Thick Branches Research Articles

The Influence of Different Media on Rooting of Litchi Plant through Air Layering

The investigations were carried out in Jabban Dargai, Malakand Agency in collaboration with Department of Agriculture Extension during 2010. “An effect of different media on rooting of litchi plant through air layering” were studied & the data were collected on number of roots plant -1 , number of shoots plant -1 , number of leaves plant -1 , root weight plant -1 & percent plant survival. One-year-old erect, vigor & healthy pencil thickness branches of litchi were selected for practices of air layering using different media i.e. silt, (silt + sawdust), & sawdust in month of July. The maximum root weight plant -1 , shoot numbers plant -1 , roots numbers plant -1 , leaves number plant -1 & percent plant survival was noted in case of silt use as a medium and the minimum root weight plant -1 , shoot number plant -1 , root number plant -1 , leaves number plant -1 and percent plant survival was noted in case of sawdust using as a medium. Keywords: Different Media, Air Layering in Litchi, Silt

Hyphal Branching during Arbuscule Development Requires Reduced Arbuscular Mycorrhiza1.

During arbuscular mycorrhizal symbiosis, arbuscule development in the root cortical cell and simultaneous deposition of the plant periarbuscular membrane generate the interface for symbiotic nutrient exchange. The transcriptional changes that accompany arbuscule development are extensive and well documented. By contrast, the transcriptional regulators that control these programs are largely unknown. Here, we provide a detailed characterization of an insertion allele of Medicago truncatula Reduced Arbuscular Mycorrhiza1 (RAM1), ram1-3, which reveals that RAM1 is not necessary to enable hyphopodium formation or hyphal entry into the root but is essential to support arbuscule branching. In ram1-3, arbuscules consist only of the arbuscule trunk and in some cases, a few initial thick hyphal branches. ram1-3 is also insensitive to phosphate-mediated regulation of the symbiosis. Transcript analysis of ram1-3 and ectopic expression of RAM1 indicate that RAM1 regulates expression of EXO70I and Stunted Arbuscule, two genes whose loss of function impacts arbuscule branching. Furthermore, RAM1 regulates expression of a transcription factor Required for Arbuscule Development (RAD1). RAD1 is also required for arbuscular mycorrhizal symbiosis, and rad1 mutants show reduced colonization. RAM1 itself is induced in colonized root cortical cells, and expression of RAM1 and RAD1 is modulated by DELLAs. Thus, the data suggest that DELLAs regulate arbuscule development through modulation of RAM1 and RAD1 and that the precise transcriptional control essential to place proteins in the periarbuscular membrane is controlled, at least in part, by RAM1.

SOBREVIVÊNCIA, CRESCIMENTO E PRODUTIVIDADE DE PLANTAS DE ERVA-MATE PRODUZIDAS POR MINIESTACAS JUVENIS E POR SEMENTES

http://dx.doi.org/10.5902/1980509819608O estabelecimento de ervais com mudas propagadas por semente, sem critérios de seleção de matrizes, pode levar à baixa produtividade e qualidade do produto, sendo o uso de clones selecionados uma alternativa para superação deste problema. Com base nisso, este trabalho objetivou avaliar a sobrevivência, o crescimento e a produtividade da erva-mate em plantio estabelecido com mudas propagadas por miniestaquia e por semente. O experimento foi instalado com quatro tratamentos: testemunha (propagada por semente) e três procedências (Bituruna, Pinhalão e São Mateus do Sul) propagadas por miniestaquia em nível de progênies. Avaliou-se a sobrevivência durante 12 meses, o crescimento por 24 meses e a produtividade aos três e cinco anos pós-plantio. Os métodos de propagação e as procedências não influenciaram a sobrevivência, obtendo-se média de 90% nesta característica, 12 meses após o plantio. O crescimento em altura total e diâmetro do colo foi semelhante entre procedências ao longo de 24 meses, sendo apenas a procedência Bituruna significativamente inferior em altura. A produtividade da segunda colheita foi, em média, sete vezes maior que a primeira para todas as procedências. Na segunda colheita, as plantas propagadas por miniestaquia produziram mais que as propagadas por sementes. A produção de mudas de erva-mate por miniestaquia de propágulos juvenis demonstra ser adequada, pois proporcionou maior produtividade de erva-mate comercial, de folha e massa total. Ervais estabelecidos com mudas propagadas por esta tecnologia produzem mais folhas e galhos finos e menor quantidade de galhos grossos em relação às propagadas por semente.

Effect of Anthropogenic Activities on Coral Distribution at Onshore and Offshore Reefs Along the Egyptian Coast, Red Sea

Using SCUBA diving, Line Intercept Transect (LIT) and under water digital camera coral distribution at onshore and offshore reefs was surveyed in respect to the effect of anthropogenic activities. Four sites were selected during this study. The onshore sites comprised Ras Gharib Petroleum Company (site 1), impacted by oil pollution, and Old Al-Qusyer Harbour (site 2) impacted by phosphate shipping. While, the offshore sites were chosen at Small Gifton Island (site 3), and Abu Ramad Island (site 4); each was impacted by diving activities. The present results showed that, 70 species belonging to 23 genera, distributed within 18 families were recorded at the studied sites, of which, 26 species have massive lifeform, 23 branching, 5 encrusting, 6 solitary and only 2 species belong hydrocorals. In addition, 7 species of a hermatypic corals were also recorded. The present study indicated that, either onshore or offshore reefs showed coral decline, but onshore reefs have more degradations. The highest percent cover of dead corals was 29.1% and 34.4 %, recorded at onshore reefs, sites 1and 2, respectively. On contrast, the lowest percent cover was 28.1% and 4.4%, detected at offshore reefs of sites 3 and 4, respectively. On the other hand, site 1 (onshore reef) recorded the highest percent cover of soft corals (40.5%) from 36% the percent of live soft and hard corals, compared with 2.7% at site 4 (offshore reef) from the percent 61.2% of live soft and hard corals. Branching corals have remarkably higher percent (47%) at offshore (site 4) than that recorded (26.5%) at onshore (site 1). However, massive corals recorded relatively higher percent (52.2%) at offshore (site 3) than (50.4%) onshore (site 2). The offshore site 3 recorded the highest diversity (2.6) and highest richness (1.7), compared with the lowest diversity (2.29) and lowest richness (1.35) recoded at onshore site 1. The equability of distributions among species at the studied reefs were 0.83, 0.78, 0.73 and 0.75 at sites 1, 2, 3 & 4, respectively. At site 1, the stony coral Stylophora pistillata was the only abundant species, with non- expected big and thick branches, while most other corals were scarce. On contrast, Porites sp. was the most dominant at sites 2 &3; while the massive coral, Goniastrea retiformis was the most dominant species at site 4.

Octocoral Species Assembly and Coexistence in Caribbean Coral Reefs.

BackgroundWhat are the determinant factors of community assemblies in the most diverse ecosystem in the ocean? Coral reefs can be divided in continental (i.e., reefs that develop on the continental shelf, including siliciclastic reefs) and oceanic (i.e., far off the continental shelf, usually on volcanic substratum); whether or not these habitat differences impose community-wide ecological divergence or species exclusion/coexistence with evolutionary consequences, is unknown.MethodsStudying Caribbean octocorals as model system, we determined the phylogenetic community structure in a coral reef community, making emphasis on species coexistence evidenced on trait evolution and environmental feedbacks. Forty-nine species represented in five families constituted the species pool from which a phylogenetic tree was reconstructed using mtDNA. We included data from 11 localities in the Western Caribbean (Colombia) including most reef types. To test diversity-environment and phenotype-environment relationships, phylogenetic community structure and trait evolution we carried out comparative analyses implementing ecological and evolutionary approaches.ResultsPhylogenetic inferences suggest clustering of oceanic reefs (e.g., atolls) contrasting with phylogenetic overdispersion of continental reefs (e.g., reefs banks). Additionally, atolls and barrier reefs had the highest species diversity (Shannon index) whereas phylogenetic diversity was higher in reef banks. The discriminant component analysis supported this differentiation between oceanic and continental reefs, where continental octocoral species tend to have greater calyx apertures, thicker branches, prominent calyces and azooxanthellate species. This analysis also indicated a clear separation between the slope and the remaining habitats, caused by the presence or absence of Symbiodinium. K statistic analysis showed that this trait is conserved as well as the branch shape.DiscussionThere was strong octocoral community structure with opposite diversity and composition patterns between oceanic and continental reefs. Even habitats with similar depths and overall environmental conditions did not share similar communities between oceanic and continental reefs. This indicates a strong regional influence over the local communities, probably due to water transparency differences between major reef types, i.e., oceanic vs. continental shelf-neritic. This was supported by contrasting patterns found in morphology, composition and evolutionary history of the species between atolls and reef banks.

Densidade básica da madeira de espécies arbóreas de Cerradão no estado de Tocantins

O objetivo desse estudo foi analisar a densidade básica de espécies arbóreas da fitofisionomia Cerradão, no domínio do Cerrado no estado do Tocantins, e estabelecer a relação entre a densidade básica da madeira dos troncos em função da densidade básica da madeira dos galhos. Amostras de 80 indivíduos foram coletadas no tronco (base, meio e topo) e galhos (galho grosso, galho médio e galho fino) para determinação da densidade básica. As espécies apresentaram valor médio de 0,650 g cm-3, sendo que para a maioria das espécies (58%) decresceu da base para o topo do tronco. A densidade básica da madeira entre posições axiais do tronco e a densidade básica entre galhos de diferentes diâmetros apresentaram relação significativa. De acordo com os modelos propostos para estimar a densidade do tronco em função da densidade de galhos, a variável densidade do galho médio apresentou o melhor ajuste na equação. As equações desenvolvidas neste trabalho são adequadas para estimativas de biomassa e estoque de carbono de espécies arbóreas da fitofisionomia Cerradão, sem amostragem destrutiva de indivíduos arbóreos.

Description of a new species of Leiopathes (Antipatharia: Leiopathidae) from the Hawaiian Islands.

The Hawaiian antipatharian coral previously identified as Leiopathes glaberrima (Esper, 1792) and Leiopathes sp. is described using polyp morphology, skeletal spine morphology and in situ photographs, and assigned the new name of Leiopathes annosa sp. nov. The species is characterized by tall (1 m or more), fan-shaped colonies, with thick, sometimes overlapping branches, and tissues that are colored bright orange when alive. Skeletal spines are smooth, hemispherical, often times multi-lobed, and typically 75 μm tall, but range between 30-225 μm. Polyps are of variable size (0.88-3.35 mm) and arranged on all sides of the corallum on thicker branches, and uniserially on terminal branches. Leiopathes annosa sp. nov differs from all other nominal species of Leiopathes by having a generally flabellate corallum with thick branches and conspicuous skeletal spines that are multi-lobed and hemispherical. The biogeographical distribution of species within the monogeneric family Leiopathidae is presented and discussed.

Aboveground tree additive biomass models in Ecuadorian highland agroforestry systems

Agroforestry land-use systems in the Andean region have great socioeconomical and biophysical relevance due to the abundance of products and services they provide. Biomass estimation in these systems constitutes a priority concern as it facilitates assessment of carbon sink potential and functionality for biomass production. In this paper, a set of equations were fitted to enable easy and reliable estimation of the total aboveground biomass of four frequently used species in Andean agroforestry systems: Acacia melanoxylon L., Alnus acuminata Kunth., Buddleja coriacea Remy. and Polylepis racemosa Ruiz&Pav. The best models for each biomass component (stem, thick branches, thin branches and leaves) per species were fitted simultaneously according to SUR methodology (seemingly unrelated regressions). All models showed high goodness of fit statistics and more than 70% of the observed variation in biomass components was explained by the independent variables. The inclusion of height as a predictive variable in the models improved their predictive reliability and expanded the application range. The models developed here are useful for assessing the sustainability of agroforestry systems and could support governmental or non-governmental forest conservation incentive programs and initiatives.

Effect of Planting Density on Knot Attributes and Branch Occlusion of Betula alnoides under Natural Pruning in Southern China

Knot-related defects are the major cause of timber quality degradation, and diminishing this kind of defects is an important issue in forest management. For the purpose of clear-wood production, knot attributes and branch occlusion of Betula alnoides under natural pruning were investigated in a 14-year-old experimental plantation with five planting densities ranging from 500 to 3333 stems per hectare in southern China, and a total of 1325 occluded branches from 30 trees were sampled and dissected. The mean occluded branch diameter (OBD), radius of knots and branch insertion angle (IA) decreased significantly with increasing planting density. Planting with high stocking density significantly reduced the frequency of thick occluded branches (diameter ≥ 20 mm) while increasing the frequency of small ones (diameter < 10 mm). Branch occlusion time (OT) also tended to increase with decreasing planting density. The results of generalized linear mixed models showed that OBD was the major factor influencing OT, radius of dead portion of knot (RDP), total radius of knot (TRK) and IA. In addition, OT was positively correlated with RDP but negatively correlated with stem diameter growth rate during branch occlusion (SDGR). Silvicultural strategies with appropriate planting density for large-diameter clear-wood production of B. alnoides were discussed.

Vegetative characters, growth habit and microsporangiate strobilus of lycopsid Minostrobus chaohuensis.

Late Devonian Minostrobus chaohuensis is one of the earliest monosporangiate-strobilate isoetaleans. Based on new material of this plant, the vegetative axis and microsporangiate strobilus are studied in detail, and the whole plant knowledge is summarized. The vegetative axis is isotomously branched. The stem is up to 55 mm in diameter with helically arranged leaf cushions. Stems and thick branches bear long fusiform leaf cushions and interareas with vertical linear ornamentations. A ligule pit, oblanceolate leaf scar, and vascular bundle scar appear on the leaf cushion. Distal axes have persistent lanceolate leaves and rhombic leaf bases. The microsporangiate strobilus is cylindrical in shape, possesses sporophyll with alate pedicel and long triangular lamina, uniseriate sporangial wall, subarchesporial pad inside the sporangium, and microspore with cingulum. Based on comparisons with other isoetaleans, the usage of the terms “leaf cushion” and “leaf base” is discussed, and Minostrobus chaohuensis is considered as a tree-like lycopsid. It suggests that arborescent isoetaleans with monosporangiate strobili had appeared and diversified in the Late Devonian. The multi-dichotomous branching system of Minostrobus provides new data on the evolution of growth architecture in rhizomorphic lycopsids.

Niche partitioning among three tree-climbing bird species in subtropical mountain forest sites with different human disturbance.

Closely related and ecologically similar species that overlap in ranges can coexist through resource partitioning without one pushing the others to extinction through competition. Understanding resource partitioning among species is essential to predicting how species decline can affect the functioning of communities and ecosystems. In this study, we analyzed niche overlap and resource partitioning of three tree-climbing bird species in disturbed and undisturbed forest sites at La Malinche National Park, Tlaxcala, Mexico. From January to December 2008, resource partitioning between the three species was examined through the frequency of sightings of individuals foraging in different sites in the trees of both forest types. We characterized the pattern of resource utilization by niche breadth and niche overlap. Finally, we tested if these birds divide tree space differentially according to forest type. Our results indicate that in undisturbed sites, pygmy nuthatches had a high niche breadth (foraging significantly more on the thin branches), while white-breasted nuthatches and brown creepers had similar medium niche breadth values (more often foraged in thick branches and lower trunk, respectively), causing the last two to have a high niche overlap. In contrast, in disturbed sites, niche breadth and overlap values were similar for all three tree-climbing species. All observed overlaps for both forest types were higher than expected, but expected values in disturbed sites suggest the possibility of competition on these sites. Pygmy nuthatches were more sighted than white-breasted nuthatches and brown creepers in both forest types. Our study shows that differences in tree use suggest resource partitioning among the three bird species, particularly at undisturbed sites. However, activities of excessive logging and grazing in the disturbed sites resulted in niche overlap among species. This could lead to changes in competitive dynamics among them.

Axillary Artery and Subscapular Artery Variation : A Case Report

Abstract A. thoracica superior, the first artery to supply thorax, is a thin vein branching from the first part of a. axillaris. There are two arteries branching from the second part of a. axillaris: One of them is a. thoraco-acromialis, being a short and thick branch, and the other one is a branch also known as a. thoracica lateralis or a. mammaria externa. A. thoracodorsalis is another vein and proceeds as a continuation of a. subscapularis and accompanies n. thoracodorsalis. Knowing variations other than normal anatomical structure is significantly important for anatomists, clinicians and especially for surgeons. We want to present an axillary artery and subscapular artery variation we have found, by using dissection method, on bilateral upper extremity of a 40-year old, white, male cadaver used for educational purposes by the Department of Anatomy, Faculty of Medicine, Inonu University. Key Words: Vascular variations, axillary artery, subscapular artery

DNA barcoding allows the accurate assessment of European maerl diversity: a Proof-of-Concept study

Two non-geniculate coralline red algae (Lithothamnion corallioides and Phymatolithon calcareum) are partially protected under the assumption that they are the main components of maerl beds in Atlantic Europe. However, what we know about the composition of maerl relies mainly on morphology-based identifications that are notoriously difficult due to a lack of diagnostic features, convergence, and widespread phenotypic plasticity. Now, this state of affairs can be improved with new alternatives that, unlike morphology, allow the unambiguous partition of a large number of rhodoliths into species regardless of their size, shape, and condition (fertile or sterile). Here, we report the first DNA barcoding assessment of the relative abundance of maerl-forming algae. The plastidial gene psbA was sequenced for 1140 rhodoliths from 15 maerl beds scattered along 2000 km from the British Isles to South Portugal; rhodoliths were randomly collected along linear transects to obtain quantitative estimates of species composition. Most (97%) of our collections belonged to three, rather than two, species that often appeared intermixed along a single transect. Lithothamnion corallioides and P. calcareum dominated in the British Isles and Brittany (NW France), but they were gradually replaced by Phymatolithon sp3 in Galicia (NW Spain) and became extremely rare in Algarve (S Portugal). Morphology (rhodolith size and shape, branch diameter, habit) varied considerably between and within beds but the three species converged to a remarkably similar habit when living in sympatry. Still, P. calcareum and L. corallioides seemed to perform best in Brittany while Phymatolithon sp3 produced the largest rhodoliths with thickest branches in Algarve. Altogether, our study shows that the replacement of species of maerl seen in northern latitudes continues to the south along the coasts of Iberia. It also serves as a proof-of-concept of the benefits of DNA barcoding for ecological and biogeographic research of these taxonomically challenging taxa.

Effect of potassium fertilization on yield and nutrition of yerba mate (Ilex paraguariensis)

Yerba mate (Ilex paraguariensis) is a tree species native to the subtropical regions of South America, and is found in Brazil predominantly in the southern region. Despite the historical importance in this region, so far, studies on crop nutrition to improve yields are scarce. Thus, this study evaluated the effect of potassium rates on K soil availability, and the yield and nutritional status of yerba mate. The experiment was conducted in São Mateus do Sul, State of Paraná, on a Humox soil, where K2O rates of 0, 20, 40, 80, 160, and 320 kg ha-1 were tested on 7-year-old plantations. The experiment was harvested 24 months after installation by removing approximately 95 % of the canopy that had sprouted from the previous harvest. The soil was evaluated for K availability in the layers 0-10, 0-20, 10-20, and 20-40 cm. The plant parts leaf fresh matter (LM), twigs (TW), thick branches (BR) and commercial yerba mate (COYM), i.e., LM+TW, were analyzed. In addition, the relationship between fresh matter/dry matter (FM/DM) and K concentration in LM, AG and BR were evaluated. The fertilization increased K availability in all evaluated soil layers, indicating good mobility of the nutrient even at low rates. Yerba mate responded positively to increasing K2O rates with higher yields of all harvested components. The crop proved K-demanding, with a maximum COYM yield of 28.5 t ha-1, when 72 mg dm-3 K was available in the 0-20 cm layer. Yerba mate in the plant production stage requires soil K availability at medium to high level; in clayey soil with low K availability, a rate of 300 kg ha-1 K2O should be applied at 24 month intervals to obtain high yields. A leaf K concentration of 16.0 g ha-1 is suitable for yerba mate in the growth stage.

Deposição de serapilheira e nutrientes em plantio de Eucalyptus urophylla × E. globulus

Objetivou-se com o presente estudo avaliar a deposição de serapilheira e nutrientes em plantio de Eucalyptus urophylla × Eucalyptus globulus, em Eldorado do Sul-RS. Foram alocadas sistematicamente quatro parcelas de 20 m × 20 m, cada uma com quatro coletores de serapilheira de 1 m². A serapilheira foi coletada quinzenalmente, entre janeiro/2007 e dezembro/2010. A produção de serapilheira foi crescente, com o aumento da idade do povoamento, sendo 6,9 Mg ha-1 aos seis e 8,5 Mg ha-1 aos nove anos. A fração folhas correspondeu, em média, a 66,9% da serapilheira total, seguida pelos galhos finos (14,7%), miscelânea (10,5%) e galhos grossos (7,9%). A deposição apresentou padrão sazonal, sendo maior no período de aumento da temperatura do ar. A fração folhas foi responsável por maior parte do retorno de nutrientes via serapilheira, variando de 58,2 a 81,8% da quantidade de Cu e N, respectivamente.

Functional morphology and comparative anatomy of appendicular musculature in Cuban Anolis lizards with different locomotor habits.

We examined the diversity of the musculoskeletal morphology in the limbs of Anolis lizards with different habitats and identified variations in functional and morphological adaptations to different ecologies or behaviors. Dissection and isolation of 40 muscles from the fore- and hindlimbs of five species of Anolis were performed, and the muscle mass and length of the moment arm were compared after body size effects were removed. Ecologically and behaviorally characteristic morphological differences were observed in several muscles. Well-developed hindlimb extensors were observed in ground-dwelling species, A. sagrei and A. bremeri, and were considered advantageous for running, whereas adept climber species possessed expanded femoral retractors for weight-bearing during climbing. Moreover, morphological variations were observed among arboreal species. Wider excursions of the forelimb joint characterized A. porcatus, presumably enabling branch-to-branch locomotion, while A. equestris and A. angusticeps possessed highly developed adductor muscles for grasping thick branches or twigs. These findings suggest divergent evolution of musculoskeletal characteristic in the limbs within the genus Anolis, with correlations observed among morphological traits, locomotor performance, and habitat uses.

Productivity of a John Deere Harvester Unit in Deciduous Stands

The aim of the presented paper was to determine the productivity of a John Deere 1070D harvester in deciduous coppices of Quercus petraea and Fagus sylvatica, in thinnings over 50 years of age. The research area was located in Tribeč mountain ridge, western Slovakia. The terrain incline did not exceed 20%. The productivity of the harvester in oak stands was 9.97 m3.h−1 without downtimes (breaks, failures, etc.). Performance with breaks was 4.98 m3.PMH−1 (productive machine hour). The productivity of the harvester was influenced by a large portion of passes of the harvester, which constituted 23.47% of the time of the operating cycle. The large number of passes was caused by the fact that the operator did not respect the technologic process and a high portion of tree extraction (8.45%). Furthermore the productivity was decreased by frequent failures of the machine and downtimes, which could be prevented by proper and regular maintenance. The productivity in beech stands was 6.36 m3.h−1 without downtimes and 5.35 m3.PMH−1 with downtimes included. Lower productivity was caused by the numerous and thick branches and frequent presence of trees with multiple tree tops, ergo unsuitable structure of the stand. Absence of a worker with a chainsaw was considered to be a disadvantage, because this worker is often a necessity when harvesters operate in deciduous stands.

Colonization of disturbed Scots pine trees by bark‐ and wood‐boring beetles

Abstract In a single stand, the colonization of 128 girdled Scots pine trees (Pinus sylvestris L.) by bark‐ and wood‐boring beetles was examined during two vegetation periods after treatment. The trees were girdled on four different dates in April, July, October and January. The time elapsed from girdling to the first attack of bark‐ and wood‐boring beetles was 1–19 months (mean = 10.7) and differed significantly among trees girdled on different dates. The part of the tree and the date and wave (rank) of colonization were the most significant factors that explained a considerable portion of the variability in the occurrence of bark‐ and wood‐boring beetles. The species composition changed dramatically from the tree base to its top and branches. The colonization of trees was initiated most frequently in the upper thin‐barked part of the trunk and in thick branches. In total, 32 species of bark‐ and wood‐boring beetles colonized the studied trees. Particular species were significantly associated with certain periods of tree dieback and colonization (colonization waves). Phaenops cyanea (F.) and Pissodes piniphilus (Hbst.) were by far the most aggressive first‐colonizing species. Pityogenes chalcographus (L.), Ips acuminatus (Gyll.) and Tomicus minor (Htg.) were shown to be moderate‐aggressive species, followed by Tomicus piniperda (L.), Monochamus galloprovincialis (Germ.) and Pissodes pini (L.). The remaining species were designated as not harmful and saprophagous.

准噶尔盆地梭梭群落生物量和碳储量

PDF HTML阅读 XML下载 导出引用 引用提醒 准噶尔盆地梭梭群落生物量和碳储量 DOI: 10.5846/stxb201306081473 作者: 作者单位: 石河子大学农学院林学系,石河子大学农学院林学系 作者简介: 通讯作者: 中图分类号: 基金项目: 新疆生产建设兵团重点公益林生物多样性及生态状况监测项目（2006.813号） Biomass and carbon storage of Haloxylon ammodendron community in Junggar Basin Author: Affiliation: Department of Forestry,Agricultural College,Xinjiang Shihezi University,Department of Forestry,Agricultural College,Xinjiang Shihezi University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:梭梭（Haloxylon ammodendron）是准噶尔盆地建群种和优势种，因此，研究其群落的生物量及碳汇功能有着重要意义。以研究区内10个固定样点为研究对象，样地内每木检尺，并结合梭梭群落各组分含碳率的实测值，对准噶尔盆地梭梭群落的生物量和碳储量进行了估算，通过实测数据及模型分析，结果表明：①梭梭的生物量随树龄增加逐渐增大，从0-5龄时1.9948 kg增加到了21-25龄时61.6480 kg，进入26龄以后，梭梭枝条出现部分枯死，其中粗枝生物量是地上生物量的主体（所占比例平均为63.53%）。②不同龄级梭梭的含碳率在49.08与53.57之间变动，加权平均值为51.60，同一龄级之间各组分之间的含碳率变化以0-5龄级最小，其变异系数为1.72%，以21-25龄级最大，变异系数为6.78%。③梭梭群落其它组分的平均含碳率分别为灌木43.84%，草本39.13%，枯落物31.47%；土壤含碳率平均值为0.0310%，随土层深度增加各层次土壤碳含量逐渐减少。④准噶尔盆地梭梭群落碳密度为5815.7183kg/hm2，总碳储量为1919万tC，采用实测含碳率作为转换系数比缺省值0.5所得出的结果高1.53%。这些结果说明，准噶尔盆地梭梭群落具备明显的碳汇功能，应加强管理，使该区域森林生态系统在北疆地区碳交易中发挥更大的作用。 Abstract:Haloxylon ammodendron was the edificators and dominant species in Junggar Basin, it is important to research biomass and carbon pool of Haloxylon ammodendron community. The study was conducted on the basis of 10 permanent plots in study area,and each tree in the plots was measured. We estmiate biomass and carbon storage of Haloxylon ammodendron community with the measured value of carbon content. Through measurement data and model analysis,basic conclusions are as follows:(1)The biomass which increases with the increasing of tree-age grew from 1.9948 kg in tree-age 0-5 to 61.6480 kg in 21-25, and branches started partly dead after 26. and the partition ratio of thick branch biomass was main (mean 63.53); (2)Carbon content moves between 49.08 and 53.57, the weighted average is 51.60. Between the various components of the same age class was different, least in 0-5 (coefficient of variation 1.72%) and largest in 21-25 (coefficient of variation 6.78%); (3)The carbon content of shrub, herb and litter is 43.84%, 39.13%, 31.47%, respectively. The mean carbon content of soil which reduces gradually with the depth is 0.0310%。(4)The carbon storage of Haloxylon ammodendron community in the Junggar Basin was revealed,which was 1919×104t in total, with a density of 5815.7183kg/hm2, and 1.53% higher using actual carbon content than the default value(0.5). Owing to the fact, Haloxylon ammodendron community has showed obvious carbon pool functions, by emphasising quality of intensive management, forest ecosystem of Junggar Basin will have greater influences on carbon sequestration of the Northern Xinjiang area. 参考文献 相似文献 引证文献

Effects of irregular stand structure on tree growth, crown extension and branchiness of plantation-grown Pinus patula

The practice of combining row and selective thinning in commercial pine plantation silviculture carries the risk of unwanted irregularities in tree distribution, a situation that is aggravated when tree selection during marking is poor. The potential consequences of poor tree selection are accentuated by gaps along row removal. This leads to spatially asymmetric growing space to adjacent trees. The effect of irregular stand structures on tree morphology and growth are investigated in this study, and are based on two stands of Pinus patula (Schiede ex Schltdl. et Cham.) in Langeni Plantation, South Africa. A comparison between trees grown in an all-sided and one-sided spatial competition situation is presented to assess the degree of differences between the two situations. Results of this study show significantly larger crown diameters, crown lengths, longer and thicker branches, disproportionately one-sided crown growth and a reduction in space-use efficiency in stands with irregular competitive status. These factors potentially negatively affect saw timber quality and volume production from the stands at final felling.