河北迁安盆地中全新世以来的植被变化及人类活动的影响

依据位于燕山南部迁安盆地蚕姑庙村和余家洼村具放射性碳年代测定支持的埋藏泥炭剖面的孢粉分析资源，揭示了迁安盆地5000a BP以来自然植被变化和人类活动对自然环境的影响。在4600～3100a BP期间，迁安盆地曾经生长着以栎为主的落叶阔叶林，至3100a BP以后，森林中阔叶树成分显下降，喜凉耐干的松树比例增加，1600a BP后，迁安盆地人类农耕活动进一步加剧，森林遭受到大规模的破坏，孢粉分析资料揭示迁安盆地人类栽培板栗的历史可以追溯到1600a BP左右，种植水稻的历史可以追溯到700a BP左右。     

浑善达克退化沙地恢复演替18年中植物群落动态变化

探讨了浑善达克退化沙地草地围封后流动沙丘的稳定程度 ,以及相应的群落特征随恢复进程的变化规律。采用空间序列代替时间序列的方法 ,从物种丰富度、生活型及功能型多样性等方面探讨了围封 18a(1985～ 2 0 0 3年 )过程中草地自然恢复演替进程。在这一过程中 ,物种多样性、丰富度和生物量随恢复演替先增加而后基本稳定或略有降低 ,呈抛物线型的变化趋势 (P<0 .0 0 1)。依群落特征变化 ,大致可将退化沙地恢复过程分为 3个阶段 :(1)流动沙丘向半固定沙丘转变的过程。在围封的前 2 a内 ,群落盖度增加 6倍 ,物种丰富度增加了 1倍 ,而物种多样性增加较缓慢 ;(2 )半固定沙丘向固定沙丘演替的过程。围封后 3～5 a内 ,尽管群落盖度只增加了约 2 0 % ,但物种丰富度和多样性显著增加 ,植物种类在 3a期间增加了 15种 ,是沙地恢复演替的关键时期 ;(3)固定沙丘稳定阶段。围封第 6 a后 ,群落总盖度、生物多样性、物种丰富度保持不变或略呈下降趋势。在恢复演替中 ,C4 植物在初期起先锋作用 ;而 C3植物在后期对群落稳定起重要作用 ;豆科植物尽管在群落中所占的比重较小 ,但可能对改善沙丘土壤养分方面起重要作用。从生活型多样性来看 ,1年生植物在恢复演替早期阶段对沙丘稳固起重要作用 ;而中后期群落则以多年生植物为     

新疆哈巴河桦木属湿地3600年以来的植被变化和人类活动

湿地是水陆相互作用形成的独特自然综合体,对全球气候变化敏感,尤其是干旱半干旱区分布的湿地对自然环境和人类活动的响应更为显著。基于新疆哈巴河地区桦木林湿地人工开挖130 cm深的地层剖面,结合较高时间分辨率的¹⁴C测年数据和孢粉组合,揭示出该区3600年来曾经历5个时段的植被变化和人类活动的影响。3540—3430 cal a BP期间,该区以蒿属(Artemisia)等旱生植物为主,湿地尚未形成;3430—2640 cal a BP期间,局地小环境较湿润,湿生草本和以沼泽蕨(Thelypteris palustris)为代表的蕨类植物大量生长,落叶阔叶的桦木属(Betula)植物开始出现;至2640—660 cal a BP期间,浅水湿地开始形成,桦木属植物迅速扩张,但在大区域仍分布着由藜科(Chenopodiaceae)和蒿属等为主要组成的荒漠植被;尤其在660—210 cal a BP期间,桦木属成为森林的优势种;值得关注的是,近200年以来,该区以藜科为代表的草本植物增多,而桦木林出现萎缩。通过对选取的典型局域湿地不同历史时期环境变化和人类活动影响的研究,揭...     

秦岭地区15kaBP以来的植被与环境

通过对秦岭海拔2200m-山间盆地沼泽沉积剖面的花粉分析和^14C年代测定,结合对该区植被与表土花粉的研究,认为秦岭的暗针叶林带15ka BP以来植被和环境经历了4个发展阶段：(1)约15450～6760a BP,植被为冷杉(Abies)-云杉(Picea)林,气候寒冷潮湿;(2)约6760～2940a BP,沉积物中花粉稀少,以冷杉、云杉、桦(Betula)、栎(Quercus)为主,出现了喜暖型植物桤木(alnus),气候暖湿;(3)2940～40a BP,植被为冷杉林,气候冷湿;(4)0～40a BP,植被为桦、栎、榛(Corylus)、桤木、铁杉(Tsuga)和小片状分布的冷杉,松(Pinus)的数量极少,气候向暖干方向发展,这是近期人为活动干扰的结果。     

论乌兰敖都地区沙丘坡面直射光的分布

乌兰敖都位于内蒙古自治区东部的科尔沁沙地中部,是西辽河中上游流域干旱地带的中心。境内分布着石质残丘和起伏的风积沙丘而呈现坨甸相间的景观,石质残丘、流动沙丘和固定沙丘占有很大比例,流动沙丘和固定沙丘(包括半固定沙丘在内)占总面积30%左右。由于地形起伏不平,下垫面性质的不同引起小气候、土壤和植被的显著差异。在本地区的半干旱气候条件下,光是决定生态系统生产力的主要因素之一,也是植物生长的唯一能源。本文根据1983—1984年实际观测资料,着重讨论乌兰敖都地区沙丘不同坡面对直射光到达量的影响,为沙地的综合利用和改造提供科学依据。一、计算方法沙丘不同坡面上直射光到达量,是指在单位时间内投射到单位坡面积上的直射光通量,     

西鄂尔多斯八种沙生植物的花粉形态与地史演化意义

西鄂尔多斯是我国西北干旱区特有植物和沙生植物集中分布区之一,该地区植物区系表现为古地中海旱生植物后裔的古老性。应用光学显微镜对西鄂尔多斯地区四科八个种的沙生植物柽柳(TamarixchinensisLour)、猫头刺(Oxytropis aciphyllaLedeb)、四合木(Tetraena mongolicaMaxi m.)、沙竹[Psammochloa villosa(Trin.)Bor]、白刺(NitrariatangutorumBobr)、白山蓟[Olgaea leucophylla(Turcz.)Iljin]、顶羽菊[Acroptilon repens(L.)DC.]、砂蓝刺头(Echinops gmeliniTurcz.)的花粉形态进行了观察和研究,结果表明:花粉形态差异较大,孔沟有单孔,三孔沟,三沟等不同类型。外壁纹饰主要是细网状纹饰和刺状纹饰。花粉形态相对于植物其它性状在演变过程中较为保守,与植物早期生长环境息息相关。这八种沙生植物对极其干旱的沙生环境都有很好的生态适应性和生境适宜性,是西鄂尔多斯地区古环境与其长期协同进化和长期适应的结果。这对重新认识西鄂尔多斯地区古气候环境的演化和荒漠地区地史变迁与沙地植被恢复和重建具有一定理论指导意义。     

模拟酸雨对蒙古栎幼苗生长和根系伤流量的影响

选择中国北方落叶阔叶林的主要组成树种蒙古栎(Quercus mongolica Fisch.ex Ledeb.)的1年生幼苗为研究对象,设置4个酸雨酸度(重度、中度、轻度和对照)和3个降雨量(自然雨量和增、减雨量30％),以期阐明酸雨对蒙古栎幼苗形态生长、生物量和根系伤流量的影响,探讨中国北方日趋严重的酸雨是否会影响蒙古栎幼苗的生长,为酸雨区森林恢复植物的选择提供依据.研究结果显示:1)在本实验的酸雨酸度下,酸雨降雨量的增加对蒙古栎幼苗各生理生态指标均有一定的促进作用;2)酸雨酸度对蒙古栎幼苗形态和生物量的影响不显著,但酸度增加降低了幼苗的根系伤流量;3)增雨的重度酸雨处理促进了蒙古栎幼苗形态生长和生物量累积;4)两因素对蒙古栎幼苗的影响没有交互作用.说明蒙古栎对酸雨具有一定的抗性,可考虑选择为酸雨区植被构建的物种.     

民勤沙区植被退化与年际降水量关系的定位研究

民勤沙区荒漠植物盖度随年际降水量变化明显,植被在随年际降水量变化的波动中退化。在一般年份,白刺、梭梭、沙蒿等灌木上部发生枯梢,在降水量偏少或分布异常年份会整株枯死,所以有的年份植被盖度和灌木高度反而会降低。不同植被群落分布的地貌条件和土壤条件有较大差异:白刺以白刺沙丘的形式存在,白刺沙丘0～30cm土壤含水率在1.4%～2.0%之间;膜果麻黄仅分布在粘砾石质滩地上,0～30cm土壤含水率<0.8%;沙蒿分布在低缓的半固定沙丘、流动沙丘和覆沙滩地上,0～30cm土壤含水率在0.9%～1.7%之间。植物通过土壤水分变化对降水作出反应,土壤水分条件对降水的反应受土壤颗粒的影响,细砂粒对降水反应灵敏。优势种植物高度与7月下旬～9月下旬的降水量之间存在较大的正相关;草本植物平均盖度与7月下旬～9月下旬和5月下旬～7月下旬期间的降水量之间存在较大的正相关。全年降水量主要影响植被总盖度。5月下旬～7月下旬的降水量对植被的影响较全年降水量更为明显。     

固沙植物根际微生物对于沙土发育和流沙固定的影响

在宁夏中卫沙坡头铁路防沙研究地段,多年人工植被沙丘的沙土不断发育,在沙丘表面形成结皮层,结皮下面形成块状沙土层,导致沙丘逐渐固定,无疑这与机械沙障固沙和植物固沙措施有直接关系。从流动沙丘向固定沙丘不仅表面发生变化,内在因素的变化也起着重要作用,分别研究这些内外因素,探讨其相互     

孢粉记录的重庆岩溶槽谷区700年来植被演替与喀斯特石漠化

在精确AMS¹⁴C测年的基础上,对采自重庆中梁山岩溶洼地的剖面样品进行了孢粉分析,并结合详细的历史文献资料,获取了该地区近700年以来的植被变迁与石漠化演化记录。结果显示：（1）1274-1553 cal a AD研究区周围主要分布以松属、柏科/杉科占优势的亚热带常绿针叶林,伴人植物花粉少量出现,人类活动相对较弱。（2）1553-1780 cal a AD,针叶树松属、柏科/杉科花粉含量下降,伴人植物花粉增多,指示研究区人类活动开始加强。（3）1780-1840 cal a AD,松属花粉含量急剧下降,灌木和伴人植物花粉急剧增加,指示该地区人类活动加剧,石漠化现象出现。（4）1840-2000 cal a AD,玉米花粉含量大幅度增加,表明人类活动更加强烈,石漠化现象进一步加剧。近700年来不断增加的人类活动是重庆地区植被退化、石漠化现象严重的重要因素。该研究结果对重庆岩溶地区的全面治理,恢复和重建自然生态环境具有重要的指示意义。     

Late Holocene Vegetation in Maili Region,Northeast China,as Inferred from a High-Resolution Pollen Record

The change of vegetation in Maili region over the last 3 400 14C years has been reconstructed based on a high-resolution pollen record. It was thought that the contrast between arboreal and herb plants in different periods might well reflect the change in relative extent of the fixed sand dunes and active sand dunes, and the evolution history of the sand dunes could be thus investigated. Before 3 100 a BP, the sand dunes around Maili bog supported a denser vegetation, with Quercus mongolica Fisch., Tilia L., Ulmus L. as its dominating taxa. Declination of the open forest and increase of major herb taxa since 3 100 a BP suggest an increasing area of semi-fixed and partly active sand dunes mainly supporting Artemisia L. and Chenopodiaeeae. Such a changing process has generally been continued through the last 3 000 years. However, the period from 1 000 a BP to 660 a BP was unique in that it witnessed a lush growth of nearly all of the taxa in the region, with the expanding of Quercus mongolica population being especially obvious. The desertification process starting at 3 100 a BP ceased during that time, and the different types of sand dunes were supporting a much denser vegetation covered in the period than any others.     

Two centuries of vegetation succession in an inland sand dune area,central Netherlands

Questions: (a) What are the rates and directions of vegetation succession in an inland sand‐dune system? (b) What are the differences in successional trajectories in different relief types? and (c) Is it possible to preserve the last areas of still active dunes and under what circumstances? Location: The study sites were located in the northern part of the Veluwe Region, central Netherlands; longitude 5°44′ E, latitude 52°20′ N, altitude 9 to 24 m a.s.l. Methods: Vegetation and relief mapping was conducted in three permanent plots, 200 m × 200 m in size, in 1988 and 2003. Phytosociological relevés (2400) were recorded in each 10 m × 10 m subplots. Age of woody species was determined by wood coring. Geographic Information System, ordination analyses, and TWINSPAN were used for data exploration and elaboration. Results: A total of 70 vascular plants and 19 bryophytes were recorded over successional stages spanning approximately190 years. The following dominant species formed the sequence of successional stages, but not all participated in all relief types: Ammophila arenaria, Festuca arenaria, Corynephorus canescens, Festuca ovina and Agrostis capillaris, and pine forest dominated in its herb layer at first by Deschampsia flexuosa and later by either Empetrum nigrum, Vaccinium myrtillus or Vaccinium vitis‐idaea. Conclusions: The successional trajectory is basically unidirectional for more than 100 years; no clear multiple successional pathways were observed, as is frequent in coastal dunes. Successional divergence was observed after approximately 130 years in the composition of the herb layer in the closed pine forest. The obvious vegetation heterogeneity in the still active sand‐blown area is related to differences in timing of vegetation establishment on particular relief types, thus the succession exhibits a terrain‐dependent asynchronous character. We conclude that the last patches of still‐active sand dunes can be preserved only by repeated strong artificial disturbances.     

放牧方式对浑善达克沙地榆树疏林退化的影响

浑善达克沙地榆树疏林是分布于草原地带的隐域植被类型,相较周边的典型草原区,其植被更加茂密,乔灌丛生,水草丰美,千百年来一直是牧民的优质冬季牧场。近半个世纪以来,因人类的过度开垦以及不合理的放牧管理,浑善达克沙地植被遭到空前的破坏,沙丘活化,载畜能力降低,生态价值和经济价值严重受损。近年来,随着国家草畜平衡以及禁牧政策的推广落实,放牧的牲畜总量得到一定程度的遏制,然而大面积草场还在继续退化。在牧民对生产生活的基本需求下,牲畜总量不可能无限制的压制。另外,适度的放牧对草原生态系统健康是有益的。因此,如何改良放牧方式,合理利用草场,在保持生态良好的基础上合理发挥草场的畜牧价值,是我们亟待探索的问题。以浑善达克沙地的典型天然植被榆树疏林为例,对不同放牧方式下的植被进行调查,基于沙地特殊的基质和植被特征,探讨适合沙地的放牧利用方式。研究表明,在相似的放牧强度下,把沙地作为冬营地,其榆树种群更新正常,植被覆盖度以及植物种类等均能保持良好,而把沙地作为夏季营地,榆树疏林植被退化严重,具体表现为:(1)榆树种群自然更新受阻;(2)灌木群落大量死亡或消失;(3)草本覆盖度显著降低,植物种类减少,多年生草本比例减少,一、二年生草本比例增加;(4)裸沙面积增加,沙丘趋于活化。本研究认为目前沙地植被的退化主要由不合理的放牧引起,并非气候因素所致。沙地适合于冬季放牧而不适合其他季节放牧。借鉴牧民的传统放牧方式,建议配合周边的典型草原区实行季节性倒场放牧,仅将沙地作为冬季营地使用,既能有效保护沙地植被又能充分发挥其畜牧价值。     

Structure, Pattern and Mechanisms of Formation of Seed Banks in Sand Dune Systems in Northeastern Inner Mongolia, China

A comparison of structure and pattern of the soil seed bank was made between active and stabilized sand dunes in northeastern Inner Mongolia, China. The objective of this paper was to determine the significance of seed bank in vegetation restoration of sand dunes. The results showed that (1) average seed density decreased from stabilized sand dune to interdune lowland of stabilized sand dune, to interdune lowland of active sand dune, and to active sand dune; (2) horizontally, along the transect from interdune lowland to ecotone and to sand dune top, a ‘V’ shaped pattern was presented in the active dune system, and a reverse ‘V’ shaped pattern in the stabilized sand dune system; (3) vertically, the proportion (accounting for the total seeds) of seeds found in 0–20 mm soil profile decreased from stabilized sand dune to interdune lowland of stabilized sand dune, to interdune lowland of active sand dune, and to active sand dune. The same order was also found in 20–50 mm and 50–100 mm soil profiles; (4) the Sokal and Sneath similarity indices in the species-composition between soil seed bank and above-ground vegetation were ranked as: the stabilized sand dune (24%) > the interdune lowland of active sand dune (21%) > the interdune lowland of stabilized sand dune (18%) > the active sand dune (5%); and (5) vegetation restoration of active sand dunes depends on the dispersal of seeds from nearby plant communities on the interdune lowlands. Much effort must be made to preserve the lowlands, as lowlands are the most important seed reservoir in the active sand dune field.     

大兴安岭火烧迹地不同恢复方式碳储量差异

为了探讨不同恢复方式对大兴安岭重度火烧迹地碳储量的影响,以人工恢复(兴安落叶松、樟子松)和天然恢复的林分为研究对象,采用干烧法对乔木层、灌木层、草本层和枯枝落叶层含碳率进行测定.采用全收获法和平均标准木法获得林分各组分生物量估算森林植被的碳储量,分析不同恢复方式下林分各组分碳储量的分配特征.结果表明： 人工恢复和天然恢复的林分灌木层平均含碳率高于乔木层和草本层.兴安落叶松人工林灌木层平均含碳率为45.8%、枯枝落叶层为45.3%、乔木层为44.4%、草本层为33.6%.樟子松人工林灌木层和乔木层平均含碳率高于50%.天然次生林乔木层、灌木层和枯枝落叶层平均含碳率在42%左右.森林植被层中,生物量贡献率从大到小依次为乔木层、灌木层和草本层.兴安落叶松人工林森林植被层和枯枝落叶层生物量总和为123.90 t·hm^-2,远高于樟子松人工林和天然次生林.火烧后人工恢复23年的兴安落叶松人工林森林植被碳储量为50.97 t·hm^-2,其中,乔木层碳储量为49.87 t·hm^-2,占森林植被层总碳储量的97.8%,草本层所占比重仅为0.02%.人工恢复的林分植被层总碳储量高于天然恢复的林分,火烧迹地在这一时段内采用人工恢复的方式较天然恢复碳汇能力更强.     

Long-Term Ecosystem Effects of Sand-Binding Vegetation in the Tengger Desert, Northern China

The planting of sand‐binding vegetation in the Shapotou region at the southeastern edge of the Tengger Desert began in 1956. Over the past 46 years, it has not only insured the smooth operation of the Baotou–Lanzhou railway in the sand dune section but has also played an important role in the restoration of the local eco‐environment; therefore, it is viewed as a successful model for desertification control and ecological restoration along the transport line in the arid desert region of China. Long‐term monitoring and focused research show that within 4–5 years of establishment of sand‐binding vegetation, the physical surface structure of the sand dunes stabilized, and inorganic soil crusts formed by atmospheric dust gradually turned into microbiotic crusts. Among the organisms comprising these crusts are cryptogams such as desert algae and mosses. In the 46 years since establishing sand‐binding vegetation, some 24 algal species occurred in the crusts. However, only five moss species were identified, which was fewer than the species number in the crust of naturally fixed sand dunes. Other results of the planting were that near‐surface wind velocity in the 46‐year‐old vegetation area was reduced by 54.2% compared with that in the moving sand area; soil organic matter increased from 0.06% in moving sand dunes to 1.34% in the 46‐year‐old vegetation area; the main nutrients N, P, K, etc., in the desert ecosystem increased; soil physicochemical properties improved; and soil‐forming processes occurred in the dune surface layer. Overall, establishment of sand‐binding vegetation significantly impacted soil water cycles, creating favorable conditions for colonization by many herbaceous species. These herbaceous species, in turn, facilitated the colonization and persistence of birds, insects, soil animals, and desert animals. Forty‐six years later, some 28 bird species and 50 insect species were identified in the vegetated dune field. Thus, establishment of a relatively simple community of sand‐binding species led to the transformation of the relatively barren dune environment into a desert ecosystem with complex structure, composition, and function. This restoration effort shows the potential for short‐term manipulation of environmental variables (i.e., plant cover via artificial vegetation establishment) to begin the long‐term process of ecological restoration, particularly in arid climates, and demonstrates several techniques that can be used to scientifically monitor progress in large‐scale restoration projects.     

Desert plant pollen production and a 160-year record of vegetation and climate change on the Alashan Plateau, NW China

Recent and subfossil pollen spectra from the Alashan Plateau are presented in order to provide information on desert plant representation and on recent changes in vegetation and climate in this remote area in northern China. The desert vegetation composition is faithfully represented by the surface pollen spectra. The comparison of the desert plant species to the related pollen taxa yielded the following sequence from over-representation to under-representation: Chenopodiaceae, Artemisia, Ephedra fragilis-type s.l., Reaumuria, Nitraria and Calligonum. A 72 cm long sediment record from a small hydrologically-closed inter-dune lake (SE Badan Jilin Sand Sea, southern Alashan Plateau) covering the past ∼160 years (dated by¹³⁷Cs) was analysed palynologically. Intervals of denser Artemisia coverage on the sand dunes around the lake, indicating wetter climate, occurred from the mid-1850s to the mid-1870s, during the first two decades of the 20th century and from the late 1930s to the beginning of the 1960s.     

Response of tundra ecosystem in southwestern Alaska to Younger-Dryas climatic oscillation

Climatic warming during the last glacial–interglacial transition (LGIT) was punctuated by reversals to glacial‐like conditions. Palaeorecords of ecosystem change can help document the geographical extent of these events and improve our understanding of biotic sensitivity to climatic forcing. To reconstruct ecosystem and climatic variations during the LGIT, we analyzed lake sediments from southwestern Alaska for fossil pollen assemblages, biogenic‐silica content (BSiO₂%), and organic‐carbon content (OC%). Betula shrub tundra replaced herb tundra as the dominant vegetation of the region around 13 600 cal BP (cal BP: ¹⁴C calibrated calendar years before present), as inferred from an increase of Betula pollen percentages from << 5% to >> 20% with associated decreases in Cyperaceae, Poaceae, and Artemisia. At c. 13 000 cal BP, a decrease of Betula pollen from 28 to << 5% suggests that shrub tundra reverted to herb tundra. Shrub tundra replaced herb tundra to resume as the dominant vegetation at 11 600 cal BP. Higher OC% and BSiO₂% values suggest more stable soils and higher aquatic productivity during shrub‐tundra periods than during herb‐tundra periods, although pollen changes lagged behind changes in the biogeochemical indicators before c. 13 000 cal BP. Comparison of our palaeoecological data with the ice‐core dδ¹⁸O record from Greenland reveals strikingly similar patterns from the onset through the termination of the Younger Dryas (YD). This similarity supports the hypothesis that, as in the North Atlantic region, pronounced YD climatic oscillations occurred in the North Pacific region. The rapidity and magnitude of ecological changes at the termination of the YD are consistent with greenhouse experiments and historic photographs demonstrating tundra sensitivity to climatic forcing.     

Dune slack restoration in Dutch mainland coastal dunes

The 45,000 ha Dutch dunes are relatively well protected but they suffer from severe desiccation. During the last decade a lot of knowledge has been obtained about the steering processes of eco-hydrology in dunes resulting in well-founded schemes to restore wet dune slack communities. In two case studies a large-scale restoration of the landscape was necessary. Since 1987 in the North-Holland Dune Reserve the groundwater catchment has been reduced (from 8 million m³ to 2 million m³ per year) and the resulting development monitored. In another case, large-scale intervention on 35 ha of the Amsterdam Water Supply Dunes in 1995 resulted in the restoration of active sand drift with opportunities for the establishment of pioneer vegetation. In small parts of the area, the surface has stabilised as a result of vegetation growth, but elsewhere drifting sand has spread and covered previously stable surfaces. Many wet to moist dune slacks developed and results relating to geomorphology, hydrology and vegetation are presented. Finally, in 1996 yet another project of 50 ha was carried out in the Meijendel dunes, in which infiltration ponds were removed to allow vegetation succession to develop from scratch. Results of these three case studies will be presented. If only hydrological restoration is carried out, sod-cutting was found to be necessary to restore the whole series of vegetation types of dune slacks. In two cases an area was denuded. The seed bank and surrounding slacks seem to play an important role in the success of restoration, this is especially true for the pioneer vegetation types. Future monitoring will prove whether critical (Red List) plant species will return.     

小叶锦鸡儿防风固沙林稳定性研究

针对科尔沁沙地小叶锦鸡儿固沙林在持续高温干旱条件下出现稳定性波动的问题。选择2、5、15、35a人工群落和天然群落进行对比研究。探讨了人工小叶锦鸡儿防风固沙林物种多样性在35a间的变化以及对大气持续干旱的抵抗力和对外界干扰的恢复能力。流动沙丘固定后,固沙林内草本植物迅速侵入。其后则缓慢发展并处于相对稳定状态。植物种类数保持在20～23种。但在人工固沙群落中1年生植物在种类数和数量上始终处于优势地位。而天然群落则是多年生植物占优势。人工固沙群落物种多样性指数逐年提高。但明显低于天然群落。在受到大气持续高温干旱的干扰时。人工群落土壤条件极度恶化。出现了明显的干沙层。最深达140cm。叶片含水量极度降低。植物生长停止。沙地植物群落对牲畜取食均具有一定的补偿的能力。在啃食较轻时表现为超补偿现象。通过建立数学模型分析。人工群落个体的补偿点和超补偿点明显低于天然群落。采用冗余理论对植物群落稳定性机制进行了论述。认为冗余结构的变化是导致群落稳定性变化的内在原因。对现有人工小叶锦鸡儿固沙林的稳定性进行了评价。并认为15a左右人工固沙林正处于相对稳定并缓慢发展状态。对于稳定的人工固沙群落应具备以下条件：(1)适于当地环境条件;(2)对外界干扰具有一定的抵抗性和恢复性;(3)具有正常生长发育和自我更新能力;(4)有较为完善的种群结构。