Partitioning of temporal activity among desert lizards in relation to prey availability and temperature

Partitioning of activity time within ecological communities potentially reduces interspecific competition and increases the number of species that can coexist. We investigated temporal activity in a highly diverse lizard assemblage in the Simpson Desert, central Australia, to determine the degree of partitioning that occurs. Three periods were defined, daytime (sunrise to sunset), early night (sunset to midnight) and late night (midnight to sunrise), and live captures of lizards were tallied for each period during two sampling months (September and November 2007). We also quantified the activity times of potential invertebrate prey and measured ambient temperatures during the different time periods to investigate any associations between these factors and lizard activity. Some 77% of captures of 13 lizard species were made by day, with Ctenotus pantherinus, Egernia inornata (Scincidae) and Nephrurus levis (Gekkonidae) the only species showing extended nocturnal activity. Activity of both species of skink was recorded at temperatures 4°C lower than those for agamid and varanid lizards early in the night, and at temperatures as low as 18–20°C. Surface‐active invertebrates differed in composition between time periods and were less abundant during the late night period in the drier of the two sample months (September), but were distributed equally over time in the other month. Termites were active in subterranean galleries at night in September and mostly by day in November, but available at all times on surface/subsurface baits. We conclude that activity is distributed unevenly within this lizard assemblage, with partitioning facilitated by the ready availability of invertebrate prey and by lizards having relatively broad temperature tolerances that, in some cases, permit opportunistic exploitation of resources beyond usual times of activity.     

民勤荒漠植被对气候变化的响应

运用民勤荒漠区1974-2009年物候观测资料和2002-2010年植被样方观测资料以及同期气象资料,分析了荒漠植被对气候变化的响应.结果表明:1961-2010年,民勤荒漠区气温升高,空气湿度增大,年均气温升高速率大于全球水平和中国近百年平均水平;植物对气温变化的响应主要表现在春季物候提前、秋季物候推迟、生长季延长;植被对降水量变化的响应主要表现为植被盖度和纯盖度随降水量减少而降低,植株密度、植物多度随降水量变化而波动;植被盖度和纯盖度与年降水量的相关性较高,然后依次为6-7月和4-5月的降水量;植株密度和植物多度与9月降水量呈正相关;植物春季物候提前的次序是芽初膨大期＞芽开放期＞开花始期＞展叶始期和展叶盛期＞花蕾序出现＞开花盛期＞开花末期＞果实成熟期;秋季物候推迟的次序是叶全变色期＞落叶始期＞叶初变色期＞落叶末期.春季气温升高对民勤荒漠区植物物候的影响大于秋季气温升高对物候的影响.     

四川唐家河自然保护区扭角羚冬春季日活动模式研究

根据相机陷阱调查获得照片的时间,研究了2008年12月～2009年5月唐家河自然保护区内野生扭角羚Budorcastaxicolor的日活动模式。通过对24个1km×1km样方的调查,共完成686个相机工作日的取样量,获得有效的扭角羚捕捉次数709次(冬季322次,春季387次),并分别计算出扭角羚冬季和春季在各时间段的相对活动强度指数RAI。结果显示,扭角羚在冬季和春季的日活动模式没有显著差异(χ2检验,P>0.1),每天都有3个活跃时期(凌晨、早上和下午)和3个紧随的不活跃时期。其中,冬季日活动的最高峰出现在下午17:00～18:00(RAI=12.42),最低谷出现在日出前3:00～6:00(RAI=0.00);春季最高峰出现在早上6:00～7:00(RAI=20.16),最低谷出现在日出前2:00～5:00(RAI=0.26)。在春季,扭角羚在上午活跃期的活动强度明显高于下午活跃期,而在冬季则相反。春季与冬季相比,扭角羚上午和下午的两个活跃时间段都有提前,可能是由于不同季节气温和光照差异的影响。研究表明,相机陷阱调查技术是研究野生动物在野外活动模式和活动节律的有效工具,可为今后深入开展扭角羚行为生态学...     

Competition and habitat selection in Namib desert tenebrionid beetles

Summary We tested whether intra- and interspecific competition could affect habitat selection in the two most abundant tenebrionid beetles,Physadesmia globosa andOnymacris rugatipennis, in a dry riverbed in the Namib desert. The spatial distributions of these beetles at the microhabitat scale were negatively correlated. We performed a removal experiment, progressively removing first 25% and then a further 25% of the population of the most abundant species,P. globosa, under the trees where most of the preferred food of both species is concentrated. There was no response ofO. rugatipennis to this removal in the tree habitat. In the open, barely-vegetated habitat where mostO. rugatipennis are found, the number of this species caught in pitfall traps increased following both removals and decreased followingP. globosa replacement under the trees. It appears that intraspecific competition forces someP. globosa to occupy the open habitat. Interspecific competition betweenP. globosa andO. rugatipennis in the open habitat reduces the number ofO. rugatipennis that can co-exist withP. globosa there. Removal ofP. globosa under the trees allows conspecifics in the open habitat to move under the trees, releasingO. rugatipennis in the open habitat from competition. This then results in an increase in the numbers ofO. rugatipennis in the open habitat as a result of immigration from neighbouring areas. We found that differences in foraging efficiency, measured as giving-up times in artificial food patches, create a likely mechanism of co-existence that explains the distinct preferences of these two species for tree and open habitats.     

Temperature and water relations in desert bees

1. 1. Desert bees do not show significant differences in most thermal parameters; mean endothermic warm-up rates are similar to those of temperate species, with no special cooling mechanisms, and normal upper critical temperatures (unlike desert ants and beetles). Thermoregulatory abilities may however be improved.

2. 2. They show the whole range of possible water balance problems; small species are acutely water-stressed when foraging, but large bees suffer from excessive generation of metabolic water in flight.

3. 3. Activity patterns are therefore either matinal, crepuscular or bimodal; essentially desert bees avoid heat and adapt to cold desert dawns and dusks. Desert plants must be coevolved to offer appropriate rewards and match the physiological constraints on their pollinators.

4. 4. Endothermy in bees may have evolved primarily in arid zones, and served as a pre-adaptation for subsequent invasion of cool temperate biomes.

     

不同干扰下阿拉善荒漠啮齿动物优势种对气候变化的响应

气候变化已对物种分布范围和丰富度产生了极大的影响。荒漠生态系统对气候变化的反应可能更加敏感。作为荒漠生态系统的重要组成者,了解荒漠啮齿动物特别是优势鼠种将对气候变化如何响应,对于荒漠地区生物多样性的维持将具有重要意义。2002—2010年,采用标志重捕法对阿拉善荒漠4种不同生境下啮齿动物优势种群进行了研究,分别利用Spearman相关分析以及典范对应分析(Canonical Correspondence analysis,CCA)对啮齿动物优势种群动态与年平均温度和年降水量的相关性进行了分析。结果表明,不同啮齿动物优势种对温度和降雨的响应不同,尤其以子午沙鼠表现最为显著。跳鼠对温度的适宜性要高于仓鼠科的子午沙鼠和黑线仓鼠,而仓鼠科啮齿动物对降雨的适宜性高于跳鼠。较小尺度上的人为干扰更可能从改变食性和生境的途径上加剧或缓冲降雨对荒漠啮齿动物优势种的影响,而不是改变温度对啮齿动物的作用。     

不同沙地共有种沙生植物对环境的生理适应机理

选择3个温带沙地(松嫩沙地、呼伦贝尔沙地、科尔沁沙地)4个共有种沙生植物(黄柳(Salix gordejevii)、差巴嘎蒿(Artimisia halodendron)、扁蓿豆(Melissitus ruthenica),猪毛菜(Salsola collina),通过自然状况下其叶片抗氧化酶活力和渗透调节物及丙二醛(MDA)含量日变化分析,探讨抗氧化酶活力和渗透调节物在沙生植物适应沙漠环境强光辐射和温度日变化中的作用,以及不同科属沙生植物抗逆生理调控机理的差异。结果表明:(1)不同沙地的4个共有沙生植物种可通过自身快速生理代谢调解,积累渗透调节物、提高抗氧化酶活力应对沙漠环境强光辐射和温度日变化,但生理调控幅度较小。(2)3个沙地不同科属的4个共有种在渗透调节物含量和抗氧化酶活力及种类上存在差异。扁蓿豆叶片日均MDA含量、POD(peroxidase)活力、CAT(catalase)活力、脯氨酸含量均最高,分别较其它3个种平均高2、10、2和2.5倍。黄柳叶片日均MDA含量较高,SOD(superoxide dismutase)活力和可溶性糖含量最高,分别较其它3个种高1.2和3倍。差巴嘎蒿和猪毛菜叶内MDA含量较低,POD、CAT、SOD活力和脯氨酸、可溶性糖含量均最低。沙生植物细胞中膜脂过氧化程度和抗氧化酶活力及渗透调节物含量呈正相关。自然状况下3个沙地的扁蓿豆和黄柳通过生理代谢调节维持细胞水分和氧自由基代谢平衡适应沙漠环境,差巴嘎蒿和猪毛菜依靠特殊的叶片形态结构变异减少光辐射吸收、降低水分蒸腾、维持叶片水分平衡、降低细胞膜脂过氧化。因此不同科属沙生植物维持叶片水分和氧自由基代谢平衡可能是其适应沙漠环境生存的重要生理调控机理。由于不同科属沙生植物种对沙漠环境适应的生理调节机理的不同,在未来农作物、林木抗逆育种中,根据具体科属植物选择合适的沙生植物作为亲本对提高抗逆育种效率是十分重要的。     

离子吸收分布与几种荒漠植物适应性的关系

用压力室灌流挤压法结合原子吸收分光光度计测定了胡杨、沙枣、柽柳、梭梭和花棒等5种荒漠优势植物组织以及细胞内和质外体溶液中K+、Na+含量,并用TPS-1型光合蒸腾测定系统和露点微伏压计测定了叶片(同化枝)的蒸腾速率和组织渗透势,以分析荒漠植物离子吸收特点与其适应性的关系。结果表明:5种植物叶片(同化枝)中K+含量差异较小,但Na+含量却有极显著差异,其中梭梭Na+含量最高、胡杨和柽柳次之、花棒和沙枣相对较低,且梭梭和柽柳的根系和组织细胞膜对Na+也具有更高的透性。另外,实验结果还显示组织Na+含量与组织渗透势和蒸腾失水率均呈显著负相关,即Na+的吸收、积累可能在渗透调节和减少水分散失中具有重要作用。由此可见,梭梭和柽柳能够通过大量吸收和积累无机离子来降低渗透势、增强吸水力,同时减少蒸腾失水,具有很强的荒漠环境适应能力;而胡杨蒸腾耗水量较大、花棒和沙枣生理吸水的动力不足,与梭梭和柽柳相比,其荒漠环境适应能力相对较弱。     

小尺度下柠条林破碎化生境对地表甲虫多样性的影响

一般认为,景观斑块面积和破碎化对物种丰富度和分布格局有重要的影响。在宁夏中部荒漠地区,天然柠条林和人工柠条林地交错排列,形成点、片、带状等大小不等的斑块性分布,表现为典型的破碎化斑块格局生境特征。本文采用巴氏罐诱法调查了在小尺度下荒漠景观人工柠条林破碎化生境不同斑块内地表甲虫的物种多样性。结果共获得10科20属29种地表甲虫,其中拟步甲科昆虫占绝对优势,阿小鳖甲Microdera kraatzi alashanica Skopin、克小鳖甲Microdera kraatzi kraatzi(Reitter)为优势种。Rarefaction曲线显示较大面积的斑块有较多的物种多样性,但群落多样性指数各斑间块差异不显著。利用斑块面积对物种数-个体数进行回归分析表明,地表甲虫的物种多样性受斑块面积的影响,生境破碎化会导致地表甲虫多样性下降。     

Seed germination of exotic and native winter annuals differentially responds to temperature and moisture,especially with climate change scenarios

Seeds of winter annuals require a summer after-ripening period for dormancy loss and low autumn temperatures for germination. With current and future changes in moisture and temperature, we tested the effects of warming along a relative humidity (RH) gradient on dormancy loss and effects of decreased diurnal temperature range (DTR) on germination. We further reasoned that the effects of changes in these variables would be disproportionate between the exotic and native winter annuals. Seeds of exotic species (Buglossoides arvensis, Lamium purpureum and Ranunculus parviflorus) and co-occurring native species (Galium aparine, Paysonia stonensis and Plantago virginica) were collected in middle Tennessee. After-ripening occurred over a 15–100% RH gradient at 25 and 30°C and germination was tested at 20/10 and 20/15°C. Niche breadth was calculated using Levins' B. Fresh Ranunculus seeds had high germination and those of other species did not. Germination for these species increased with after-ripening, mostly across the RH gradient irrespective of temperature. A decrease in DTR showed mixed results – the extreme being Ranunculus with no germination at 20/15°C. Most exotic species had wider germination niche breadths than native species. With climate change, we suggest that a decrease in DTR may have a larger effect on germination than increasing moisture or warming on dormancy break. Moreover, there is not a clear-cut winner with climate change when we compare exotic versus native species because the responses of our six species were species specific.     

内蒙古荒漠草原牧户对气候变化的感知和适应

荒漠草原是气候变化影响的脆弱和敏感地区.荒漠草原的牧户主要依赖天然草原维持生计,正面临着严峻的气候变化挑战.本文采用问卷调查的实证分析方法,在获取内蒙古苏尼特右旗荒漠草原牧户对气候变化和极端气候事件感知和适应的第一手资料基础上,分析了荒漠草原牧户对气候变化趋势和极端气候事件感知和适应的现状与行为特征.结果表明:在降水稀少、气象灾害频繁发生的荒漠草原,干旱是影响范围最广、影响程度最深、发生频率最高的极端气候事件;牧户不仅对干旱的敏感度远高于其他极端气候事件,而且对大风、沙尘暴和大雪等极端气候事件的深刻感知伴随着对干旱的感知而产生;相对于长期气候变化的感知,牧户对短期气候变化趋势的感知更深刻、准确,并主要依据近10年气候变化的感知结果来判断较长期气候变化的总体趋势;牧户认为,气候变化在很大程度上影响了牲畜健康和草场产量,但牧户应对气候变化的行为相对单一,且多为自发性被动适应,缺乏行之有效的主动适应.     

Tenebrionid beetles in the shortgrass prairie: daily and seasonal patterns of activity and temperature

ABSTRACT. 1. Patterns of daily and seasonal activity for seven species of tenebrionid beetles, genus Eleodes , were investigated in the shortgrass prairie of northeastern Colorado. The relationship between time of activity, body temperatures, and rates of water loss of the beetles was examined in the field and in laboratory experiments.
2. Common species were active from April until the end of October; however, asynchronous peaks of abundance occurred.
3. Beetles were diurnally active with peaks of daily activity occurring 2–4 h after sunrise and before sunset. Less than a 2 h shift in mean time of activity occurred between seasons.
4. Within species, body temperatures measured in the field closely corresponded to temperatures selected in an experimental thermal gradient; hence, species seemed to prefer particular body temperatures and were most active during times when those temperatures could be achieved. Body temperatures measured in the field approximated ambient temperatures measured in the vicinity of the beetle.
5. Significant differences among several species were found for times of daily activity and corresponding body temperatures.
6. Ability to resist water loss by evaporation was not correlated with daily or seasonal activity patterns.     

荒漠景观下柠条豆象的空间分布及其对景观斑块格局的反应

柠条豆象Kytorhinus immixtus Motschulsky是危害柠条种子的主要种实害虫之一。本文应用了多个聚集度指标和回归分析方法,研究探讨了柠条豆象卵、幼虫在宁夏盐池、灵武、银川等荒漠景观中11个生境斑块中的空间分布型及种群对景观斑块格局的反应情况。结果表明:在11个景观样地中,柠条豆象卵和幼虫在各种生境斑块中均呈聚集型的负二项分布;卵和幼虫空间分布的Iwao回归方程分别为m*=2.23695+1.64742m(r=0.8273)和m*=2.24418+1.42084m(r=0.8889)、Taylor幂模型分别为logS2=0.51292+1.41118logm(r=0.9344)和logS2=0.59645+1.14736logm(r=0.9786),种群分布的基本成分为个体群,个体间相互吸引,有密度依赖性,聚集主要由环境因素和种间竞争引起的,聚集强度随种群密度的升高而增加。在荒漠景观下,柠条豆象的种群发生与寄主植物的种类、在斑块内的分布格局有着密切的关系,与斑块面积相关性较低(R2=0.1995)。主成分分析显示柠条林生长的土壤类型、生长方式是影响柠条豆象寄生的主要因素。     

不同气候变化情景下荒漠草原生态系统碳动态模拟

荒漠草原生态系统对气候变化十分敏感,但其碳循环过程如何响应气候变化尚不明确。基于Biome-BGC模型和1958—2017年的气象观测资料,模拟了宁夏盐池荒漠草原生态系统在4种不同气候情景下的碳储量变化。结果表明:(1)4种气候情景下,盐池荒漠草原生态系统年均总碳储量在2.3208—2.3652 kg/m^2,土壤碳储量占总碳储量的94.03%,枯落物与植被碳储量分别占4.03%和1.94%。(2)近60 a间,基准情景下的土壤碳储量以每年0.0020 kg/m^2的速度累积,总碳储量呈波动性上升趋势。(3)植被、枯落物碳储量的年内变化与季节变化紧密相关,土壤碳储量在夏秋季较低,冬春较高。(4)单独的气温升高会导致土壤碳、植被碳及枯落物碳储量的略微降低,而单独降水波动增加会导致碳储量的明显增高,二者综合作用会导致碳储量的升高;此外,枯落物碳储量对气候变化的响应最敏感,其次是植被碳储量,土壤碳储量对气候变化的响应敏感度最低。研究结果揭示了荒漠草原碳储量随不同气候变化情景的变化规律,可为地方政府制定应对气候变化策略和生态恢复政策提供科学依据。     

血雉繁殖初期和育雏期的日活动模式及集群行为研究

2013年4—7月,利用红外相机在四川王朗自然保护区研究了血雉（Ithaginis cruentus）在繁殖初期和育雏期的日活动模式和集群行为。结果表明,血雉具有明显的昼行性活动规律,繁殖初期的活动高峰为6：00—14：00（n=42,P=84.00%）,育雏期的活动高峰为6：00—12：00（n=111,P=60.33%）,次高峰为12：00—18：00（n=63,P=34.24%）。繁殖初期记录了50群76只血雉,雌雄性比为1∶2.41,集群大小为（1.52±0.68）只/群,以孤雄（n=23,P=46.00%）和混合群（n=29,P=30.00%）为主。育雏期记录了184群321只血雉,雌雄性比为1∶1.81,集群大小为（1.74±1.21）只/群,以孤雄（n=75,P=40.76%）和家庭群（n=51,P=27.72%）为主。在繁殖初期和育雏期,不同集群类型出现的频率差异均极显著（繁殖初期：χ2=17.680,df=3,P〈0.01;育雏期：χ2=79.478,df=4,P〈0.01）。血雉的集群性较强,即使在以家庭生活为主的育雏期也常集群活动。     

贡嘎山国家级自然保护区兔狲的活动节律与适宜栖息地预测

2016年6月-2017年5月,采用红外相机陷阱法研究了四川贡嘎山国家级自然保护区兔狲Otocolobus manul的活动节律,以样线法和红外相机调查得到的兔狲分布点为数据源,采用最大熵(MaxEnt)模型预测了兔狲的适宜栖息地分布。结果显示:(1)兔狲分布在海拔3 780~4 956 m的灌丛、草甸和流石滩生境,其中87.2%的分布点位于海拔4 500 m以上;(2)日活动差异指数为0.071 2,昼行性指数为0.34,兔狲的活动高峰为05∶00-07∶00和20∶00-22∶00;(3)增强型植被指数2年最大值均值、海拔、平均日较差和气温年较差是影响兔狲栖息地选择的主要环境因子,兔狲偏好在海拔4 000 m以上、温差较大的高山流石滩生境活动,保护区兔狲的适宜栖息地面积为187 km^2,占保护区总面积的4.56%。本研究充实了兔狲的生物学、生态学资料,也为该物种的保护管理提供了参考资料。     

民勤荒漠区不同生活型植物物候响应气候变暖的差异

运用1974年以来民勤荒漠区植物物候观测资料和气象观测资料,将22种植物分别按生长类型划分为乔木、灌木和草本植物3种生活型,再按更新芽着生部位将22种植物划分为高位芽植物、地上芽植物和地面芽植物植物3种生活型,分析了按这2种方法划分的不同生活型植物物候响应气候变化的差异.结果表明:1)不论以哪种方法划分的植物生活型,春季物候响应气温变化的敏感程度均大干秋季;2)按生长类型划分的3种生活型植物之间的物候变化差异较按更新芽着生部位划分的3种生活型植物之间的物候变化差异大,主要表现为乔木和灌木的物候差异较大;3)当地植物的生长期长度、乔木的春季物候提前幅度和高位芽植物的春季物候提前幅度大干其他文献报导;4)更新芽着生部位越高,春季物候响应当月和当年气温变暖越敏感,表明在地面以上、乔木高度以内,距地面越高气温对春季物候的影响越显著.     

Geographical gradients in seed mass in relation to climate

Aim To determine whether latitudinal and longitudinal gradients in seed mass are related to variation in climatic features including temperature, solar radiation and rainfall. Location Australia. Methods Seed mass was estimated from over 1600 provenances covering the latitudinal and longitudinal extents of 34 perennial Glycine taxa in Australia. Climatic data were obtained from ANUCLIM 5.1 for collection locations based on long‐term meteorological records across Australia. These climatic data were subject to principal components analysis to extract three components as climatic indices. Generalized linear models were used in three separate sets of analyses to evaluate whether seed mass–latitude and seed mass–longitude relationships persisted after taking climatic variation into account. First, relationships were examined across species in analyses that did not explicitly consider phylogenetic relationships. Secondly, phylogenetic regressions were performed to examine patterns of correlated evolutionary change throughout the Glycine phylogeny. Within‐species analysis was also performed to examine consistency across different taxonomic levels. Results Geographical variation in seed mass among species was related primarily to temperature and solar radiation, while rainfall was much less influential upon seed mass. Partialing out the influence of temperature and solar radiation in models resulted in the disappearance of significant seed mass–latitude and seed mass–longitude relationships. Patterns within species were generally consistent with patterns among species. However, in several species, factors additional to these climatic variables may contribute to the origin and maintenance of geographical gradients in seed mass, as significant seed mass–latitude and seed mass–longitude relationships remained after controlling for the influence of climatic variables. Main conclusions Our empirical results support the hypotheses that (1) seed mass is larger at low latitudes and in the interior of the Australian continent due to increased metabolic costs at high temperatures, and that (2) higher levels of solar radiation result in an increase in the availability of photosynthate, which in turn leads to an increase in biomass for the production of large seeds. In effect, our findings show that greater energy is available precisely where needed, that is, where high temperatures require large seed mass on the basis of metabolic requirements.     

天山北麓典型地段植被对景观格局和动态的指示意义

景观是由气候、地貌、水文、土壤、植被等组分构成的综合体。这些组分之间相互影响、相互作用,其中植被对其它组分的反映最为敏感。研究了天山中段北坡从中山开始,向下经准噶尔盆地南缘壤质和黏土荒漠,到古尔班通古特沙漠南缘的范围内,以典型温带荒漠植被为主的天然植被格局及其与环境梯度的关系,并以此为基础探讨了干旱区荒漠植被对于景观格局及相应的景观过程的指示意义。结果表明,土壤质地对研究区植被类型有显著的影响,白梭梭-梭梭群落、梭梭群落、琵琶柴群落对细粒物质的偏好依次增大,对粗粒物质含量则有相反的规律;研究区壤质和黏土荒漠中的白梭梭-梭梭群落可以作为景观中土壤沙化过程的指示体。在对土壤含盐量的适应性方面,琵琶柴群落高于梭梭群落,分布在总盐含量更高的生境中,柽柳群落则对土壤盐分没有明显的偏好;盐生矮半灌木群落可以作为土壤盐渍化过程的指示体。在对土壤水分与地下水位的适应性方面,柽柳群落表现出较明显的对高的土壤含水率的偏好,可以指示景观中具有优良生境的斑块。荒漠化过程是干旱区重要的景观生态过程,主要表现为土壤沙化和土壤盐渍化,而这两个过程都有非常明显的植被表征,因此,在以荒漠化动态为目标的干旱区景观动态分析中,可以通过植被的演化来推断景观格局的动态变化,进而推断荒漠化动态。     

干旱区荒漠生态系统的土壤呼吸

采用LI-8100土壤碳通量测量系统测定了准噶尔盆地高(B)、低(A)两个盖度级3个典型荒漠植物群落梭梭、盐穗木、假木贼的土壤呼吸速率,比较分析了各样地土壤呼吸的变化特征及水热因子对荒漠土壤呼吸特征的可能影响.结果表明:生长季,土壤呼吸速率存在明显的日变化和季节变化规律,不同盖度和群落类型的荒漠土壤呼吸速率变化形式基本相同.日变化格局最高值出现在12:00～14:00,最低值在8:00或20:00;夏季各月(6、7、8月份)土壤呼吸速率高于秋季月份(9、10月份),春季(5月份)最低.高盖度梭梭群落样地日平均土壤呼吸速率与其他样地存在显著差异.各样地土壤呼吸速率与地表温度呈不同程度的正相关,而与土壤温度的相关性较弱;高盖度盐穗木样地(土壤湿度最高)、梭梭样地(土壤湿度最低)土壤呼吸速率与土壤湿度呈显著负相关.地表温度-土壤湿度的多变量模型能在更大空间尺度解释荒漠土壤呼吸速率时间变化的61.9%.样地间土壤呼吸速率的差异可能主要受土壤湿度影响.高、低盖度的梭梭、盐穗木和假木贼群落的Q10值分别为1.34、1.3、1.65、1.58、1.17和1.31,平均值1.39.