We detected the spatial patterns of plant populations in semi-natural grasslands at five spatial scales using binary data, and discuss the characteristics of spatial pattern at varying scales and their relationship to the propagation type and architecture of plants. A 5×5-m square was established in each of two grasslands. Each area was divided into 1600, 12.5×12.5-cm cells. All the plant species in each cell were recorded. The betabinomial series was introduced as a model to describe the spatial heterogeneity of the populations. The data was analyzed at five scales, from 25×25cm to 100×100cm, by combining adjacent cells. Empirically, the beta-binomial series was shown to be a good model for describing the frequency of occurrence of each population at various scales. The populations were categorized into five types by measuring the spatial heterogeneity at different quadrat sizes. These types were interpreted as showing whether a population forms patches, the spatial heterogeneity between and within patches, and patch size. We suggest that the characteristic spatial patterns shown by these populations are mainly due to the propagation type.

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Canopy dynamics in a bahiagrass (Paspalum notatum Flugge) pasture under cattle grazing were investigated for 2 years in terms of herbage mass and relating structural components, i.e. tiller density, tiller weight, lamina weight per tiller, stem (inclusive of leaf sheaths) weight per tiller, number of laminae per tiller, mean lamina length and mean lamina weight per unit length, in an effort to evaluate contributions of the individual components to variations in herbage mass. Herbage mass, tiller weight, lamina weight per tiller, stem weight per tiller and mean lamina length showed large variations with time (CV=0.46-0.67), being high in summer-autumn and low in other seasons. On the contrary, tiller density, number of laminae per tiller and mean lamina weight per unit length were least variable (CV=0.07-0.10). Variations in herbage mass were associated with variations in tiller weight (r=0.818), lamina weight per tiller (r=0.742), stem weight per tiller (r=0.753) and mean lamina length (r=0.680). Tiller weight was highly correlated with both lamia weight and stem weight per tiller (r=0.874-0.939), and lamina weight per tiller with mean lamina length (r=0.973). Thus, variations in herbage mass were attributed to variations in tiller weight, which originated from variations in mean lamina length and stem weight per tiller.

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Spatial distribution of herbage consumption (rate of defoliation and utilization) by cattle was monitored two-dimensionally in a bahiagrass pasture (1.06 ha) by quantifying changes in herbage mass (HM) during 3 grazing periods (May, August and October). HM was estimated using an electronic capacitance probe for 1464 permanent positions (50cm×50cm) whose centers formed 1.5m×1.5m grids in the central 90m×34.5m area of the pasture. The two-dimensional chartings well illustrated the characteristics of the spatial distributions of herbage consumption, highlighting which positions of the pasture were heavily grazed (utilized) or lightly grazed (utilized) by animals. Finer-scale data which were continuously taken at 451 positions (20cm×20cm) along two permanent line transects (90m) to examine the appropriateness of the grid size showed similar distributions of HM and herbage consumption to data from the two-dimensional monitoring. Despite this similarity, patch-gap analysis with the finerscale data detected smaller common patch sizes in herbage consumption than the grid interval in the measurement area (1.5m) in October. It was concluded that a grid size of <1.5m is needed to monitor herbage consumption of grazing animals at a small-patch scale.

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Canopy structure and light extinction within the canopy were investigated in bahiagrass (Paspalum notatum Flugge) swards subjected to different cutting heights, i.e. 2 (LL), 7 (L), 12 (M), 17 (H) and 22 (HH) cm above ground level. Swards under lower cutting heights were always more leafy and greener with less dead material. Extensive accumulation of dead material in M, H and HH swards modified light extinction within the canopy, due to absorption of radiation by dead material. In May, swards subjected to lower cutting heights showed higher leaf densities, with a greater part of leaves being distributed above non-photosynthetic organs, and less declines in radiation flux density with increased cumulative leaf area index. These canopy characteristics of severely defoliated swards in early growing season are considered to contribute to high tolerance of bahiagrass to close defoliation, through high light utilization efficiency for plant production. The results also imply that maintaining a bahiagrass sward short in winter to mid-spring (December-April) by closely defoliating the sward in autumn is an important sward management strategy leading to high quantity and quality of herbage and high tiller densities in early growing season.

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Four Holstein steers fitted with cannulas in the rumen, proximal duodenum and distal ileum were rotationally grazed on orchardgrass (Dactylis glomerata L., OG) and meadow fescue (Festuca pratensis Huds., MF) pastures from May to October and examined for nitrogen (N) degradation in the rumen, N flow to the duodenum and digestion in the small intestine. N intake on MF pasture was higher than that of OG pasture and was different among the experimental periods. The dietary N degradability in the rumen increased with increase in N content in herbage and it was negatively related to NDF and neutral detergent insoluble N (NDIN) content in herbage. Non-ammonia nitrogen (NAN) flow to duodenum did not increase linearly with increase of N intake due to the increase of N absorption from the rumen. The proportion of NAN flow to duodenum to N intake was negatively related to the proportion of rumen degradable N to the intake of OM truly digested in the rumen. There was a significant difference in N digestibility in the small intestine between OG and MF pasture (P <0.01). N absorption from small intestine was influenced by the acid detergent insoluble N (ADIN) content in the herbage and the amount of N flow to duodenum. N absorption was higher in steers grazing OG pasture than in steers grazing MF pasture.

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The use of cattle slurry has been associated with weedseed invasion of farmland. Accordingly, a study was conducted to determine the temperatures and retention times lethal to weed seeds in cattle slurry. Seeds of six alien weed species (Solanum carolinense L., S. amencanum Mill., Abutilon theophrasti Medic., Phytolacca americana L., Amaranthus spinosus L., and A. patulus Bertoloni) were heated for up to 9 days in deionized water and cattle slurry, respectively. In deionized water, almost all seeds lost viability after one day at 55℃. Seed viability in response to temperatures of 35 and 45℃ varied with species. The species tested were divided into three groups-namely, 1) species in respect of which viability was barely reduced at both temperatures (S. carolinense, and A. spinosus), 2) species in respect of which viability was barely reduced at 35℃, and in respect of which viability decreased as retention time increased at 45℃ (S. americanum, and A. patulus), and 3) species in respect of which viability decreased as retention time increased at both temperatures (A. theophrasti, and P. americana). In cattle slurry, almost all seeds lost viability after one day at 50℃. At 45℃, S. carolinense seeds retained viability for up to five days, and seeds of Amaranthus spp. retained viability for two days, while seed viability of the other three species was lost after one day. The viability of S. carolinense seeds was not reduced after they were held at 35℃ for nine days; however, some decrease in viability was detected at 40℃. At both temperatures, seed viability of Amaranthus spp. decreased as retention time increased ; however, viability had not been reduced to zero after nine days. Seed viability of S. americanum, A. theophrasti and P. americana was almost completely lost in five and two days at 35 and 40℃, respectively. For S. carolinense, which was most tolerant to heat in this study, a logistic regression equation was calculated between retention time and seed viability in cattle slurry in 45℃. A 95% confidence interval for the retention time at which viability was reduced to 10% was estimated as 7.0-8.4 days. From these findings, it is recommended that the retention times of cattle slurry should be longer than one and nine days at 50 and 45℃, respectively, in order to kill all weed seeds.

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Effect of seeding rate, chemical control of weeds, firming methods of seed bed and trimming on germination and early growth of seedlings were determined to accelerate establishment of Kentucky bluegrass (Poa pratensis L., KB) pasture in Hokkaido. Increase in seeding rate from 30 to 240 kg/ha reduced the individual growth of KB seedlings, although raised productivity in unit area. Thus, less seeding rate was recommended to protect seedlings from pulling and trampling damage by cattle grazing. In the 30kg/ha of seeding rate, firming seed bed with Cambridge roller provided much more KB seedlings than that with smooth roller. Trimming increased the number of tiller, but decreased the growth of aerial part and rhizome. It controlled only annual weeds. However, Glyphosate application just before seeding controlled not only annual weeds but also perennial weeds such as dock. Therefore, Glyphosate application just before seeding with 30kg/ha rate, firming seed bed with Cambridge roller and no trimming was recommended to accelerate establishment of KB pasture in Hokkaido.

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The objective of this study was to determine the factors that affect herbage intake of dairy cows grazed on intensively managed pasture. Two cows per ha were grazed all day, and about half of the total digestible nutrients (TDN) demand of cows was supplied by supplements. Means of herbage mass (dry matter g/m^2, 4cm in cutting height) and content of TDN (%) were 164.1±66.3 and 70.9±4.2 in the daytime pasture and 99.2± 25.7 and 68.1±4.5 in the nighttime pasture, respectively. Mean daily milk yield and herbage intake of cows were 31 kg/head and 1.75 kg/100 kg of body weight, respectively. Herbage intake was most greatly affected by herbage mass and decreased as intake of supplement increased. The grass species in the pasture had only a slight effect on herbage intake, and the TDN content of herbage had almost no effect on herbage intake. A positive correlation was seen between herbage mass and TDN intake from grazing for cows that were grazed in a daytime pasture in which the herbage mass per 100 kg of body weight was less than 8 dry matter kg.

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