landforms, which acts as disturbance to vegetation, promoting diversity including a variety of succession stages.
Kamikochi area's landscape consists of fossil and active landforms based on the formation process. Fossil landforms, such as glacial (e.g., cirques and U-shaped valleys) and periglacial (e.g., rock glaciers and periglacial smooth slopes) features, are formed when the process is no longer active or only locally active. Active landforms, including volcanic, landslide, and fluvial features, occur at lower elevations and continue to generate new landforms; in the case of high-frequency processes, such as fluvial processes, the land surface continues to be regenerated even during the Anthropocene period. The existing landforms, fossil or active, continue to be deformed by slope and fluvial processes.
Human activities in the Anthropocene have different impacts on fossil and active landforms in terms of the mechanisms of loss of geodiversity and related biodiversity. Fossil landforms can provide habitat for glacial relict species; therefore, landform loss due to development in the Anthropocene may directly lead to biodiversity loss. Fortunately, in Kamikochi, such landforms are at high elevations, away from human activity; thus, the anthropogenic loss of landforms has been minimal. However, active landforms provide habitats for disturbance-dependent species when surface regenerations are frequent. Controlling processes to prevent landform changes leads to loss of biodiversity. Since the low-elevation areas where frequent fluvial landforms are distributed overlap with human-populated areas, construction for geomorphic-process control is often conducted to prevent disasters. It is necessary to consider development and disaster prevention methods that consider minimizing the loss of geodiversity and related biodiversity.
Different aspects of the relationship between geodiversity and biodiversity are highlighted at different time scales when the two are considered based on the relationship between landforms and vegetation. For example, in the Kamikochi area of central Japan, uplift and igneous activity were crucial in the formation of the landforms at a scale of millions to tens of millions of years. These processes determined the arrangement of the main ridges and the valley through which the Azusa River flows, as well as the slope relief energy. The process of landform formation at this scale may have affected species dispersal and contributed to shaping the regional species’ characteristics and phylogeny. At the scale of thousands to hundreds of thousands of years, glacial and periglacial processes and the accompanying climatic changes are noteworthy; they shaped landforms in the high-elevation areas in the Kamikochi area. The current distribution of alpine plant communities and the location of forest limits correspond to the microlandforms created through these processes; the diversity of the landforms contributes to the diversity of the vegetation. At the scale of years to hundreds of years, volcanic processes, mass movements, and fluvial processes are important; they form landforms, which acts as disturbance to vegetation, promoting diversity including a variety of succession stages.
Kamikochi area's landscape consists of fossil and active landforms based on the formation process. Fossil landforms, such as glacial (e.g., cirques and U-shaped valleys) and periglacial (e.g., rock glaciers and periglacial smooth slopes) features, are formed when the process is no longer active or only locally active. Active landforms, including volcanic, landslide, and fluvial features, occur at lower elevations and continue to generate new landforms; in the case of high-frequency processes, such as fluvial processes, the land surface continues to be regenerated even during the Anthropocene period. The existing landforms, fossil or active, continue to be deformed by slope and fluvial processes.
Human activities in the Anthropocene have different impacts on fossil and active landforms in terms of the mechanisms of loss of geodiversity and related biodiversity. Fossil landforms can provide habitat for glacial relict species; therefore, landform loss due to development in the Anthropocene may directly lead to biodiversity loss. Fortunately, in Kamikochi, such landforms are at high elevations, away from human activity; thus, the anthropogenic loss of landforms has been minimal. However, active landforms provide habitats for disturbance-dependent species when surface regenerations are frequent. Controlling processes to prevent landform changes leads to loss of biodiversity. Since the low-elevation areas where frequent fluvial landforms are distributed overlap with human-populated areas, construction for geomorphic-process control is often conducted to prevent disasters. It is necessary to consider development and disaster prevention methods that consider minimizing the loss of geodiversity and related biodiversity.