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1.
白藤是中国热带、南亚热带森林中重要的伴生藤本和非木质森林资源。为探究白藤种子萌发的最佳处理,采用赤霉素（GA3）浸种对白藤种子发芽特性进行研究。结果表明：发芽率以50 mg/L的GA3溶液浸种处理最高（91.82%）,该处理能提高白藤种子发芽率;发芽势和发芽指数均以400 mg/L GA3溶液浸种处理最高（83.18%,16.67）,20 mg/L GA3溶液浸种处理最低（50.65%,11.50）。建议采用GA3溶液浸种与催芽技术相结合,以提高白藤种子发芽率、发芽势和发芽指数。 相似文献
2.
Portable, non-destructive chlorophyll meters could be a valuable tool for forest managers and researchers. The ability of such meters to assess both chlorophyll and nitrogen content has been well established for many agricultural species, but not well-studied for North American forest tree species. The objective of this study was to evaluate the ability of a portable chlorophyll meter to estimate chlorophyll (CHL) and nitrogen (N) content in sugar maple (Acer saccharum Marsh.) leaves by testing correlations between chlorophyll content index values (CCI) and extractable CHL and N in large heterogeneous samples. Significant correlations were observed between CCI and CHL (P ≤ 0.001, r2 = 76%) and CCI and N (P ≤ 0.001, r2 = 64%). These data indicate that the meter tested can be an effective tool for estimating relative chlorophyll and nitrogen content in sugar maple leaves. 相似文献
3.
Gregory J. Jordan Bradley M. Potts Anthony R. Clarke 《Forest Ecology and Management》2002,160(1-3):189-199
Sawflies (Perga species) are leaf-damaging pests of the major plantation tree species Eucalyptus globulus ssp. globulus. This work describes the patterns of quantitative genetic variation in susceptibility to attack by Perga affinis ssp. insularis, based on data from a large open-pollinated trial containing genetic material from throughout the geographic range of E. globulus ssp. globulus. Forty three per cent of the trees in the trial exhibited damage from sawflies in either their sixth or seventh growth seasons. The incidence of damage was genetically based, with significant variation between geographic races of E. globulus ssp. globulus and highly heritable (h2=0.43±0.05) variation in damage incidence within races. Susceptibility to sawfly damage significantly affects plant fitness with both genetic and environmental correlations demonstrating that sawfly damage causes slow growth and increased mortality of trees. Mild and severe sawfly damage resulted in 16 and 31% reduction in the basal area of surviving trees, and the effect was consistent across races and families. Based on this data, we propose a model predicting relative plantation productivity of races of different susceptibility under different infestation regimes. 相似文献
4.
Ingvar Backus Brge Pettersson Lennart Strmquist C. Ruffo 《Forest Ecology and Management》2006,230(1-3):171-178
Tree vegetation and size structure was sampled in a miombo woodland area in E Tanzania and related to environmental factors, particularly soil and disturbance history. A total of 86 tree species was found. Four plant communities were distinguished through multivariate classification. Community 1 was dominated by Brachystegia boehmii, Brachystegia bussei and Julbernardia globiflora, and community 2 by B. boehmii and Brachystegia spiciformis. Community 1 was found on grey, eroded soil and community 2 on red, residual soil, a fact that opens up possibilities to use soil signals of satellite data for vegetation mapping. Community 3 is heavily disturbed miombo woodland near villages and community 4 was found on more clayey soil where miombo woodland is not expected.
At our 42 sampled sites, density ranged from 74 to 1041 individuals ha−1 and basal area from 3.9 to 16.7 m2 ha−1. Regeneration is generally good but large sized trees are less prominent in communities 3 and 4 due to harvesting. With reduced disturbance miombo species may rapidly resume dominance in community 3. A higher than expected representation by the size class 30–40 (−50) cm dbh in community 2 is probably related to disturbance history. Prevalence of certain species (Pseudolachnostylis maprouneifolia, Pterocarpus angolensis and Diplorhynchos condylocarpon) may be related to frequent fires. Selective logging will soon cause extinction of Dalbergia melanoxylon, whereas Pterocarpus angolensis still has good regeneration, possibly because individuals below logging size have a good seed set.
A way to get an easy overview of size classes in all species in an area using PCA is discussed. 相似文献
5.
S. N. Aitken W. T. Adams N. Schermann L. H. Fuchigami 《Forest Ecology and Management》1996,80(1-3):187-195
In order to assess the genetics of fall cold hardiness in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco), shoot cuttings were collected in October from saplings (9-year-old trees) of open-pollinated families in two progeny tests in each of two breeding zones in Washington, one in the Coast range (80 families) and one on the west slope of the Cascade Mountains (89 families). Samples from over 5500 trees were subjected to artificial freezing and visually evaluated for needle, stem and bud tissue injury. The extent to which cold injury is genetically related to tree height and shoot phenology (timing of bud burst and bud set) was also evaluated.
Significant family variation was found for all cold hardiness traits; however, individual heritability estimates were relatively low (ranging from 0.09 to 0.22). Significant family-by-test site interaction was detected for needle injury in the Cascade breeding zone, but not in the coastal zone. Genetic correlations (rA) among needle, stem and bud tissues for cold damage were weak (0.16 ≤ rA ≤ 0.58) indicating that genes controlling fall hardening are somewhat different for different tissues. Timing of bud burst and bud set were only weakly correlated with cold injury (rA ≤ 0.49). Thus, bud phenology is a poor predictor of fall cold hardiness in this species. There was no consistent relationship between tree height and cold injury in the coastal zone. In the Cascade zone, taller trees appeared to be more susceptible to cold injury, but the association was weak (mean rA = 0.38, range 0.20 – 0.72). 相似文献
6.
Biomass, leaf area, canopy photosynthesis, photosynthetic nitrogen-use efficiency (PNUE), nitrogen-partitioning ratio (NPR: ratio of nitrogen taken up by jack pine relative to two different competitor species), and nitrogen uptake (NU) of jack pine (Pinus banksiana Lamb.) competing with large-leaved aster (Aster macrophyllus L.) and Canada blue-joint grass (Calamagrostis canadensis (Michx.) Beauv.) were examined at three nitrogen levels in a controlled-environment growth chamber. When grown with large-leaved aster, jack pine biomass, photosynthesis and PNUE (p<0.001) increased as nitrogen level increased. Jack pine biomass, photosynthesis and NPR (p<0.001) decreased as nitrogen level increased when grown with Canada blue-joint grass. At the lowest nitrogen supply level, jack pine photosynthesis decreased as competitor PNUE increased (r2=0.84, p<0.001). Jack pine photosynthesis decreased as NU of large-leaved aster (37.5 mg N l−1: r2=0.75, p<0.001; 100 mg N l−1: r2=0.86, p<0.001) and Canada blue-joint grass (37.5 mg N l−1: r2=0.96, p<0.001; 100 mg N l−1: r2=0.84, p<0.001) increased. NU and PNUE may play an important role in the outcome of interactions between jack pine seedlings and competing forest vegetation in newly planted stands. 相似文献
7.
8.
Periodic variations in the concentration, deposition and canopy impact of different forms of N on annual N deposition through rainfall, throughfall and stemflow in 5 and 8 year old stands of Casuarina equisetifolia were studied. Throughfall and stemflow ranged from 70 to 76% and 5–6% of annual precipitation respectively. The total N deposition by rainfall was 11.1 kg ha−1 year−1, and by throughfall was 13.6 kg ha−1 year−1 and 16.5 kg ha−1 year−1 in 5-year-old and 8-year old plantations, respectively. The quantities of N deposited through stemflow in the two plantations were nearly identical, accounting for 1.6 kg ha−1 year−1. Observations of the monthly deposition of NH4,N, NO3-N, Kjeldahl-N and organic-N revealed that maximum deposition occurred in July and the minimum in September. Organic-N deposition was 17% less (5-year) than the rainwater content. Net deposition of N, as an effect of canopy, was 7–8.7 kg ha−1 year−1, which was added directly to the available nutrient pool of soil. 相似文献
9.
Two thinning and fertilization studies, the first in 1969 and the second in 1971, were established to evaluate the question of nutrient limitation to tree growth and the consequences of stand manipulation of soil moisture supply. Fertilizer was applied yearly for the first 5 years in both studies; growth response has been measured through 1987. Results indicate that thinning is necessary to obtain a growth response to fertilizer applied at the rate of 111 kg nitrogen ha−1. The response to fertilization after fertilization ended lasted for 4 years in plots thinned to 800 stems ha−1, while a significant response continued for only 2 years in plots thinned to 1600 stems ha−1.
A soil water-balance model was calibrated for the control and treatment plots of these two studies. Soil water-deficits were estimated and correlated with yearly average basal-area growth per tree. Results indicated that there is a correlation between seasonal soil-moisture deficit and growth during the years when soil moisture was measured for the unthinned control plots (r2 = −0.787, P = 0.002) but not for the thinned and fertilized plots (r2 = −0.652, P = 0.057). 相似文献
10.
Raf Aerts Wouter Maes Eva November Aklilu Negussie Martin Hermy Bart Muys 《Forest Ecology and Management》2006,230(1-3):23-31
To identify the perspectives of seed sowing for reforestation of degraded dry Afromontane savanna in exclosures in northern Ethiopia, seeds of a fleshy-fruited, secondary climax tree, Olea europaea ssp. cuspidata, were placed under two pioneer shrub species (Euclea racemosa and Acacia etbaica) and in open microhabitats. Seed removal and germination rates were examined. The effects of bird ingestion, manual pulp removal and mechanical endocarp treatments on germination rates were also studied.
Pulp removal promoted seed germination, in particular in seeds without endocarp manipulation. Seed removal, presumably by rodents, was concentrated in narrow strips along linear soil conservation structures, and not different between shrubs and open microhabitats. In the absence of water stress, humus types did not have a significant effect on germination rates. Under field conditions however, germination was higher under Euclea canopies. The observed facilitative effect of Euclea shrubs on germination may be attributed to moisture retention effects, related to the deep humus layer and canopy architecture, preventing desiccation and promoting imbibition of seeds. When readily available Olea seeds are not used for seedling production, direct sowing of seeds in the humus under dense Euclea shrubs could offer a cheap complement to planting of nursery-raised seedlings for forest restoration projects in recovering Afromontane savanna. 相似文献
11.
Annual litter fall of Acacia mangium in the period of September 1995 to August 1996 was estimated at 5939 kg ha−1 year−1 and from September 1995 to August 1996 at 6048 kg ha−1 year−1, with the highest seasonal production in the dry season. The litter fall was dominated mainly by leaves, 4446 kg (75%) and 4137 kg (68%), respectively. Seed production in the litter fall was estimated at 42.4 kg ha−1 year−1 (4.1 million seeds ha−1) and 39 kg ha−1 year−1 (3.8 million seeds ha−1), with the highest in the dry season from June to October. The accumulated litter fall in the forest floor together with shrubs and grass provide a high fuel load, increasing fire risk. 相似文献
12.
云南甜龙竹（Dendrocalamus brandisii）是优异的笋材两用大型丛生竹种,但常规无性繁殖技术培育的苗木因价格高而极大地阻碍了该竹种的推广栽培。文章以云南甜龙竹种子萌发的无菌苗为外植体,研究植物生长调节剂对试管苗快速繁殖及生根的影响。结果表明：丛生芽诱导的最佳培养基为MS+6-苄氨基腺嘌呤（6-BA）3.0 mg/L+萘乙酸（NAA）0.7 mg/L,诱导率可达86.33%;最佳继代增殖培养基为MS+NAA 0.3 mg/L+6-BA 6.0 mg/L+噻苯隆（TDZ）0.001 mg/L,增殖系数可达4.90;最佳生根培养基为1/2MS+NAA 2.0 mg/L+吲哚丁酸（IBA）4.0 mg/L,生根率可达71.45%。研究结果可为云南甜龙竹工厂化育苗提供技术支撑。 相似文献
13.
In 1989, the first recorded outbreak of hemlock looper (Lambdina fiscellaria fiscellaria (Guen.)) occurred in New Brunswick, Canada. Data were collected from ten plots established in an area infested from 1992–1994, to assess impacts of hemlock looper. Ocular and branch sample assessments of current defoliation and ocular assessments of total defoliation (all age classes of foliage) were conducted for balsam fir (Abies balsamea [L.] Mill.), white spruce (Picea glauca [Moench] Voss), and black spruce (Picea mariana (Mill.) B.S.P.). Stand response was assessed and related to cumulative defoliation. Ocular assessments were found to accurately estimate defoliation, which was significantly related to tree mortality. Ninety-two percent of balsam fir trees that had cumulative defoliation >90% died. Mortality of balsam fir was significantly (p < 0.05) related to tree size, in both lightly and severely defoliated plots; trees with DBH <11 cm sustained 22–48% higher mortality than larger trees. Mortality of balsam fir, in terms of both percent stems/ha and m3/ha merchantable volume, increased exponentially in relation to three estimates of cumulative (summed) plot mean defoliation. The strongest relationships (r2 = 0.75–0.79) were between mortality and the ocular defoliation assessment for 1990–1993 foliage. Tree mortality caused by the looper outbreak ranged from 4–14% stems/ha in lightly defoliated and from 32–100% in severely defoliated plots; merchantable volume killed was 3–14 m3/ha and 51–119 m3/ha, respectively. Relationships between mortality and defoliation were similar when defoliation was assessed for 1987–1993 and 1990–1993 foliage age classes. 相似文献
14.
To assess the effects of clearcutting on snowshoe hare (Lepus americanus) relative abundance, we surveyed pellets in 1 m2 circular plots and, vegetation and browse surveys in 4.5 m2 circular plots among four different aged clearcut (30, 20, 10, 5 years post-harvest) and mature forests (>150 years old) in central Labrador, Canada. Data were modelled at three grain sizes: transect (4400 m2), plot (314 m2) and subplot scales (4.5 m2). Betula papyrifera, distance from mature forest edge, tree and herb cover as well as remotely sensed forest inventory data were used as predictors for hare pellets. We found pellet abundance was 5 and 37 times greater (new and old pellets, respectively) in clearcut stands 30 years old than the next highest in 20 year old cuts. There were few hare pellets in the remaining stand ages. B. papyrifera was the most proportionately used browse species and most important of our fine-detailed vegetation in predicting hare pellets. The coarse-detailed, forest inventory and topographic data better predicted hare pellets than the fine-detailed vegetation data. 相似文献
15.
Gideon N. Gathaara Edward L. Glumac Peter Felker 《Forest Ecology and Management》1991,40(3-4):189-198
The productivity of Leucaena leucocephala and a superior L. pulverulenta family were examined over a 3-year period at spacings (1.5 m×1.5 m and 1.5×3.0 m) chosen to compare two mechanical weeding operations. Leucaena pulverulenta was examined since faster-growing families of this cold-hardy, low-mimosine leucaena species were recently identified. There was no significant difference in yields between the species (P = 0.9060) but there was a significant difference between spacings (P = 0.0491). There was no significant spacing×species, species×year or spacing×year interaction. The annual growth rates for the first, second, and third seasons' growth for L. leucocephala were 3.73, 10.11 and 6.00 t ha−1 at the close spacing and 3.03, 7.14 and 5.04 for the wider spacing. The annual growth-rates for the first, second and third seasons' growth for L. pulverulenta were 2.03, 8.35 and 8.31 t ha−1 at the close spacing and 1.25, 9.38 and 5.29 at the wider spacing. Despite the fact that L. leucocephala froze to the ground in the first and second winter when L. pulverulenta was nearly undamaged, the L. leucocephala coppice resprout was greater than the second year's growth for L. pulverulenta. 相似文献
16.
Two strains of the nuclear polyhedrosis virus of the gypsy moth, Lymantria dispar, are compared in field applications on experimental plots. With dosages 2 × 1011–1012 PIB ha−1 received, corrected mortalities of larvae varied from 70% to 92%. At the same time, natural mortality of untreated populations ranged form 27% to 55% at the peak of the outbreak. The total reduction with ‘Gypchek’ the U.S. commercial formulation, reached 95%, compared with 93% after application of non-formulated material of a local strain under identical conditions. The American strain of NPV of the gypsy moth does not differ significantly in its effect from the local NPV on European populations of the gypsy moth. 相似文献
17.
The N dynamics following clear felling, focusing on NO3− turnover, were studied at four forested sites in southern Sweden. Two different methods were used to study N availability: (i) an in vivo nitrate reductase activity (NRA) bioassay and (ii) measurements of natural abundance of stable N isotopes in leaves of the grass species Deschampsia flexuosa, and in organic soil horizons. At each of the four sites, six plots were established and each year, for 5 consecutive years (1989–1993), one plot per site was felled. Thus, in 1993 there were five plots with different ages since clear felling and one control (closed forest) plot at each site. NRA was analyzed three times annually during the years 1989–1993. Samples for grass and soil analysis of δ15N, total N and soil pH were taken in 1993 only. NRA rapidly increased after the felling and remained high throughout the studied period. This suggests that there was an increased pool of plant-available soil NO3− more than 5 years after clear felling. Despite differences in site productivity and N deposition between the four sites, no significant differences in NRA were found between the sites. There were also rapid changes in δ15N in leaves of D. flexuosa, coinciding with the increases in NRA, during the first 3 years after felling. In contrast to NRA, shoot δ15N decreased 3–4 years after the felling at three out of four sites. Variations in the δ15N figures between sites may have been largely due to between-site differences in field-layer retention of N. At two of the sites, where NO3− leaching was also measured, a correlation was found between the NO3− concentration in the water and the difference in δ15N between D. flexuosa leaves from felled and closed forest plots. The data presented here suggest that NO3− leakage after clear felling is a rapid process, which is influenced by the development of field-layer biomass after the felling. Furthermore, losses of NO3− through leaching rapidly change the natural abundance of the plant available N pools in the soil. 相似文献
18.
Marjoriitta Mttnen Tarja Lehto Pedro J. Aphalo Mikko Kukkola Eino Mlknen 《Forest Ecology and Management》2003,180(1-3):401-412
The effects of boron (B) fertilizer applied 10 growing seasons earlier were studied in mature Norway spruce (Picea abies (L.) Karst.) trees in long-term factorial fertilization experiments at two field sites. Needle nutrient status, above-ground and below-ground growth and δ13C and carbon concentrations in the annual rings were measured. Needle B concentrations varied between 4 and 19 mg kg−1 on the plots that had not received B fertilization. On the B-fertilized plots they varied between 15 and 39 mg kg−1. The lowest B concentrations were on the plots that had received N or NCa fertilization. Needle Mn and Zn concentrations were lower on the B plots than on the plots that had not received B fertilization, although not significantly. Mean annual volume growth was slightly higher on the B plots at the more fertile site, but not at the less fertile one. The living:dead fine root mass ratio and living fine root length were also higher on the B-fertilized plots than on the unfertilized plots, but δ13C was not significantly affected, suggesting that the water status of the trees was not markedly altered by the increase in root growth. The carbon concentration in the annual rings was higher in the B-fertilized trees than in the unfertilized ones, suggesting the importance of B for wood formation. 相似文献
19.
Seasonality in rooting of cuttings and its relationship with some environmental conditions and growth parameters of Prosopis chilensis (Mol. Stunz) were studied. It was observed that rooting could be induced in cuttings taken from field collections only during the dry season, the period corresponding to the highest vegetative growth and reproductive activity (September to March); however, percentages did not exceed 15%. The rooting response does not occur during the dormant period (May to September). When using cuttings from clonal material growing in the glasshouse, rootings exceeding 80% were obtained in liquid aerated media.
In-vitro micropropagation was assessed in P. chilensis using nodal and apical segments collected both from the field and from clonal material and plantlets grown from seed in the glasshouse. Juvenile material gave an 80% regeneration rate of complete plants in Murashige-Skoog medium fortified with 5 mg naphtaleneacetic acid 1−1 and 10 mg cysteine 1−1. In this same medium, the regenerative response of segments obtained from rooted cuttings was 60%. The material collected from the field showed no rooting responses. 相似文献
20.
The pine processionary moth, Thaumetopoea pityocampa (Den. & Schiff.) is one of the most destructive pine pests in the Mediterranean countries. The first objective of this study was to analyse the spatial distribution of this insect on the tree on Pinus pinaster Ait., in northeast Portugal. The second objective was to develop two sampling plans: a sampling plan with fixed levels of precision for estimating T. pityocampa populations and a sequential sampling plan to classify the pest. Population estimates were made by registering the number of insect egg batches on 90 trees distributed over 3 stands during a 3-year study (1997–2000). Taylor's power law and Iwao regression were used to analyse the spatial distribution of the pest. Taylor's power law fitted the data better (r2 = 0.775) than Iwao's regression model (r2 = 0.704). The aggregation indices (b and β) were both significantly greater than one, indicating the aggregation of T. pityocampa egg batches. Optimal sample sizes for fixed precision levels of 0.10, 0.15 and 0.25 were estimated with Taylor's regression coefficients. Required sample sizes increased dramatically with increased levels of precision. The two sampling plans presented should be a tool for research on population dynamics and pest management decision. 相似文献