Tamarix Ramosissima Research Articles

Pontibacter brevis sp. nov., isolated from rhizosphere soil of Tamarix ramosissima.

A Gram-stain-negative, oval-shaped and light pink pigmented bacterium, designated XAAS-2T, was isolated from rhizosphere soil of Tamarix ramosissima. The sole respiratory quinone of the type strain XAAS-2T was MK-7, and the principal cellular fatty acids were summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) and iso-C15 : 0. The major polar lipids were phosphatidylethanolamine and two unidentified lipids. 16S rRNA gene sequence analysis indicated that strain XAAS-2T belonged to the genus Pontibacter within the family Cytophagaceae with sequence similarities of 93.9-97.1 % to other type species of the genus Pontibacter and to Pontibacter xinjiangensis CCTCC AB 207200T as the closest neighbour. The DNA G+C content of strain XAAS-2T was 50.6 mol%. The level of DNA-DNA relatedness of XAAS-2T and P. xinjiangensis CCTCC AB 207200T was 47.5 % (sd=3.27). Phenotypic and genotypic data suggested that strain XAAS-2T represents a novel species of the genus Pontibacter, for which the name Pontibacterbrevis sp. nov. is proposed, with the type strain XAAS-2T (=CCTCC AB 2016135T=JCM 31443T).

The Relation between Soil Parameters and Growth Characteristics of Tamarix ramosissima in Abyaneh, Isfahan Province

The Relation between Soil Parameters and Growth Characteristics of Tamarix ramosissima in Abyaneh, Isfahan Province

Comparable water use of two contrasting riparian forests in the lower Heihe River basin, Northwest China

Understanding forest ecosystem evapotranspiration (ET) is crucial for water-limited environments, particularly those that lack adequate quantified data such as the lower Heihe River basin of northwest China which is primarily dominated by Tamarix ramosissima Ledeb. and Populus euphratica Oliv. forests. Accordingly, we selected the growing season for 2 years (2012 and 2014) of two such forests under similar meteorological conditions to compare ET using the eddy covariance (EC) technique. During the growing seasons, daily ET of T. ramosissima ranged from 0.3 to 8.0 mm day−1 with a mean of 3.6 mm day−1, and daily ET of P. euphratica ranged from 0.9 to 7.9 mm day−1 with a mean of 4.6 mm day−1 for a total of 548 and 707 mm, respectively. The significantly higher ET of the P. euphratica stand was directly linked to high soil evaporation rates under sufficient water availability from irrigation. When the soil evaporation was disregarded, water use was comparable to two contrasting riparian forests, a P. euphratica forest with a total transpiration of 465 mm and a T. ramosissima forest with 473 mm. Regression analysis demonstrated that climate factors accounted for at least 80% of ET variation in both forest types. In conclusion, water use of the riparian forests was low and comparable in this arid region, that suggest the long-term plant adaptation to the local climate and conditions of water availability.

A spatial model for rare binary events

Many predominant spatial methods for binary data use a latent Gaussian process to capture spatial dependence. However, this may not be appropriate for rare data because these methods based on Gaussian processes are asymptotically independent as the event probability goes to zero. In this paper, we propose a method for rare binary data that builds on spatial extreme value theory. We model binary events as exceedances of a max-stable process and show that this construction maintains spatial dependence even as the event probability goes to zero. We compare our model to spatial probit and logistic methods through a simulation study and analysis of a survey of Tamarix ramosissima and Hedysarum scoparium. We find some evidence that for very rare data the max-stable extension provides an improvement in spatial prediction compared to Gaussian models.

STUDY OF CHEMICAL COMPOSITION OF TAMARIX RAMOSISSIMA ESSENTIAL OIL

Samples of essential oil from Tamarix ramosissima plant growing in the Astrakhan region were obtained by steam distillation and the dependence of its yield on the vegetative period of the plant was studied. The duration of the process of steam distillation was established experimentally on the basis of a study of the dynamics of the change in the yield of essential oil in time. The yield of essential oil was determined in % by weight of absolutely dry raw material. The largest yield of essential oil was obtained from plants in the flowering phase (0,23–0,3%). By method of gas-liquid chromatography carried out a quantitative analysis of the main components of essential oil Tamarix ramosissima. The quantitative content of essential oil components was calculated from the areas of gas chromatography peaks without the use of correction factors. Qualitative analysis was carried out by comparing the linear retention indices. It was found that the composition of the essential oil of Tamarix is very specific. It includes hydrocarbons (9,51%), alcohols (3,46%), aldehydes (2,55%), monoterpene hydrocarbons (5,4%), oxygenated terpenes (23,06%), sesquiterpene hydrocarbons (1,48%), oxygenated diterpenoids (3,37%), and a significant amount of fatty acids and their esters (45,43%). The main components of the essential oil are tetrahydrogeranilacetone (21,35%), nonane (12,63%), decanoic (9,82%) acids and dihydroactin diolide (5,40%).

Regeneration and invasion of cottonwood riparian forest following wildfire

Populus deltoides is considered to be a weak resprouter and highly susceptible to wildfire, but few post‐wildfire studies have tracked P. deltoides response and resprouting within the Great Plains of North America. Following a wildfire in southwestern Kansas, U.S.A., we surveyed burned and unburned areas of a cottonwood riparian forest along the Cimarron River that included a major understory invader, tamarisk (Tamarix ramosissima Ledeb.). We tested the following hypotheses, which are consistent with the current understanding of P. deltoides response to wildfire in the Great Plains: (1) regeneration of P. deltoides will be low in areas burned by the wildfire; (2) the number of dead P. deltoides individuals will be greater in the wildfire than unburned areas; and (3) tamarisk regeneration will be higher than P. deltoides regeneration in the wildfire areas because tamarisk is considered a stronger resprouter. We found evidence contrary to two of our hypotheses 3 years following the wildfire. (1) P. deltoides regeneration was high following the wildfire, averaging 692 individuals/ha. (2) The number of dead mature cottonwood trees was greater in wildfire plots than in unburned plots. (3) There was more P. deltoides regeneration than tamarisk regeneration following wildfire. These findings, which diverge from the majority of studies examining P. deltoides regeneration in the Great Plains, suggest that differing local environmental and forest stand conditions, coupled with the timing and intensity of the fire, could be important determinants of riparian forest species' responses to wildfire.

Soil aggregation and aggregate-associated organic carbon under typical natural halophyte communities in arid saline areas of Northwest China

Information on the effects of halophyte communities on soil organic carbon (SOC) is useful for sequestrating C in arid regions. In this study, we identified four typical natural halophyte communities in the Manasi River Basin in Xinjiang Province, Northeast China, namely, Karelinia caspia (Pall.) Less., Bassia dasyphylla (Fisch. et C. A. Mey.) Kuntze, Haloxylon ammodendron (C. A. Mey.) Bunge, and Tamarix ramosissima Lour. We compared soil aggregation and aggregated-associated SOC under these communities. The aggregate fraction of 0.053–0.25 mm accounted for 47%–75% of the total soil mass, significantly more than the > 0.25 and < 0.053 mm fractions, under all the halophyte communities. Significant differences in soil aggregate size distribution were observed among the plant communities, with the H. ammodendron and B. dasyphylla communities showing the highest proportions of > 0.25 mm aggregates (13.3%–43.8%) and T. ramosissima community having more < 0.053 mm aggregates (14.1%–27.2%). Aggregate-associated SOC concentrations were generally the highest in the > 0.25 mm fraction, followed by the < 0.053 mm fraction, and were the lowest in the 0.053–0.25 mm fraction; however, because of their large mass, 0.25–0.053 mm aggregates contributed significantly more to the total SOC. Total SOC concentrations (0–60 cm depth) decreased in the order of H. ammodendron (5.7 g kg−1) > T. ramosissima (4.9 g kg−1) > K. caspia (4.2 g kg−1) > B. dasyphylla (3.4 g kg−1). The H. ammodendron community had the highest total SOC and aggregate-associated SOC, which was primarily because aggregate-associated SOC content at the 0–10 and 10–20 cm depths under this community were higher than those under other plant communities. The H. ammodendron community could be beneficial for increasing SOC in saline soils in the arid region.

P26 Tamaractam, a natural lactam, induces apoptosis and inhibits inflammation in rheumatoid arthritis fibroblast-like synoviocytes

Tamaractam is a novel lactam isolated from Tamarix ramosissima Ledeb., a traditional herbal medicine used for rheumatoid arthritis (RA) treatment in northwest China. The present study investigated the pro-apoptotic and anti-inflammatory effects of tamaractam on fibroblast-like synoviocytes (FLS) from RA patients. Apoptosis was assessed by TUNEL assay and caspase-3 activity was assessed by a colorimetric assay. The expression levels of apoptosis-related proteins including Bcl-2, Bax, p-Akt and p53 were determined by western blot analyses. The levels of IL-1β, IL-6, MMP-9 and COX-2 were measured using ELISA, and the mRNA expressions of these pro-inflammatory mediators were measured with quantitative real-time PCR. Tamaractam (0.1 and 1 μM) treatment induced cellular apoptosis of RA-FLS and also resulted in a significant increase in caspase-3 activity. It was found that tamaractam could regulate the protein expression of Bcl-2, Bax, p53 and pAkt. The concentrations and mRNA expression levels of IL-1β, IL-6, MMP-9 and COX-2 from RA-FLS were suppressed by tamaractam treatment in a dose-dependent manner. In conclusion, tamaractam treatment was found to induce apoptosis of RA-FLS through regulation of apoptosis related protein expression and to reduce the level of pro-inflammatory factors through inhibition of pro-inflammatory gene expression in RA-FLS. These results suggest that the pro-apoptotic and anti-inflammatory activities of tamaractam may be used as a possible therapeutic option for RA.

Seasonal variations of soil enzyme activities in typical plant communities in the Ebinur Lake wetland, China

In this study, the soil catalase, phosphatase and urease activities of typical plant communities of reed (Phragmites australis) and tamarisk (Tamarix ramosissima) and their influencing factors were investigated in Ebinur Lake wetland. The results showed that three soil enzyme activities of reed and tamarisk had seasonal dynamic characteristics during different growth periods. For the reed community, the peak concentrations of soil catalase, phosphatase and urease appeared at vigorous stage with 3.26, 0.60 and 0.33 mg·g-1, respectively, and the minimum value occurred at budding stage and leaf-expansion stage. For the tamarisk community, the peak values of three soil enzyme activities appeared at withered stage with values of 6.33, 0.58 and 0.21 mg·g-1, respectively, and the valley values were observed at flowering and vigorous stages. Urease was stable during different growth periods, and it could be used as an indicator to identify the differences of soil enzyme activities in the wetlands. The enzyme activities of reed and tamarisk had significant positive correlation with soil organic matter and total P in all growth periods, while there was no significant relationship between enzyme activities and soil water content. The enzyme activities of reed had significant positive correlation with ammonium nitrogen in the rapid growth period. There were no significant relationships between enzyme activities and soil salinity in both communities. The soil enzyme activities of reed and tamarisk were controlled by many factors. Soil organic matter, soil water and soil temperature were the main factors influencing the enzyme activities in the Ebinur Lake wetland.

Litter decomposition and nutrient dynamics of three woody halophytes in the Taklimakan Desert Highway Shelterbelt

ABSTRACTLitter decomposition is a crucial biogeochemical process for C and nutrient cycling in nutrient-constrained environments, but the controlling factors on litter decomposition in an extremely arid desert region such as the Taklimakan Desert are relatively unknown. To evaluate the litter decomposition and nutrient dynamic characteristics, five primary litter types of three woody halophytes (Haloxylon ammodendron, Calligonum arborescens, and Tamarix ramosissima) along the Taklimakan Desert Highway Shelterbelt were monitored in litterbags during 420 days, when placed on the soil surface and buried by sand, respectively. The results indicated that the decomposition rate decreased in the order of assimilative branches of H. ammodendron (HA, 0.94), branches of T. ramosissima (TB, 0.55), assimilative branches of C. arborescens (CA, 0.53), seeds of C. arborescens (CS, 0.41), and old branches of H. ammodendron (HB, 0.21) in the surface placement. In contrast, the litters buried by sand displayed a significantly accelerated decomposition rate (F = 12.28, P < 0.01), which were 1.3, 1.8, 1.3, 2.3, and 2.8 times of that at surface placement for HA, TB, CA, CS, and HB, respectively. Decomposition of the litters was primarily affected by initial content of C and K, lignin and cellulose in both placements, and varied among decomposition stages and conditions. The old branches of H. ammodendron and branches of T. ramosissima presented P accumulation in both placements, whereas nutrients (N, P, K) and C showed a release pattern during the litter decomposition process, which was influenced by initial litter contents and decomposition rate.

Woody plants in street landscaping of urban-type settlement Alexeevka (Samara Oblast)

Our results support that introducents (72,1% of 68 found species) might have important impact on ecosystem of urban-type settlement Alexeevka, Kinel Urban Okrug of Samara Region. The local community of woody plants include 68 species from 48 genera, 21 families, 2 classes (Pinopsida, Magnoliopsida) and 2 divisions (Pinophyta, Magnoliophyta). 30 species (44,1%) of trees and 25 species (36,8%) of bushes are dominant plants. They are basically summer-green, cross-pollinated (entomophilous) species, mesotrophes, mesophytes, sciogeliophytes and mezotermes, which fruits and seeds are spread by animals. Introducents (Eurasian, European-American and European types of habitats) were planted at different times. Rosaceae (21 species, 30,9%) are well represented and the largest number of species contain genuses Populus (6 species), Rosa (4 species), Ulmus, Crataegus and Acer (3 species). We found seven rare species used in street landscaping: Juniperus communis L., J. sabina L., Crataegus volgensis Pojark., Tamarix ramosissima Ledeb., Cotoneaster melanocarpus Fisch. ex Blytt, Populus alba L. and Salix alba L. The change in variability of local communities has significant implications for our ability to predict how the patterns of biodiversity and ecosystem function will respond to environmental changes.

Different mechanisms of ion homeostasis are dominant in the recretohalophyte Tamarix ramosissima under different soil salinity

Total ion (Na+, K+, Ca2+, SO4 2− and Cl−) accumulation by plants, ion contents in plant tissues and ion secretion by salt glands on the surface of shoots of Tamarix ramosissima adapted to different soil salinity, namely low (0.06 mmol Na+/g soil), moderate (3.14–4.85 mmol Na+/g soil) and strong (7.56 mmol Na+/g soil) were analyzed. There are two stages of interrelated and complementary regulation of ion homeostasis in whole T. ramosissima plants: (1) regulation of ion influx into the plant from the soil and (2) changing the secretion efficiency of salt glands on shoots. The secretion efficiency of salt glands was appraised by the ratio of ion secretion to tissue ion content. Independent of soil salinity, the accumulation of K+ and Ca2+ was higher than the contents of these ions in the soil. Furthermore, the accumulation of K+, Ca2+ and SO4 2− ions by plants was maintained within a narrow range of values. Under low soil salinity, Na+ was accumulated, whereas under moderate and strong salinity, the influxes of Na+ were limited. However, under strong salinity, the accumulation of Na+ was threefold higher than that under low soil salinity. This led to a change in the Na+/K+ ratio (tenfold), an increase in the activity of salt glands (tenfold) and a reduction in plant growth (fivefold). An apparently high Na+/K+ ratio was the main factor determining over-active functioning of salt glands under strong salinity. Principal component analysis showed that K+ ions played a key role in ion homeostasis at all levels of salinity. Ca2+ played a significant role at low salinity, whereas Cl− and interrelated regulatory components (K+ and proline) played a role under strong salinity. Proline, despite its low concentration under strong salinity, was involved in the regulation of secretion by salt glands. Different stages and mechanisms of ion homeostasis were dominant in T. ramosissima plants adapted to different levels of salinity. These mechanisms facilitated the accumulation of Na+ in plants under low soil salinity, the limitation of Na+ under moderate salinity and the over-activation of Na+ secretion by salt glands under strong salinity, which are all necessary for maintaining ion homeostasis and water potential in the whole plant.

Effects of Tamarix removal on the community dynamics of riparian birds in a semiarid grassland

AbstractInvasion of riparian habitats by non‐native plants is a global problem that requires an understanding of community‐level responses by native plants and animals. In the Great Plains, resource managers have initiated efforts to control the eastward incursion of Tamarix as a non‐native bottomland plant (Tamarix ramosissima) along the Cimarron River in southwestern Kansas, United States. To understand how native avifauna interact with non‐native plants, we studied the effects of Tamarix removal on riparian bird communities. We compared avian site occupancy of three foraging guilds, abundance of four nesting guilds, and assessed community dynamics with dynamic, multiseason occupancy models across three replicated treatments. Community parameters were estimated for Tamarix‐dominated sites (untreated), Tamarix‐removal sites (treated), and reference sites with native cottonwood sites (Populus deltoides). Estimates of initial occupancy (ψ2006) for the ground‐to‐shrub foraging guild tended to be highest at Tamarix‐dominated sites, while initial occupancy of the upper‐canopy foraging and mid‐canopy foraging guilds were highest in the treated and reference sites, respectively. Estimates of relative abundance for four nesting guilds indicated that the reference habitat supported the highest relative abundance of birds overall, although the untreated habitat had higher abundance of shrub‐nesters than treated or reference habitats. Riparian sites where invasive Tamarix is dominant in the Great Plains can provide nesting habitat for some native bird species, with avian abundance and diversity that are comparable to remnant riparian sites with native vegetation. Moreover, presence of some native vegetation in Tamarix‐dominated and Tamarix‐removal sites may increase abundance of riparian birds such as cavity‐nesters. Overall, our study demonstrates that Tamarix may substitute for native flora in providing nesting habitat for riparian birds at the eastern edge of its North American range.

Differentiating Tree and Shrub LAI in a Mixed Forest With ICESat/GLAS Spaceborne LiDAR

Leaf area index (LAI) is an important descriptor of many biological and physical processes of vegetation. However, the challenges associated with differentiating tree and shrub LAI (tsLAI) have hindered research in mixed forests. Being the first spaceborne LiDAR system, geoscience laser altimeter system (GLAS) has demonstrated its advantage in collecting extensive forest structure information. In this study, we aimed to estimate tsLAI in a mixed forest with GLAS. The refined Levenberg–Marquardt algorithm for Gaussian decomposition was implemented to decompose GLAS data into ground and multiple vegetation signals, within which it is hypothesized that each vegetation signal corresponds to a particular height layer. Subsequently, the height of each layer was extracted through the decomposed GLAS signals, and a height threshold method to distinguish trees from shrubs was developed. Then, a tsLAI-specific ratio defined as ground-to-total energy return of the GLAS signal was calculated, and tsLAI was predicted by a linear regression model established from field measurements and the ratio. Finally, a study site in Ejina, China, where the dominant species are Populus euphratica (tree) and Tamarix ramosissima (shrub) was used to calibrate and validate the methods. Compared with the field measurement LAI, GLAS-predicted LAI presented a high agreement in which R2 , RMSE, and %RMSE of trees were determined to be 0.797, 0.087, and 19.176, respectively. In contrast, R2 , RMSE, and %RMSE of shrubs were found to be 0.676, 0.081, and 21.825, respectively. Overall, our study provided a feasible and effective approach for estimating tsLAI with GLAS over a flat region.

Water sources of Populus euphratica and Tamarix ramosissima in Ejina Delta, the lower reaches of the Heihe River, China

Water sources of Populus euphratica and Tamarix ramosissima in Ejina Delta, the lower reaches of the Heihe River, China

塔里木沙漠公路防护林地表凋落物分解对施肥的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 塔里木沙漠公路防护林地表凋落物分解对施肥的响应 DOI: 10.5846/stxb201509061830 作者: 作者单位: 中国科学院新疆生态与地理研究所,中国科学院新疆生态与地理研究所,中国科学院新疆生态与地理研究所,中国科学院新疆生态与地理研究所,中国科学院新疆生态与地理研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41271341，41030530，41301038）；塔里木油田公司项目（971012080007）；水利公益性行业科研专项（201401049） Effects of fertilizer addition on surface litter decomposition in the Tarim Desert Highway shelterbelt Author: Affiliation: Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences,Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences,Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences,Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences,Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences 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:为探讨沙漠公路防护林地表凋落物的分解速率和养分释放动态对施肥的响应，采用凋落物分解袋法，对塔里木沙漠公路防护林地乔木状沙拐枣（Calligonum arborescens）同化枝、梭梭（Haloxylon ammodendron）同化枝和多枝柽柳（Tamarix ramosissima）枝凋落物在施肥处理下的分解及养分释放特征进行研究。结果表明：经过420d的分解，3种凋落物质量残留率在对照（不施肥）、施用氮肥、施用磷钾复合肥处理间存在显著性差异（P < 0.05）。乔木状沙拐枣同化枝、梭梭同化枝和多枝柽柳枝在对照处理下的质量残留率分别为56.95%、31.32%和50.24%。施肥处理下3种凋落物均呈现出梭梭同化枝分解速率最快，多枝柽柳枝次之，乔木状沙拐枣同化枝分解最慢。施用磷钾复合肥极显著提高了3种凋落物的分解速率（P < 0.01）；施用氮肥则促进多枝柽柳枝的分解，抑制乔木状沙拐枣和梭梭同化枝的分解。凋落物分解过程中，对照组3种植物凋落物的C、N、P和K元素均呈现净释放状态；施肥后凋落物的N、P和K元素呈现出富集-释放的模式。凋落物初始P含量和C/N、C/P比值是分解初期的主导因素，初始K、木质素、纤维素含量和C/N、木质素/N比值是分解后期的主要控制因素。研究表明，施肥显著影响沙漠公路防护林地表凋落物的分解，增加防护林地表凋落物的养分归还量，延后养分释放的时间，改善塔里木沙漠公路防护林地的土壤肥力。凋落物初始C/N比值是预测塔里木沙漠凋落物分解的重要因素，且不同分解时期影响凋落物分解的初始化学组成有所差异。 Abstract:Litter decomposition determines the nutrient and carbon cycling processes and regulates nutrient return to the soil in many terrestrial ecosystems. Wood plant litter decomposition is a crucial biogeochemical process for carbon and nutrient cycling, especially in arid and nutrient-constrained ecosystems. However, the role of litter decomposition in extreme drought deserts and the determining factors remain debatable and poorly understood. The Tarim Desert Highway Shelterbelt consists of three artificial plant species that account for the majority of net primary productivity, and their litters are the major contributors to carbon and nutrient recycling. In such artificial desert shelter forests, the addition of fertilizer causes contradictory effects on litter decomposition and nutrient dynamics. This study aims to (1) examine how the addition of fertilizer affects surface litter decomposition and nutrient dynamics, and (2) determine the major factors influencing litter decomposition in arid deserts. The litterbag method was used to investigate the assimilative branches decomposition of Calligonum arborescens and Haloxylon ammodendron, and the branches decomposition of Tamarix ramosissima in the Taklimakan Desert Research Station. Filled litterbags were placed on soil surfaces at different plots in March 2013. Fertilizer addition and irrigation were implemented from March to November during the experiment. Litterbags were collected in May, July, September, and November of 2013, and in March and May of 2014. The mass remaining, elemental content (carbon, nitrogen, phosphorus, and potassium), and decomposition rates of litter were analyzed at each decomposition stage. Results showed that after 420 days of decomposition, significant differences were found among control (without fertilizer), addition of nitrogen fertilizer, and phosphorus and potassium compound fertilizer treatments. The mass remaining for the assimilative branches of C. arborescens, assimilative branches of H. ammodendron, and branches of T. ramosissima without fertilizer addition were 56.95%, 31.32%, and 50.24%, respectively. The decomposition rate of fertilizer treatments among different litters was the highest for the assimilative branches of H. ammodendron, followed by the branches of T. ramosissima, and then the assimilative branches of C. arborescens. The addition of phosphorus and potassium compound fertilizer significantly accelerated the litter decomposition rate of the three plant species, whereas nitrogen fertilizer increased the decomposition rate of the branches of T. ramosissima and restrained the decomposition rate of the assimilative branches of C. arborescens and H. ammodendron. During the decomposition process, litter nutrients presented net release patterns in the treatments without fertilizer. In contrast, the nitrogen, phosphorus, and potassium contents of the fertilizer treatments showed an accumulation-release pattern. The litter decomposition rate was determined by the initial phosphorus content and C/N and C/P ratios at the initial decomposition stage. However, the decomposition rate was controlled by the initial potassium, lignin, and cellulose contents and C/N, and lignin/N ratios at the final stage. Overall, the results suggest that the addition of fertilizer significantly changed the decomposition rate of surface litters, increased the amount of returned nutrients, and postponed the time of nutrient release. Improving soil fertility in the Tarim Desert Highway shelterbelt is essential in enhancing the quality of this valuable ecosystem. The initial litter C/N ratio is critical to surface litter decomposition in the Tarim Desert, and the initial chemical composition to surface litter decomposition rate varies at different decomposition stages. 参考文献 相似文献 引证文献

黑河下游柽柳根系水力提升对林分蒸散的贡献

黑河下游柽柳根系水力提升对林分蒸散的贡献

Tamarix ramosissima stand evapotranspiration and its association with hydroclimatic factors in an arid region in northwest China

There is currently only limited quantitative data available on riparian forest evapotranspiration (ET) of saltcedar (Tamarix spp.) in northwest China. We measured ET over a two year period using eddy covariance (EC) in Tamarix ramosissima stands in the lower Heihe River basin, China. We found that during the growing season, measured ET was approximately 520 mm yr−1 with a mean of 2.82 mm d−1. This was comparable to results from the lower Tarim River basin in central Asia where Tamarix spp is a native species. Comparisons between measured and estimated daily ET yielded an underestimation of approximately 30%, which could be partly due to errors in EC and nighttime transpiration. Whether directly measured or estimated, T. ramosissima stands were lower in its native environments compared to the western U.S.. Moreover, environmental parameters, such as climate and soil water content, accounted for at least 68%–78% of hourly and daily ET variation, respectively. Soil water factors were more important in accounting for daily ET variation than climate factors, but the opposite was true on a hourly timescale. Results showed that lower water use in T. ramosissima stands in the central Asia likely resulted from its long-term adaptation to hydroclimatic regimes.

Evaluation and Adaptation of Attractive Toxic Sugar Baits For Culex tarsalis and Culex quinquefasciatus Control In The Coachella Valley, Southern California.

The project goal was to determine how a new vector control strategy that targets the sugar-feeding behavior of mosquitoes, attractive toxic sugar baits (ATSBs), can be used to more effectively control West Nile virus (WNV) vectors in the Coachella Valley, California. Three laboratory studies were conducted to determine the utility of this method for control against Culex quinquefasciatus and Culex tarsalis : 1) efficacy evaluations of 2 formulations of ATSB, microencapsulated garlic oil, and a combination of microencapsulated garlic oil and 1% boric acid; 2) choice assays to determine the attractiveness of ATSB with the microencapsulated garlic oil against attractive sugar baits (ASB; the attractant alone; without toxin) and a 10% sucrose solution; and 3) vegetation efficacy tests on 3 common plant species in the Coachella Valley, Atriplex lentiformis, Tamarix ramosissima , and Pluchea sericea. At 48 h the average mortality for Cx. quinquefasciatus was 91% after exposure to ATSB with microencapsulated garlic oil and 99% on ATSB garlic + 1% boric acid solution. Culex tarsalis averaged 86% and 91% mortality following the ATSB microencapsulated garlic oil solution and the ATSB garlic + 1% boric acid solution, respectively. Choice assays indicated that the there were differences in preferences between the solutions and between species. Both Cx. quinquefasciatus and Cx. tarsalis were found to prefer the ASB and ATSB solutions to the 10% sucrose solution. However, when comparing the ASB to ATSB, Cx. quinquefasciatus significantly preferred the ASB solution (t = 3.6, df = 25, P = 0.0008). There were no significant differences in the preference of Cx. tarsalis to feed on the ASB or ATSB solutions as indicated in the choice assays (t = 1.9, df = 25, P = 0.07). Assays indicated that applications of ATSB to the 3 common plants in the Coachella Valley resulted in high mortality in both Cx. quinquefasciatus and Cx. tarsalis. There were significant differences in the treatments compared to the control (F = 40.15, df1,2 = 4,72, P < 0.001) but no significant differences among the different plants and ATSB treatments (F = 1.06, df1,2 = 4,72, P = 0.38). Laboratory findings suggest that ATSB is effective for use against WNV vectors in California. Further evaluations are needed in the field to determine how the environment may impact ATSB applications to influence mosquito mortality and nontarget organisms in arid environments in the United States.

Consumption of Salt Cedar and Willow Baccharis by Boer-Cross Goats

Both salt cedar (Tamarix ramosissima Ledeb.) and willow baccharis (Baccharis salicina Torr. & Gray) are readily invading rivers, streams, and lake basins throughout Texas. Both outcompete desirable vegetation and reduce biodiversity. The purpose of this study was to determine if goats would consume either plant and if protein supplementation would improve intake. In Trial 1, 36 recently weaned Boer-cross goats were randomly allocated to four treatments. Treatments included feeding salt cedar, willow baccharis, both, or neither plant. Goats were fed salt cedar and/or willow baccharis for 1 h daily for 14 d with intake measured daily. All goats were also fed alfalfa pellets (2% body weight [BW]) throughout the trial to meet maintenance requirements. Goats ate more (P < 0.05) salt cedar than willow baccharis and increased intake of salt cedar over the 14 d of feeding. In Trial 2, 20 recently weaned Boer-cross goats were randomly allocated to two treatments. One treatment received a protein supplement (37%) daily in addition to salt cedar. The other treatment did not receive any additional protein. Regardless of treatment, all goats received alfalfa pellets (2.5% BW) to meet maintenance requirements. Both groups increased intake of salt cedar over 10 d of feeding. Protein supplementation did not improve intake of the plant. Given a choice, goats will consume more salt cedar than willow baccharis and will readily consume the plant. Protein supplementation will not improve intake of the plant, but goats will increase intake of the plant when fed the plant at weaning.