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1.
The aim of this study was to investigate the role of rhizosphere organic phosphorus(P) in soil P supply in semiarid forests and the effects of tree species on rihizosphere organic P. We examined organic P fractions in rhizosphere and bulk soils of mono-specific Simon poplar(Populus simonii) and Mongolian pine(Pinus sylvestris var. mongolica) plantations in a semiarid sandy soil of Horqin Sandy Land in Northeast China. Total organic P(TPo) accounted for 76% of total P across the two stands. The concentration of organic P(Po) fractions decreased in the order of Na OH-Po>Res-Po>HCl-Po>Na HCO3-Po in both plantations. The concentration of Na HCO3-Po was 38% and 43% lower in rhizosphere soil than in bulk soil in Simon poplar and Mongolian pine plantations, respectively. In contrast, total P, TPo and Na OH-Po significantly accumulated in rhizosphere soil in Simon poplar plantations, but no change in Mongolian pine plantations. Soil recalcitrant organic P fractions were positively correlated with soil organic carbon. The results suggest that rhizosphere labile organic P was an important source of plant-available P in this semiarid region, but the dynamic of rhizosphere recalcitrant organic P fractions varied with tree species and was correlated to organic carbon dynamics. 相似文献
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阜新市主要园林树种叶片生态化学计量特征 总被引：2，自引：0，他引：2
以阜新市主要园林树种为研究对象,分析各树种叶片C、N、P化学计量特征。结果表明：园林树种叶片C、N和P含量分别为496~664 mg•g-1、7.5~26.6 mg•g-1和1.0~2.2 mg•g-1,C/N、C/P和N/P分别为22.4~74.3、262~522和5.4~13.8,且叶片N含量与C/N和N/P之间显著相关（P＜0.001）。常绿针叶树种叶片N、P含量和N/P显著低于阔叶落叶树种（P＜0.05）,而C/N和C/P显著高于阔叶落叶树种（P＜0.05）;乔木树种叶片N含量和N/P显著高于灌木树种（P＜0.05）,而叶片P含量及C/N和C/P二者之间差异不显著（P＞0.05）,表明园林树种具有较高的储C能力及养分利用效率。根据叶片N/P发现,阜新市园林树种生长主要受N限制。 相似文献
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华北土石山区不同造林密度的油松林结构与功能研究 总被引：7，自引：0，他引：7
对北京八达岭林场32年生5种造林密度(2000株/hm2、1500株/hm2、1200株/hm2、1000株/hm2、800株/hm2)阴坡油松林生物多样性、碳密度、水源涵养等功能进行调查与实验,结果表明:随着林分密度的减小,林木生长状况良好,林下植被层各种生物多样性指数较其它林分高,并伴随着出现辽东栎等其它栎类更树种的生长;800株/hm2的阴坡油松林蓄积为108.19m3/hm2,是2000株/hm2油松林蓄积的1.22倍;不同密度油松林生态系统碳密度范围为107.43 t/hm2-174.30 t/hm2,平均碳密度为135.99 t/hm2,且随着密度增大而减小。油松林碳密度主要有三个部分组成:植被层、枯落物层和土壤层,其空间部分为土壤层>植被层>枯落物层,林地土壤的碳密度是相当可观大的,碳密度平均为90.34 t/hm2以上,地上部分碳密度与地下(包括土壤、树根和死地被物)碳密度之比平均为1?3.173;油松林地的稳渗速率、产流量随林分密度的增大而减小,这对增加该地区的径流水量、涵养水源能力具有重大意义。产沙量也随密度的增加而减少,这对选择油松800株/hm2作为最优林分密度是不利因素,但从北京的多年降雨来看,这种影响对我们选取油松在800株/hm2作为首选经营密度还是较小的。 相似文献
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Information is presented on new occurrences of two homopteran pests,Matsucoccus josephi Bodenheimer et Harpaz (Matsucoccidae) andPineus pini (Macquart) (Adelgidae), in Israel, Jordan and southern Lebanon.M. josephi occurs in Israel in almost all natural relicts of Aleppo pine (Pinus halepensis). It infests all plantations of Aleppo pine, brutia pine (Pinus brutia ssp.brutia) and Eldar pine (P. brutia ssp.eldarica) north of 31°12′ lat. N. Heavy damage has been observed in the Judean Foothills, Judean Mts. and northern Samaria.M. josephi and its specific predator,Elatophilus hebraicus Pericart (Hemiptera: Anthocoridae), are recorded for the first time in Jordan and southern Lebanon. The scale was found in
all visited Aleppo pine and brutia pine stands in Jordan and in natural and planted brutia pine in southeastern Lebanon. Damage
byM. josephi in Jordan was observed only in young plantations of Aleppo pine; in Lebanon no signs of injury were recorded.P. pini was found for the first time in Jordan, where it causes severe damage to young stands of Aleppo pine and stone pine (Pinus pinea).
Contribution from the Agricultural Research Organization. No. 1225-E, 1993 series. 相似文献
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Carbon(C) storage has received significant attention for its relevance to agricultural security and climate change. Afforestation can increase C storage in terrestrial ecosystems, and has been recognized as an important measure to offset CO_2 emissions. In order to analyze the C benefits of planting wolfberry(Lycium barbarum L.) on the secondary saline lands in arid areas, we conducted a case study on the dynamics of biomass carbon(BC) storage and soil organic carbon(SOC) storage in different-aged wolfberry plantations(4-, 7-and 11-year-old) established on a secondary saline land as well as on the influence of wolfberry plantations on C storage in the plant-soil system in an arid irrigated area(Jingtai County) of Gansu Province, China. The C sequestration and its potential in the wolfberry plantations of Gansu Province were also evaluated. An intact secondary saline land was selected as control. Results show that wolfberry planting could decrease soil salinity, and increase BC, SOC and litter C storage of the secondary saline land significantly, especially in the first 4 years after planting. The aboveground and belowground BC storage values in the intact secondary saline land(control) accounted for only 1.0% and 1.2% of those in the wolfberry plantations, respectively. Compared to the intact secondary saline land, the SOC storage values in the 4-, 7-and 11-year-old wolfberry plantations increased by 36.4%, 37.3% and 43.3%, respectively, and the SOC storage in the wolfberry plantations occupied more than 92% of the ecosystem C storage. The average BC and SOC sequestration rates of the wolfberry plantations for the age group of 0–11 years were 0.73 and 3.30 Mg C/(hm~2·a), respectively. There were no significant difference in BC and SOC storage between the 7-year-old and 11-year-old wolfberry plantations, which may be due in part to the large amounts of C offtakes in new branches and fruits. In Gansu Province, the C storage in the wolfberry plantations has reached up to 3.574 Tg in 2013, and the C sequestration potential of the existing wolfberry plantations was 0.134 Tg C/a. These results indicate that wolfberry planting is an ideal agricultural model to restore the degraded saline lands and increase the C sequestration capacity of agricultural lands in arid areas. 相似文献
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Alpine meadow ecosystem is fragile and highly sensitive to climate change.An understanding of the allocation of above-and below-ground plant biomass and correlations with environmental factors in alpine meadow ecosystem can result in better protection and effective utilization of alpine meadow vegetation.We chose an alpine meadow in the Qinghai-Tibetan Plateau of China as the study area and designed experimental warming plots using a randomized block experimental design.We used single-tube infrared radiators as warming devices,established the warming treatments,and measured plant above- (AGB) and below-ground biomass (BGB) during the growing seasons (May to September) in 2012 and 2013.We determined the allocation of biomass and the relationship between biomass and soil environment under the warming treatment.Biomass indices including above-ground biomass,below-ground biomass and the ratio of root to shoot (R/S) ,and soil factors including soil moisture and soil temperature at different depths were measured.The results showed that (1) BGB of the alpine meadow had the most significant allometric correlation with its AGB (y=298.7x~ (0.44) ,P0.001) ,but the relationship decreased under warming treatment and the determination coefficient of the functional equation was 0.102 which was less than that of 0.188 of the unwarming treatment (control) ; (2) BGB increased,especially in the deeper soil layers under warming treatment (P0.05) .At 0–10 cm soil depth,the percentages of BGB under warming treatment were smaller than those of the control treatment with the decreases being 8.52% and 8.23% in 2012 and 2013,respectively.However,the BGB increased 2.13% and 2.06% in 2012 and 2013,respectively,at 10–50 cm soil depths; (3) BGB had significant positive correlations with soil moisture at 100 cm depth and with soil temperature at 20–100 cm depths (P0.05) ,but the mean correlation coefficient of soil temperature was 0.354,greater than the 0.245 of soil moisture.R/S ratio had a significant negative correlation with soil temperature at 20 cm depth (P0.05) .The warmer soil temperatures in shallow layers increased the biomass allocation to above-ground plant parts,which leading to the increase in AGB;whereas the enhanced thawing of frozen soil in deep layers causing by warming treatment produced more moisture that affected plant biomass allocation. 相似文献
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The regrowth of Calystegia sepium was studied in three types of experiments during spring 2003 and spring 2004. In one glasshouse experiment, rhizome fragments were planted in pots and either harvested at six different developmental stages to assess their undisturbed development and growth or harvested at 420 day degrees after burial to measure their regenerative capacity. Regrowth gradually declined as the plants had more expanded leaves at the time of burial. Minimum regenerative capacity was found when plants had four to eight fully expanded leaves and this coincided with the growth stage of minimum dry weight of underground regenerative organs. The effects of burial depth and rhizome fragment length were studied in outdoor container experiments. Burial at 15 or 25 cm reduced above- and below-ground biomass in 2004, while 25 cm deep burial was necessary to reduce regrowth in 2003. Fragmentation had generally little effect on production of above- and below-ground biomass, whereas burial and fragmentation delayed emergence time. Sensitivity of rhizomes to drying was studied in a growth chamber. Drying periods of 12 or 24 h did not have an influence on the production of aerial shoots, whereas 48 or 96 h reduced production of above-ground biomass significantly. The experiments indicated that the minimum regenerative capacity would be at about 5–6 leaf stage and that mechanical disturbance at this stage would optimise weed control. 相似文献
10.
Cogongrass ( Imperata cylindrica (L.) Beauv.), an invasive C4 perennial grass, negatively influences native plant communities by forming dense monotypic stands that alter ecosystem properties and lower local species diversity. A hypothesized mechanism by which cogongrass achieves competitive dominance is a novel use of below-ground vegetative disturbance of neighboring vegetation (i.e. puncturing). However, very little empirical evidence is found in the peer-reviewed literature to quantify this phenomenon, much less establish it as a true form of competitive interaction. The present field study was conducted to quantify the occurrence of rhizome-mediated, below-ground vegetative penetration, both interspecifically and intraspecifically, document how this phenomenon is influenced by spatial location relative to the cogongrass stand, and determine the role that above-ground and below-ground biomass might have in the process. Analyses of 100 sod samples indicated that rhizome-mediated, below-ground vegetative penetration is a much larger intraspecific phenomenon than an interspecific one. The data also strongly suggested spatial location as a significant factor, with most penetrations occurring in the interior of a cogongrass stand as opposed to the advancing border. Significant correlations between rhizome-mediated, below-ground vegetative penetration and above-ground cogongrass biomass were found in the overall plot analysis and most strongly in the advancing border of the cogongrass stands. 相似文献
11.
Matteo Garbelotto Marco Pautasso 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(1):101-116
Mediterranean ecosystems are hotspots of biodiversity. Because of a coincidence of high species richness and human presence,
Mediterranean biodiversity is particularly threatened by processes such as habitat degradation, fragmentation and loss, pollution,
climate change and introduction of invasive species. Invasive tree pathogens are among the problematic exotic species of California,
Chile, the Mediterranean, South Africa and Australia. In this review, we provide an update on a selection of non-native tree
pathogens currently posing a threat in Mediterranean ecosystems. The impact of exotic forest pathogens range from large-scale
tree and shrub mortality in native ecosystems (Phytophthora ramorum on the West Coast of the USA) to disruption of plantations of exotic (e.g., Seiridium cardinale on planted Monterey cypress in California, Fusarium circinatum on Monterey pine worldwide) and native trees (introduction of the North American Heterobasidion irregulare in stone pine woodland in Italy). Genetic analyses are instrumental in improving our understanding and management of these
outbreaks. There is a need for more empirical data on how novel pathosystems are likely to develop under novel climates, as
well as interdisciplinary collaborations among forest pathologists, theoretical modellers and climatologists. The magnitude
of the observed effects of some exotic tree diseases makes it important to try and minimize the risk of the inadvertent movement
of plant pathogens when planning assisted migration activities to enable plant species to cope with rapid climate change. 相似文献
12.
Zahra JAFARI 《干旱区科学》2020,12(3):495-507
Scarce and scattered precipitation in arid regions is detrimental for newly planted seedlings. It is essential to provide required water storage for seedlings in restoration projects in the first year of their establishment. The subsurface irrigation can be much more effective than the surface irrigation because of the regulation of water availability and reduction in water evaporation. We studied the effect of surface and subsurface irrigation methods on the growth and survival of four common tree species including heaven tree(Ailanthus altissima(Mill.) Swingle), China berry(Melia azedarach L.), white mulberry(Morus alba L.), and black locust(Robinia pseudoacacia L.) by installing underground clay reservoirs with different permeabilities in Isfahan City, Iran. Different amounts of animal manure and wheat straw were mixed with clay fraction and cooked in a pottery kiln at 900°C to produce reservoirs with different permeabilities. The experimental treatments consisting of irrigation and tree species were considered with a factorial arrangement in a completely randomized design with three replications in 2016 and 2017. Leaf water potential of seedlings, which is indirectly related to drought resistance, was measured by a portable pressure chamber. The results showed that saplings height, basal diameter, number of leaves, chlorophyll content and stomatal conductance were significantly(P0.05) higher in the subsurface irrigation with low permeability than in the surface irrigation, but the number of branches of the studied species were not significantly(P0.05) affected by the irrigation methods and different permeabilities of clay reservoirs. The clay reservoirs with low and medium permeabilities constantly provide better conditions for plant growth, and water with lower pressure and longer time intervals to the plant roots as compared with the reservoirs with high permeability. Analysis of variance of the data showed that year and interaction between year and permeability of reservoir had significant effects(P0.05) on all growth parameters, except for the chlorophyll content. In addition, the highest percentage of survival was 100% associated with the subsurface irrigation and the control treatment had the lowest survival percentages of 60%, 70%, 80% and 100% for M. alba, M. azedarach, A. altissima and R. pseudoacacia, respectively. Finally, the values of leaf water potential showed that R. pseudoacacia was the most drought resistant species. 相似文献
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Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet(UV) radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar(Populus × xiaozhuanica) and Mongolian pine(Pinus sylvestris var. mongolica) plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations. 相似文献
14.
In Hebei Province of North China, forest was recovered with natural recruitment in plantations with large area of clear-cutting Chinese pine(Pinus tabuliformis). This study was aimed to demonstrate the dynamic characteristics of recruits during the natural recruitment. Both plot survey and the spatial point-pattern analysis were performed. Five developmental stages of natural recruitment were selected and studied, including 1 year before and 2, 5, 8, and 11 years after clear-cutting. Different slope aspects were also included. Natural recruitment was always dominated by Chinese pine with a proportion of higher than 90%. For plots of 1 year before clear-cutting on east-and north-facing slopes, recruit densities were 7886 and 5036 stems/hm2, the average heights were 0.78(±0.85) and 1.06(±1.15) m, and the average diameters at breast height(DBH) were 3.21(±1.38) and 2.91(±1.38) cm, respectively. After clear-cutting, recruit density was initially increased, then it was gradually declined with time; however, the variation of average DBH was contrary to that of recruit density. Both of them were no longer varied between 8 and 11 years after clear-cutting. The average height of recruits continued to increase after clear-cutting. For the plots of 11 years after clear-cutting on east-and north-facing slopes, average heights of recruits reached 2.00(±1.14) and 2.24(±1.20) m, respectively. The statuses of recruits on north-facing slopes were better than those on east-facing slopes after clear-cutting. Meanwhile, recruits on east-facing slopes were always aggregated at small scales, while spatial pattern of recruits varied with time on north-facing slopes. Moreover, forest was recovered more quickly by natural recruitment than by artificial afforestation after clear-cutting. The structural diversity was higher in naturally regenerated forests than in plantations of the same age. Our results demonstrated that clear-cutting of Chinese pine plantations recovered by natural recruitment has the potential to be an effective approach for establishing multifunctional forest. 相似文献
15.
宁夏旱区湿地生态系统碳汇功能研究 总被引：3，自引：0，他引：3
采用3S技术对2012年宁夏旱区TM卫星假彩色数字影像进行解译,并利用GPS仪进行了野外考察验证,实地调查了宁夏湿地典型植被,获取了较为全面、完整和系统的宁夏湿地资源数据,在此基础上研究了不同湿地类型碳汇功能。结果表明:宁夏湿地总面积为19.65万hm2,占国土面积的3.1%,位居我国西部干旱半干旱地区之首。其中自然湿地面积(包括河流湿地、湖泊湿地、沼泽湿地)为17.03万hm2,占宁夏湿地面积的82.38%,主要分布在宁夏沿黄经济区。宁夏湿地总碳储量为1502.80万t,约占宁夏旱区五种主要生态系统(林地、灌木、草地、湿地、特色经果林)碳汇的45.03%,比全球湿地总碳储量占全球陆地生态系统碳库的百分比(10%-35%)高出10多个百分点。预测了2015年的碳汇潜力为1593.48万t,与2012年相比,2015年湿地面积增加0.34万hm2,碳汇量增加90.68万t。 相似文献
16.
AISHAN Tayierjiang HALIK Ü mü t Florian BETZ TIYIP Tashpolat DING Jianli NUERMAIMAITI Yiliyasijiang 《干旱区科学》2015,7(4):544-554
Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphratica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter(height means the height of a tree and diameter means the diameter at breast height(DBH) of a tree) relationship of trees in different vitality classes(i.e. healthy, good, medium, senesced, dying, dead and fallen). Trees classified as healthy and good accounted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH(tree height) and DBH ranged from 0–19 m and 0–125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees by determining the height-diameter correlation coefficient, and the coefficient would be a new parameter for detecting degradation and assessing sustainable management of floodplain forests in arid regions. In addition, tree vitality should be taken into account to make an accurate height-diameter model for tree height prediction. 相似文献
17.
《干旱区科学》2017,(5)
Afforestation is conducive to soil carbon(C) sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon(SOC) fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages(12-and 25-year-old) on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon(LFOC) and microbial biomass carbon(MBC). The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios: under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes(i.e., control sites), with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations(18.53 g C/(m~2·a); 0–12 years) than in old C. microphylla plantations(16.24 g C/(m~2·a); 12–25 years), and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils. 相似文献
18.
利用宁夏自治区第三次至第七次森林资源普查数据及林业生态建设工程数据,采用材积源生物量法分析研究了宁夏森林及林业生态建设工程的固碳能力和潜力。结果表明:"十五"和"十一五"林业生态建设与保护工程实施期间,宁夏自治区森林主要面积、蓄积量、森林总生物量和碳贮量等均呈增加趋势。林业生态建设与保护工程增加森林面积、天然林林分面积和人工林林分面积分别为18.30万hm2、0.88万hm2、5.76万hm2;增加活立木蓄积量、林分蓄积量分别为300.29万m3、267.48万m3,其中人工林林分蓄积量增加为207.24万m3。"十五"和"十一五"期间,宁夏林业生态建设与保护工程共增加森林碳贮量124.99万t,其中三北防护林工程、天然林保护工程和经济林工程合计增加森林碳贮量91.45万t。预计到2020年,宁夏森林总碳贮量将达到430.52万t。 相似文献
19.
天山云杉林碳储量研究 总被引：6，自引：1，他引：5
以南山林场为例,对天山云杉林碳储量进行研究。结果表明:南山林场的总碳储量为332664.4305t,碳密度为59.5492 tC/hm2,高于全国的平均水平;针叶林碳储量占全林场碳储量的96.16%,而天山云杉的碳储量就占全林场的95.67%;成龄林的碳储量占全林场的95.09%;由此说明天山云杉是该林区碳储量的主要来源,但该林区正处于碳积累速率下降的成熟阶段,要加大对成熟林中幼树更新以及幼龄林的人工抚育的力度。以确保在森林碳储量急剧下降时,幼龄林已成长起来,使该林区的碳储量处于较稳定的状态。 相似文献
20.
Control of Taraxacum officinale (common dandelion) and other broad-leaved weeds in temperate turfgrass has been readily achieved with phenoxy herbicides. The herbicide option has been revoked through municipal and provincial legislation in many regions of Canada, necessitating alternative approaches. We examined the effects of dandelion accessions, age and grass competition on the performance of Sclerotinia minor (IMI 344141) as a biological control for dandelion in turfgrass. Disease symptoms were identical on all 14 different accessions of dandelion and the above- and below-ground biomass were reduced by 94% and 96%, respectively, with no difference among accessions. Foliar damage and dandelion mortality caused by S. minor was affected by plant age and the presence of grass competition. Dandelions of all ages were more severely affected by S. minor in the presence of grass competition. Grass competition had greater impact on foliar biomass, whereas the fungus had a greater impact on root biomass of newly established dandelions. In addition to competition for resources, we were hypothesised that the grass sward provides a microenvironment favouring the success of S. minor as a biological control agent of dandelion. Thus, proper management of the turfgrass environment may be complementary to the efficacy of S. minor as a biocontrol for dandelion. 相似文献