Distribution pattern and characteristics of Ammopiptanthus mongolicus in several different habitat conditions
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Abstract:
By the comparative study of the characteristics,age structure and distribution pattern of Ammopiptanthus mongolicus in three different habitat conditions,we got the results that:1) The average density,height,crown and branches of the natural A.mongolicus growing in sunny slope are higher than that growing in shade side of rocky slope;The average density of the plant which growing in fixed sand is smaller,but due to the effection of wind and sand buried,the number of branches are more.2)The main individual growing in rocky slope are young and stable,but the natural regeneration is difficult,there are little seedlings,lacking of reserve resources will be most likely recession;The main individuals growing in fixed sand are old and has no seedlings,they has been declining significantly.3) The habitat conditions of the plants lead to the distribution pattern.The plants growing in sunny rocky slope and fixed sand appear uniformly distribution,while that in shade side of rocky slope appear cluster distribution.Keywords:
Steep slope
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Taking root suckers of Hippophae rhamnoides artificial population as the research object,based on the field investigation of produced number of clones,space distribution and growth condition,basic characteristics of ramet and relationship of environmental factors and root suckers were studied systematically in different habitats in Zhifanggou hilly-gully regions.The results showed that the regeneration of H.rhamnoides depended on asexual propagation.Seedlings from seed germination were rarely in investigation area.The artificial population grew vigorously better on shady slope than that on sunny slope;the number of ramet,horizontal extending area and individual growth,and upper mountain slope were superior to lower slope.Deadwood existed in different habitats,the least was on shady slope(5%),and the most was on sunny slope(20%).5~6 years-old ramet revealed the highest dead rate in among different age classes.Spatial distribution showed that dense distributing area was in the surface soils(2~6 cm).Horizontal extension in up slope could reach 3 m,further than lower slope not more than 1.5 m.The spatial distribution of ramets emergence was effected most by slope position,less by slope direction.Although H.rhamnoides forest posses the capability of self-renewing in hilly and gully region,habitats with enough water and loose soil structure should be the first choice to meet the need of growing and soil and water conservation.
Hippophae rhamnoides
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Sand dune stabilization
Environmental gradient
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Twelve plots of artificial Caragana korshinkill population in both sunny and shady slope in Zhifanggou hilly area of the Loess Plateau were investigated from the aspects of community characteristics and asexual reproduction characteristics.The main conclusions were as fllows.Vegetative propagation of C.korshinskill in sunny slope was more vigorous than that in shady slope,and it was better in upslope than in lower slope.Extending area and ramet number were also better in sunny slope.Death ramet were found in every habitats,which were more in up slope than in lower slope,and the number was more in sunny upslope with the maximum of 25.9%.Maximun death rates were found in 1~2-year seedpings among all age classes.Analysis on space distribution scope of root sucker showed that the root of C.korshinskill in upslope was concentrated between 6~30 cm,and that in lower slope was concentrated between 6~20 cm.Root horizontal spread distance of C.korshinskill in upslope was longer than that in lower slope.The spatial distribution pattern of germination point were greatly influenced by slope position,slope direction showed little influence.Owing to strong compatibility and reproduction ability of C.korshinskill,artificial stands could complete self-updating in Loess hilly regions,and it was a perfect tree species in the recovery of vegetation in harsh condition.
Loess plateau
Caragana
Asexual reproduction
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Bedrock
Root system
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Herbaceous plant
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Sand dune stabilization
Population density
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Sand dune stabilization
Artemisia
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Sand mining is used to extract sand through an open pit. After completion of mining activities sand pits usually undergo rehabilitation: firstly they are graded and then planted with trees and shrubs, but very often sand pits are abandoned to regenerate themselves. The sand pit becomes a source of dust and a hardly healed wound on the earth’s surface. In order to provide an adequate revegetation on such substrates, it is necessary to study ecological peculiarities of growing plants in a very specific environment characterized by high stiffness of slopes and high mobility of the substrate. The vegetation of the sand pits is expected to have a xerophytic habitus and will be similar to desert plants, but that is not the case. The zonal component affects the habitus of the vegetation. However all plants of sand pits have characteristics of psammophytes directly or indirectly. The flora and vegetation of Zvenigorodsky and Dzerzhinsky sand pits on the slopes of southern and northern exposures were studied during this work. It was found that the projective cover constitutes 20-30%. Species diversity is determined by the successions occurring spontaneously after a rough anthropogenic intervention, under the influence of such environmental factors as lighting, texture, moisture and richness of soil. Exactly 98 species of plants were discovered, diversity on the southern slopes was more than twice as higher than on the northern ones. Mesophytes dominated among the plants with a high occurrence, but a lot of xeromesophytes were found as well. The dominance of therophytes in sand pits was not confirmed: the predominance of hemicryptophytes as in the Middle zone of Russia is identified. We can only note the predominance of hemicryptophytes on the northern slopes, as well as the migratio of phanerophytes to the southern slopes. According to the classification of life forms by I. G. Serebryakov, sand slopes are dominated by herbaceous perennial polycarpics, among which long- and short rhizome plants and tap rooted plants are in majority. A significant proportion of tap rooted plants is due to their high degree of adaptation to strong light conditions and resistance to drought. Dominant ecological-coenotic group is that of meadow plants. One should note the lack of affinity of sand pits species diversity with neighboring plant communities (coefficient of P. Jaccard is equal to zero). There are weed and wetland species that migrate on slopes from the bottom of the sand pits. The rate of adventive species is low.
Revegetation
Dominance (genetics)
Sand dune stabilization
Plant cover
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Details on the nature of density—dependent processes in desert annuals and their interaction with density—independent factors are critical to an understanding of adaptation to variable environments and the role of environmental variation in the maintenance of species coexistence. In this study we examined intra— and interspecific competitive interactions along a topographic gradient for two co—occurring species of desert winter annuals, Plantago patagonica and Pectocarya recurvata. This investigation was carried out in a creosote flat in the Sonoran Desert during 1987—1988, a growing season with high plant densities and low rainfall. Three stations were established along the topographic gradient: one in the sandy rivulets of a tertiary wash or arroyo, one in the sandy clay soil at the base of a small hill, and the third on the southeast side of the gently sloping (9°) hill. The wash habitat had the greatest moisture availability (soil water potential) shortly after rainfall. Yet it dried out quickly, presumably due to greater evaporation and percolation, leaving the base of the hill with the greater average moisture availability. The slope had the lowest moisture availability. Competition experiments were set up at each station using a neighborhood design with varying density in either mono— or mixed cultures. Target plants were scored for survival, fecundity, and size. Plantago and Pectocarya were found to have equivalent competitive effects in all three habitats using either species as a target: the species identity of neighbors had no measurable effects so that competition coefficients appear to be equal. However, density—response curves had different slopes in the different habitats along the gradient: both species had flat density—response curves on the slope, while Plantago had its steepest curve in the wash and Pectocarya had its steepest curve at the base of the hill. While density—dependent processes were important determinants of success for these desert annuals in this low—rainfall year, the strength of the density response varied spatially. We argue that the habitat—density interactions that differ among species may promote their coexistence.
Larrea
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In this study 4 habitat types(bottomland,bottom,slope and ridge of sand dunes)are classified for researching the age structure and its dynamic change of Sabina vulgaris populations based on the local conditions, such as the groundwater regime and terrain in Mu Us sandy land.The aim of the study is to determine how the different habitats affect the stability and development of S.vulgaris populations.The plant age is determined by measuring the number of growth rings with the WinDENDRO~(TM)analyzing system.Regression equations between the basal diameter and the age of S.vulgaris populations are developed for the selected young and mature plant samples,and then the equations are used for estimating the age of individuals across each plot based on measuring the basal diameters. The results show that the proportion of the younger-aged(less than 10 years)plants growing on the bottomland and the bottom of the sand dunes is as high as 94%of the populations,the age structure is in a typical pyramid pattern,and the populations are in an expansion.On the slope of the sand dunes,the age structure of the plants is cone-shaped,the middle-aged(21 to 30 years old)plants are dominant,and the populations are stable. On the ridge of sand dunes,the S.vulgaris populations are dominated by the mature and old plants(51 to 60 years old),and the age structure of the populations is reverse-pyramid-shaped,indicating the typical ageing populations.
Basal area
Sand dune stabilization
Pyramid (geometry)
Age structure
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