High clay content accelerates the decomposition of fresh organic matter in artificial soils     

《Soil biology & biochemistry》2014

Clay is generally considered an important stabiliser that reduces the rate of decomposition of organic matter (OM) in soils. However, several recent studies have shown trends contradicting this widely held view, emphasising our poor understanding of the mechanisms underlying the clay effects on OM decomposition. Here, an incubation experiment was conducted using artificial soils differing in clay content (0, 5, and 50%) at different temperatures (5, 15, and 25 °C) to determine the effects of clay content, temperature and their interaction on fresh OM decomposition. CO₂ efflux was measured throughout the experiment. Phospholipid fatty acids (PLFAs), enzyme activities, microbial biomass carbon (MBC), and dissolved organic carbon (DOC) were also measured at the end of the pre-incubation and incubation periods in order to follow changes in microbial community structure, functioning, and substrate availability. The results showed that higher clay contents promoted OM decomposition probably by increasing substrate availability and by sustaining a greater microbial biomass, albeit with a different community structure and with higher activities of most of the extracellular enzymes assayed. Higher clay content induced increases in the PLFA contents of all bacterial functional groups relative to fungal PLFA content. However, clay content did not change the temperature sensitivity (Q₁₀) of OM decomposition. The higher substrate availability in the high clay artificial soils sustained more soil microbial biomass, resulting in a different community structure and different functioning. The higher microbial biomass, as well as the changed community structure and functions, accelerated OM decomposition. From these observations, an alternative pathway to understanding the effects of clay on OM decomposition is proposed, in which clay may not only accelerate the decomposition of organic materials in soils but also facilitate the SOM accumulation as microbial products in the long term. Our results highlight the importance of clay content as a control over OM decomposition and greater attention is required to elucidate the underlying mechanisms.  相似文献   

Phenotypic plasticity in the morphology of small benthic Icelandic Arctic charr (Salvelinus alpinus)          下载免费PDF全文

Bjarni K. Kristjánsson  Camille A.‐L. Leblanc  Skúli Skúlason  Sigurður S. Snorrason  David L.G. Noakes 《Ecology of Freshwater Fish》2018,27(3):636-645

Intraspecific phenotypic diversity is the raw material for evolution, so understanding its origin and maintenance is critically important for conservation of biodiversity. Intraspecific diversity in a trait or a suite of traits can result from genetic diversity and/or phenotypic plasticity. The two are, however, not independent as plasticity has been shown to evolve. In this study, we evaluated the importance of phenotypic plasticity in generating morphological diversity in populations of small benthic Arctic charr in Iceland, using a rearing experiment with contrasting modes of feeding. We also examined the association between phenotypic plasticity in offspring groups generated by the contrasting feeding modes and important ecological variables characterising the natural habitats of the respective populations. Although the level of plasticity could not be related to any of the ecological measurements, clear differences in morphological reaction norms among populations suggest that plasticity is an important aspect of morphological diversity of the charr. It is not clear whether that plasticity is adaptive, but it is notable that reaction norms in all populations have similar reaction to the treatments.  相似文献   

气候变化适应及其影响因素研究——山东胶州湾地区居民的实证分析   总被引：1，自引：0，他引：1  

汪海欧  於琍  杨书运  吕明辉 《中国农学通报》2019,35(11):103-109

为探索气候变化感知在适应决策过程中的作用机理，本研究以深度访谈数据为基础，基于“感知－适应”分析框架，采用二元Probit模型和泊松回归模型，分析胶州湾地区居民气候变化适应决策和适应选择的影响因素。研究表明，胶州湾地区绝大多数居民已经感知到气候变化，半数以上居民采取了一定的适应措施，大多数居民对适应措施效果的感到满意。居民采取适应措施介于0-4项，平均为1.07项，适应措施的普及率和多样化仍有提升空间。影响胶州湾地区居民气候变化适应决策与适应选择的主要因素存在一定差异性，但“居民对气候变化的感知”不论是对适应决策还是对适应选择的影响都较大，其中又以“对降水变化的感知”和“对气象灾害损失的感知”最为显著。  相似文献   

北京地区不同秋眠级苜蓿品种适应性评价   总被引：1，自引：0，他引：1  

刘艺杉  刘自学  苏爱莲  李晓光 《草业科学》2008,25(2):60-63

对14个紫花苜蓿Medicago sativa品种在北京地区的表现进行观测,并对主要性状指标进行分析.结果表明:参试各品种秋眠级不同其春季生长速度、秋季生长速度、产草量及越冬率都有明显的差异,秋眠级高的品种生长速度快、产草量高,但越冬率低、秋眠级低的品种与之相反;地温也影响苜蓿生长速度;茎叶比与鲜干比各品种之间无明显变化,但与茬次有显著变化.  相似文献   

四种暖季型草坪草对长期盐胁迫的生长反应   总被引：19，自引：7，他引：12  

陈静波  阎君  张婷婷  刘建秀  郭海林 《草业学报》2008,17(5):30-36

通过盐水灌溉法,研究了长期盐胁迫对4种暖季型草坪草优良新品系沟叶结缕草'Z123'、结缕草'Z080'、狗牙根'C291'和海雀稗'P006'生长的影响,以评价其抗盐性及对长期盐胁迫的适应性生长反应.结果表明,根据绿叶盖度和植株总干重,这4种草坪草的抗盐性依次为'Z123'＞'P006'＞'C291'＞'Z080'.长期的盐胁迫显著抑制了'Z123,和'Z080'的叶重、枝条干重和枝条长度,而'P006'和'C291'在10～20 g/L以上的盐度下才受显著抑制.'Z123'、'C291'和'P006'可以分别在20,10和5 g/L以内的盐度下维持稳定的枝条数量,血'Z080'在5 g/L下显著降低.5～10 g/L左右的低盐度对4种草坪草地下茎和根系生长的影响不显著,较高盐度下才受显著抑制,但'P006'和'C291'在5 g/L下具有更稳定的根系干重.长期盐胁迫不同程度地提高了4种草坪草的地下部分地上部分干重比,但抗盐越弱的草比值增加越快.不同草坪草的同一器官对盐胁迫的反应不一致,反应了其抗盐机制的差异.  相似文献   

Study on Karyotype of Hobby (Falco subbuteo) and Kestrel (Falco tinnunculus)     

王明力  陈凤英 《林业研究》1998,(2)

IntroductionHobbiesandKestrelsaremiddleandsmallbirdsofpreyinFalconiformes,withverywidedistributioninChina,livingindifferenttypesofforests,shrubbery's,forestedges,waterareasornearinhabitants.Theylivesolitarilyorinpairs,flyveryrapidlyandpreyonsmallmammalssuchasrodents,youngbirdsandalsoinsects.Theirfoodhabitisverybeneficialtothepreservationofforestsandtheregulationoftherelativeequilibriumofforestecosystems,sothattheyarelistedintheprotectedanimalsClasslllilBirdsofFalconiformesinChinaareclassifi…  相似文献   

Study on karyotype of Hobby (Falco subbuteo) and Kestrel (Falco tinnunculus)     

Wang Mingli  Chen Fengying 《林业研究》1998,9(2):108-110

This paper reported karyotypes of the Hobby and Kestrel collected from the suburb of Qiqihaer City. These karyotypes were compared and analyzed, on the basis of the study of karyotypes of nine birds species in Falconiformes by Bian Xiaozhuang and Li Qingwei. It was considered that differences in habits of birds and ecological environment not only cause falcons to differ from others, but also differences in a genus, even within a species. This difference may result from fusion of microchromosomes.  相似文献   

Endophytic bacterial communities in the periderm of potato tubers and their potential to improve resistance to soil-borne plant pathogens   总被引：17，自引：0，他引：17  

Sturz  Christie  Matheson  Arsenault  & Buchanan 《Plant pathology》1999,48(3):360-369

To evaluate whether the location of bacterial endophyte communities contributes to disease resistance in potato tubers ( Solanum tuberosum ), the population density, biodiversity and antibiotic activity of endophytic bacteria was examined from the tuber peel (periderm plus top 3 mm of tissue) of four cultivars (Russet Burbank, Kennebec, Butte and Shepody). There were no significant differences for population density of bacteria among the layers of peel examined and no cultivar × peel layer interaction. Endophytic bacteria from several layers of peel were challenged in in vitro bioassays to the soil-borne plant pathogens Fusarium sambucinum , Fusarium avenaceum , Fusarium oxysporum and Phytophthora infestans (mating types A1 and A2). In general, antibiosis of bacterial endophytes against these pathogens was significantly higher ( P  = 0.01) in isolates recovered from the outermost layer of tuber peel and decreased progressively toward the centre of the tuber. Antibiosis against P. infestans was variable, with a progressive decrease in antibiotic activity from outer to inner layers of peel occurring in cvs Russet Burbank and Kennebec only. For antibiosis there were significant cultivar × peel, and cultivar × pathogen interactions ( P  = 0.01). In all cases the inhibitory activity of endophytic bacteria was significantly greater ( P  = 0.01) against the A1 than the A2 mating type of P. infestans . In four of seven cases, where the same species of bacteria were recovered from all three peel layers, antibiosis to pathogens decreased significantly ( P  = 0.01) with depth of recovery (from the periderm to inside the tuber), indicating that in certain communities of endophytic bacteria, defence against pathogens may be related to bacterial adaptation to location within a host and may be tissue-type and tissue-site specific.  相似文献   

Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish          下载免费PDF全文

Lea D. Schneider  P. Anders Nilsson  Johan Höjesjö  E. Martin Österling 《水产资源保护:海洋与淡水生态系统》2017,27(6):1261-1269

Settlement behavior of American lobster (Homarus americanus): effect of female origin and developmental temperature          下载免费PDF全文

Léo Barret  Gilles Miron  Patrick Ouellet  Réjean Tremblay 《Fisheries Oceanography》2017,26(1):69-82

The benthic settlement success of American lobster (Homarus americanus) postlarvae is a key factor in population dynamics, with the temperature being a key factor. Given the spatial distribution of the species, its pelagic larvae probably encounter various thermal zones during development. Little information is available on the ability of lobster larvae to acclimate to temperature or if this ability varies among geographic areas. The main objectives of this study were to characterize (i) the settlement behavior of the postlarvae in relation to (a) temperature during larval development and (b) the geographic origin of the maternal parent and (ii) the behavioral response of postlarvae with different thermal histories in the presence/absence of a thermocline. Results did not support the hypothesis of thermal adaptation among local populations, as settlement behavior of postlarvae did not differ among females from different geographic regions. In contrast, larval survival and settlement behavior and postlarval energetic conditions varied with development temperature. Behavioral plasticity in the benthic settlement was observed in relation to temperature structure of the experimental water column. This study suggests that there may be links between development temperature and the natural variability in survival and settlement of American lobsters. Findings emphasize the need for an integrated approach in lobster recruitment studies with the inclusion of behavior in dispersion models.  相似文献