辽宁东部山区高龄日本落叶松林的生长分析

以辽宁省东部山区残存的少量高龄日本落叶松人工林为对象，调查分析了林分及林木的生长特征。结果表明，在林龄60～86年生的日本落叶松人工林分当中，直径≥30cm的大径材比率均在90％以上；各调查林分的胸径连年生长量还维持着一定的旺盛生长势，间伐后胸径生长变化率向正的方向转变趋势明显；与日本落叶松原产地日本长野县相比，林木的树高和胸径生长几乎没有差异。按照日本的落叶松长伐期经营标准，这些调查林分还具有较大的生长潜力，可进一步大幅度延长其培育年限，实施长伐期经营。     

Freezing cycles enhance winter injury in Picea rubens

We examined changes in chlorophyll absorbency in red spruce (Picea rubens Sarg.) foliage in response to simulated freezing cycles. Current-year branch tips were collected from 16 trees on January 8, January 20, February 8 and February 26, 1996. Tissue was subjected to freezing cycle treatments with a minimum of -35 degrees C and a maximum of 3 degrees C for a one-cycle treatment, and -9, -6, -3, 0 or 3 degrees C for four-cycle treatments. Samples were frozen at a rate of 5 degrees C h(-1), and warmed at 12 to 15 degrees C h(-1). Controls were held at -9 degrees C. Temperatures during the three-day periods preceding each sample date averaged -18, 4.7, -9.6 and 3.7 degrees C, respectively. On January 8, treated trees showed no significant (P > 0.1) increase in the breakdown of chlorophyll, as measured by the ratio of chlorophyll a absorbency (435 nm) to phaeophytin a absorbency (415 nm), compared with control branch tips. On later sampling dates, seven trees consistently exhibited needle reddening and nine exhibited few symptoms (< 10% of total needle surface reddened) after four-cycle treatments. On February 26, chlorophyll degradation in trees with needle reddening differed (P < 0.05) from the control by 26, 26, 16, 14 and 15% for the 3, 0, -3, -6 and -9 degrees C maxima, respectively. No detectable chlorophyll degradation occurred after a one-cycle treatment in any trees on any sampling date. Freezing cycles with sub-zero maxima and a -35 degrees C minimum enhanced winter injury in red spruce after a midwinter thaw had rendered the trees susceptible to freezing damage.     

Winter Frost Hardiness of two Chilean Provenances of Nothofagus procera in Scotland

The frost hardiness of the shoots of individual trees withintwo Chilean provenances of Nothofagus procera (Poepp & Endl.)Oerst. was measured once in each of the months January, February,November and December 1989 and January and February 1990. Therewere significant (P<0.05) differences of frost hardinessbetween provenances but only one tree could be shown to be significantlymore frost hardy than the others within the same provenance.During the winter of 1989/90 both provenances were hardy toabout –14°C (temperature killing 50 per cent of shoots)in December, but the shoots dehardened to about –9°Cin January before hardening again in February. This patternof alternate hardening and dehardening seemed to mirror changesin air temperature and could render N. procera liable to frostdamage where (as happened in 1988/9 in the UK) mild spells occurin winter followed by severe frosts.     

Dendroclimatic response of Abies spectabilis at treeline ecotone of Barun Valley,eastern Nepal Himalaya

A dendroclimatic study was conducted in the treeline ecotone of Barun Valley,eastern Nepal,to determine the tree-ring climate response and ring width trend of Abies spectabilis.A 160-year-old chronology,from 1850 to 2010,was developed from 38 tree-ring samples.No higher growth in recent decades was observed in tree-ring width in this area.The mean temperature of the current year in February and in the combined winter months of December,January,and February showed significant positive correlation with tree-ring width,although no significant correlation was found between tree-ring width and the precipitation pattern of the region.This tree-ring climate response result is different from that in other studies in Nepal,which could be attributed to location and elevation.     

龙山县日本落叶松人工林林分生长与结构调查

对龙山县日本落叶松人工林林分生长与结构进行调查,结果表明:龙山县中山区日本落叶松人工林表现良好,林龄12~13年平均胸径8.43 cm,大小相差0.9倍;平均树高6.34 m,大小相差1.1倍;平均蓄积12.84 m3/hm2,大小相差34.6倍。该人工林为结构单一的纯林,日本落叶松株数97.2%、阔叶树株数2.8%;天然阔叶树仅为响叶杨、檫木及光皮桦等,优质树种缺乏,需人工补植优质阔叶树。日本落叶松人工林稳定性较强,2008年特大冰冻灾害后保存正常植株86.4%;日本落叶松林可划分为"单一纯林"及"较稀疏的人工林"两种类型,宜开展近自然改造。     

Modeling shoot water contents in high-elevation Picea rubens during winter

During the winter of 1990-1991, a meteorological tower was established at an 880-m elevation site within the spruce-fir zone on Mt. Moosilauke, New Hampshire, USA. Hourly means of air, needle and trunk temperatures, wind velocity, relative humidity and solar radiation were recorded. On a weekly basis, shoots that had elongated during the preceding growing season were collected from four red spruce (Picea rubens Sarg.) trees and their relative water contents (RWC) determined. Cuticular resistances of needles from these shoots were measured four times during the winter.Measured meteorological parameters were used in a previously developed model to simulate changes in red spruce shoot RWC during the winter. The modeled results were compared to measured shoot RWCs. The predictive power of the model was improved when it was modified to include measured values of cuticular resistance and needle and trunk temperatures. The new version of the model accurately predicted RWC from late December 1990 to the beginning of April 1991, after which spring recharge appeared to occur. We conclude that water lost from foliage was easily replaced by stored reserves and that uptake of water by the roots was not required to maintain an adequate foliar water content during the winter.     

Bole water content shows little seasonal variation in century-old Douglas-fir trees

Purportedly, large Douglas-fir trees in the American Pacific Northwest use water stored in bole tissues to ameliorate the effects of seasonal summer drought, the water content of bole tissues being drawn down over the summer months and replenished during the winter. Continuous monitoring of bole relative water content (RWC) in two 110-120-year-old Douglas-fir trees with ThetaProbe impedance devices provided an integrated measure of phloem-sapwood water content over 4 years. Seasonal changes in RWC closely tracked cambial activity and wood formation, but lagged changes in soil water content by 2-3 months. The RWC in the combined phloem and sapwood markedly increased during earlywood production in the late spring and early summer to maximum values of 64-77% as plant available soil water (ASW) decreased by approximately 60%. With transition and latewood formation, RWC decreased to minimum values of 59-72%, even as ASW increased in the fall. The difference between minimum RWC in the fall and maximum RWC in midsummer was only approximately 5%. Seasonal changes in bole RWC corresponded to cambial phenology, although decreasing AWS appeared to trigger the shift from earlywood to latewood formation.     

Within-tree variation of heartwood and ring width in maritime pine (Pinus pinaster Ait.)

The development of heartwood and sapwood in maritime pine (Pinus pinaster Ait.) in relation with tree and cambial age and growth rate was studied in ten trees randomly sampled at harvest (54–85-year-old) in a commercial stand in central Portugal. Average ring width at stem base was 1.84 ± 0.34 mm for 50 years of age. Growth rate decreased with cambial age and for the same cambial age increased along the stem with tree height.

The number of heartwood rings was strongly correlated with cambial age. Heartwood formation was estimated to start at approximately 21 years of age and to proceed at a constant annual rate that increased with age (0.5 and 0.7 rings year⁻¹ below and above 50 years of age). Within the tree, heartwood decreased with stem height, but in the lower part of the stem two patterns of variation were shown: a continuous decrease or an increase from stem base to a maximum at 2–3 m and a decrease afterwards. Sapwood radial width remained approximately constant within the tree and correlated positively with tree growth.     

Ethylene evolution,radial growth and carbohydrate concentrations in Abies balsamea shoots ringed with Ethrel

The terminal (1-year-old) shoot of quiescent, 2-year-old Abies balsamea (L.) Mill. seedlings was either left untreated or ringed with 0, 1 or 10 mg Ethrel g(-1) lanolin. After 5 weeks of culture under environmental conditions favorable for growth, the shoots were harvested to measure ethylene evolution and carbohydrate concentrations by gas chromatography, and tracheid number and bark radial width by microscopy. In untreated shoots, the basal rate of ethylene evolution followed the order: cambial region > cortex + periderm = xylem + pith = needles. Wound-induced ethylene production was not detected until at least 4 h after excision, but was evident in all fractions 24 h after excision; the increase in wound-induced ethylene evolution followed the order: cambial region > cortex + periderm > xylem + pith > needles. Compared with untreated controls, the application of plain lanolin, which involved the removal of needles and periderm, increased bark radial width and wound-induced ethylene production by the cambial region and the cortex + periderm, but decreased cambial region concentrations of fructose, glucose and starch at the application point. At the application point, Ethrel concomitantly increased ethylene evolution from the cambial region and the cortex + periderm, tracheid number, bark radial width, and the cambial region concentrations of fructose, glucose, sucrose and starch. No effects of Ethrel treatment were detected above or below the application point, with the exception that the 10 mg g(-1) Ethrel treatment stimulated ethylene evolution and decreased starch concentration of the cambial region. The results indicate that: (1) the cambial region is the major source of endogenous ethylene in the 1-year-old shoot; (2) the magnitude of the difference in ethylene evolution between particular shoot fractions is different before and after the start of wound-induced ethylene production; (3) the Ethrel-induced increase in tracheid number and bark radial width at the application point is positively related to ethylene evolution from the cambial region and the cortex + periderm, respectively; and (4) ethylene derived from Ethrel applied laterally to a woody stem can mobilize carbohydrates to the application point.     

An analysis of sap flow in mountain ash (Eucalyptus regnans) forests of different age

Diurnal measurements of sap velocity were made in 50-, 90-, 150- and 230-year-old mountain ash (Eucalyptus regnans F. Muell.) forests in the North Maroondah catchment (southeast Australia) over the periods January 8, 1990 to April 4, 1990 and October 29, 1990 to April 16, 1991. Over the two periods, daily mean sap velocities for the four forests, in order of increasing age, were 11.5, 11.4, 9.9 and 11.8 cm h(-1) respectively. Daily mean sap velocity did not differ significantly among the 50-, 90- and 230-year-old plots. However, in the 150-year-old trees it was significantly smaller by an average of 14%. Sap velocity varied diurnally and also between positions within individual trees and among trees both within and between stands. Despite this variability, the sampling intensity and duration were sufficient to establish that behavior was highly correlated among individuals within plots. There was a significant decline with age in the overstory sapwood conducting area of these forests. In order of increasing age, the values were 6.7, 6.1, 4.2 and 4.0 m(-2) ha(-1), respectively. When combined with daily mean sap velocity, these data allowed the calculation of overstory water use. Over the experimental period, water use of the overstory decreased with age ranging, on average, from 1.86 mm day(-1) for the 50-year-old plot to 0.81 mm day(-1) for the 230-year-old plot. Mean daily water use for the two intermediate-aged forests was 1.67 and 1.00 mm day(-1), respectively. Annual water use decreased with forest age from 679 mm for the 50-year-old stand to 296 mm for the 230-year-old stand. This difference corresponds to 3.8 x 10(3) m(3) ha(-1). The annual water use of the intermediate-aged stands was 610 and 365 mm for the 90- and 150-year-old stands, respectively.     

Silvopastoral practices sustain timber and forage production in commercial loblolly pine plantations of northwest Louisiana, USA

Four forage management treatments, bahiagrass, common bermudagrass, Coastal bermudagrass, and timber only were established in 26-year-old loblolly pine plantation. Pine growth data were collected in 1984, 1990, and 1995, and forage production was evaluated at 21-day intervals from April to October from 1991 through 1995. Forage management practices improved timber production, increasing five-year merchantable volume growth by 13 m³ ha^-1. Mean five-year forage crop yields differed among treatments (P = 0.05) with daily dry matter yields averaging 39, 46, and 48 kg ha^-1 for bahiagrass, common bermudagrass, and Coastal bermudagrass, respectively. Forage nutritional quality did not differ among forage crops. Forage management treatment future net values were computed for a 5% real interest rate. Although the future net value for bahiagrass and common bermudagrass exceeded Coastal bermudagrass, the mean forage crop future net value was similar to the timber only treatment. This revised version was published online in June 2006 with corrections to the Cover Date.     

草坪草耐干热低温性能研究

通过测定经干热和低温处理的草坪草样本浸泡液的电导率,结合自然干热、低温条件下的表现,比较冷、暖季型草坪草属间、种间或品种间的耐干热、耐低温性能的差异．结果表明,冷季型草坪草耐干热性能,属间存在着显著差异：羊茅草属＞早熟禾属＞黑麦草属＞翦股颖属;同属的种间大部分也存在着显著差异．暖季型草种中,地毯草、假俭草、狗牙根、细叶结缕草等耐干热性能较为理想;细叶结缕草、黑画眉草、结缕草、鼠尾粟、假俭草等的抗寒性能较强．测试结果与田间观测表现一致,说明测定电导率是检测草坪草耐性的一种简便、快速、有效的方法     

Laterally applied Ethrel causes local increases in radial growth and indole-3-acetic acid concentration in Abies balsamea shoots

The terminal (1-year-old) shoot of quiescent, two-year-old balsam fir (Abies balsamea (L.) Mill.) seedlings was ringed with lanolin containing 0, 1 or 10 mg g(-1) Ethrel, an ethylene-generating compound, and cultured for 6 weeks under environmental conditions favorable for growth. Bud break and the elongation of the current-year terminal shoot were monitored, and the subjacent previous-year terminal shoot that had been treated with Ethrel was harvested to measure stem radial growth by microscopy, shoot ethylene evolution by gas chromatography, and cambial region indole-3-acetic acid (IAA) concentration by combined gas chromatography-mass spectrometry. Compared with the lanolin controls, Ethrel at 1 and 10 mg g(-1) did not affect bud break or longitudinal growth, but stimulated tracheid production and bark increment up to about 2-fold at the application site, though not above or below it. In addition, the 1 and 10 mg g(-1) Ethrel treatments increased the cambial region IAA concentration about 3-fold and the evolution of ethylene at least 40-fold at the application site, compared with unwounded portions of both treated and control shoots. The 10 mg g(-1) Ethrel treatment also stimulated ethylene evolution about 10-fold, both above and below the application site. However, this stimulation was not associated with an elevation in cambial region IAA concentration. Similarly, the lanolin control treatment increased ethylene evolution at the application site about 10-fold, without affecting the cambial region IAA concentration. Our results suggest that the localized stimulation of radial growth in woody shoots ringed with Ethrel is mediated by an increase in IAA concentration, which in turn is induced by a threshold, abnormally high concentration of Ethrel-derived ethylene.     

Temporal water deficit and wood formation in Cryptomeria japonica

Cell behavior in the cambium and developing xylem of 3-year-old Japanese cedar (Cryptomeria japonica D. Don.) trees, during and after an 11-day suspension of irrigation, was analyzed. Leaf xylem pressure potential and tangential strain of the stem surface were monitored throughout the experiment. Anatomical features and numbers of developing tracheids and cambial cells were observed in four trees, sampled on Days 0, 4, 8 and 11 after irrigation was suspended. Daytime xylem pressure potential decreased to -1.9 MPa on Day 7 and remained the same until irrigation was resumed on Day 11. The transverse dimensions of the tracheids, which began to form secondary walls, began to decrease on Day 4. The number of cells in the cambial zone and cell expansion zone decreased abruptly on Day 8. Tangentially aligned developing tracheids with collapsed cell walls were observed in samples harvested on Days 8 and 11. Secondary wall formation was recognized in these tracheids. After the resumption of irrigation, xylem pressure potential recovered rapidly to the same value as before the suspension of irrigation. Tangential strain increased within 30 min after the resumption of irrigation, and continued to increase until the onset of light the next day. Eighteen days after the resumption of irrigation, anatomical features of cells in the cambium and cell-expansion zone were similar to those observed before suspension of irrigation.     

5种水生植物在冬季对小沿河水体脱氮除磷效果的研究

指出了冬季水生植物脱氮除磷效果的研究对低温地区水体的净化具有重要意义。通过人工模拟徐州小沿河冬季的自然条件,探讨了西伯利亚鸢尾、菹草、狐尾藻、伊乐藻、燕麦草5种水生植物对水体脱氮除磷的效果。结果表明：5种水生植物都能较好地吸收水体中的氮磷等营养物质,但不同水生植物对水体脱氮除磷的效果存在明显差异。对总氮的去除效果依次为：西伯利亚鸢尾〉燕麦草〉伊乐藻〉狐尾藻〉菹草;而对总磷的去除效果则随时间的变化有所改变,但总体表现为：燕麦草〉伊乐藻〉西伯利亚鸢尾〉狐尾藻〉菹草。不同月份水生植物去除水体氮磷的变化特点为：11月和3月去除效果较好,12月、1月和2月较差;而且西伯利亚鸢尾和燕麦草对总磷的去除效果受月份影响较小,表现较为稳定。西伯利亚鸢尾、燕麦草和伊乐藻可以作为冬季徐州小沿河水体氮磷去除的优选水生植物。     

冬樱花物候及观赏期观测

云南各地冬樱花花期有一定差异,但大都集中在12月上旬至1月中旬,紫色叶呈现期为12月下旬至1月上旬.果实成熟期为3月至4月.最佳观花期为12月中旬至1月上旬,持续时间昆明为12～15 d,思茅和景谷为10～12 d.最佳观紫色叶期为12月下旬至1月上旬,昆明为7～8 d,思茅为4～5 d.最佳现果期昆明为4月上、中旬,持续10～15 d,思茅和景谷为3月下旬至4月上旬,10～12 d.由不同地区和同一地区不同年份冬樱花物候的差异,认为冬樱花属低温春化才能开花的植物.     

Identification and quantitation of indole-3-acetic and abscisic acids in the cambial region of Quercus robur by combined gas chromatography-mass spectrometry

A technique is described for the rapid purification of indole-3-acetic acid (IAA) and abscisic acid (ABA) from small quantities of the basal trunk cambial region tissues of 34-year-old trees of Quercus robur L. Mass spectra of IAA and ABA obtained from the purified extracts provide the first reported unequivocal identification of endogenous IAA and ABA in the cambial region of a hardwood species. By use of the combined gas chromatography-mass spectrometry technique of multiple ion monitoring, with deuterated analogs as internal standards, it was shown that the levels of IAA in the cambial region tissues varied from ~1 to ~20 microg g(-1) and those of ABA from ~1 to ~5 microg g(-1) dry weight during the growing season. The high levels of IAA are similar to those found in the newly differentiating xylem tissues of softwoods.     

Seasonal changes in the xanthophyll cycle and antioxidants in sun-exposed and shaded parts of the crown of Cryptomeria japonica in relation to rhodoxanthin accumulation during cold acclimation

Xanthophyll rhodoxanthin, which is present in sun-exposed needles of certain gymnosperms in winter, may have a photoprotective role during long-term cold acclimation. To examine how cold acclimation processes vary within tree crowns and to examine putative correlations between xanthophyll cycle pigments (VAZ), rhodoxanthin and the water-water cycle in photoprotection, we monitored seasonal changes in the activities of two key antioxidant enzymes (ascorbate peroxidase (APX) and glutathione reductase (GR)), pigment composition and chlorophyll fluorescence parameters in sun and shade needles of crowns of the gymnosperm Cryptomeria japonica D. Don. Although APX and GR activities in both sun and shade needles were higher in winter than in summer when assayed at 20 degrees C, differences between seasons were less pronounced when enzymatic activities in summer and winter were assayed at 20 and 5 degrees C, respectively. These results suggest that increases in the potential activity of antioxidant enzymes in winter is an adaptation that helps counterbalance reductions in absolute enzyme activity caused by low temperature, and thus allows the photoprotective capacity of the water-water cycle in C. japonica to be maintained at a roughly constant value throughout the year. In shade needles, the concentration of VAZ increased in winter, but no rhodoxanthin accumulated. Photosynthetic activity was maintained in winter. In sun needles, however, the electron transport rate (ETR) and photochemical quenching (q(P)) decreased to their lowest values in December, just before the accumulation of rhodoxanthin, which coincided with the highest amount of VAZ. Changes in rhodoxanthin concentration mirrored changes in VAZ concentration from January to March. Winter values of ETR and q(P) were comparable with summer values after accumulation of rhodoxanthin, indicating that rhodoxanthin may play a more important role than the VAZ cycle in protecting the photosynthetic apparatus from photodamage in winter. Photosynthetic activity may be modulated, as a result of the interception of light by rhodoxanthin, to match the extent to which absorbed light energy can be utilized in winter when the VAZ cycle is unable to operate effectively because of low temperatures.     

Cambial Anatomy and Annual Rhythm of Secondary Xylem Development in the Twigs of Azadirachta indica A. Juss. (Meliaceae) Growing in Different Forests of Gujarat State

Abstract

Seasonal behavior of vascular cambium and development of secondary xylem were studied in the 2-3-years-old branches of Azadirachta indica A. Juss. (Meliaceae) growing in moist deciduous (MDF), dry deciduous (DDF) and scrub land (SF) forests of Gujarat State. Development of xylem began with the sprouting of new leaves in January in both MDF and DDF. Xylem production culminated in July in MDF whereas it reached peak in April and July in DDF. Cambial cells ceased to divide with the maturation of leaves in November and October in MDF and DDF, respectively. Mature xylem and phloem derivatives surrounded the cambium in December in MDF and November in DDF. Radial growth in the branches of trees growing in SF was found continuous throughout the year with peak cambial activity in April, July and November. In all the three forests, maximal radial growth was encountered in July when the rains were heavy. Cambial activity and xylem development showed significant correlation with the phenology of the trees in MDF and DDF whereas cambium was found active throughout the year and no correlation was found between the cambial activity and phenology in SF.     

沙地樟子松天然更新与降水因子的灰色关联度分析

沙地樟子松人工固沙林的天然更新在大部分引种地不能很好地进行，其天然更新存在着某些障碍因子。通过对辽宁省昌图县傅家林场樟子松天然更新情况的调查，采用灰色关联度分析的方法，对更新与降水因子的关系进行了分析。结果表明，更新产生的当年12月和翌年1，2月的降水量，即冬季降雪情况与天然更新关联最大。说明了冬季降雪是影响樟子松天然更新的一个关键因子。