Aboveground biomass and litterfall ofPinus pumila scrubs growing on the Kiso mountain range in central Japan

Aboveground biomass and litterfall ofPinus pumila scrubs, growing on the Kiso mountain range in central Japan, were investigated from 1984 to 1985. The biomass of two research plots (P1 and P2) with different scrub heights was estimated by two methods, the stratified clip technique and the allometric method. Aboveground total biomass estimated by the latter method reached 181 ton d.w. ha⁻¹ in P1 and 132 ton d.w. ha⁻¹ in P2. Creeping stems contributed to about half of the total biomass. Although estimates of woody organs differed between the two plots, leaf biomass estimates were almost the same at 15.5 ton d.w. ha⁻¹. The canopies of the twoP. pumila scrubs were characterized by a large mean leaf area density of 5.0 m² m⁻³. Despite this large area density, relatively moderate attenuation of light intensity was observed. Specific leaf area generally increased with reduced leaf height. Annual total litterfall was estimated to be 3.60 ton d.w. ha⁻¹ yr⁻¹ in P1 and 2.39 ton d.w. ha⁻¹ yr⁻¹ in P2. Annual leaf fall in both plots was approximately 2.0 ton d.w. ha⁻¹ yr⁻¹. Leaves fell mainly in early autumn. Annual loss rates of branches, estimated as the sum of annual branch litterfall and the amount of newly formed attached dead branches, were 0.29 ton d.w. ha⁻¹ yr⁻¹ in P1 and 0.37 ton d.w. ha⁻¹ yr⁻¹ in P2.     

Effects of wounds on the terpene content of twigs of maritime pine (Pinus pinaster Ait.)

Summary The effect of wounds on the volatile terpene composition of the living bark of Pinus pinaster Ait. (maritime pine) twigs was investigated with respect to the processes of mono- and sesquiterpene hydrocarbon biosynthesis. The large increase in the amounts of - and -pinene is a characteristic feature after a mechanical injury, whereas the quantities of the other terpenes are only slightly increased. This is due to the reactivation of the resin duct secretory cells of primary origin located in cortical tissues. The effect of wounding is observed over a long period and the terpene profiles are very different at the end of the experiments as compared with the initial profiles of the same tissues. The traumatic essential oil (obtained after mechanical traumatism) resembles an oleoresin extracted from tissues of secondary origin. Statistical analysis underlines the effects of the between-tree variations and of the dates of application of the wound.     

Development of Bursaphelenchus xylophilus Populations in Wood Chips with Different Moisture Contents

Bags of Pinus strobus wood chips with moisture contents of 38, 92, 164, and 217% (oven dry weight) were inoculated with Bursaphelenchus xylophilus and incubated at 30 C in order to determine the effect of wood moisture on nematode population development. Nematodes were extracted after 2, 4, 8, and 12 weeks. Population levels were greatest in wood chips with a moisture content of 38% and decreased successively with each higher moisture content. In chips with the three lower moisture contents, populations peaked at 2 weeks, but at 217% moisture, they peaked at 8 weeks. By 12 weeks, nematode populations had declined in wood chips with 92 and 164% moisture contents. The fungi most frequently isolated from the wood chips were Alternaria, Fusarium, Gliocladium, Graphium, Penicillium, Trichoderma, and Mucorales.     

Influence of induced water stress in ponderosa pine on pine sawflies

Summary Three levels of water stress were induced on pole-size ponderosa pine (Pinus ponderosa) to determine the influence of plant moisture stress on oviposition, survival, and growth of two species of pine sawfly (Neodiprion fulviceps and N. autumnalis). It was found that water stress affected oviposition and subsequent egg survival but not larval development or survival. Stress had a negative effect on early season oviposition (N. fulviceps) and a positive effect on late season oviposition (N. autumnalis). Egg hatch was different between species and years and among treatment levels. Larval development, feeding, and survival were not affected by water stress. Overall, the effect of stress was not sufficient to explain population outbreaks of sawflies. Several hypotheses are presented as possible explanations for the observed experimental results.     

Increases in cytokinin levels in Scots pine in relation to chilling and bud burst

Levels of isopentenyladenosine and zeatin riboside were monitored in buds and needles of Scots pine ( Pinus sylvestris L.) seedlings grown under controlled climatic conditions and in field-grown trees. Extracts were purified by immunoaffinity chromatography and high-performance liquid chromatography. Cytokinin levels were quantified with an enzyme-linked immunosorbent assay. The cytokinin content was low in buds and needles of dormant seedlings but increased during dormancy release, reaching peak values in buds just before resumption of shoot growth. Samples collected in the field also showed a marked increase in the levels of cytokinins just prior to bud burst. Further, the biological activity of applied cytokinins in activating the dormant buds of Scots pine is shown. The results indicate a probable role of cytokinins in seedlings during dormancy release.     

Nutrients and mass in litter and top soil of ten tropical tree plantations

The importance of litter to nutrient and organic matter storage and the possible influence of species selection on soil fertility in ten stands each consisting of a separate tree species were examined in this study. The plantations had been grown under similar conditions in an arboretum in the Luquillo Experimental Forest, Puerto Rico. The species involved were: Anthocephalus chinensis, Eucalyptus × patentinervis, E. saligna, Hernandia sonora, Hibiscus elatus, Khaya nyasica, Pinus caribaea var. hondurensis, P. elliottii var. densa, Swietenia macrophylla, and Terminalia ivorensis. After 26 yr, litter mass ranged from 5 mg ha^-1 in the H. sonora stand to 27.2 Mg ha^-1 in the P. caribaea stand. Nutrients in the litter (N, P, K, Ca, and Mg) also varied widely, but stands were ranked in different order when ranked by nutrients in the litter than then ranked according to accumulation of mass. Only E. saligna and A. chinensis stands were ranked similarly in accumulation of both nutrients and mass, and the stand of H. elatus was ranked higher with respect to nutrient accumulation than to accumulation of mass. The nutrient concentration in standing leaf litter generally increased in the order of recently fallen <old intact< fragmented. Nutrient concentration of standing leaf litter appears to increase with age and depth in the litter layer. The amount of nutrients stored in the litter compartment of these plantations was in the same order of magnitude as the quantity of available nutrients in the top 10-cm of mineral soil. Total litter mass was negatively correlated with the mass-weighted concentration of N, K, and Mg. The same relationship was found for Ca in the leaf litter and N in the fine wood litter compartments. In some stands (notably P. caribaea, P. elliottii, and E. saligna), leaf litter derived from species other than the species planted in that particular stand had higher nutrient concentration than leaf litter from the planted species. Soils of the 10 stands were classified in the same soil series and had similar texture (clay soils). However, significantly different chemical characteristics were found. Results obtained by analysis of covariance and by limiting comparisons to adjacent stands with similar soil texture, indicate that different species have had different influences on the concentration of available nutrients in soil.     

Chloroplast DNA in Pinus monticola

Summary Within-species variability of a restriction site in the chloroplast (cp) DNA in Pinus monticola has been surveyed. Frequencies of two variants of the cp genome are significantly different in interior versus coastal populations. Paternal inheritance of the cp genome predominates, though some individuals have both variants of the genome. The presence of heteroplasmic individuals indicates occasional biparental inheritance.     

Growth, dry weight partitioning and wood properties of Pinus radiata D. Don after 2 years of CO2 enrichment

Abstract Advanced selections (families 20010 and 20062) of P. radiata D. Don were exposed to either 340 or 660 μmol CO₂ mol ¹ for 2 years to establish if growth responses to high CO₂ would persist during the development of woody tissues. The experiment was carried out in glasshouses and some of the trees at each CO₂ concentration were subjected to phosphorus deficiency and to periodic drought. CO₂ enrichment increased whole-plant dry matter production irrespective of water availability, but only when phosphorus supply was adequate. The greatest increase occurred during the exponential period of growth and appeared to be tied to increased rates of photosynthesis, which caused accelerated production of leaf area. The increase in whole-plant dry matter production was similar for both families; however, family 20010 partitioned larger amounts of dry weight to the trunks than family 20062. which favoured the roots and branches. Wood density was generally increased by elevated CO₂ and for family 20010 this increase was due to thickening of the tracheid walls. Tracheid length was similar at both CO₂ levels but differed between families. These results suggest that, as the atmospheric CO₂ concentration rises, field-grown P. radiata should produce more dry weight at sites where phosphorus is not acutely deficient, even where drought limits growth; however, increases in wood production are likely only for genotypes which continue to partition at least the same proportion of dry weight to wood in the trunk.     

红松越冬针叶的电子自旋共振（ESR）波谱

用ESR波谱仪在越冬红松针叶及叶绿体冻干粉中检出了g值分别为2.0044和2.0037的明确的单峰信号。针叶伤害愈重,信号愈强。此信号可被Vc或富含SOD等多种自由基清除剂的沙棘果汁所抑制。针叶受害愈重,沙棘果汁对信号的抑制作用愈强,Vc的抑制作用愈弱。据此认为红松苗越冬伤害和有机自由基的形成有关。在伤害发展的不同阶段,有机自由基的种类组成也不同。     

Non-morphogenic metabolism during shoot induction in radiata pine cotyledon explants

Summary The effects of excision, light and cytokinin (N⁶-benzyladenine) on¹⁴C-acetate metabolism in cotyledons ofPinus radiata (D. Don) were determined.¹⁴CO₂ was released and the distribution of radioactivity into lipids, sugars, organic acids and amino acids was determined. While light and cytokinin generally caused some increase in metabolism, the effect of excision, i.e., wounding, was most pronounced. Specific metabolites examined (citrate, malate, succinate, alanine, aspartate, glutamate and glutamine) were at least 50% greater in¹⁴C-labeling in excised cotyledons as compared to intact seedlings. This enhancement of wound metabolism would mask possible morphogenically-related changes occurring at that time. This research was supported by the Natural Sciences and Engineering Research Council of Canada Grant A-6467 to T.A. Thorpe.