北方农牧交错带退耕还林与还草对地面节肢动物群落结构的影响

在中国北方农牧交错带宁夏盐池县,以农田为对照,以人工柠条林地、杨树林地和弃耕后自然恢复草地为研究样地,采用陷阱诱捕法,调查了退耕还林与还草4种类型样地的地面节肢动物群落结构特征,旨在分析农牧交错带退耕还林与还草措施对地面节肢动物群落结构生态效应的差异性。结果显示:(1)调查共获得地面节肢动物7目23科25类,其中优势类群为蜉金龟科和蚁科,其个体数占总个体数45.30%;常见类群13类,其个体数占总个体数49.17%;其余10类为稀有类群,其个体数占总个体数5.53%。(2)农田和草地生境的优势类群均有4个类群,而柠条林地和杨树林地生境的优势类群只有1个类群(即蚁科),但草地生境的优势类群种类组成完全不同于农田生境;优势度从农田的86.67%降为杨树林地的54.90%、柠条林地的63.16%和草地的61.70%。退耕还林还草后常见类群数及其优势度均呈现显著增加趋势。另外,4种类型样地生境中均无稀有类群。(3)退耕还林与还草仅对地面节肢动物类群数和Shannon指数产生显著影响(P0.05),而对个体数和优势度指数均无显著影响(P0.05)。地面节肢动物类群数和Shannon指数均表现为草地最高,杨树林地次之,农田和柠条林地最低。(4)不同生境类型样地间Jaccard指数均较低,介于0.13—0.39之间,属于不相似或中等不相似。(5)偏RDA分析表明,土壤含水量和总氮含量是影响地面节肢动物群落个体数分布的关键驱动因子。研究表明,退耕还柠条林地和弃耕后自然恢复草地对土壤性质改善均具有显著影响,并且弃耕后自然恢复草地更有利于节肢动物多样性的恢复。     

松嫩平原农牧交错区牲畜放牧场的空间转移

研究了松嫩平原农牧交错区牲畜放牧场空间转移动态、不同放牧场对当地畜牧业的贡献率。研究结果表明 :松嫩平原农牧交错区的牲畜放牧场月际变化很大 ,草地、防护林草地和农田在不同阶段是牲畜的主要放牧场 ;牲畜放牧场具有明显的空间转移现象 ,总体趋势为农田 (1～ 3月份 )→草地 (4～ 6月份 )→防护林草地 (7～ 10月份 )→农田 (11～ 12月份 ) ;3种放牧场在不同时期对畜牧业的贡献率变化也很大 ,其变化趋势与放牧场空间转移趋势基本一致 ;草地、防护林草地和农田对松嫩平原农牧交错区畜牧业均起着重要作用 ,贡献率大小分别为农田 (38.8% ) >防护林草地 (31.8% ) >草地 (2 9.4 % )。草地在当地畜牧业中的地位明显下降 ,农田和防护林草地对当地畜牧业的贡献已相当重要。因此 ,应加强松嫩平原农牧交错区防护林草地放牧和农田放牧研究 ,在保护防护林的基础上合理利用防护林草地和杨树叶资源 ,充分利用农田杂草和农田残茬 ,增加可获得性牧草资源 ,促进地区畜牧业发展。     

沙质荒漠化土地景观分类与制图：以毛乌纱沙地为例

对景观分类理论和方法进行了探索,并以毛乌素沙地为研究对象,提出了一套适用于农牧交错区沙质荒漠化土地景观分类与制图的方法,由于沙丘分布广泛,与地带性植被和土壤的分布相迭加,增加了地表景观的破碎程度,使农牧交错区沙地的主要景观要素类型在结构上具有复合性,为了更好地描述沙地景观的复合性特征,作者提出景观基本结构组分的概念,首先确定景观基本结构组分,根据景观基本结构组分的不同组合确定景观要素类型;然后在野     

沙质荒漠化土地景观分类与制图—以毛乌素沙地为例

对景观分类理论和方法进行了探索,并以毛乌素沙地为研究对象,提出了一套适用于农牧交错区沙质荒漠化土地景观分类与制图的方法。由于沙丘分布广泛,与地带性植被和土壤的分布相迭加,增加了地表景观的破碎程度,使农牧交错区沙地的主要景观要素类型在结构上具有复合性。为了更好地描述沙地景观的复合性特征,作者提出景观基本结构组分的概念。首先确定景观基本结构组分,根据景观基本结构组分的不同组合确定景观要素类型;然后在野外调查的基础上,通过对遥感数据的解译和判读进行景观要素类型的划分;最后在GIS支持下成图。该方法对我国北方农牧交错区沙质荒漠化土地具有普遍意义。     

浑善达克沙化草地C4植物资源及其与植被演替的关系

根据野外调查和文献资料研究了浑善达克沙化草地 C4 植物的种类组成及其与沙化草地植被演替的关系。浑善达克沙化草地共有野生 C4 植物 2 7种 ,分属于 7科、2 2个属 ,其中以禾本科最多 ,有 16种 ,藜科次之 ,有 6种。该区域的 C4植物中 1年生植物约占 6 3% ,且多为沙化演替的先锋物种。C4 植物数量和 C4 / C3比基本随沙化演替的进行而增加 ,尤其在弃耕地和流动沙丘阶段 C4 / C3比均在 2 0 %以上 ,体现了 C4 植物抗逆性强的生物学特点     

川西亚高山林牧交错区土壤动物多样性

交错区复杂的生境常常导致相对较高的物种多样性。为探讨牧压条件形成的林牧交错区土壤动物多样性,研究了川西亚高山典型林牧交错区的土壤动物群落结构与多样性。在交错区5种生境下,共获得土壤动物49837只,隶属7门16纲33目126类。从草甸到针叶林的过渡生境中,土壤动物明显受到放牧干扰影响,其个体密度随干扰的减弱呈逐步上升趋势,而类群数则呈单峰型变化趋势;Shannon-Wiener、DG多样性指数都呈现逐步上升趋势;Wilson-Shmida多样性指数表明相邻干扰梯度下土壤动物类群替代率相近。大型土壤动物生物量在草甸最低,阔叶林最高。CCA排序显示凋落物厚度与中小型土壤动物存正相关,pH与其存负相关,不同类群对环境因子响应存在差异。这些结果表明农牧交错区不同干扰梯度下土壤动物群落结构和多样性存在明显差异。     

内蒙古奈曼旗农牧交错区土地利用/覆被变化的区域分异

基于内蒙古奈曼旗1975、1985、1995和2005年4期遥感影像,运用土地利用动态度、土地利用相对变化率对研究区土地利用动态变化的区域分异进行了分析,并选取多度和重要值分析了研究区土地利用/覆被变化的空间分布特征.结果表明：1975—2005年间,研究区土地利用/覆被类型趋于多样化,年变化率较大,区域分异显著.研究区北部冲积平原区以林地面积的大幅增加和沙地面积的显著减少为主要特点,其草地和沙地的变化速度最大,居民地的变化速度最小,沙地转化为耕地和沙地转化为林地这两种变化形式在该区的分布最广泛;中部沙区以沙地分布为主,各土地利用类型的变化相对较小,以耕地和沙地的互相转化为该区的主要变化形式;南部黄土区以耕地面积占绝对优势,且变化速度最小,草地和沙地的变化速度最大,该区以草地转化为耕地和草地转化为林地为主要变化形式.自然因素决定了研究区各区域土地利用结构的主体特征,人为因素决定了区域内各土地利用类型的动态变化趋势.     

内蒙古奈曼旗农牧交错区土地利用/覆被变化的区域分异

基于内蒙古奈曼旗1975、1985、1995和2005年4期遥感影像,运用土地利用动态度、土地利用相对变化率对研究区土地利用动态变化的区域分异进行了分析,并选取多度和重要值分析了研究区土地利用/覆被变化的空间分布特征.结果表明：1975—2005年间,研究区土地利用/覆被类型趋于多样化,年变化率较大,区域分异显著.研究区北部冲积平原区以林地面积的大幅增加和沙地面积的显著减少为主要特点,其草地和沙地的变化速度最大,居民地的变化速度最小,沙地转化为耕地和沙地转化为林地这两种变化形式在该区的分布最广泛;中部沙区以沙地分布为主,各土地利用类型的变化相对较小,以耕地和沙地的互相转化为该区的主要变化形式;南部黄土区以耕地面积占绝对优势,且变化速度最小,草地和沙地的变化速度最大,该区以草地转化为耕地和草地转化为林地为主要变化形式.自然因素决定了研究区各区域土地利用结构的主体特征,人为因素决定了区域内各土地利用类型的动态变化趋势.     

长爪沙鼠种群繁殖的季节性特征

长爪沙鼠是分布于我国北方典型和荒漠草原及农牧交错区的优势鼠种之一。2000 年10 月至2004 年10 月通过标志重捕法研究了栖息于内蒙古农牧交错区草地生境的种群动态。对其不同季节出生群性成熟特征和种群性成熟比率、繁殖个体比例、个体月补充率等繁殖参数的季节特征研究显示:冬季和春季出生的个体性成熟较夏季出生的个体快,尤雌鼠表现突出,其3 个季节出生群的性成熟时间分别为4. 6 ± 0.2、4. 4 ± 0.8 和7.7 ± 0.4月龄。种群性成熟比率、繁殖个体比例和个体补充率月间差异显著,季节消长明显,即春季最高,秋季(9 ～10月间)最低。结果还显示,种群性成熟比率与气温和降水负相关。长爪沙鼠喜栖于植被稀疏、低矮的干燥沙质土壤环境。从初春到夏末,随降水和气温增加其栖息生境的植被由低矮稀疏变得高而稠密,土壤湿度和粘性亦随之提高,地面种子库因发芽贮量减少,适宜生境的减少可能加剧了社群竞争,抑制了种群的繁殖表现。长爪沙鼠种群繁殖的季节变化反映了其生活史对策中适应高纬度气候和食物的季节波动的重要特征。     

漓江流域不同弃耕年限下4种常见草本植物功能性状种内变化及其影响因素

为探究不同弃耕年限下植物功能性状的种内变化及其影响因素,加深对弃耕地植被恢复演替过程的认识,该研究聚焦于漓江流域桂林市临桂区几个村庄的农田边界、弃耕草地、灌草丛和林地4种一定程度上反映弃耕地植被恢复程度的生境,以分布较广的草本植物,即白茅(Imperatacylindrica)、双穗雀稗(Paspalumdistichum)、鬼针草(Bidenspilosa)和喜旱莲子草(Alternanthera philoxeroides)为研究对象,研究不同弃耕年限下其比叶质量、叶干物质含量、叶片氮含量、叶片磷含量和植株高度5个功能性状的种内变化,并阐明土壤氮含量、磷含量、pH和木本植物盖度对其的影响。主要发现如下:随弃耕年限增加,样地土壤氮、磷含量显著下降,土壤氮磷比先增加后下降,木本植物盖度显著增加。白茅叶片氮含量随弃耕年限增加而增加,叶片磷含量随弃耕年限增加而下降,这是由于叶片氮含量与土壤磷含量呈负相关关系,叶片磷含量与土壤磷含量呈正相关关系。双穗雀稗比叶质量和叶干物质含量随弃耕年限增加而增加,植株高度随弃耕年限增加而降低。鬼针草植株高度随弃耕年限增加而降低,这是由于其植株高度随木本植物盖...     

Photosynthetic pathway and morphological functional types in the vegetation from North-Beijing agro-pastoral ecotone, China

Photosynthetic pathways (C₃, C₄, and CAM) and morphological functional types were identified for the species from vegetation in agro-pastoral ecotone, North Beijing. 792 vascular plant species (nearly half of the total species in the ecotone), in 66 families and 317 genera, were identified with C₃, C₄, and CAM photosynthesis (Table 1). 710 species (90 % of the identified species in Table 1) in 268 genera and 64 families were found with C₃ photosynthesis, 68 species (9 % of the total identified species) in 40 genera and 7 families with C₄ photosynthesis, and 14 species in 4 genera and 1 family with CAM photosynthesis. Gramineae is the leading family with C₄ photosynthesis (43 species), Cyperaceae ranks the second (16 species) followed by Chenopodiaceae (5 species). The significant increase of C₄ proportion (C₄/total species) with land deterioration suggested the plants of this type are remarkably responsive to land use in the ecotone. 792 species were classified into nine morphological functional types and the changes of most of these types (e.g. perennial forbs (PEF), annual grasses (ANG), and annual forbs (ANF)) were consistent with habitats and vegetation dynamics in the agro-pastoral ecotone. Hence the photosynthetic pathways, combined with the morphological functional types, are efficient indications for studying the linkage between species and ecosystems in the ecotone.     

The occurrence of C4 photosynthesis in Yunnan province, a tropical region in South-western China

Floristic composition, morphological functional types, and altitudinal distribution pattern for C₄ species were studied in Yunnan province, South-western China. 159 species, in 6 families and 60 genera, were identified with C₄ photosynthesis. 93 % of these C₄ species were found in Monocotyledoneae, e.g. Cyperaceae (18 species), Gramineae (129 species), and Commelinaceae (1 species), the other 7 % was in Dicotyledoneae, e.g. Amaranthaceae (5 species), Portulacaceae (4 species), and Chenopodiaceae (2 species). Hence C₄ plants mainly occurred in very few families in the tropical region. Compared with those in semi-arid grasslands and arid deserts in North China, more C₄ grasses and much less Chenopodiaceae C₄ species occurred in the tropical region. This indicates the physiological responses of C₄ plants from the two families are very different. Chenopodiaceae C₄ species may be more fit semi-arid and arid environments, while C₄ grasses are more fit the moist tropical conditions. There was a strong relationship between C₄ distribution and altitude in the tropical region. Altitudinal distribution pattern for C₄ species in the region was consistent with altitude, climate, and habitats.     

Photosynthetic and morphological functional types for native species from mixed prairie in Southern Saskatchewan, Canada

Photosynthetic pathways (e.g. C₃, C₄) and morphological functional types (e.g. trees, shrubs, high perennial grasses, perennial forbs) were identified for the native species from the Saskatchewan mixed prairie, using the data from references published between 1950 and 2003. Of the total 219 identified species in 145 genera and 45 families, 208 species in 137 genera and 44 families were found with C₃ photosynthesis, and most of these species are dominants (e.g. Agropyron dasystachyum Hook. and Stipa spartea var. curtiseta Hitchc.). 11 species in 10 genera and 3 families were identified with C₄ photosynthesis (e.g. Atriplex argentea Nutt., Andropogon scoparius Michx., Boutelou gracilis Lag., Calamovilfa longifolia Hook.). The amount of total identified C₄ species in the region is much less than that from the South Dakota mixed prairie (27 species). Gramineae is the leading family with C₄ photosynthesis (8 species), Chenopodiaceae ranks the second (2 species). Relatively less forb types [50 % perennial forbs (PEF) and 12 % annual forbs (ANF)] and more graminoid types (25 %) composition suggested that the rangelands in the region are relatively stable. Lacking of the knowledge on the optimal traits for PFTs classification in the region, further studies (e.g. C₃ and C₄ plant identification and optimal trait selection) are needed to explore the relationships between PFTs and vegetation variations, as well as land-use and climate changes.     

Comparative Anatomy and Morphology of Leaves between C3 and C4 Species in Panicum

Anatomical and morphological structures of leaf blades werecompared between C₃ and C₄ species in Panicum. Inter-specificvariation of stomatal density, longitudinal vein density andmesophyll thickness was highly correlative either plus or minuswithin respective groups. The two groups could not be distinguishedby a single character, since the variation ranges overlappedeach other. However, the quantitative relations between veindensity and the other two characters differentiated the twogroups well. In C₃, stomatal density seemed to be a primaryfactor for regulating water balance, while in C₄ vein systemwas considered to be important for the regulation. The specieswith intermediate photosynthesis behaved similar to the C₃ species.In the C₃ group, correlative variation was observed betweenleaf width, leaf angle and the three characters mentioned above.Variation of light-receiving area due to the changes of widthand angle of leaf blades was considered to be one of the adaptivestrategies of this group. Increase of light-receiving area wasin connection with the thinning of leaves. On the other hand,in the C₄ correlations between length, width and angle of leaveswere low. Such loose character correlation may be achieved byits efficiency of CO₂ utilization and its well developed veinsystems. Besides, NAD-me type species tended to have relativelylower stomatal and vein densities as compared with the otherdecarboxylation types in this group. Panicum, photosynthesis, C₃, C₄, decarboxylation types, leaf, stomata, vein     

Plant functional types and their ecological responses to salinization in saline grasslands, Northeastern China

Photosynthetic pathways (C₃, C₄, and CAM) and morphological functional types (e.g. shrubs, high perennial grasses, short perennial graminaceous plants, annual grasses, annual forbs, perennial forbs, halophytes, and hydrophytes) were identified for the species from salinity grasslands in Northeastern China, using the data from both stable carbon isotope ratios (¹³C) and from the references published between 1993 and 2002. 150 species, in 99 genera and 37 families, were found with C₃ photosynthesis, and most of these species are dominants [e.g. Leymus chinensis (Trin.) Tzvel., Calamagrostis epigeios (L.), Suaeda corniculata (C.A. Mey.) Bunge]. 40 species in 25 genera and 8 families were identified with C₄ photosynthesis [e.g. Chloris virgata Sw., Aeluropus littoralis (Gouan) Parlat] and 1 species with CAM photosynthesis. Gramineae is the leading family with C₄ photosynthesis (27 species), Chenopodiaceae ranks the second (5 species). The significant increase of C₄ proportions with intense salinity suggested this type plant is remarkable response to the grassland salinization in the region. 191 species were classified into eight morphological functional types and the changes of most of these types (e.g. PEF, HAL, and HPG) were consistent with habitats and vegetation dynamics in the saline grassland. My findings suggest that the photosynthetic pathways, combined with morphological functional types, are efficient means for studying the linkage between species and ecosystems in this type of saline grassland in Northeastern China.This revised version was published online in March 2005 with corrections to the page numbers.     

Partial Reduction in Activities of Photorespiratory Enzymes in C3-C4 Intermediates of Alternanthera and Parthenium

The maximum catalytic activities of several photorespiratoryand photosynthetic enzymes were determined in leaf extractsof three C₃–C₄ intermediates (Alternanthera ficoides,A. tenella and Parthenium hysterophorus) and were compared tothose of C₃ (A. sessiles, Pisum sativum) and C₄ (A. pungens,Zea mays and Amaranthus hypochondriacus) species. The activitylevels of key photorespiratory enzymes, glycolate oxidase, catalase,NADH-hydroxypyruvate reductase and glycerate kinase were less(28 to 35% reduced) in intermediates than those of typical C₃species. Similarly, the activities of photorespiratory aminotransferasesin the C₃–C₄ intermediates were also partially reduced(23 to 37% reduction). The activities of phosphoenolpyruvatecarboxylase (PEPC), pyruvate, orthophosphate dikinase and NAD-malicenzyme were higher (2 to 7 times) in leaf extracts of the intermediatesthan those of C₃ species. But the ratios of PEPC/rubisco inthe C₃–C₄ intermediates were more like C₃ than C₄ species.We draw attention to the partial reduction in enzyme activityof photorespiratory metabolism, which could be an importantfactor for restriction of photorespiration in the C₃–C₄intermediate species, in addition to enzyme compartmentationand/or operation of a ‘C₄-like’ cycle Key words: C₃–C₄ intermediates, C₄ pathway, enzyme profile, glycolate metabolism, photorespiration, photosynthesis     

The occurrence of C4 plants and their morphological functional types in the vegetation of Xinjiang, China

Floristic composition, morphological functional types and habitat distributions for C₄ species were studied in Xinjiang, North-western China. 89 species, in 9 families and 41 genera, were identified with C₄ photosynthesis. 48 % of these C₄ species were found in Monocotyledoneae, e.g. Cyperaceae (5 species), Gramineae (38 species), the other 52 % was in Dicotyledoneae, e.g. Chenopodiaceae (29 species), Amaranthaceae (7 species), and Polygonaceae (5 species). Compared with those in semi-arid grasslands in North China and tropical forests in South China, more plant families were found with the occurrence of C₄ plants in this arid region. Relatively higher annual species (63 %), shrubs (18 %), and Chenopodiaceae C₄ species (33 %) compositions were the primary characteristics for the C₄ species occurring in Xinjiang, and this was remarkably related with its arid environment. More Chenopodiaceae C₄ species occurring in the region suggested that this type of C₄ species may have higher capacity to fit the air and soil droughts. There was a strong relationship between C₄ occurrence and habitat distributions, more than half of the total 89 C₄ species were found in disturbed and cultivated lands and early stages of vegetation successions, indicating C₄ occurrence was not only related with climate changes, but also with land uses and vegetation dynamics.     

Plant functional types and their ecological responses to salinization in saline grasslands,Northeastern China

Photosynthetic pathways (C₃, C₄, and CAM) and morphological functional types (e.g. shrubs, high perennial grasses, short perennial graminaceous plants, annual grasses, annual forbs, perennial forbs, halophytes, and hydrophytes) were identified for the species from salinity grasslands in Northeastern China, using the data from both stable carbon isotope ratios (δ¹³C) and from the references published between 1993 and 2002. 150 species, in 99 genera and 37 families, were found with C₃ photosynthesis, and most of these species are dominants [e.g. Leymus chinensis (Trin.) Tzvel., Calamagrostis epigeios (L.), Suaeda corniculata (C.A. Mey.) Bunge]. 40 species in 25 genera and 8 families were identified with C₄ photosynthesis [e.g. Chloris virgata Sw., Aeluropus littoralis (Gouan) Parlat] and 1 species with CAM photosynthesis. Gramineae is the leading family with C₄ photosynthesis (27 species), Chenopodiaceae ranks the second (5 species). The significant increase of C₄ proportions with intense salinity suggested this type plant is remarkable response to the grassland salinization in the region. 191 species were classified into eight morphological functional types and the changes of most of these types (e.g. PEF, HAL, and HPG) were consistent with habitats and vegetation dynamics in the saline grassland. My findings suggest that the photosynthetic pathways, combined with morphological functional types, are efficient means for studying the linkage between species and ecosystems in this type of saline grassland in Northeastern China.     

Quantitative Determination of RuBP Carboxylase-Oxygenase Protein in Leaves of Several C3 and C4 Plants

RuBP carboxylase-oxygenase protein in three C₃ species (Nicotianatabacum L., Solanum tuberosum L., Triticum aestivum L.) andthree C₄ species (Panicum miliaceum L., Panicum texanum Buckl.,Zea mays L.) was quantitatively determined by sucrose densitygradient centrifugation and by immunochemical assay using antibodyraised to crystallized tobacco leaf RuBP carboxylase-oxygenase.The C₃ species had 3- to 6-fold higher concentrations of RuBPcarboxylase-oxygenase than the C₄ species when expressed oneither a chlorophyll or a leaf area basis. The C₃ species alsoallocated a higher fraction of their total soluble protein tothis enzyme (from 25 to 60% for the C₃ species compared to 8to 23% for the C₄ species). There was no RuBP carboxylase-oxygenaseprotein or activity in the C₄ mesophyll cells, while the enzymeconstituted from 20 to 40% of the total soluble protein in theC₄ bundle sheath cells. A close correlation (r = +0·91)was found between catalytic activity and level of the enzymeprotein in the species examined.