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101.
102.
短花针茅荒漠草原主要牧草再生特性及其影响因素的研究 总被引:14,自引:1,他引:13
本试验对短花针茅荒漠草原建群种、优势种、次优势种和主要伴生种的再生性及其影响因素进行研究探讨。结果表明该草地供试草种的再生能力不同,再生性及其强弱主要取决于草种的生物学特性和再生期间的环境条件以及留茬高度、灌水和施肥等栽培措施。年内连续多次刈割,使牧草贮藏养分(主要是可溶性碳水化合物)含量下降,到初霜后降至最低点。 相似文献
103.
K. D. Sharma Praveen Kumar L. P. Gough J. R. Sanfilipo 《Land Degradation \u0026amp; Development》2004,15(2):163-176
Extensive lignite mining in the Indian (Thar) Desert commenced within the past decade. Accompanying extraction of this valuable resource there have been visible, important environmental impacts. The resultant land degradation has prompted concern from both public and regulatory bodies. This research assesses the success of rehabilitation plans implemented to revegetate a lignite mine‐disturbed area, near the village of Giral in western Rajasthan State. Rehabilitation success was achieved within the environmental constraints of this northwest Indian hot‐desert ecosystem using a combination of: (1) backfilling (abandoned pits) with minespoil and of covering the backfilled‐surfaces with fresh topsoil to a thickness of about 0·30 m; (2) use of micro‐catchment rainwater harvesting (MCWH) technique; (3) soil profile modification approaches; (4) plant establishment methodologies; and (5) the selection of appropriate germplasm material (trees, shrubs and grasses). Preliminary results indicate that the resulting vegetative cover will be capable of self‐perpetuation under natural conditions while at the same time meeting the land‐use requirements of the local people. The minespoil is alkaline in nature and has high electrical conductance. The average content of organic carbon, N, P and K is lower than in the regional topsoil. However, the concentration of Ca, Mg, Na and total S in the minespoil is much higher than in the topsoil. Further, the spoil material has no biological activity. Enhanced plant growth was achieved in MCWH plots, compared to control plots, where minespoil moisture storage was improved by 18–43 per cent. The rehabilitation protocol used at the site appears to have been successful because, in addition to the planted species, desirable native invasive species have become established. This study developed methods for the rehabilitation of lignite mine‐disturbed areas and has also resulted in an understanding of rehabilitation processes in arid regions with an emphasis on the long‐term monitoring of rehabilitation success. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
104.
Soil microarthropods were sampled in plots centered on creosotebushes (Larrea tridentata) and in plots centered on mesquite (Prosopis glandulosa) coppice dunes. Nine plots in each area were covered by rain-out shelters with greenhouse plastic roofs which excluded natural
rainfall and nine plots received natural rainfall. There were differences in the abundance of several mite taxa in soils from
the mesquite coppice dune plots. Some taxa (Stigmaeidae, Nanorchestidae, and Entomobryidae) occurred in significantly lower
numbers in the soils of the drought plots. Other taxa (Tarsonemidae and Cunaxidae) were more abundant in the drought plots
in the mesquite coppice dunes. There were no significant differences in the abundance of any of the dominant taxa of soil
microarthropods in the drought and control plots centered on creosotebush. In the creosotebush habitat, there were significantly
fewer Prostigmata in the plots exposed to drought. In an area with both creosotebush and mesquite, there were no significant
differences in microarthropod population responses to drought and in recovery from drought. The differences in responses of
soil microarthropods to drought in creosotebush and mesquite habitats are attributed to the differences in soil stability,
litter accumulations, and microclimate associated with the shrubs.
Received: 29 December 1997 相似文献
105.
Few studies on the characteristics and mineralogical trends of the soils in the Sahara Desert have been reported in the literature. This work aims at studying the morphology, the classification, and the mineralogy of desert alluvial soils of the Mzab region in the Northern Sahara, Algeria. Morphological and analytical studies carried out on fourteen pedons of wadi Zegrir over a range of elevations (250–850?m) indicate that the soils are sandy to silty clay, nonsaline (electrical conductivity, EC?0.53 dS/m), moderately to slightly alkaline (pH 7.46–8.52), and poor in organic matter content (0.02–2.38%) with good drainage conditions. In addition, the nature and composition of the soils show that they can be classified as aridisols (haplocambids and haplocalcids) and entisols (torriorthents, torrifluvents, and torripsamments). They have well-stratified layers, especially in the downstream part of the wadi, indicating interactions between alluvial and aeolian processes in which evaporite tertiary and secondary formations play an important role in the formation of contemporary minerals. Thin-section observations revealed that the occurrence of calcite in these soils is related to allochthonous mechanisms and in situ crystallization. X-ray diffraction analysis indicates that palygorskite and illite are present throughout the clay fraction of the soil samples in all studied profiles. Kaolinite and chlorite are less abundant, whereas smectite is present in minor amounts. 相似文献
106.
WANG Junqiang 《干旱区科学》2016,8(3):350-363
Soil organic matter content in water-stable aggregates(WSA) in the arid ecosystems(abandoned agricultural lands especially) of China is poorly understood. In this study, we examined the WSA sizes and stability, and soil organic carbon(OC) and nitrogen(N) contents in agricultural lands with abandonment ages of 0, 3, 12, 20, 30 and 40 years, respectively, in the Minqin Oasis of Northwest China. The total soil OC and N contents at depths of 0–20, 20–40 and 40–60 cm in abandoned agricultural lands were compared to those in cultivated land(the control). Agricultural land abandonment significantly(P0.05) influenced the distribution of MWD(mean weight diameter), and OC and N contents. There were significant increases in MWD and the proportion of macroaggregates(sizes 0.25 mm) as the age of agricultural land abandonment increased. The effect of abandonment ages of agricultural lands on MWD was determined by the changes of OC and N accumulation in WSA sizes 2 mm. The total OC and N contents presented a stratification phenomenon across soil depths in this arid ecosystem. That is, both of them decreased significantly at depths of 0–20 and 40–60 cm while increased at the depth of 20–40 cm. The WSA sizes 0.053 mm had the highest soil OC and N contents(accounting for 51.41%–55.59% and 42.61%–48.94% of their total, respectively). Soil OC and N contents in microaggregates(sizes 0.053–0.25 mm) were the dominant factors that influenced the variations of total OC and N contents in abandoned agricultural lands. The results of this study suggested that agricultural land abandonment may result in the recovery of WSA stability and the shifting of soil organic matter from the silt+clay(0.053 mm) and microaggregate fractions to the macroaggregate fractions. However, agricultural land abandonment did not increase total soil OC and N contents in the short-term. 相似文献
107.
黄河乌兰布和沙漠段沿岸沙丘形态及其运移特征 总被引:2,自引:0,他引:2
为更合理、精确地计算黄河乌兰布和沙漠段的入黄沙量,探明其对黄河沿岸植被造成的影响程度,以黄河乌兰布和沙漠段沿岸沙丘为研究对象,通过野外地貌调查、沙丘形态测量和遥感解译对其沙丘的形态特征及其运移特征进行了系统研究。结果表明:乌兰布和沙漠沿黄段沙丘以走向西南—东北的新月型沙丘和新月型沙丘链为主,沙丘剖面形态不对称,具有明显落沙坡;在发育过程中同时受到了西南风和西北风的显著影响,5年内以沙丘整体向河道推进为主,共移动19.45m,具有单向快速运移的特点,且沙丘不断向黄河侵袭,应采取措施予以遏制。 相似文献
108.
5-氨基乙酰丙酸和叶面肥对荒漠区设施番茄和辣椒生长发育、产量和品质的影响 总被引:2,自引:0,他引:2
为外源5-氨基乙酰丙酸(ALA)在荒漠地区设施园艺中的推广和应用,以番茄和辣椒为材料,设置清水、叶面肥和外源ALA(5-氨基乙酰丙酸)3个处理,研究外源ALA和叶面肥处理对荒漠区番茄和辣椒生长及产量品质的影响。结果表明,外源ALA和叶面肥均可促进荒漠区番茄和辣椒的生长,并显著改善果实相关品质。其中ALA处理的番茄株高、茎粗、叶片数和冠径与对照相比分别提高15.45%、8.33%、13.69%和8.58%,辣椒叶片数提高22.79%;番茄果实固酸比提高8.86%,辣椒可溶性固形物质量分数提高8.59%,并且还能够提高番茄和辣椒的产量。可见,ALA和叶面肥对荒漠区设施番茄和辣椒的生长都表现一定的促进作用,对品质有不同程度的改善,同时也提高了产量。 相似文献
109.
110.
Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico
and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria
(Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite
amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation.
Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured
as transpiration and diffusive resistance, when these trees were cultivated without water restrictions. 相似文献