Long-term and multidisciplinary research networks on biodiversity and terrestrial ecosystems: findings and insights from Takayama super-site, central Japan

Muraoka Hiroyuki,Saitoh Taku M.,Murayama Shohei 한국생태학회 2023 Journal of Ecology and Environment Vol.47 No.4

Growing complexity in ecosystem structure and functions, under impacts of climate and land-use changes, requires interdisciplinary understandings of processes and the whole-system, and accurate estimates of the changing functions. In the last three decades, observation networks for biodiversity, ecosystems, and ecosystem functions under climate change, have been developed by interested scientists, research institutions and universities. In this paper we will review (1) the development and on-going activities of those observation networks, (2) some outcomes from forest carbon cycle studies at our super-site “Takayama site” in Japan, and (3) a few ideas how we connect in-situ and satellite observations as well as fill observation gaps in the Asia-Oceania region. There have been many intensive research and networking efforts to promote investigations for ecosystem change and functions (e.g., Long-Term Ecological Research Network), measurements of greenhouse gas, heat, and water fluxes (flux network), and biodiversity from genetic to ecosystem level (Biodiversity Observation Network). Combining those in-situ field research data with modeling analysis and satellite remote sensing allows the research communities to up-scale spatially from local to global, and temporally from the past to future. These observation networks oftern use different methodologies and target different scientific disciplines. However growing needs for comprehensive observations to understand the response of biodiversity and ecosystem functions to climate and societal changes at local, national, regional, and global scales are providing opportunities and expectations to network these networks. Among the challenges to produce and share integrated knowledge on climate, ecosystem functions and biodiversity, filling scale-gaps in space and time among the phenomena is crucial. To showcase such efforts, interdisciplinary research at ‘Takayama super-site’ was reviewed by focusing on studies on forest carbon cycle and phenology. A key approach to respond to multidisciplinary questions is to integrate in-situ field research, ecosystem modeling, and satellite remote sensing by developing crossscale methodologies at long-term observation field sites called “super-sites”. The research approach at ‘Takayama site’ in Japan showcases this response to the needs of multidisciplinary questions and further development of terrestrial ecosystem research to address environmental change issues from local to national, regional and global scales.

A3 Foresight Program special issue: carbon studies in forested ecosystems

손요환,Hiroyuki Muraoka,Jingyun Fang 한국산림과학회 2012 Forest Science And Technology Vol.8 No.2

Experimental warming studies on tree species and forest ecosystems: a literature review

Chung, Haegeun,Muraoka, Hiroyuki,Nakamura, Masahiro,Han, Saerom,Muller, Onno,Son, Yowhan Springer-Verlag 2013 Journal of plant research Vol.126 No.4

Vegetation Classification Using Seasonal Variation MODIS Data

최현아,이우균,손요환,Toshiharu Kojima,Hiroyuki Muraoka 대한원격탐사학회 2010 大韓遠隔探査學會誌 Vol.26 No.6

The role of remote sensing in phenological studies is increasingly regarded as a key in understanding large area seasonal phenomena. This paper describes the application of Moderate Resolution Imaging Spectroradiometer (MODIS) time series data for vegetation classification using seasonal variation patterns. The vegetation seasonal variation phase of Seoul and provinces in Korea was inferred using 8 day composite MODIS NDVI (Normalized Difference Vegetation Index) dataset of 2006. The seasonal vegetation classification approach is performed with reclassification of 4 categories as urban, crop land, broad-leaf and needle-leaf forest area. The BISE (Best Index Slope Extraction) filtering algorithm was applied for a smoothing processing of MODIS NDVI time series data and fuzzy classification method was used for vegetation classification. The overall accuracy of classification was 77.5% and the kappa coefficient was 0.61%, thus suggesting overall high classification accuracy.

Examination of the extinction coefficient in the Beer–Lambert law for an accurate estimation of the forest canopy leaf area index

Taku M. Saitoh,Shin Nagai,Hibiki M. Noda,Hiroyuki Muraoka,Kenlo Nishida Nasahara 한국산림과학회 2012 Forest Science And Technology Vol.8 No.2

Leaf area index (LAI) is a crucial ecological parameter that represents canopy structure and controls many ecosystem functions and processes, but direct measurement and long-term monitoring of LAI are difficult, especially in forests. An indirect method to estimate the seasonal pattern of LAI in a given forest is to measure the attenuation of photosynthetically active radiation (PAR) by the canopy and then calculate LAI by the Beer–Lambert law. Use of this method requires an estimate of the PAR extinction coefficient (k), a parameter needed to calculate PAR attenuation. However, the determination of k itself requires direct measurement of LAI over seasons. Our goals were to determine (1) the best way to model k values that may vary seasonally in a forest, and (2) the sensitivity of estimates of canopy ecosystem functions to the errors in estimated LAI. We first analyzed the seasonal pattern of the ‘‘true’’ k (k_p) under cloudy and sunny conditions in a Japanese deciduous broadleaved forest by using the inverted form of the Beer–Lambert law with the true LAI and PAR. We next calculated the errors of PAR-based LAIs estimated with an assumed constant k (LAI_pred) and determined under what conditions we should expect k to be approximately constant during the growing period. Finally, we examined the effect of errors in LAI_pred on estimates of gross primary production (GPP), net ecosystem production (NEP), and latent heat flux (LE) calculated with a land-surface model using LAI_pred as an input parameter. During the growing period, cloudy kp varied from 0.47 to 1.12 and sunny kp from 0.45 to 1.59. Results suggest that the value of LAI_pred was adequately estimated with the k_p obtained under cloudy conditions during the fully-leaved period (0.53–0.57). However, LAI_pred was overestimated by up to 0.6 m2 m–2 inMay and November. The errors in LAIpred propagated to errors in modeled carbon and latent heat fluxes of –0.21 to 0.32 g C m^–2 day^–1 in GPP, –0.09 to 0.19 g C m^–2 day^–1 in NEP, and –3.2 to 3.9 Wm^–2 in LE, which is close to the measurement errors recognized in the tower flux measurement. LAI_pred estimated with an assumed constant k can be useful for some ecosystem studies as a second-best alternative if k is equated to the value of k_p measured under cloudy conditions especially during the fully-leaved period.

The necessity and availability of noise-free daily satellite-observed NDVI during rapid phenological changes in terrestrial ecosystems in East Asia

Shin Nagai,Taku M. Saitoh,Rikie Suzuki,Kenlo Nishida Nasahara,이우균,손요환,Hiroyuki Muraoka 한국산림과학회 2011 Forest Science And Technology Vol.7 No.4

General, global, long-term, and comprehensive phenological observations are required to evaluate the variability of photosynthetic activities due to environmental changes in terrestrial ecosystems. The observation of seasonal changes and detection of interannual variation in canopy phenology over regional and global scales require satellite data with high temporal resolution (i.e. a daily time step). However, satellite data often include noise caused by snow cover on vegetation, cloud contamination, and atmospheric aerosols. To accurately detect the timing of leaf-expansion and leaf-fall, which occur rapidly, and their rates, it is necessary to examine the observational frequency of noise-free satellite-observed vegetation index data during each phenological period. In this study, we investigated the spatiotemporal distribution of the number of observational days (NUMdays) in the Terra/MODIS (Moderate Resolution Imaging Spectroradiometer)-observed daily high-quality normalized difference vegetation index (NDVIhigh) data with no effects of snow cover, cloud contamination, or atmospheric noise. These data were examined for each month over 10 years in the various ecosystems of East Asia. To ground-truth the relationship between the Terra/MODISobserved daily NDVIhigh data and canopy surface images, we performed a long-term continuous field study in a cooltemperate deciduous broad-leaved forest in central Japan. During the leaf-expansion and leaf-fall periods, the NUMdays for NDVIhigh data in southern Russia, northeastern China, the Tibetan Plateau, Korea, and maritime Japan was about 3–7 for each month. The NUMdays for NDVIhigh data exceeded 10 for each month in arid regions during the growing season and in the subtropical region including northeastern India, Myanmar, and southwestern China during the dry season. In contrast, the NUMdays for NDVIhigh data was almost 0 for each month in southeastern China throughout the year and in the subtropical region during the southeastern monsoon season (July and August). By considering observations from both the Terra/MODIS and Aqua/MODIS satellites, the NUMdays for NDVIhigh data in the deciduous broad-leaved forest in Japan was increased by 40% compared with only Terra/MODIS satellite observations. Our findings indicate that daily NDVI data from multiple satellites detect the seasonal changes in the various ecosystems of East Asia more accurately than 8-day or biweekly composite NDVI data.

Seasonal variability of soil respiration in multiple ecosystems under the same physical–geographical environmental conditions in central Japan

Tomoharu Inoue,Shin Nagai,Shota Inoue,Masahiro Ozaki,Shohei Sakai,Hiroyuki Muraoka,Hiroshi Koizumi 한국산림과학회 2012 Forest Science And Technology Vol.8 No.2

We investigated the relationships between soil respiration and environmental factors during foliation and defoliation periods in three ecosystems under the same physical–geographical environmental conditions in central Japan. These ecosystems comprised deciduous broad-leaved forest (Quercus crispula dominated, site Q), deciduous needle-leaved forest (Larix kaempferi dominated, site L), and grassland (Zoysia japonica dominated, site Z). Field measurements of soil respiration were made using a closed chamber method with an infrared gas analyzer at monthly intervals in the snow-free seasons from May 2010 to November 2011. Soil respiration began to increase in May, peaked rapidly in summer (July to September), and decreased in November. The seasonal patterns of soil respiration and soil temperature were nearly parallel among the three sites, with one exception, which may have been caused by the decrease in soil water content during summer months (July to September). Although Q_10 values based on the entire measurement period in 2010 were roughly the same as those in 2011 at the three sites, there was a large difference in Q_10 between the foliation and defoliation periods in both years, especially at the two forest sites. These differences among the three sites may be caused by differences in soil temperature dynamics and precipitation activity. To better understand the relationship between soil respiration and environmental factors, continuous observations are needed of soil respiration, environmental factors, and biological activities both below ground and above ground under the same physical–geographical environmental conditions.

Vegetation Classification Using Seasonal Variation MODIS Data

Choi, Hyun-Ah,Lee, Woo-Kyun,Son, Yo-Whan,Kojima, Toshiharu,Muraoka, Hiroyuki The Korean Society of Remote Sensing 2010 大韓遠隔探査學會誌 Vol.26 No.6

The role of remote sensing in phenological studies is increasingly regarded as a key in understanding large area seasonal phenomena. This paper describes the application of Moderate Resolution Imaging Spectroradiometer (MODIS) time series data for vegetation classification using seasonal variation patterns. The vegetation seasonal variation phase of Seoul and provinces in Korea was inferred using 8 day composite MODIS NDVI (Normalized Difference Vegetation Index) dataset of 2006. The seasonal vegetation classification approach is performed with reclassification of 4 categories as urban, crop land, broad-leaf and needle-leaf forest area. The BISE (Best Index Slope Extraction) filtering algorithm was applied for a smoothing processing of MODIS NDVI time series data and fuzzy classification method was used for vegetation classification. The overall accuracy of classification was 77.5% and the kappa coefficient was 0.61%, thus suggesting overall high classification accuracy.

Vegetation Classification Using Seasonal Variation MODIS Data

Hyun Ah Choi,Woo Kyun Lee,Yo Whan Son,Toshiharu Kojima,Hiroyuki Muraoka 大韓遠隔探査學會 2010 大韓遠隔探査學會誌 Vol.26 No.6

The role of remote sensing in phenological studies is increasingly regarded as a key in understanding large area seasonal phenomena. This paper describes the application of Moderate Resolution Imaging Spectroradiometer (MODIS) time series data for vegetation classification using seasonal variation patterns. The vegetation seasonal variation phase of Seoul and provinces in Korea was inferred using 8 day composite MODIS NDVI (Normalized Difference Vegetation Index) dataset of 2006. The seasonal vegetation classification approach is performed with reclassification of 4 categories as urban, crop land, broad-leaf and needle-leaf forest area. The BISE (Best Index Slope Extraction) filtering algorithm was applied for a smoothing processing of MODIS NDVI time series data and fuzzy classification method was used for vegetation classification. The overall accuracy of classification was 77.5% and the kappa coefficient was 0.61%, thus suggesting overall high classification accuracy.

Carbon and nitrogen dynamics in a <i>Pinus densiflora</i> forest with low and high stand densities

Noh, Nam Jin,Kim, Choonsig,Bae, Sang Won,Lee, Woo Kyun,Yoon, Tae Kyung,Muraoka, Hiroyuki,Son, Yowhan Oxford University Press 2013 Journal of plant ecology Vol.6 No.5

<P><B>Aims</B></P><P>Understanding carbon (C) and nitrogen (N) dynamics and their dependence on the stand density of an even-aged, mature forest provides knowledge that is important for forest management. This study investigated the differences in ecosystem total C and N storage and flux between a low-density stand (LD) and a high-density stand (HD) and examined the effects of stand density on aboveground net primary productivity (ANPP), total belowground C allocation (TBCA) and net ecosystem production (NEP) in a naturally regenerated, 65- to 75-year-old <I>Pinus densiflora</I> S. et Z. forest.</P><P><B>Methods</B></P><P>LD (450 trees ha<SUP>−1</SUP>) and HD (842 trees ha<SUP>−1</SUP>) were established in an even-aged, mature <I>P. densiflora</I> forest in September 2006. The forest had been naturally regenerated following harvesting, and the stand density was naturally maintained without any artificial management such as thinning. The diameter at breast height (DBH ≥ 5.0cm) of all live stems within the stands was measured yearly from 2007 to 2011. To compare C and N storage and fluxes in LD and HD, C and N pools in aboveground and belowground biomass, the forest floor, coarse woody debris (CWD) and soil; soil CO<SUB>2</SUB> efflux (<I>R</I> <SUB>S</SUB>); autotrophic respiration (<I>R</I> <SUB>A</SUB>); litter production; and soil N availability were measured. Further, ANPP, TBCA and NEP were estimated from plot-based measurement data.</P><P><B>Important Findings</B></P><P>Ecosystem C (Mg C ha<SUP>−1</SUP>) and N (Mg N ha<SUP>−1</SUP>) storage was, respectively, 173.0±7.3 (mean ± SE) and 4.69±0.30 for LD and 162±11.8 and 4.08±0.18 for HD. There were no significant differences in C and N storage in the ecosystem components, except for soils, between the two stands. In contrast, there were significant differences in aboveground ANPP and TBCA between the two stands (<I>P</I> < 0.05). Litterfall, biomass increment and <I>R</I> <SUB>S</SUB> were major C flux components with values of, respectively, 3.89, 3.74 and 9.07 Mg C ha<SUP>−1</SUP> year<SUP>−1</SUP> in LD and 3.15, 2.94 and 7.06 Mg C ha<SUP>−1</SUP> year<SUP>−1</SUP> in HD. Biometric-based NEP (Mg C ha<SUP>−1</SUP> year<SUP>−1</SUP>) was 4.18 in LD and 5.50 in HD. Although the even-aged, mature <I>P. densiflora</I> forest had similar C and N allocation patterns, it showed different C and N dynamics depending on stand density. The results of the current study will be useful for elucidating the effects of stand density on C and N storage and fluxes, which are important issues in managing natural mature forest ecosystems.</P>