赛加羚羊引种区植被特征研究

在植物区系研究的基础上,作者于１９８８￣１９９３年在甘肃省武威市进一步研究了赛加羚羊引种区的植物群落特征,观察了３０种植物的物候期,用常规方法化验了７２种植物的营养成分,从植被特征出发,综合评价其对赛加羚羊的适宜性。     

我国的羚羊亚科兽类

羚羊亚税兽类在我国共有４属６种。它们分布在我国西部高原、荒漠草原及沙漠等偏远地区,我国已将羚羊亚科６种全部列入国家一、二级保护动物。本文对其种的数量、分布,形态特征等作了简要概述。     

华北晚中新世羚羊的食性与古环境——稳定碳同位素的证据

通过分析华北晚中新世保德期三个经典地点的羚羊牙齿釉质之稳定碳同位素,结合相同地点的单纯食叶者(鹿科)与食草者(三趾马)的数据,推断其食性取向。结果显示这些晚中新世生态系统中C_3植物占据主导地位,但也含有一小部分的C_4植物(可能小于30%)。高冠羚羊(Gazella dorcadoides类型)取食约20%的C_4植物,而中冠羚羊(G．paotehensis类型)与低冠羚羊(G．gaudryi类型)为纯C_3植物消费者。鹿科动物单纯取食C_3植物,而三趾马与G．dorcadoides类型的羚羊取食C_4植物的比例在统计上难以区分。碳同位素数据与G．gaud- ryi类型的食叶性以及G．dorcadoides类型以草食为主的观点相一致。参照这些类群的地理分布,当前的数据支持晚中新世黄土高原东南部处于相对于西北部更为封闭环境的观点。这种环境梯度的分布方向与模式可能是该地区东亚季风体系的早期信号。     

原羚属分类地位研究兼论中国羚羊的分类

中国羚羊类动物在世界羚羊类动物中有着特殊的地位,其中普氏原羚、藏原羚和藏羚是中国特有的珍稀物种,普氏原羚是极度濒危动物.开展中国羚羊类动物的分类和进化研究是当务之急.本研究利用形态特征、头骨测量及线粒体DNA的12S rRNA(440 bp)和16S rRNA(590 bp)对原羚属的分类地位及中国其他几种羚羊分类地位进行了探讨,发现对质量性状和数量性状数据的聚类分析的结果差异大,而且质量性状的聚类结果比较符合传统的分类系统.分子分类也得到相似结果,但在属下的分析存在较大差异.7种牛科动物的12S rRNA和16S rRNA序列差异分别为0.2%～7.1%和0.3%～8.4%.系统进化分析表明原羚属3种羚羊形成单系群,且蒙古瞪羚与普氏原羚的关系较藏原羚与普氏原羚的关系近.赛加羚应归宿于羚羊亚科,而不是与羊亚科的藏羚形成独立的赛加羚亚科.原羚属的进化可能与青藏高原的隆起有关.     

赛加羚羊Saiga tatarica引种区植被特征研究 Ⅰ．植物区系特征及其适宜性评价

通过对甘肃濒危野生动物繁育中心所在地──武威东沙窝及其周围地区植物区系调查,共获２２科、８４属、１１６种植物,以菊科、禾本科、藜科和豆科为主,占６８．９７％。以草本、、强旱生、中温、阳性、沙生等为主要生态型。以亚洲中部成分、地中海－西亚－中亚成分,为主要地理成分。植物类群接近赛加羚羊现代分布区植物类群,而且多数类群可被羚羊采食。     

赛加羚羊Saiga tatarica引种区植被特征研究 Ⅰ.植物区系特征及其适宜...

通过对甘肃濒危野生动物繁育中心所在地－－武威东沙窝及其周围地区植物区系调查,共获２２科、８４属、１１６种植物,以菊科、禾本科、藜科和豆科为主,占６８．９７％,以草本、强旱生、中温、阳性、沙生等为主要生态型。以亚洲中部成分、地中海－西亚－中亚成分,为主要地理成分。植物类群接近赛加羚羊现代分布区植物类群,而且多数类群可被羚羊采食。     

赛加羚羊头骨的三维重建研究及其精确度评价

为建立赛加羚羊（Saiga tatarica）头骨三维可视化模型,进一步研究赛加羚羊头骨的解剖特征,建立赛加羚羊头骨的“数字化标本”,以提高其疾病诊治的准确率和物种保护的有效性。本研究以国家林业局甘肃濒危动物保护中心的赛加羚羊为研究对象,经锥形束CT扫描获得影像数据,运用MIMICS 20.0软件对赛加羚羊头骨扫描数据进行处理和三维重建,以建立赛加羚羊的“数字化头骨”用于形态研究。运用MIMICS 20.0软件对数字化头骨的26项形态学指标（n = 8）进行三维测量,且与头骨标本游标卡尺的测量值（n = 8）进行配对样本t检验分析,经与真实测量值比较后评价数字化模型及其三维测量的准确性。结果显示,26项形态测量指标均与真实头骨无显著性差异（P > 0.05）,例如颅全长游标卡尺测量值为（227.147 ± 10.646）mm,三维测量值为（227.130 ± 10.638）mm,P = 0.635,表明三维重建后的数字化头骨和真实的头骨标本高度相似,且“数字标本”能够实现任意角度的旋转、剖切和测量。本研究可为赛加羚羊头部疾病如骨折等的治疗及骨骼系统的三维可视化研究提供基础依据和技术支撑,同时可为CT扫描和医学图像三维可视化技术在野生动物的临床应用和相关研究提供理论基础。     

赛加羚羊保护概况

赛加羚羊是生活在蒙古、哈萨克斯坦、乌兹别克斯坦、土库曼斯坦和俄罗斯的稀有物种,其在中国的野外种群已经于20世纪中叶灭绝。对于赛加羚羊分布地的游牧民来说,赛加羚羊是中亚干旱草原的象征。几个世纪以来,它们与人类共同分享着这片栖息地,是游牧民的食物来源和精神源泉。目前,赛加羚羊被公认有两个亚种:蒙古亚种生活在蒙古的小草原区域,俄罗斯亚种生活在中亚和里海西北部区域的广阔平原上。在欧亚大陆上,人类活动导致了数个被互相孤立的赛加羚羊种群,俄罗斯亚种分布在里海西北     

陕西省常见蜜源植物花粉形态的研究

运用扫描电子显微镜,对陕西省境内３０种常见蜜源植物的花粉粒进行了观察研究,描述了花粉粒的大小、萌发孔类型及其表面纹饰等形态特征。结果表明：绝大多数种的蜜源植物,其花粉粒的形态特征明显不同。本文还就花粉粒形态特征,在鉴定蜜源植物花粉的属种,确定蜂蜜的产地、评价蜂蜜的品质等方面进行了探讨。     

西双版纳保护植物特征研究

经过重新统计和分析,确定了西双版纳地区一共分布有国家级(60种)和省级(41种)保护植物101种,对它们的一些特征进行了初步研究.主要研究了种类及数量特征、分布特征,包括其分布的海拔、植被、区域特征和保护价值等,并且就西双版纳地区保护植物的保护措施提出了建议.     

长白山阔叶红松林植物群落与昆虫群落的相互关系研究

通过季节性的观察,系统研究了长白山植物群落、昆虫群落多样性及它们之间关系。结果表明,植物群落物种丰富度指数与植食性昆虫丰富度指数呈负相关,而与捕食性天敌昆虫丰富度指数呈正相关,与寄生性天敌的丰富度指数呈负相关;昆虫群落的均匀度与植物群落的均匀度相关显著。植物群落的多样性指数与捕食性、寄生性天敌的多样性指数呈正相关。而与植食性昆虫的多样性指数呈负相关,这表明植物群落的多样性影响昆虫群落的多样性。     

Influence of microclimate and species interactions on the composition of plant and invertebrate communities in alpine northern Norway

We assessed the effects of both biotic processes and abiotic factors on the community composition of vascular plant species and invertebrates at a site in northern Norway. Plant species were assigned to functional (woody versus herbaceous) and biogeographic (boreal versus alpine) groups. Invertebrate species were classified as either herbivore or predator. When species interactions and effects of the abiotic environment were partitioned, boreal species appeared to influence the distribution of alpine species and woody species the distribution of herbaceous species. Analysis of partial correlations indicated that facilitation was the dominant mode of interaction between the two pairs of plant groups. Among abiotic factors, the thermal environment probably influenced all components of the plant and invertebrate communities, except for predatory invertebrates, and wind appeared important in determining the composition of woody and alpine components of the plant community but not the herbaceous component. The composition of the boreal component of the plant community apparently influenced the composition of all invertebrate communities, except for predatory invertebrates. The composition of the woody component of the plant community influenced the composition of both herbivore and predator communities. The alpine plant-community composition influenced predatory invertebrate community composition. Woody plant community composition influenced the composition of both herbivore and predator communities. Our analytic approach, based on two kinds of structural equation models (d-separation and path analysis), provides a useful method for identifying the biotic as well as abiotic factors that influence community structure.     

滇西北高原纳帕海湖滨湿地退化特征、规律与过程

采用双向指示种分析(TWINSPAN)和典范对应分析(CCA)方法,研究了滇西北高原纳帕海湖滨湿地退化特征、规律与过程.结果表明: 纳帕海湖滨湿地植物群落可以划分为4个群丛,群落演替规律为水生植物群落→沼泽植物群落→沼泽化草甸植物群落→草甸植物群落.随植物群落演替,群落盖度、密度、多样性指数、物种丰富度和地上生物量均增大,群落高度减小;植物水分生态型演替规律为水生植物→沼生植物→湿生植物→中生植物.随群落演替,湿地水体矿化度、硬度和碱度均降低,氨氮和总磷含量升高,总氮和硝态氮含量变化不明显;土壤pH、有机质和全氮含量逐渐降低,全磷和全钾含量逐渐升高,速效氮和速效磷含量先增大后减小.CCA分析表明,群落结构和物种组成主要受水分梯度影响,土壤pH、全磷和湿地水的总氮、氨氮对湿地植物物种分布和群落演替影响显著.     

植物功能群去除对高寒草甸群落结构、多样性及生产力的影响

群落中物种的丧失在干扰下普遍存在,但对生态系统过程和功能的影响仍存在较大不确定性。选取青藏高原东缘典型高寒草甸为对象,开展优势植物功能群的梯度去除试验,以模拟长期过牧干扰下物种的损失。经过连续两个生长季的功能群去除,我们对群落的物种组成、结构、多样性和生物量等特征进行了分析,探讨了上述指标的响应过程和机制。研究结果表明：（1）功能群的去除降低了群落高度,增加了物种均匀度,并显著影响了禾草、杂草优势比以及功能群多样性和优势度;（2）同时,去除操作显著减小了凋落物量与禾草生物量,并显著影响了群落地上生物量;（3）进一步分析还发现,禾草、莎草和杂草功能群之间存在显著的竞争关系,群落生产力主要取决于禾草功能群并随物种均匀度的增大而显著减小。上述结果表明,禾草在高寒草甸群落中占据竞争优势地位,植物功能群的损失主要通过改变种间竞争关系、引起有机物质丢失影响群落过程和功能。     

Plant community responses to nitrogen addition and increased precipitation: the importance of water availability and species traits

Global nitrogen (N) enrichment and changing precipitation regimes are likely to alter plant community structure and composition, with consequent influences on biodiversity and ecosystem functioning. Responses of plant community structure and composition to N addition and increased precipitation were examined in a temperate steppe in northern China. Increased precipitation and N addition stimulated and suppressed community species richness, respectively, across 6 years (2005–2010) of the manipulative experiment. N addition and increased precipitation significantly altered plant community structure and composition at functional groups levels. The significant relationship between species richness and soil moisture (SM) suggests that plant community structure is mediated by water under changing environmental conditions. In addition, plant height played an important role in affecting the responses of plant communities to N addition, and the effects of increased precipitation on plant community were dependent on species rooting depth. Our results highlight the importance and complexity of both abiotic (SM) and biotic factors (species traits) in structuring plant community under changing environmental scenarios. These findings indicate that knowledge of species traits can contribute to mechanistic understanding and projection of vegetation dynamics in response to future environmental change.     

Effects of earthworms and arbuscular mycorrhizal fungi depend on the successional stage of a grassland plant community

Earthworms and arbuscular mycorrhizal fungi (AMF) have profound impacts on plant performance. However, it is largely unknown if and how earthworms and AMF may affect plant succession. We planted mesocosms with an early-mid successional and a mid-late successional grassland plant community and added endogeic earthworms and commercial AMF in a full-factorial way to natural background soil. Earthworms had a positive effect on the total root and shoot biomass of both plant communities, with the effect on the shoots being slightly enhanced by co-inoculation with AMF. Surprisingly, the earthworm effect on the mid successional plant species depended on the successional stage of the plant community. Earthworms had a positive effect on the mid successional plant species when they were growing in the mid-late successional plant community, but no effect when the same plant species were growing in the early-mid successional plant community. Addition of AMF alone tended to reduce the shoot biomass of the early successional plant species, while the addition of earthworms in the presence or absence of AMF increased their shoot biomass. We conclude that the impacts of earthworms on plant species may depend on the successional stage of the plant community, while the effect of AMF addition depends on the successional stage of the plant community and may be changed by the presence of earthworms. Earthworms and AMF addition affect plants and plant communities of different successional stages differently with potential effects on plant succession.     

Differences in vegetation composition and plant species identity lead to only minor changes in soil-borne microbial communities in a former arable field

To examine the relationship between plant species composition and microbial community diversity and structure, we carried out a molecular analysis of microbial community structure and diversity in two field experiments. In the first experiment, we examined bacterial community structure in bulk and rhizosphere soils in fields exposed to different plant diversity treatments, via a 16S rRNA gene clone library approach. Clear differences were observed between bacterial communities of the bulk soil and the rhizosphere, with the latter containing lower bacterial diversity. The second experiment focused on the influence of 12 different native grassland plant species on bacterial community size and structure in the rhizosphere, as well as the structure of Acidobacteria and Verrucomicrobia community structures. In general, bacterial and phylum-specific quantitative PCR and PCR-denaturing gradient gel electrophoresis revealed only weak influences of plant species on rhizosphere communities. Thus, although plants did exert an influence on microbial species composition and diversity, these interactions were not specific and selective enough to lead to major impacts of vegetation composition and plant species on below-ground microbial communities.     

Community‐level plant–soil feedbacks explain landscape distribution of native and non‐native plants

Plant–soil feedbacks (PSFs) have gained attention for their potential role in explaining plant growth and invasion. While promising, most PSF research has measured plant monoculture growth on different soils in short‐term, greenhouse experiments. Here, five soil types were conditioned by growing one native species, three non‐native species, or a mixed plant community in different plots in a common‐garden experiment. After 4 years, plants were removed and one native and one non‐native plant community were planted into replicate plots of each soil type. After three additional years, the percentage cover of each of the three target species in each community was measured. These data were used to parameterize a plant community growth model. Model predictions were compared to native and non‐native abundance on the landscape. Native community cover was lowest on soil conditioned by the dominant non‐native, Centaurea diffusa, and non‐native community cover was lowest on soil cultivated by the dominant native, Pseudoroegneria spicata. Consistent with plant growth on the landscape, the plant growth model predicted that the positive PSFs observed in the common‐garden experiment would result in two distinct communities on the landscape: a native plant community on native soils and a non‐native plant community on non‐native soils. In contrast, when PSF effects were removed, the model predicted that non‐native plants would dominate all soils, which was not consistent with plant growth on the landscape. Results provide an example where PSF effects were large enough to change the rank‐order abundance of native and non‐native plant communities and to explain plant distributions on the landscape. The positive PSFs that contributed to this effect reflected the ability of the two dominant plant species to suppress each other's growth. Results suggest that plant dominance, at least in this system, reflects the ability of a species to suppress the growth of dominant competitors through soil‐mediated effects.     

Effect of different root endophytic fungi on plant community structure in experimental microcosms

Understanding the effects of root‐associated microbes in explaining plant community patterns represents a challenge in community ecology. Although typically overlooked, several lines of evidence point out that nonmycorrhizal, root endophytic fungi in the Ascomycota may have the potential to drive changes in plant community ecology given their ubiquitous presence, wide host ranges, and plant species‐specific fitness effects. Thus, we experimentally manipulated the presence of root endophytic fungal species in microcosms and measured its effects on plant communities. Specifically, we tested whether (1) three different root endophyte species can modify plant community structure; (2) those changes can also modified the way plant respond to different soil types; and (3) the effects are modified when all the fungi are present. As a model system, we used plant and fungal species that naturally co‐occur in a temperate grassland. Further, the soil types used in our experiment reflected a strong gradient in soil texture that has been shown to drive changes in plant and fungal community structure in the field. Results showed that each plant species responded differently to infection, resulting in distinct patterns of plant community structure depending on the identity of the fungus present. Those effects depended on the soil type. For example, large positive effects due to presence of the fungi were able to compensate for less nutrients levels in one soil type. Further, host responses when all three fungi were present were different from the ones observed in single fungal inoculations, suggesting that endophyte–endophyte interactions may be important in structuring plant communities. Overall, these results indicate that plant responses to changes in the species identity of nonmycorrhizal fungal community species and their interactions can modify plant community structure.     

Plant community response to loss of large herbivores: comparing consequences in a South African and a North American grassland

Loss of biodiversity poses one of the greatest threats to natural ecosystems throughout the world. However, a comprehensive understanding of the impacts of species losses from upper trophic levels is still emerging. Here we compare the impacts of large mammalian herbivore species loss on grassland plant community structure and composition in a South African and North American grassland. Herbaceous plant communities were surveyed at sites without large mammalian herbivores present and at sites with a single species of herbivore present in both locations, and additionally at one site in South Africa with multiple herbivore species. At both the North American and South African locations, plant communities on sites with a single herbivore species were more diverse and species rich than on sites with no herbivores. At the multi-herbivore site in South Africa, plant diversity and richness were comparable to that of the single herbivore site early in the growing season and to the no herbivore site late in the growing season. Analyses of plant community composition, however, indicated strong differences between the multi-herbivore site and the single and no herbivore sites, which were more similar to each other. In moderate to high-productivity ecosystems with one or a few species of large herbivores, loss of herbivores can cause a significant decrease in plant diversity and richness, and can have pronounced impacts on grassland plant community composition. In ecosystems with higher herbivore richness, species loss may also significantly alter plant community structure and composition, although standard metrics of community structure may obscure these differences.