科尔沁沙地21种植物水分提升作用的实证检验

对科尔沁沙地21种植物开展了水分提升作用检测和发生特点研究.试验采用上下层土壤隔离的自制栽植箱,通过控制上、下层土壤水分含量的方法检测植物水分提升作用.结果表明:有19个参试物种观测到水分提升作用,水分提升作用可能是沙生植物适应干旱环境的普遍特性;植物水分提升作用在00:00-06:00时段内发生频率和提升数量较高;不...     

辽宁北部地区土地沙漠化及其防治对策

科尔沁沙地日益加剧的土地沙漠化进程 ,已成为辽宁北部地区农牧业经济发展的主要灾害因素 ,并对沈阳等重工业城市生态环境构成严重威胁。辽宁省沙漠化土地面积约 2 0 .13万hm2 ,主要分布在北部的康平、彰武、法库、昌图和西部的阜新、北票等地区。其中受科尔沁沙地影响而形成的风沙地占沙漠化面积的 80 %以上。调查结果表明 ,由于沙漠化的危害造成土壤结构发生变化 ,土壤中细粒物质减少 ,粗大粒级物质增多 ,形成地表粗化过程。有机质含量从沙化初期的 1.4 0 2 %减少到 0 .4 12 % ,到严重沙漠化阶段可减少到 0 .0 95%。调整土地结构、优化土地利用模式 ;恢复与营造人工植被、建立绿色生态屏障 ;控制人口增长、改变能源结构 ,是我省北部地区土地沙漠化的有效防治对策     

Comparison of seed germination of four Artemisia species (Asteraceae) in northeastern Inner Mongolia, China

Two psammophile-dominated Artemisia semi-shrubs (A.wudanica and A.halodendron) and two annual Artemisia forbs (A.sieversiana and A.scoparia) bear significant ecological functions in Horqin Sandy Land,but systematical information on their achenes' germination is very limited.A set of studies were conducted to evaluate seed germination responses to storage periods and methods,different temperatures,lights conditions and sand burial depths,in order to determine inter-specific germination variation in the same genus and to explain how the species adapt to its microhabitat.Fresh achenes of A.wudanica,A.halodendron and A.sieversiana showed high germination capacities,but those of A.scoparia had obvious innate dormancy,which could be broken by chilling and dry storage,especially long-term dry storage.Achene germination of the two semi-shrubs preferred lower temperature fluctuation (10 to 22oC) and was not sensitive to light.But the two annuals preferred higher temperature fluctuation (34 to 22oC) and strong light for their achene germination.These four Artemisia species showed similar responses to sand burial,i.e.soil surface was most favorable for seedling emergence,and the deeper the sand burial,the fewer the seedling emergence.For the two semi-shrubs,their microhabitats are sand dunes with high temperature and intense light,which are not favorable for germination and seedling survival.Only rainfall contributes to temporary decrease of temperature and then triggers germination.We deduced that germination is not the main but a supplementary reproductive mode for the two semi-shrubs in sand dunes.For the two annuals,achene germination is the only reproductive mode,but different responses have been developed for microhabitat adaptation.For A.sieversiana,high germination capacities in wide temperature ranges and all light conditions could improve its competition and advancement in the wettest microhabitats.For A.scoparia,obvious innate dormancy of fresh achenes and germination inhabitation under unfavorable conditions are important adaptation to environmental disturbances.     

Foliar Values and Water Use Efficiency of Semi-arid Plants in Horqin Sandy Land,China

Water was a key factor restricting the plantation in sandy areas.Foliar δ13C value regarded as an indicator of longterm water use efficiency (WUE) of plants was generally used to evaluate the adaptability of plants to arid and semi-arid environment.In Horqin sandy land of China,the foliar δ13C values of 114 species in 35 families naturally growing in the area,and 15 species of sand-fixing trees and shrubs were measured and analyzed in 2012.The results showed that 97 species in all 114 species were C3 plants and only 17 species were C4 plants.Most C4 plants belonged to Gramineae family.The foliar δ13C value of C3 plants was between-25.000 and-31.075‰ with an average of-28.226‰,while those of C4 plants between-12.578 and -16.334‰,with an average of-13.678‰.The δ13C values of mature leaves collected in August were averagely 0.85‰ less than that of juvenile leaves collected in June.The foliar δ13C values and WUE of 15 sand-fixing tree species in Horqin sandy land ranked in the order as:S.vulgaris ＞H.rhamnoides ＞C.ovata ＞P.mongolica ＞ T.chinensis ＞R.typhina ＞S.matsudana ＞E.angustifolia ＞U.pumila ＞S.gordejevii ＞X.sorbifolia ＞C.microphylla ＞H.fruticosum ＞C.korshinskii ＞E.bungeanus.     

The return and loss of litter phosphorus in different types of sand dunes in Horqin Sandy Land, northeastern China

Litter phosphorus(P) return is important to maintain the P cycle and balance in the sandy land of arid areas.In this study,we determined the loss and return of litter P in sand dune areas and elucidated their relationship.We investigated litter production and litter P amount,and simulated leaf litter moving dynamics to understand the relationships between the loss of litter P and the total litter P,and between the return of litter P and the total litter P in active(AD),semi-stabilized(SSD) and stabilized(SD) dunes in Inner Mongolia,northeastern China.The vegetation litter P was 12.6,94.5,and 201.6 mg P/m2 in AD,SSD,and SD,respectively.A significant movement and loss of leaf litter P with time occurred on the three types of sand dunes.As a result,the loss of P was 7.4,46.9,and 69.8 mg P/m2 and the return of P was 5.5,47.6,and 131.8 mg P/m2 in AD,SSD,and SD,respectively.The relationship between both loss and return of P and total litter P in AD,SSD,and SD was revealed by linear regression.The slope of the regression line indicated the rate of loss or return of litter P.From AD to SD,the loss rate showed a declining slope(0.52,0.32,and 0.17 for AD,SSD,and SD,respectively),and the return rate showed a rising slope(0.48,0.67,and 0.83 for AD,SSD,and SD,respectively).The loss of litter P should be regarded in the local management of vegetation and land in sand dune areas.Improved vegetation restoration measures are necessary to decrease litter P loss to maintain the stability of ecosystems in sand dune areas.     

Effect of sand-fixing vegetation on the hydrological regulation function of sand dunes and its practical significance

Soil water content is a key controlling factor for vegetation restoration in sand dunes. The deep seepage and lateral migration of water in dunes affect the recharge process of deep soil water and groundwater in sand dune ecosystems. To determine the influence of vegetation on the hydrological regulation function of sand dunes, we examined the deep seepage and lateral migration of dune water with different vegetation coverages during the growing season in the Horqin Sandy Land, China. The results showed that the deep seepage and lateral migration of water decreased with the increase in vegetation coverage on the dunes. The accumulated deep seepage water of mobile dunes (vegetation coverage<5%) and dunes with vegetation coverage of 18.03%, 27.12%, and 50.65% accounted for 56.53%, 51.82%, 18.98%, and 0.26%, respectively, of the rainfall in the same period. The accumulated lateral migration of water in these dunes accounted for 12.39%, 6.33%, 2.23%, and 7.61% of the rainfall in the same period. The direction and position of the dune slope affected the soil water deep seepage and lateral migration process. The amounts of deep seepage and lateral migration of water on the windward slope were lower than those on the leeward slope. The amounts of deep seepage and lateral migration of water showed a decreasing trend from the bottom to the middle and to the top of the dune slope. According to the above results, during the construction of sand-control projects in sandy regions, we suggest that a certain area of mobile dunes (>13.75%) should be retained as a water resource reservoir to maintain the water balance of artificial fixed dune ecosystems. These findings provide reliable evidence for the accurate assessment of water resources within the sand dune ecosystem and guide the construction of desertification control projects.     

Characteristics of soil water consumption of typical shrubs (Caragana microphylla) and trees (Pinus sylvestris) in the Horqin Sandy Land area, China

Reforestation is one of the most effective ways to reduce the impacts of desertification. Caragana microphylla Lam. and Pinus sylvestris var. mongolica Litrin have been widely used to stabilize shifting sands in the Horqin sandy land area since the 1980s. However, soil water depletion has been of major concern in C. microphylla and P. ongolica plantations and in many places current soil moisture cannot meet the demand of growing plants. To determine the water budget of C. microphylla and P. mongolica plantations, we studied the effect of plantations on soil moisture and assessed the evapotranspiration in plantations of both species. Investigations were conducted at a fenced plot at Wulanaodu (42°29′N, 119°30′E, 479 m a. s. l), located at the western edge of the Horqin Sandy Land area in Inner Mongolia, northern China. Five year old C. microphylla and seven year old P. mongolica plants were selected from the plantations and transplanted to iron boxes (400 cm×200 cm×120 cm) which can drain extra water. Plant spacing of 1 m×1 m was applied to P. mongolica, and two plant spacings of 1 m×1 m and 1 m×2 m to C. microphylla. The transplanted plants grew for two years in the boxes. Soil moisture from soil surface to a depth 80 cm were measured at 20 cm intervals in boxes every 10 d (2004) or 3 d (2005) during the growing season with a TDR water meter. The evapotranspiration was estimated from a mathematical formula and the characteristics of soil water consumption and evapotranspiration of these two plantations were analyzed. The soil water of P. mongolica was more than that of C. microphylla at the same 1 m×1m spacing. The soil water of C. microphylla with the 1 m×2 m spacing was more than that of the 1 m×1 m spacing. The evapotranspiration ranged from high to low as follows: C. microphylla (1 m×1 m), C. microphylla (1 m×2 m) and P. mongolica (1 m×1 m) during the growing seasons. The evapotranspiration of individual plants ranging from high to low was C. microphylla (1 m×2 m), C. microphylla (1 m×1 m), and P. mongolica (1 m×1 m) during the growing season. C. microphylla grown for five year consumed more water than P. mongolica grown for seven years at the same spacing. __________ Translated from Acta Ecological Sinica, 2008, 28(5): 1981–1990 [译自: 生态学报]