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Han Q.,Japan Forestry and Forest Products Research Institute | Han Q.,Hokkaido Research Center | Kabeya D.,Japan Forestry and Forest Products Research Institute | Iio A.,University of Shizuoka | And 2 more authors.
Oecologia | Year: 2014

It is generally assumed that the production of a large crop of seeds depletes stores of resources and that these take more than 1 year to replenish; this is accepted, theoretically, as the proximate mechanism of mast seeding (resource budget model). However, direct evidence of resource depletion in masting trees is very rare. Here, we trace seasonal and inter-annual variations in nitrogen (N) concentration and estimate the N storage pool of individuals after full masting of Fagus crenata in two stands. In 2005, a full masting year, the amount of N in fruit litter represented half of the N present in mature leaves in an old stand (age 190-260 years), and was about equivalent to the amount of N in mature leaves in a younger stand (age 83-84 years). Due to this additional burden, both tissue N concentration and individual N storage decreased in 2006; this was followed by significant replenishment in 2007, although a substantial N store remained even after full masting. These results indicate that internal storage may be important and that N may be the limiting factor for fruiting. In the 4 years following full masting, the old stand experienced two moderate masting events separated by 2 years, whilst trees in the younger stand did not fruit. This different fruiting behavior may be related to different "costs of reproduction" in the full masting year 2005, thus providing more evidence that N may limit fruiting. Compared to the non-fruiting stand, individuals in the fruiting stand exhibited an additional increase in N concentrations in roots early in the 2007 growing season, suggesting additional N uptake from the soil to supply resource demand. The enhanced uptake may alleviate the N storage depletion observed in the full masting year. This study suggests that masting affects N cycle dynamics in mature Fagus crenata and N may be one factor limiting fruiting. © 2013 Springer-Verlag Berlin Heidelberg. Source

Noguchi K.,Japan Forestry and Forest Products Research Institute | Dannoura M.,Kyoto University | Jomura M.,Nihon University | Awazuhara-Noguchi M.,Ochanomizu University | Matsuura Y.,FFPRI
Polar Science | Year: 2012

The root system of forest trees account for a significant proportion of the total forest biomass. However, data is particularly limited for forests in permafrost regions. In this study, therefore, we estimated the above- and belowground biomass of a black spruce (Picea mariana) stand underlain with permafrost in interior Alaska. Allometric equations were established using 4-6 sample trees to estimate the biomass of the aboveground parts and the coarse roots (roots >5 mm in diameter) of P. mariana trees. The aboveground biomass of understory plants and the fine-root biomass were estimated by destructive sampling. The aboveground and coarse-root biomasses of the P. mariana trees were estimated to be 3.97 and 2.31 kg m -2, respectively. The aboveground biomass of understory vascular plants such as Ledum groenlandicum and the biomass of forest floor mosses and lichens were 0.10 and 0.62 kg m -2, respectively. The biomass of fine roots <5 mm in diameter was 1.27 kg m -2. Thus, the above- and belowground biomasses of vascular plants in the P. mariana stand were estimated to be 4.07 and 3.58 kg m -2, respectively, indicating that belowground biomass accounted for 47% of the total biomass of vascular plants. Fine-root biomass was 36% of the total root biomass, of which 90% was accumulated in the surface organic layer. Thus, this P. mariana stand can be characterized as having extremely high belowground biomass allocation, which would make it possible to grow on permafrost with limited soil resource availability. © 2011 Elsevier B.V. and NIPR. Source

Guariguata M.R.,Center for International Forestry Research | Okabe K.,FFPRI | Bahamondez C.,INFOR | Nasi R.,Center for International Forestry Research | And 2 more authors.
Ecology and Society | Year: 2013

Forest degradation is broadly defined as a reduction in the capacity of a forest to produce ecosystem services such as carbon storage and wood products as a result of anthropogenic and environmental changes. The main causes of degradation include unsustainable logging, agriculture, invasive species, fire, fuelwood gathering, and livestock grazing. Forest degradation is widespread and has become an important consideration in global policy processes that deal with biodiversity, climate change, and forest management. There is, however, no generally recognized way to identify a degraded forest because perceptions of forest degradation vary depending on the cause, the particular goods or services of interest, and the temporal and spatial scales considered. Here, we suggest that there are types of forest degradation that produce a continuum of decline in provision of ecosystem services, from those in primary forests through various forms of managed forests to deforestation. Forest degradation must be measured against a desired baseline condition, and the types of degradation can be represented using five criteria that relate to the drivers of degradation, loss of ecosystem services and sustainable management, including: productivity, biodiversity, unusual disturbances, protective functions, and carbon storage. These criteria are not meant to be equivalent and some might be considered more important than others, depending on the local forest management objectives. We propose a minimum subset of seven indicators for the five criteria that should be assessed to determine forest degradation under a sustainable ecosystem management regime. The indicators can be remotely sensed (although improving calibration requires ground work) and aggregated from stand to management unit or landscape levels and ultimately to sub-national and national scales. © 2013 by the author(s). Source

Morishita T.,Japan Forestry and Forest Products Research Institute | Aizawa S.,Soil Plant Ecosystem Group | Yoshinaga S.,Kyushu Research Center | Kaneko S.,FFPRI
Journal of Forest Research | Year: 2011

Temperate forest soils are one source of nitrous oxide (N2O), which is an important greenhouse gas and the most important ozone-depleting substance. To clarify N2O flux mechanisms in relation to soil temperature, moisture, and nitrification activity, we measured N2O fluxes and net nitrification rates over 3 years at the lower (Japanese cedar) and upper (deciduous broad-leaved trees) parts of a hill slope in a small forest catchment in the northern Kanto region of Japan. The N2O flux was measured by the closed-chamber technique every month, along with soil temperature and water-filled pore space (WFPS). At the lower slope, the N2O flux increased with increasing soil temperature (r2 = 0.383, P < 0.01) owing to an increase in the nitrification rate. At the upper slope, no positive linear correlation of N2O flux with soil temperature, WFPS, or nitrification rate was observed. The low N2O flux at the upper slope during summer was caused by the low summertime WFPS there. We attributed the higher mean N2O fluxes observed at the lower slope (median 2.36 μg N m-2 h-1) than at the upper slope (median 1.10 μg N m-2 h-1) to a high soil moisture during summer season in the surface soil of the lower slope. © 2011 The Japanese Forest Society and Springer. Source

Ishizuka S.,Japan Forestry and Forest Products Research Institute | Kawamuro K.,Nanzan University | Imaya A.,FFPRI | Torii A.,Kansai Research Center | Morisada K.,Japan Forestry and Forest Products Research Institute
Biogeochemistry | Year: 2014

Black Soil in Japanese forests is believed to have formed under grasslands, on the basis of pollen and stable carbon isotopic analyses. Carbon stable isotope ratios (δ13C) have indicated that the δ13C value widely ranged from -25 to -17 ‰ in various land-use soils. We measured the δ13C of soil organic carbon (SOC) in Black Soil in forests from northern (43°N) to southern (31°N) Japan. The δ13C values in topmost soils were contaminated by carbon from current C3 vegetation. Excluding these soils, the average contribution ratio of C4 grass in Black Soils was estimated to be ~44.6 % of SOC by mass balance calculation from the δ13C of SOC. The proportion of C4 plants supplying soil carbon was smaller at higher latitudes, this indicating that the δ13C values of SOC were affected by the competitiveness of C4 grass and C3 plants which might depend on the temperature. The melanic index, which is an index of humus properties and divides the humus into "Type A" (≤1.7) and other humus (>1.7), correlates negatively with δ13C values. This result indicates that C4 grass played an important role in generating the dark-colored organic matter in Japanese Black Soils. The δ13C values of soil profiles with key tephra are therefore potentially useful for the study of past climate dynamics and vegetation responses. © 2013 Springer Science+Business Media Dordrecht. Source

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