Influence of artificial gaps in tropical forest on survival, growth, and Phytolyma lata attack on Milicia excelsa

Milicia excelsa and M. regia are important timber species in moist tropical areas of Africa. They have not been successfully grown largely because of attacks by gall-forming psyllids in the genus Phytolyma. Our objectives were to evaluate the growth of planted Milicia seedlings and incidence of psyllid attack in small (4.2 m²), medium (18.5 m²) and large (>500 m²) artificial gaps in the Bobiri Forest Reserve in the Moist Semi-Deciduous Forest of Ghana. After 13 months, height and diameter growth of Milicia seedlings were significantly greater in the medium and large gaps than in the small gaps. Insect attacks occurred first and most severely in the large gaps, but spread to gaps of all sizes between the 11th and 13th months after planting. While gap size significantly affected the susceptibility of seedlings to psyllid attack, it is not the only factor important in determining susceptibility of Milicia excelsa under field conditions. We conclude that gap sizes in the range of 10–50 m², where irradiances are from 30–60% of full sunlight, in forests similar to those at the study site, seem to be most suitable for regeneration of Milicia.     

Physiological and growth responses of three sizes of containerized Picea mariana seedlings outplanted with and without vegetation control

Three different stock sizes of containerized black spruce (Picea mariana [Mill.] B.S.P.) seedlings were planted in an abandoned agricultural field. The small planting stock was of a conventional type produced in 110 cm³ containers. The experimental medium and large stock types were produced in 340 and 700 cm³ containers, respectively. Gas exchange, xylem water potential and dry masses were measured six times during each of the first two growing seasons in field plots with and without vegetation control. During the first growing season, the effect of planting shock masked most physiological and growth differences among seedling types. During the second growing season, in plots with vegetation control, small and medium seedlings had similar values of physiological variables and of growth as measured by relative growth rates (RGR), but the large seedlings showed lower values of both net photosynthesis and of RGR, a difference attributed to low initial quality of the root system in the larger seedlings. In plots without vegetation control, the trend was identical, but differences were not significant; the greater height of the larger seedlings, and the resulting greater access to light, compensated for their lower initial quality. The similarity in response between the medium and the small seedlings shows that a fourfold increase in shoot size (1.68–6.82 g) in the initial size and a doubling of the shoot : root ratio (2.17–4.54) of the planting stock did not result in increased planting shock or reduced growth in these containerized conifer stock types. The results also show the importance of the interaction between stock height and the vertical light profile created by the competing vegetation in the final assessment of stock performance.     

短枝木麻黄种子散布模式及子代群体的遗传多样性分析

目的 利用短枝木麻黄(Casuarina equisetifolia L.)实生人工林群体及其自由落种长成的天然更新群体,开展短枝木麻黄种子散布规律研究,比较天然更新群体(子代群体)与其母本群体以及30年生实生人工林群体的遗传多样性差异,为人工促进木麻黄天然更新提供理论依据。 方法 利用木麻黄11个SSR标记位点的遗传分型数据,通过亲本分析软件Cervus 3.0对天然更新群体植株的母本进行确定,分析短枝木麻黄种子散布的距离和模式,并利用遗传多样性参数对这3个群体的遗传多样性进行比较。 结果 （1）子代和母本群体共367个个体样本在11个SSR位点共检测出137个等位基因,每个位点的等位基因数为6～24,平均有效等位基因数为4.95,平均期望杂合度、观测杂合度和多态性信息量分别为0.75、0.77和0.72,所有位点均属于中或高度多态性位点。（2）在80%的置信区间下,利用11个标记位点的分型数据,可为148株子代确定它们的母本,占鉴定子代总数的72.20%;种子的有效散布距离为10～130 m,平均散布距离为71 m,属于短距离传播;天然更新群体的母本主要集中在样地的东北和东部,2个方向的母本对子代的贡献率为75.00%。（3）从3个群体中各选择84株个体的DNA样品进行遗传多样性比较,结果显示：天然更新群体在各个遗传多样性参数上均低于母本群体和实生人工林群体,但其参数表明该群体仍具有较高的遗传多样性。 结论 短枝木麻黄种子散布属于短距离传播,天然更新群体可以保持较高的遗传多样性,这为人工促进木麻黄实生林的天然更新提供了理论基础。     

Testing site index–site-factor relationships for predicting Pinus contorta and Picea engelmannii×P. glauca productivity in central British Columbia, Canada

Measures of forest productivity for various site conditions are necessary for forest management planning, where timber production is the objective. This study was undertaken to test whether autecological productivity relationships developed for lodgepole pine (Pinus contorta) and interior spruce (Picea engelmannii×P. glauca) using the biogeoclimatic ecosystem classification system of British Columbia are useful as practical field-based procedures to predict site index. Independent data sets consisting of 111 plots for pine and 114 plots for spruce were collected for use in testing the bias and precision of the models. A regression on residuals (predicted minus test values) indicated that the lodgepole pine model was unbiased in estimating site index (p=0.08). However, there was a lack of precision, with a square root of the mean squared prediction error (root-MSPR) of 2.8 m. Only 56% of the test plots had differences from the predicted values of 2.0 m or less. Residual analysis showed that the interior spruce model was biased in estimating site index (p<0.01), generally predicting greater site index than the test values. The model also lacked precision, with a root-MSPR of 3.2 m. Only 44% of the test plots had differences from the predicted values of 2.0 m or less. Forest managers requiring a site-index prediction tool need to decide whether the degree of accuracy precision provided by these models is acceptable.     

Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae) oviposition on seven naturally co-occurring Eucalyptus species

Gonipterus scutellatus is a significant insect pest of eucalypts in most countries where that genus has been introduced, but is usually only of minor significance in its native Australia. Because of this, much of the research on its biology and host preferences has been done outside Australia. This fact has the potential to produce misleading results as the insect may be forced to choose less preferred hosts, if normally preferred species are unavailable. In part of its native range, in Tasmania, oviposition of G. scutellatus was recorded on seven naturally co-occurring Eucalyptus species that were planted in even aged, replicated plots. Among the seven species were the economically important species, E. globulus and E. viminalis, which have been previously reported as highly preferred hosts. Within plots, oviposition occurred most commonly on three peppermint species (E. pulchella, E. tenuiramis and E. amygdalina) and was rare or absent on the other species (E. globulus, E. viminalis, E. ovata and E. obliqua). Of the peppermints, E. pulchella was the most preferred species for oviposition at this site. A low percentage of peppermints in mixed forest (containing these seven species) immediately adjacent to plots was always matched by low numbers of G. scutellatus eggs within plots; but high percentages of peppermints outside plots could either be matched by high or low numbers of eggs within plots. In the discussion, we suggest that previous studies of G. scutellatus host range may have been limited because the insect was not exposed to hosts it naturally encounters.     

短枝木麻黄无性系鉴定及其指纹图谱构建

[目的]构建木麻黄无性系的DNA指纹图谱鉴定体系,为今后短枝木麻黄的品种鉴定、品种权保护、新品种的选育提供依据。[方法]从71对EST-SSR引物中筛选出扩增条带清晰、多态性好、扩增稳定的12对引物,采用降落PCR和毛细管电泳的基因分型方法,以采集的9个短枝木麻黄标准无性系的基因分型结果为参照,对华南沿海地区采集的109个短枝木麻黄无性系单株进行鉴定,并结合引物组合法构建基于EST-SSR分子标记的短枝木麻黄无性系鉴定体系。[结果]12对EST-SSR引物对109个短枝木麻黄无性系单株进行PCR扩增,共检测到50个等位基因,每个位点的等位基因数为3～6个,平均为4.2个,每对引物可区分2～5个短枝木麻黄无性系。根据鉴定结果,最终所有样品被划分为22个无性系,除已知的9个标准无性系外,另有13个无性系为不知名无性系,说明不同地区的无性系存在重复命名现象;利用引物组合法进一步优化后,发现只需7对引物就可将22个短枝木麻黄无性系完全区分,并依此建立了基于7对EST-SSR引物的22个短枝木麻黄无性系的指纹图谱,每个无性系都获得了一个7位数的指纹图谱编码。[结论]利用7对EST-SSR引物构建的22个短枝木麻黄无性系的DNA指纹图谱可用于短枝木麻黄无性系的鉴别,研究表明,华南沿海地区部分短枝木麻黄无性系存在命名混乱、同物异名、无性系数量少的现象,新品种选育工作亟待开展和加强。     

Fine litterfall and nutrient dynamics during forest regrowth in the humid subtropics of north-eastern India

Fine litterfall and nutrient return patterns were studied in three subtropical humid forest stands (7-, 13- and 16-year old), regrowing after selective tree cutting in north-eastern India. The seasonality of fine litterfall was unimodal, with a peak during spring and a trough during rainy season in the forest regrowths of three different ages. The rate of fine litterfall increased with increasing basal area of the woody vegetation during forest regrowth. Leaf litter accounted for 83% of the total litterfall. N concentration was maximum during autumn and minimum during rainy season; nutrient concentrations were highest in the leaf litter. Seasonal variation in P concentration was small. Maximum and minimum input of N and P to the forest floor through fine litter coincided with the respective periods of litter production.     

Structure of silver fir (Abies alba Mill.) natural regeneration in the ‘Jata'' reserve in Poland

Over the last 20 years, investigations have been carried out to determine the influence of various ecological factors on silver fir natural regeneration in highlands and mountains. However, there has been little research on the structure and development of fir regeneration in lowlands. Results of this study indicate that three main stand characteristics play a very important part in the structure of fir regeneration in the lowland. The results revealed that the quantity, frequency and growth rate of fir regeneration were affected by site conditions. One of the most important ecological factors differentiating quantity and quality of fir regeneration was the proportion of fir in a stand. It was found that, with an increase in the percentage of fir in a stand, the quantity and the sum of heights and the sum of height increments of fir regeneration tends to increase. Results of this study showed that the number and development of fir regeneration were influenced by species composition of a stand; fir regenerated not only in pure fir stands but also in mixed forests. A positive influence of pine and birch canopy on initiation and development of fir regeneration was confirmed. Optimal conditions for the growth and development of fir with respect to species composition were found in mixed fir stands with an admixture of hornbeam. In contrast, results of the study suggest that the worst conditions for fir regeneration were found in the stands composed of species, such as ash, alder, oak, aspen, lime and spruce.     

短枝木麻黄根际放线菌及其抗细菌活性

目的 分离并鉴定短枝木麻黄根际土壤中的放线菌,测定短枝木麻黄根际放线菌的抗细菌活性,并从中筛选出活性放线菌菌株。 方法 采用热击稀释法分离短枝木麻黄根际土壤中的放线菌,通过形态学观察和分子生物学相结合的方法对分离得到的放线菌菌株进行鉴定,采用薄层层析（TLC）-生物自显影法测定短枝木麻黄根际放线菌次生代谢产物对不同供试细菌的抑制活性,进一步采用高效液相色谱（HPLC）分析根际放线菌乙酸乙酯层提取物中次生代谢产物的情况。 结果 从短枝木麻黄根际土壤中共分离鉴定得到12株放线菌,均为链霉菌属（Streptomyces sp.）放线菌,最大相似度均在97%以上。活性测定的结果表明：菌株S. spinosus Ceaf-4和S. chattanoogensis Ceaf-12对木麻黄青枯病菌（Ralstonia solanacearum）表现出较强的抑制活性,抑菌斑的直径均在10 mm以上;菌株S. spinosus Ceaf-4对大肠杆菌（Escherichia coli）和溶血葡萄球菌（Staphylococcus haemolyticus）的抑菌斑直径也大于10 mm。高效液相色谱分析的结果表明,菌株S.spinosus Ceaf-4和S. chattanoogensis Ceaf-12均含有丰富的次生代谢产物,但次生代谢产物的类型和相对含量均存在明显差异。 结论 短枝木麻黄根际土壤中存在以链霉菌属为优势种群的放线菌,菌株S. spinosus Ceaf-4和S. chattanoogensis Ceaf-12对木麻黄青枯病菌表现出较强的抑制活性且含有丰富的次生代谢产物,可作为候选菌株进一步发掘其抗菌活性成分。     

Nitrogen deposition in Casuarina equisetifolia (Forst.) plantation stands in the dry tropics of Sonbhadra, India

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.     

木麻黄与根系微生物关系研究进展

木麻黄是我国沿海防护林基干林带中的主栽树种,与土壤中的微生物可以形成共生关系,提高自身耐干旱、抗贫瘠、抗盐碱等适应恶劣环境的能力。土壤中的细菌和真菌能够与木麻黄根系形成稳定的相互作用的微生态系统,其中微生物主导的物质代谢循环是植物获取营养的主要来源之一,反之木麻黄的根系分泌物可以为微生物的生长提供养分。文中综述了木麻黄与根系微生物之间相互作用的相关研究,尤其是接种弗兰克氏菌（Frankia）及菌根菌提高木麻黄抗逆性方面的研究进展,对木麻黄与根系微生物体系的促生、抗逆机制进行了探讨和展望。     

木麻黄害虫星天牛生活习性及防治

木麻黄害虫星天牛生活习性及防治＊徐起关键词木麻黄星天牛生活习性防治近年来，浙江省沿海防护林的主栽树种——木麻黄（ＣａｓｕａｒｉｎａｅｑｕｉｓｅｔｉｆｏｌｉａＬ．）受星天牛（ＡｎｏｐｌｏｐｈｏｒａｃｈｉｎｅｎｓｉｓＦｏｒｓｔｅｒ）危害日益严重。据作者对...     

Modifying the microclimate around young oaks through vegetation manipulation: Effects on seedling growth and branching

The objective of this research was to evaluate the influence of vegetation control on the microclimate (light, air temperature, vapor-pressure deficit (VPD)) and on the growth of young planted, sessile oak seedlings. Three types of vegetation control, creating a range of above-ground interaction intensity, were compared. In the open treatment, vegetation was chemically controlled and was maintained at a low height; in the closed treatment, vegetation was manually controlled and a few dominant individuals that overtopped the oak seedlings were cut; and in the sheath treatment, the vegetation in a 0.5-m diameter circle around each seedling was manually cut to a height equal to three quarters of the total seedling height. In all treatments, a strong reduction of incoming radiation was observed, as well as an increase in air temperature and VPD during the day, and a decrease in daily PET, compared to the reference located 4 m above the vegetation. However, the neighboring vegetation did not modify the microclimate around the seedling to a level that could have induced a significant reduction in seedling photosynthesis and, thus, in seedling growth. Seven years after planting, seedlings were shortest in the open treatment and tallest in the closed treatment (334, 372, 378 cm in the open, sheath and closed treatments, respectively). Seedlings in the open treatment allocated proportionally more biomass to diameter increment than to height growth, compared to seedlings in the sheath and closed treatments. The seedlings averaged 1.77, 1.10 and 1.00 forks in the open, sheath and closed treatments, respectively, and the average height of the lowest fork was 171, 206 and 226 cm in the same treatments. The reduction of the number of forks per seedling was not related to a reduction of the appearance of new forks, but rather to a reduction in the persistence of the existing forks. These changes in stem allometry and in fork development seemed to be related to the lateral shade afforded by the vegetation.     

Xylanase-producing microflora in Eastern Ghats of Andhra Pradesh,India

We screened soil samples collected from underneath shrubs and/or large trees at different locations in the Eastern Ghats of Andhra Pradesh for xylanase-producing microorganisms. Xylose-utilizing bacteria were numerically dominant in soils of most locations whereas xylose-and xylan-utilizing actinobacteria were minor components. Xylan-utilizing fungi constituted a major share of total microbial populations in soil samples collected at half of the sites, whereas xylan-utilizing bacteria were predominant at other sampling locations. Some of the isolates of fungi exhibited xylanase activity with a range of400–4000 U/ml, indicating great potential for their uses in paper, pulping and bioethanol industries for producing value-added products.     

Patterns of forest use and endemism in resident bird communities of north-central Michoacán, Mexico

We compared breeding avian communities among 11 habitat types in north-central Michoacán, Mexico, to determine patterns of forest use by endemic and nonendemic resident species. Point counts of birds and vegetation measurements were conducted at 124 sampling localities from May through July, in 1994 and 1995. Six native forest types sampled were pine, pine–oak, oak–pine, oak, fir, and cloud forests; three habitat types were plantations of Eucalyptus, pine, and mixed species; and the remaining two habitats were shrublands and pastures. Pastures had lower bird-species richness and abundance than pine, oak–pine, and mixed-species plantations. Pine forests had greater bird abundance and species richness than oak forests and shrublands. Species richness and abundance of endemics were greatest in fir forests, followed by cloud forests. Bird abundance and richness significantly increased with greater tree-layer complexity, although sites with intermediate tree complexity also supported high abundances. When detrended correspondence-analysis scores were plotted for each site, bird species composition did not differ substantially among the four native oak-and-pine forest types, but cloud and fir forests, Eucalyptus plantations, and mixed-species plantations formed relatively distinct groups. Plantations supported a mixture of species found in native forests, shrublands, and pastures. Pastures and shrublands shared many species in common, varied greatly among sites in bird-species composition, and contained more species specific to these habitats than did forest types.     

Some nutrient dynamics associated with litterfall and litter decomposition in hoop pine plantations of southeast Queensland, Australia

Litterfall was collected over a 12-month period with littertraps in hoop pine (Araucaria cunninghamii) plantations aged 10, 14 and 62 years in southeast Queensland, Australia. The bulk of litterfall occurred during spring, mainly as hoop pine foliage with the annual litterfall ranging between 6.0 and 10.9 t ha⁻¹, respectively, for the younger stands (10 and 14 years) and the mature 62-year old stand. The amount of nitrogen (N) and phosphorous (P) recycled annually through litterfall was lower in the younger stands (28–37 kg N ha⁻¹ and 4.4–5.3 kg P ha⁻¹) compared with that of the mature stand (85 N ha⁻¹ and 6.2 kg P ha⁻¹). The N and P retranslocated during senescence varied across the three stands studied with a trend for N and P retranslocation to increase as availability of soil mineral-N decreased.

Decomposition of the hoop pine foliage component of litter was also studied in the same stands using a litterbag technique and mass-balance analysis. The estimated half-life of hoop pine foliage mass ranged between 1.5 and 1.8 years. Litter-mass loss was strongly correlated with litter substrate quality indicators of N, C, P, C/N ratio, lignin, lignin/N ratio and polyphenols. During the course of the study, there was no difference in litter-mass loss between the stands of different ages. During the 15-month period, the order of element release from the hoop pine litter was K>Na>C>Mg>P, with N, Ca and Mn generally demonstrating varying degrees of net accumulation. During the course of the study, the lignin/C ratio of the hoop pine litter increased from 0.61 to 0.96. This suggested that the litter-C was predominantly in a recalcitrant form and, therefore, the associated N was unlikely to be rapidly released in the hoop pine litter layer.     

木麻黄接种弗兰克氏菌海藻酸钙菌剂大田试验研究

在广东省西部的阳西县、东部惠来县和中部台山市的滨海潲丘进行木麻黄接种弗兰克氏菌海藻酸钙菌剂的大田试验。结果表明：接菌树木的高生长比对照增加６．６￣５３．１％,胸径增加１６．８￣４５．９％;叶片的Ｎ含量增加１８．１￣４０．２％;土壤营养元素除了Ｋ比造林前降你外,其余均增加６４．３￣２４９．９％,其中速效Ｎ增加最多;极际土壤弗兰克氏菌数量增加了２７７．４％,接菌效果可以持续到造林后第４年,但在第年时效     

Small-mammal abundance at three elevations on a mountain in central Vermont, USA: a sixteen-year record

As part of a study of forest resilience to gypsy moth (Lymantria dispar) defoliation, small mammals were sampled with live (box) and pitfall traps for 16 years at three elevations on a mountain in west-central Vermont, USA. The more mesic, lower-slope location had the most diverse small-mammal community. White-footed mice (Peromyscus leucopus) were the most commonly captured small mammal at all locations, but less so at the lowest elevation. Southern red-backed voles (Clethrionomys gapperi), eastern chipmunks (Tamias striatus), and northern short-tailed shrews (Blarina brevicauda) were also regularly captured over the 16 years. Captures of all species showed considerable year-to-year variation. During the study, white-footed mouse density ranged from 3.7/ha (lower-slope June 1984) to 93.4/ha (mid-slope, July 1985). Over the 16 years, median density estimates across locations ranged from 12 to 19/ha in June and from 25 to 32/ha in July. Annual fluctuations in mouse abundance were synchronous across elevations, probably in response to regional-scale fluctuations in acorn production. In addition to those for white-footed mice, standardized capture rates are presented for the three other common species, and time to first capture is presented for 11 infrequently encountered species. The study demonstrates the importance of long-term surveys to properly characterize a small mammal community.     

The impact of aspect on forest structure and floristics in some Eastern Australian sites

Aspect exerts a major influence on the structure and floristics of forests at upslope positions on steep ridges near the escarpment of north-eastern New South Wales. The vegetation of northwest facing sites differed from that of the southeast aspect in species richness and diversity, canopy cover, and canopy height, whilst differences between northeast and southwest aspects were significant for fewer attributes. The gross effect of aspect was in segregating eucalypt and rainforest communities. Aspect-induced differences in light, heat, moisture and edaphic conditions produced a sort of potential canopy species during recruitment. In the absence of substantial disturbance, the divergence of the structural character of developing forest canopies between aspects tends to enhance the floristic divergence in the subcanopy space. Although the study area is representative of a large region of forested steeplands in the hinterland of north-eastern New South Wales, the upper slope segments and four aspects studied can be expected to represent the extreme manipulation. In any event, it is unlikely that the extent of site divergence represented in these old-growth forests would be maintained under managed re-growth strategies.     

Mitigating fire risk to late-successional forest reserves on the east slope of the Washington Cascade Range, USA

A fire-risk model was developed using a stand-structure approach for the forests of the eastern slopes of the Washington Cascade Range, USA. The model was used to evaluate effects of seven landscape-scale silvicultural regimes on fire risk at two spatial scales: (1) the risk to the entire landscape; and (2) the risk to three reserve stands with stand structures associated with high conservation priorities (layered canopy, large trees, multiple species). A 1000 ha landscape was projected five decades for each management regime using an individual tree, distance-independent growth model. Results suggest that a variety of silvicultural approaches will reduce landscape fire risk; however, reserve stand fire risk is minimally decreased by thinning treatments to neighboring stands. Intensive fuel reduction through prescribed burning and selection of reserve stands in favorable topographic positions provide substantial fire risk reductions.