Bayandala,Tohoku University |
Masaka K.,Hokkaido Forestry Research Institute |
Seiwa K.,Tohoku University
Oecologia | Year: 2016
In forests, negative density/distance-dependent seedling mortality (NDD) caused by natural enemies plays a key role in maintaining species diversity [Janzen–Connell (J–C) model]. However, the relative importance of natural enemies in mediating NDD under heterogeneous light conditions has remained unclear. We examined the relative importance of pathogens (i.e., soil pathogens, leaf diseases) on seedling performance in forest understories (FUs) and gaps (gaps) during a 3-year period (results of first year of our study have been previously reported). For the hardwood, Prunus grayana, we investigated seedling mortality, morbidity agents, growth, and root infection by arbuscular mycorrhizal fungi (AMF) beneath conspecific and heterospecific adults in FUs and gaps. Seedling mortality was higher beneath conspecific than heterospecific adults throughout 3 years at both sites, mainly due to continuous leaf disease (i.e., angular leaf spot), whereas damping-off diseases caused mortality only in the first year. Beneath each adult, seedling mortality was higher in FUs than in gaps until second year, but it did not differ between two habitat types in the third year, because leaf diseases caused severe damage even in gaps. Seedling mass was significantly lower beneath conspecific adults. AMF infection of seedlings was also lower beneath conspecific adults, while it was higher in gaps than in FUs beneath both adults. This study demonstrates that the J–C model in a hardwood tree, P. grayana is mainly driven by high NDD seedling mortality caused by airborne leaf diseases, which continuously attack seedlings in a NDD manner regardless of environmental light conditions. © 2016 Springer-Verlag Berlin Heidelberg
PubMed | Tohoku University and Hokkaido Forestry Research Institute
Type: | Journal: Oecologia | Year: 2016
In forests, negative density/distance-dependent seedling mortality (NDD) caused by natural enemies plays a key role in maintaining species diversity [Janzen-Connell (J-C) model]. However, the relative importance of natural enemies in mediating NDD under heterogeneous light conditions has remained unclear. We examined the relative importance of pathogens (i.e., soil pathogens, leaf diseases) on seedling performance in forest understories (FUs) and gaps (gaps) during a 3-year period (results of first year of our study have been previously reported). For the hardwood, Prunus grayana, we investigated seedling mortality, morbidity agents, growth, and root infection by arbuscular mycorrhizal fungi (AMF) beneath conspecific and heterospecific adults in FUs and gaps. Seedling mortality was higher beneath conspecific than heterospecific adults throughout 3years at both sites, mainly due to continuous leaf disease (i.e., angular leaf spot), whereas damping-off diseases caused mortality only in the first year. Beneath each adult, seedling mortality was higher in FUs than in gaps until second year, but it did not differ between two habitat types in the third year, because leaf diseases caused severe damage even in gaps. Seedling mass was significantly lower beneath conspecific adults. AMF infection of seedlings was also lower beneath conspecific adults, while it was higher in gaps than in FUs beneath both adults. This study demonstrates that the J-C model in a hardwood tree, P. grayana is mainly driven by high NDD seedling mortality caused by airborne leaf diseases, which continuously attack seedlings in a NDD manner regardless of environmental light conditions.
Takiya M.,Hokkaido Forestry Research Institute |
Koyama H.,Yamagata University |
Umeki K.,Chiba University |
Yasaka M.,Hokkaido Forestry Research Institute |
And 3 more authors.
Journal of Forest Research | Year: 2010
We examined the effect of early and intense pruning on light intensity under the canopy, individual growth, diameter-height relationships, and epicormic shoot dynamics in young hybrid larch (Larix gmelinii var. japonica × L. kaempferi) to establish a new effective management method for hybrid larch plantations. The objective is to produce high-quality wood while reducing silviculture costs using a combination of low-density planting and early and intense pruning. In a young hybrid larch plantation, we pruned branches to two different heights (2 and 4 m above ground level) using a no-pruning treatment as a control. Although the growth rates were lower in the heavy pruning treatment (4 m above the ground level) than in other treatments in the year following pruning, when measured 4 years later, growth did not differ between treatments. The number of epicormic shoots increased in the year following pruning, as did the relative photosynthetic photon flux density (rPPFD). The number of epicormic shoots was also dependent on the size of individual trees. However, survival of epicormic shoots was not sufficiently high to be problematic for high-quality timber production. If branches are pruned carefully such that the rPPFD does not rise above 20%, the emergence of epicormic shoots can also be controlled. Our results indicate that early and intense pruning is an effective component of a new management system for hybrid larch plantations. © The Japanese Forest Society and Springer 2009.
Kochi K.,Hokkaido University of Science |
Kochi K.,Saitama University |
Mishima Y.,Hokkaido University of Science |
Nagasaka A.,Hokkaido Forestry Research Institute
Limnology | Year: 2010
In forested streams, surrounding riparian forests provide essential supplies of organic matter to aquatic ecosystems. We focused on two pathways of particulate organic matter inputs: direct input from upper riparian forests and indirect lateral input from bank slopes, for which there are limited quantitative data. We investigated the inputs of coarse particulate organic matter (CPOM) and carbon and nitrogen in the CPOM into the uppermost reaches of a headwater stream with steep bank slopes in Hokkaido, Japan. CPOM collected by litter traps was divided into categories (e. g., leaves, twigs) and weighed. Monthly nitrogen and carbon inputs were also estimated. The annual direct input of CPOM (ash-free dry mass) was 472 g m-2, a common value for temperate riparian forests. The annual lateral CPOM input was 353 g m-1 and 941 g m-2 when they were converted to area base. This value surpassed the direct input. Organic matter that we could not separate from inorganic sediments contributed to the total lateral input from the bank slopes (124 g m-1); this organic matter contained relatively high amounts of nitrogen and carbon. At uppermost stream reaches, the bank slope would be a key factor to understanding the carbon and nitrogen pathways from the surrounding terrestrial ecosystem to the aquatic ecosystem. © The Japanese Society of Limnology 2009.
Johns R.C.,Natural Resources Canada |
Johns R.C.,Japan Forestry and Forest Products Research Institute |
Tobita H.,Japan Forestry and Forest Products Research Institute |
Hara H.,Hokkaido Forestry Research Institute |
Ozaki K.,Japan Forestry and Forest Products Research Institute
Ecological Research | Year: 2015
Few herbivores are well adapted to feeding on all foliage age classes available and most have evolved traits that are attuned to the characteristics of either developing or mature foliage; however, recent evidence has shown a number of insect herbivores that may mix different-aged foliage as a means of enhancing fitness. We carried out a series of laboratory and field experiments to investigate whether larvae of Asian gypsy moth [L. umbrosa (Butler) = L. dispar hokkaidoensis Goldschmidt] (Lepidoptera: Lymantriidae) engage in and benefit from foliage-age dietary mixing in common conifer species that naturally occur in its native range of Hokkaido, Japan. In a laboratory experiment, early instar larvae were observed on both developing and mature foliage when both age classes were available; however, larval survival and weight were highest on hosts with developing foliage available (larch, fir, and pine), whereas all larvae died on spruce where only mature foliage was available. In contrast, laboratory and field experiments indicated that late-instar larvae often consumed both developing and mature foliage on all conifer species studied, although there was general preference bias towards mature foliage. Field bioassays indicated that late-instar larvae provided both foliage age classes (a ‘mixed’ diet) had similar performance to those provided only developing or mature foliage. Results of this study indicate that larvae obtain limited performance benefits from mixing different foliage age-classes into their diet, other than perhaps the benefits accrued from having a broader resource pool available on a single host tree. © 2015, Her Majesty the Queen in Right of Canada as represented by: The Minister of Natural Resources.
Koike T.,Hokkaido University |
Mao Q.,Hokkaido University |
Inada N.,Hokkaido University |
Kawaguchi K.,Hokkaido University |
And 3 more authors.
Asian Journal of Atmospheric Environment | Year: 2012
We studied the effects of elevated ozone ([O 3]) and CO 2 concentrations ([CO 2]) on the growth and photosynthesis of the hybrid larch F 1 (F 1) and on its parents (the Dahurian larch and Japanese larch). F 1 is a promising species for timber production in northeast Asia. Seedlings of the three species were grown in 16 open top chambers and were exposed to two levels of O 3 (<10 ppb and 60 ppb for 7 h per day) in combination with two levels of CO 2 (ambient and 600 ppm for daytime) over an entire growing season. Ozone reduced the growth as measured by height and diameter, and reduced the needle dry mass and net photosynthetic rate of F 1, but had almost no effect on the Dahurian larch or Japanese larch. There was a significant increase in whole-plant dry mass induced by elevated [CO 2] in F 1 but not in the other two species. Photosynthetic acclimation to elevated [CO 2] was observed in all species. The net photosynthetic rate measured at the growing [CO 2] (i.e. 380 ppm for ambient treatment and 600 ppm for elevated CO 2 treatment) was nevertheless greater in the seedlings of all species grown at elevated [CO 2]. The high [CO 2] partly compensated for the reduction of stem diameter growth of F 1 at high [O 3]; no similar trend was found in the other growth and photosynthetic parameters, or in the oth
Mao Q.Z.,Hokkaido University |
Watanabe M.,Hokkaido University |
Makoto K.,Hokkaido University |
Makoto K.,Yokohama National University |
And 2 more authors.
Landscape and Ecological Engineering | Year: 2014
A recently developed hybrid larch F1 (F1: Larix gmelinii var. japonica × L. kaempferi) is being planted widely in re- and afforestation projects in northeast Asia. Nitrogen (N) deposition to forest ecosystems has been rapidly increasing in this region, due mainly to industrialization and overuse of N fertilizer. Together with excess N, phosphorus (P) is considered to be the key determinant of tree growth in northeast Asia, because most soils have originated from immature volcanic ash. To predict the response of the F1 to increasing N deposition and its relation with soil P availability related to immature volcanic ash soil in northern Japan, planting stocks of F1 were grown in potted brown forest soil and categorised into eight treatments, comprising four N treatments covering the amount of N deposition observed and predicted in northeast Asia in combination with two P levels. N application increased the biomass and the light-saturated net photosynthetic rate (A sat) of the F1 at all concentrations. Despite expectations, P did not have any effect on these parameters. As N application increased the content of potassium (K), magnesium (Mg) and chlorophyll (Chl) in needles, a positive correlation was found between the content of N, K, P and A sat. These results suggest that N deposition improves the growth of the hybrid larch F1 at least by improving the needle N condition, as well as the concentration of other macronutrients in the initial stage of plantation. © 2012 International Consortium of Landscape and Ecological Engineering and Springer Japan.
Konno S.,Senshu University |
Araya K.,Senshu University |
Teramoto C.,Senshu University |
Wakita Y.,Hokkaido Forestry Research Institute |
And 3 more authors.
Engineering in Agriculture, Environment and Food | Year: 2010
In order to separate haskaop berry and leaf during harvest, a vertical separation column was envisaged. The air drag coefficients of berry and leaf were measured to determine the proper air velocity in the separation column. The results show that the air drag coefficient of a berry set horizontally in the air flow was 0.959-2.21, and that of a berry set vertically was 0.322-0.977. The air drag coefficient of the leaves was 0.622-2.36. The minimum terminal velocity of berries (horizontally, 9.1 ms -1 and vertically, 11.0 ms -1) was significantly different from the maximum terminal velocity of the leaves (2.35 ms -1). Therefore, it should be possible to separate the berries and leaves using the air velocity from trial experiments in the separation column.
Unno A.,Hokkaido Forestry Research Institute |
Nakata K.,Hokkaido Forestry Research Institute
Journal of Forest Research | Year: 2010
In deciduous forests, tree seeds and seedlings are frequently exposed to high predation by small rodents, and this predation can have an important effect on forest regeneration. However, damage to large trees by small rodents has not been studied, except for damage observed during timber production. To determine factors affecting damage to large trees by the grey red-backed vole (Myodes rufocanus bedfordiae), the characteristics and spatial patterns of tree damage by voles at vole wintering sites were examined over 3 years in a deciduous forest in Hokkaido. This study found that the location of damaged trees was related to vole wintering sites. Vole damage was affected by tree species. Damaged trees were heavily concentrated in small areas. Leaning trees and trees that had suffered previous damage were more likely to be damaged. However, the diameter at breast height was not significantly related to vole damage. These differences in susceptibility to vole damage may result in different tree mortality. © 2010 The Japanese Forest Society and Springer.
PubMed | Hokkaido Forestry Research Institute and Hokkaido University
Type: | Journal: Environmental science and pollution research international | Year: 2017