共查询到20条相似文献，搜索用时 218 毫秒
1.
2001-2016年毛乌素沙地植被的生长状况 总被引：1，自引：0，他引：1
[目的]对2001-2016年毛乌素沙地植被生长状况进行研究,为该区域生态系统的可持续发展提供理论支持。[方法]基于MODIS EVI植被指数分析2001-2016年毛乌素沙地生长季和非生长季的植被生长状况,并讨论植被生长与气候变化、人类活动的关系。[结果]①毛乌素沙地植被覆盖度偏低,南部植被覆盖度明显高于北部区域。②毛乌素沙地2001-2016年植被覆盖度好转趋势明显。③生长季,毛乌素沙地南部和东部地区植被覆盖度变化速率大于中部和北部地区;且南部和东部的植被覆盖度部分呈显著增加,部分呈显著减小趋势。非生长季,南部地区植被覆盖度以显著增加为主。④毛乌素沙地EVI年最大值与降水呈正相关,与气温呈弱负相关;EVI年最小值与降水呈强正相关,与气温呈弱正相关。⑤农作物种植面积的增加、大规模人工造林以及大牲畜规模的控制等人类活动有助于植被覆盖度的提高。[结论]受气候因素和人类活动影响,21世纪以来毛乌素沙地植被生长状况好转。 相似文献
2.
[目的] 对比分析西鄂尔多斯地区四合木与红砂灌丛的阻沙能力,为原生草原与荒漠过渡带植物的多样性保护和珍稀濒危物种保育提供理论依据与数据支持。 [方法] 以西鄂尔多斯国家级自然保护区内四合木(Tetraena mongolica)、红砂(Reaumuria soongorica)灌丛沙堆为研究对象,运用典型样方法对四合木和红砂灌丛沙堆形态与生长状况进行系统测定,探讨沙堆形态发育及阻沙能力与四合木和红砂灌丛形态的关系。 [结果] ①四合木和红砂灌丛沙堆均呈半椭球型发育,四合木灌丛沙堆形态参数显著大于红砂灌丛沙堆(p＜0.05); ②四合木、红砂灌丛与沙堆形态参数间(灌丛高度除外)具有显著相关性(p＜0.01)。四合木灌丛沙堆长轴、短轴、半径与高度之间均呈二次函数关系,表明四合木灌丛可能进入衰退阶段,而红砂灌丛沙堆长轴、短轴、半径与高度之间均呈线性关系,表明红砂灌丛沙堆仍在发育; ③当冠幅面积(Sp)≤1.44 m2时,红砂灌丛沙堆的体积大于四合木灌丛沙堆,当Sp＞1.44 m2时,四合木灌丛沙堆的体积一直大于红砂灌丛沙堆。四合木和红砂灌丛单位冠幅面积所拦截的沙物质体积分别为0.13和0.06 m3。 [结论] 可以初步判断四合木的阻沙能力大于红砂。整体来看,四合木对风沙环境的适应性较红砂强,随着冠幅面积的增长四合木灌丛拦截沙物质的能力更强。 相似文献
3.
针对当前毛乌素沙地沙柳灌丛衰退问题,设计维持丛状结构特征可持续的生态平茬方法,研究不同平茬方法下沙柳灌丛的风场结构与防风效益,为今后毛乌素沙地沙柳生态平茬提供理论指导。试验设定6种平茬强度(0、0.2Ф、0.4Ф、0.6Ф、0.8Ф、1.0Ф,Ф为灌丛蓬径),3种平茬模式(模式A:按平茬强度沿主风向从灌丛迎风面向背风面平茬、模式B:按平茬强度沿主风向从灌丛两侧向中间同时平茬、模式C:按平茬强度沿主风向从灌丛中间1/2处同时向两侧平茬,下同)来维持灌丛结构的可持续存在,分析平茬后灌丛保留结构的自身形态参数和防风效益的关系,并依此选出最优平茬方法。试验结果表明:平茬强度在0～0.4Ф范围内,模式A和B的灌丛形态参数和防风效益指标均无显著变化,但模式B防风效益优于模式A;而强度为0.6Ф及以上,3种平茬模式下,背风面的风速降幅均明显减小,防风距离逐渐缩短,与原灌丛防风效益差异显著,强度为0.4Ф是防风效益发生突变的临界点。对防风效益影响最大的形态参数是疏透度。研究得出合理的平茬方法为:沙柳灌丛以模式B进行平茬,平茬强度为0.4Ф。 相似文献
4.
《水土保持学报》2015,(4)
通过调查青海湖地区典型固沙植物沙蒿(Artemisa desterorum Spreng.)、沙棘(Hippophae rhamnoides Linn.)和乌柳(Salix cheilophila)的根系分布情况,测定灌丛根下及裸沙地土壤温湿度、土壤有机质、土壤养分等理化指标,初步分析了3种典型固沙植物在植被恢复初期对土壤的改良作用。结果表明,土壤温度均高于空气温度,其中裸沙地和沙棘根下土壤温度略高;植物根下土壤水分均低于裸沙地,植物生长耗水表现为沙蒿沙棘乌柳;3种植物对土壤养分及土壤有机质的提高均发挥出较大的作用,尤其是对表层土壤(0-10cm)的改良效果明显。自然植被沙蒿对土壤养分的改良效果最明显,而人工植被乌柳能够显著提高土壤有机质含量。在极端贫瘠的高寒沙地,人工植被能够改善植被恢复区土壤有机质及土壤养分状况,从而进一步促进自然植被的恢复。 相似文献
5.
丘间低地不同年龄沙柳表层土壤水分与容重的空间变异 总被引：1，自引：1，他引：1
以毛乌素沙地丘间低地不同年龄(2~4年)沙柳为研究对象,采用地统计学方法对各年龄沙柳表层(0~20cm)土壤水分与容重空间变异进行研究。结果表明:随着年龄的增长,表层土壤水分含量表现出增大的趋势,且各年龄沙柳表层土壤水分含量间表现出一定的差异性(P<0.05);表层土壤容重差异不显著。空间变异分析显示,随着年龄的增长,沙柳表层土壤水分与容重具有高度的空间变异性,由空间自相关部分引起的空间变异向更强烈空间相关性转变,空间分布格局趋于复杂化;但不同年龄沙柳表层土壤水分含量的空间变异与容重的空间变异相关性不显著(P>0.05)。 相似文献
6.
通过设置不同平茬时间、不同留茬高度，开展了退化沙拐枣林平茬复壮的田间试验，以研究区域内植物多样性、不同处理下沙拐枣生长状况和土壤含水量为评价指标，综合分析了平茬措施对退化沙拐枣林的更新复壮效果。结果表明：(1)不同平茬时间、不同留茬高度下，沙拐枣均表现出较好的生长特性，但在冬季平茬，留茬高度为0 cm时沙拐枣的冠幅、新枝高度、新枝基径高于其他处理；(2)研究区中植被有沙拐枣、梭梭、沙米、刺沙蓬、雾冰藜5种，沙拐枣为优势种，沙米、刺沙蓬和雾冰藜为一年生草本植物，且其重要值比较高；(3)研究区0～20 cm深度土层平茬区土壤含水量高于未平茬区，20～60 cm深度土层平茬区土壤含水量低于未平茬区，60～120 cm深度土层平茬区与未平茬区土壤含水量变化无明显规律。因此，荒漠区退化沙拐枣林可以通过冬季平茬措施进行更新复壮，且留茬高度为0 cm时沙拐枣林生长状况更好。 相似文献
7.
不同绿竹种源含水率与持水量研究 总被引：1，自引：0，他引：1
绿竹在福建分布广泛,发展潜力巨大。为了进一步挖掘绿竹优良品种种质资源,对水土流失区引种绿竹种源含水率与持水量进行了研究。试验点设在永安和龙海两地,各设11个种源。研究结果表明不同种源的生物量与持水量呈正相关,林冠层持水量随生物量增加的幅度较大,地下部分增加的幅度较小,林下植被与凋落物层居中。永安试验点各种源林冠层和地下部分生物量、持水量高,植被层生物量高于龙海,但持水量低于后者,永安试验点的①⑤②号种源,龙海的③号种源林冠层和地下部分生物量较大,持水量较高,永安的⑧号种源,龙海的④号种源两指标均较小,林下植被与凋落物层的生物量与持水量则较高。 相似文献
8.
为揭示毛乌素沙地西南缘农田、荒地、草地、灌丛沙堆和林地等土地利用类型的土壤分形特征与防风固沙效果的关系,采用野外取样与室内粒度分析相结合的方法,分析了该区5种土地利用类型的土壤颗粒粒径分布、分形维数以及土层深度与分形维数间关系。结果表明:(1)草地、灌丛沙堆以及林地的土壤粒度组成以极细沙、细沙和中砂为主,耕地和荒地则以粉粒和细砂为主;(2)研究区不同土地利用方式的土壤粒径分布和分形维数差异明显,荒地>农田>灌丛沙堆>草地>林地,随土层深度增加,林地分形维数值减小,草地分形维数值增大,荒地、农田和灌丛沙堆分形维数值变化不大;(3)分形维数与<100 μm和>100 μm粒径含量分别呈显著正相关和负相关,其大小由<100 μm的极细砂粒和粉粒含量决定。研究区内5种土地利用类型土壤颗粒粒径分布与分形维数差异显著,这综合反映出在不同植被效应与人为耕作后,土壤的颗粒组成会发生明显变化。研究结果可为毛乌素沙地西南缘防沙治沙以及土壤恢复提供理论依据。 相似文献
9.
为了解藜麦种质资源在甘肃省陇中旱作区农艺性状和产量的关系,更高效的选育藜麦新品种,以38份藜麦种质资源为材料,采用相关性分析、主成分分析和聚类分析方法对影响产量的主要农艺性状进行了分析。结果表明,藜麦产量与各个农艺性状的相关程度从高到低依次为冠幅、全生育期、籽粒直径、千粒重、株高,全生育期与其余农艺性状均存在极显著相关性。冠幅、全生育期、籽粒直径、千粒重、株高等5个农艺性状可以归为3个主成分因子,其累积贡献率为76.657%,同时在类间距离为17.5处,将所有种质资源可分为三大类群。 相似文献
10.
内蒙毛乌素砂区中东部固定砂丘土壤的发生发育及其利用 总被引：1，自引：0，他引：1
毛乌素砂区位于我国内蒙伊克昭盟南部、陕西北部和宁夏河东地区。研究地区属毛乌素砂区中东部,为干草原淡栗钙土亚地带。经两年来的调查,发现该砂区中东部固定砂丘成土条件的植被因素较复杂,除砂生植物外,还夹有草本成分,个别砂丘全部生长针叶灌丛——臭栢。由于风积和风蚀频繁,砂丘上的土壤不易保存完整的剖面。因此,土壤形成中的时间因素也就起着明显的作用。 相似文献
11.
12.
13.
Realizing value of genetic resources of <Emphasis Type="Italic">Allium</Emphasis> in India 总被引：1，自引：1，他引：0
Anjula Pandey Ruchira Pandey K. S. Negi J. Radhamani 《Genetic Resources and Crop Evolution》2008,55(7):985-994
The genetic resources of Allium in India are potential source of genes for widening the crop genetic base. Despite their high economic value, limited number
of germplasm accessions of wild species have been collected and conserved mainly due to difficult access to areas of occurrence.
The present work mainly highlights information on species diversity distribution and utilization of wild Allium species to assess the value of Indian germplasm and prioritization for future collection and conservation programmes. 相似文献
14.
Alessandra Maria Moreira Reis Dario Grattapaglia 《Genetic Resources and Crop Evolution》2004,51(5):529-538
RAPD markers were used to investigate the distribution of genetic variability in a germplasm collection of the dioecious tropical tree Aroeira (Myracrodruon urundeuva) composed of open pollinated maternal half-sib families collected from trees at least 300 meters apart and grouped in nine collection areas throughout its geographical range in Brazil. Open pollinated families from nearby trees from two natural populations were also included in the study. A Principal Coordinate Analysis (PCO) based on genetic similarities estimated with 83 RAPD markers showed no defined clustering among individuals from the same collection areas. However, a matrix correlation test showed low, but significant correlation between genetic and geographic distances (r = 0.17; p < 0.02). An AMOVA showed that 92% of the genetic variation is found within collection areas. Significant variation was found both between regions and between areas within regions although only 3.54 and 4.44% of the variation was found at these levels respectively. An AMOVA on the individuals from the two natural populations resulted in a pattern of distribution congruent to the one found for the collection areas, with 97% of variability within populations. An analysis of 10 open-pollinated half-sib families revealed that between 75% and 89% of the variability is contained within families, suggesting that seeds from one tree represent a significant proportion of the variability found in the population. These results indicate that, either for the establishment of in situ genetic reserves or for ex situ conservation, efforts should be directed to the conservation of several individual trees or collection of open pollinated seed families in a few distant sites. In addition, if resources are available to enlarge the genetic base of the existing collection, expeditions should prioritize collection sites located in areas at significant distances to those already sampled. 相似文献
15.
沙地土壤C∶N∶P比对早期植物群落物种多样性的影响 总被引：1，自引：0，他引：1
为揭示土壤碳∶氮∶磷(C∶N∶P)比对植物群落物种多样性的影响,以宁夏哈巴湖国家级自然保护区内沙地植物群落(沙柳群落和油蒿群落)为研究对象,调查计算了沙地植物群落的物种多样性,测定了群落中土壤C、N、P含量,分析讨论了土壤C∶N∶P比与沙地植物群落物种多样性之间的关系。结果表明,分布于流动、半固定沙地的沙柳群落其土壤C∶N∶P比对物种多样性的影响不显著,而分布于半固定、固定沙地的油蒿群落其土壤C∶N∶P比对物种多样性的影响显著。这说明沙地植物群落生物量不断增大的同时,枯枝落叶增多,土壤C、N、P显著增多,较大的土壤C∶N比与N∶P比与不断增大的物种多样性有趋同变化,因此,土壤的C∶N∶P比能够影响沙地植物群落的物种多样性。 相似文献
16.
Jingbo Chen Junqin Zong Yanzhi Gao Yu Chen Qiaofeng Jiang Yiqi Zheng 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(5):416-424
Bermudagrass (Cynodon dactylon (L.) Pers.) is a widely used turfgrass in tropical, subtropical and warm-temperate regions in the world. It is a salinity-tolerant plant, but much genetic variation exists among its genotypes. Genetic diversity has been shown to exist from a morphologic level to a molecular level among Chinese natural bermudagrass germplasm resources; however, the extent of variation in their salinity tolerance has remained unclear. We conducted greenhouse hydroponic and sand culture experiments to evaluate the variation in salinity tolerance of natural bermudagrass germplasm resources obtained from their main areas of distribution in China and treated at a 33 dS m?1 salinity level for three weeks. Compared with non-saline controls, salinity stress significantly decreased shoot clipping weight (46.5% and 44.2%) and increased leaf firing (41.1% and 37.6%) in hydroponic and sand culture experiments, respectively, across all genotypes. However, significant genetic variations in relative leaf firing percentage (RLF) and relative shoot weight (RSW) were found among genotypes in both experiments, and their coefficients of variation ranged from 25.5% to 41.6%, indicating that considerable variation exists in the salinity tolerance of Chinese natural bermudagrass germplasm resources. Shoot Na+ concentrations increased under salinity stress for all genotypes in both experiments. However, significant genetic variations were also found in shoot Na+ concentrations. Salinity tolerance in bermudagrass genotypes was found to be significantly negatively correlated with shoot Na+ concentrations in both experiments. Using a cluster analysis of RLF and RSW data, all genotypes were classified into four groups with different salinity tolerances. The results of our evaluation indicate that there is much potential for improving salinity tolerance among Chinese natural bermudagrass cultivars. 相似文献
17.
为探究不同生态修复模式对露天矿区排土场边坡产流产沙规律的影响，采用野外径流小区试验方法，对矿区排土场边坡不同生态修复模式的产流产沙进行了1个雨季的连续观测。结果表明：（1）研究区降雨年内分配不均，主要集中在汛期7—9月，该时期降雨量占到年均降雨量的77.03%，是年内径流泥沙损失最多的时期。（2）不同生态修复模式与对照（只撒播灌草种子）相比均具有减流减沙效果，但是不同生态修复模式的减流减沙效益有显著差异，减流效果从大到小依次为沙柳网格模式（64.35%）>生态棒模式（56.56%）>生态袋模式（52.74%）>铁丝石笼模式（48.70%）>植物篱模式（45.51%）>土壤改良模式（35.89%）>无纺布覆盖模式（33.97%）>砾石压盖模式（8.19%）；减沙效果依次为沙柳网格模式（69.41%）>生态棒模式（61.28%）>生态袋模式（55.09%）>铁丝石笼模式（52.43%）>植物篱模式（48.72%）>土壤改良模式（42.09%）>无纺布覆盖模式（38.31%）>砾石压盖模式（19.34%）。（3）不同生态修复模式产沙量对产流量响应特征均呈极显著正相关（P<0.05，r>0），沙柳网格模式产沙量对产流量响应程度较小，生态棒模式次之，对照产沙量对产流量响应程度最大。 相似文献
18.
Faris Hailu Arnulf Merker Harjit-Singh Getachew Belay Eva Johansson 《Genetic Resources and Crop Evolution》2006,53(6):1089-1098
The variability of 2420 plants of tetraploid (2n = 4x = 28, AABB genome) wheat germplasm representing 121 accessions from Ethiopia were evaluated for 23 agro-morphological traits at Debre Zeit Agricultural Research Center area, Akaki substation, during the 2003 main season using multivariate methods. This enabled to assess the extent and pattern of variation of the germplasm with respect to regions, altitude classes and species and to identify the major traits contributing to the diversity. The first three and two principal components explained about 83 and 80% of the total variance among regions and altitudinal class, respectively. In the first principal component plant height, days to heading, the length and density of the spike, and kernel color were the most important traits contributing to variation that explained about 50% of regional variance. Cluster analysis grouped the accessions into 15 clusters, with 9 accessions remaining ungrouped. Based on the observed patterns of variation, it is concluded that there exists great variation in the germplasm, which provides opportunities to be utilized for genetic improvement. 相似文献
19.
Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields 总被引：4，自引：0，他引：4
A. Tullu I. Kusmenoglu K.E. McPhee F.J. Muehlbauer 《Genetic Resources and Crop Evolution》2001,48(2):143-152
Increasing and maintaining crop residues in predominantly cereal-based rotations of the US Pacific Northwest is critical to controlling soil erosion. The core collection of lentil (Lens culinaris Medik.) germplasm comprising 287 accessions was evaluated for variation in phenological, morphological and growth parameters including seed yields and residue amounts over a two-year period under conventional tillage and no-till conditions. The objectives of this study were (i) assess lentil genetic variation in germplasm for variation in biomass production and seed yield, (ii) assess the relationship of phenological and morphological traits with biomass and seed yield and (iii) identify high biomass producing germplasm for use as parents in the breeding program. Days to flowering and days to maturity ranged from 31 to 78 and from 71 to 106 days, respectively. Time to flowering in terms of cumulative heat units was a more efficient measurement than days to flowering. Plant height and plant canopy width had a significant association with total biomass, seed yield and residue amounts. Total biomass ranged from 788–6389 kg ha–1 under conventional tillage, while the range under no-till conditions was 1045–6195 kg ha–1. Most of the lines with higher biomass also produced the highest seed yields and residue amounts. Overall, only one accession produced more residue than `Laird'. In the more favorable environment of 1997, six accessions exceeded the control cultivars, `Laird' and `Indianhead', for residue amounts, and seven and twenty-four accessions exceeded control cultivars, `Pardina' and `Brewer', for seed yield. Results indicated that plant height, canopy width at maturity and seed yield explained most of the variation in biomass and residue production. Large seeded germplasm consistently had a longer reproductive growth period than small seeded accessions and had 17%, 7% and 21% more biomass, seed yield and residue, respectively. Our data indicated significant variation in lentil germplasm for biomass, seed yield and residue amounts to warrant their use in the breeding program. 相似文献
20.
This paper presents an effective method for prioritizing areas within a country for acquisition of germplasm of a crop gene
pool for ex situ conservation. The method was applied to the rare wild pepper species, Capsicum flexuosum Sendtn., in south-east Paraguay. A model to prioritize areas for collecting germplasm was constructed by combining (1) a
prediction of the species' geographic distribution based on the climate at previous collection points, (2) the distribution
of forest margins (the species' natural habitat) and (3) areas accessible by road. The model was then tested in the field
by visiting 20 sites having both high and low predicted probability of occurrence of C. flexuosum. Six new populations were found, representing a significant improvement over two previous collecting missions for the species
in the same region, undertaken without the use of GIS targeting. Using the most optimistic analysis of model performance,
C. flexuosum was found at five out of seven points predicted to harbour the species and not found at four of five points predicted not
to harbour the species. The model was then improved by the use of higher resolution climate surfaces. It is recommended that
future explorers use more recent and higher resolution satellite images to locate suitable habitats. The method is replicable
for different species in different geographic regions and is offered as a means of optimizing efficiency in financially constrained,
national plant genetic resources programs. 相似文献