Development of height curves for Japanese larch in relation to GIS-derived site index

The objectives of this study were: (1) to relate the height growth pattern to the GIS-derived site index, (2) to construct various types of polymorphic height curves, and (3) to select the most accurate height curve for Japanese larch (Larix kaempferi). A total of 14 dominant trees were felled for stem analysis. Richards' function was first fitted to the height/age dataset recorded from stem analyses of 14 trees, and its parameters (i.e., A, k, and m) were then estimated for each sample tree. The relationship between parameter A and the GIS-derived site index was significant, while that of parameters k and m were not significant. The 12 height curve equation forms developed from the Richards' function were then fitted to the dataset consisting of 563 observations of height, age, and GIS-derived site index derived from 14 trees. All height curves were unbiased and provided an equally good fit. The shape of the height curves differed among sites of different site indices. These results indicated that Richards' function was sufficiently flexible to represent the polymorphic height growth pattern of Japanese larch. Finally, the best-fit height curve was selected so that accurate height growth predictions would be possible at any given age and site.     

The <Emphasis Type="Italic">Arabidopsis NST3/SND1</Emphasis> promoter is active in secondary woody tissue in poplar

Wood biomass is one of the promising future materials for biofuels with no competing food uses. However, the higher cost to produce bioethanol from wood feedstocks is regarded as a priority issue. Genetic engineering techniques have been proposed to enhance the quality and quantity of wood materials to overcome the cost problem. Although many genetically engineered trees with applicable traits such as low lignin, a high syringyl to guaiacyl ratio and high cellulose content are generated, ectopic expression of an effector gene under a constitutive promoter can sometimes induce untoward side effects on plant growth and development. Our recent study demonstrated that AtNST3/SND1 promoter of Arabidopsis thaliana is a candidate tool for driving a potent activator to enhance wood biomass production in poplar without any growth retardation. However, the tissue- and cell-dependent activity of the promoter remains to be elucidated. In the present study, we generated transgenic poplar expressing AtNST3/SND1promoter::GUS to examine in detail the activity of the AtNST3/SND1 promoter. Histochemical analysis revealed that the promoter was predominantly active in secondary woody tissue. Our result indicates that the AtNST3/SND1 promoter is an option for expressing an effector gene to modify secondary cell wall components and wood biomass.     

A cat with acute myeloblastic leukemia without maturation (M1) treated with combination chemotherapy

A 2-year-old domestic shorthair cat was presented to us with decreased activity and anorexia. Hematologic findings revealed a mild non-regenerative anemia, thrombocytopenia, and leukocytosis with an increase in blast cells. Bone marrow aspirates also revealed a marked increase of blasts. The blastic cells were shown to be positive for peroxidase. Acute myeloblastic leukemia without maturation (M1) was diagnosed according to the FAB classification. Chemotherapy was initiated with cyclophosphamide, vincristine, prednisolone, and cytosine arabinoside. The cat responded partially. In total, the cats were given 7 blood transfusions. The cat died 14 weeks after first being presented to us.     

Effects of topography and management history on natural forest recovery in abandoned forest after clear-cutting in Miyazaki, Japan

We investigated factors limiting the recovery of natural forest in former large-scale conifer plantations abandoned after clear-cutting in southwestern Japan. We analyzed forest recovery status (“recovered” sites covered by evergreen broad-leaved trees, and “unrecovered” sites covered by pioneer community or nonvegetated sites) using aerial photographs and field survey. We applied logistic regression analyses to evaluate the effects of topography, construction of harvesting roads, distance from remnant forest, stand condition before clear-cutting, and prior land-use history on forest recovery. Human factors, i.e., land use and clear-cutting age, were found to affect to forest recovery more than environmental factors such as topography. Harvesting roads had the strongest negative impact on forest recovery. Forest recovery after clear-cutting of young sugi plantations also took longer than after clear-cutting of old sugi plantations or evergreen broad-leaved forests. Furthermore, areas formerly utilized as meadows recovered less successfully than those that had been managed as coppices. The influences of these factors were thought to be promoted by the advance reproduction as the regeneration sources for forest recovery. The influence of stand age before logging suggested an effect of thinning, which might alter the abundance of advanced reproduction in the understory. However, distance from remnant forest appeared to be less important. An influence of topography was also detected, but this could be partly explained by the existence of advance reproduction in the understory in certain topographic positions. Thus, our analysis suggests that regeneration sources originating from advanced reproduction in plantations play a significant role for the recovery of natural forest after clear-cutting.     

Geographical variation in age–height relationships for dominant trees in Japanese cedar (Cryptomeria japonica D. Don) forests in Japan

In this study, we analyzed Japanese National Forest Inventory data to investigate the geographical variation in the relationship between tree height and age for dominant trees, and the effects of climatic conditions on these relationships. Our analysis focused on Cryptomeria japonica forests in 13 regions of Japan. The age–height relationships were classified into two regional groups that were distinguished by their climatic conditions. Several categories of climatic variables (warmth, solar radiation, precipitation, and snow depth) were significantly correlated with the parameters of a model for the age–height relationships. Our results also suggest the existence of a latitudinal cline for the maximum tree height of C. japonica in Japan. In regions with cold temperatures, deep snow, low solar radiation, and low summer precipitation, C. japonica shows a late-maturity pattern for height increase, with slow initial growth and a large maximum size. In regions with the opposite climatic conditions, it shows an early-maturity pattern with fast initial growth and small maximum size.     

Growth recovery of young hinoki (Chamaecyparis obtusa) subsequent to late weeding

The effects of late weeding treatment on the growth of young hinoki (Chamaecyparis obtusa) during the sixth growing season after planting were examined. Furthermore, the contribution toward hinoki growth recovery of crown productivity (NAR) and biomass allocation to crown (CAR) were determined. In the late weeding plot, no decline in height growth was observed subsequent to weeding, and growth in diameter at breast height (DBH) and crown projection area (CPA) began to recover subsequent to weeding; however, DBH and CPA were reduced and experienced a 1- to 1.5-year growth delay compared to values associated with the weeding plot at the end of the second year subsequent to weeding. Relative growth rate (RGR) and NAR in the late weeding plot recovered and possessed similar values to those of the weeding plot in the second year subsequent to weeding. CAR values of the late weeding plot were similar to those of the weeding plot both before and after weeding. These results suggested that the recovery of NAR rather than that of CAR was primarily responsible for the recovery of RGR. The present study demonstrated that hinoki were able to quickly acclimate to an environment dramatically altered by late weeding and recover growth rate within a short period of time. The present study also showed that delays in crown expansion associated with late weeding may have impeded subsequent matter production. Therefore, it was concluded that late weeding treatments should be employed only when the associated delays in growth are taken into account.     

Predicting the site index of sugi plantations from GIS-derived environmental factors in Miyazaki Prefecture

We constructed sugi site index models using digital-terrain-analysis-based environmental factors for Miyazaki Prefecture. We selected 18 sugi plantation stands which were pure, undisturbed, and over 40 years old, planted with the same sugi-cutting cultivar, and managed by normal forest operations. The dominant tree in each stand was felled for stem analysis. Site index, defined here as dominant tree height at 40 years old, was estimated by stem analysis for each stand. Five types of DEMs were used: 100- and 50-m resolution derived from DEMs published by the Geographical Survey Institute, and 50-, 25-, and 12.5-m resolution derived from digital contour map manually generated from a 1:25,000 topographic map. A total of 14 indices categorized into solar radiation index, wetness index, and topographic exposure index were used to model the site index by multiple linear regression analysis. Through model selection procedures, the best-fitted site index models were selected for each type of DEM. The most precise model was that of the 12.5-m-resolution DEM (R ² = 0.692), following the model of the published 50-m-resolution DEM (R ² = 0.665). Site productivity of sugi was severely limited by direct solar radiation. Soil wetness also affected sugi site productivity; however, it can only be represented using a high-resolution DEM derived from fine-scale data. Our results suggest that the 50-m-resolution DEM published by the Geographical Survey Institute can be used for site index modeling.     

Use of GIS-derived environmental factors in predicting site indices in Japanese larch plantations in Hokkaido

The objectives of this study were (1) to evaluate the effects of environmental factors derived from GIS on tree-height growth of Japanese larch (Larix kaempferi) and (2) to develop a best-fit regression model for its site index. Based on data from 40 sample plots situated in an even-aged (38 years), pure, and undamaged Japanese larch stand, multiple regression models for a site index of Japanese larch were constructed using environmental factors as independent variables. The average slope gradient, effective relief, distance from ridge, flow accumulation, degree of exposure, shading, solar radiation index, and gravitational water index were used as environmental factors and calculated on GIS using digital elevation model data. These factors were related to the Japanese larch site index through multiple-regression analysis. The result showed that the most effective factor for estimating site index was the degree of exposure. Through a backward stepwise procedure, the degree of exposure, shading, and average slope gradient were selected for a best-fit regression model. This model explained 72% of the variance in site index, with standard error estimates of 1.75 m. This strong relationship suggests that GIS-derived environmental factors can be used to predict site indices of Japanese larch. This study was supported by the experimental forest of Kyushu University.     

Early growth of hinoki (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>) trees under different topography and edge aspects at a strip-clearcut site in Kyushu,Southern Japan

The positive and negative effects of the residual stand edge at a strip-clearcut site were examined on the initial growth of hinoki (Chamaecyparis obtusa) planted in areas with diverse topography. On the south edge, the gap light index was lower than on the north edge and strip center; however, the vapor pressure deficit was also lower than on the north edge and strip center, which resulted in lower physiological stress of hinoki on the south edge. Tree size on the south edge did not exceed that on the north edge and strip center. These results indicated that low light conditions due to residual trees negatively affected growth on the south edge even under the positive effect of microclimate alleviation. In valley, tree size in the second year after planting was smaller than on ridge and slope; however, tree growth during the following 2 years was higher in valley. Surface soil in valley was thinner with rockier substrates than on ridge and slope; that is, soil sedimentation type and substrates influenced the initial growth of hinoki with undeveloped roots, and after that, topography started to influence growth, probably because hinoki roots penetrated into deeper soil, which is influenced by the water gathering capacity of the valley. The initial growth of hinoki at the strip-clearcut site was predominantly affected by light rather than microclimate alleviation. This alleviation is expected to disappear when hinoki trees planted in the strip center grow enough to give additional shade to slow-growing edge hinoki.     

Factors affecting the occurrence of woody plants in understory of sugi (Cryptomeria japonica D. Don) plantations in a warm-temperate region in Japan

We compared the occurrence of woody plants present in sugi (Cryptomeria japonica D. Don) plantations and evergreen broad-leaved natural forests in a warm-temperate region in order to characterize the understory vegetation of sugi plantations. The influence of stand attributes on species occurrence in the plantations was evaluated using logistic regression analysis. Out of 163 species, 65 plantation-preferring species and 31 natural forest-preferring species were detected. The plantation-preferring species group contained deciduous species (38 of 65 species) that are characteristic of coppice woodland, but all the natural forest-preferring species were evergreen plants. This indicates that the composition of the woody understory in sugi plantations of the region is characterized by the species of open, disturbed habitats. Stand age and the distance from the nearest natural forests were found to significantly affect the occurrence of evergreen shrubs and plants with gravity-dispersed seeds, respectively, but the light environment of the stand had less effect. According to the regression model analyses, long-term strategies such as lengthening the rotation (logging age) or creating patch mosaics of plantations in the matrix of natural forests appeared to be effective in conserving woodland species that are characteristic of evergreen, broad-leaved forests. On the other hand, increasing light penetration through thinning practices is a short-term strategy that is less likely to be effective in promoting these species.