The porosphere as an ecological medium emphasized in Professor Ghilarov's work on soil animal adaptations

Summary The author recalls that the late Professor Mercury S. Ghilarov, from the Institute of Animal Morphology and Ecology in Moscow, was a great pioneer in soil zoology and a far-sighted scientist in the evolution of terrestrial faunas. Professor Ghilarov agreed that during their evolution insects passed through the soil as a transitional medium from aquatic to terrestrial habitats. His theory, which is based on morphological and physiological observations, fits the thermodynamics of soil water the author describes when considering all porous bodies (porosphere), such as soil and other media, permitting a slow and gradual transition from an aquatic towards a xeric aerial system. In conclusion, a general concept of water accessibility for soil animals is formulated.Dedicated to the late Prof. Dr. M.S. Ghilarov     

Impact of three silvicultural treatments on growth,light-energy processing,and related needle-level adaptive traits of Pinus strobus from two regions

Our goal was to quantify and compare the impact of three silvicultural treatments (STs) on growth, light-energy processing, and needle-level morphological adaptive traits for eastern white pine (Pinus strobus L.) from large, central Ontario (ON) and small, isolated Newfoundland (NL) populations. The interest in STs is to reduce weevil (Pissodes strobi) incidence; however, there are potential adaptive changes and productivity trade-offs. The light levels for the STs were, on average, 100%, 42.0%, and 20.4% transmittance for the full-sun, and intermediate- and high-shade STs, respectively. After 8 years, overall height growth was 4.10, 3.25, and 1.70 m for full-sun, and intermediate- and high-shade STs, respectively (P < 0.001). Across all STs, ON populations had greater total height (14%), basal diameter (12%), current leader length (25%), and tree volume (49%) than NL populations (all P < 0.001). At low light levels (10 and 25 μmol m⁻² s⁻¹), high-shade ST trees had higher photochemical quenching (qP) and lower chlorophyll fluorescence (F_pc) compared with intermediate-shade and full-sun STs. At 100 μmol m⁻² s⁻¹ and beyond, full-sun ST trees had higher qP and lower F_pc than intermediate- and high-shade STs. Average total chlorophyll concentration (CHL) and content (CHLC), and carotenoid concentration (CAR), increased in response to the intermediate-shade ST but did not respond further, or decreased in the high-shade ST. Region was significant for CHL, CAR, chlorophyll a:b and CHL:CAR ratios and CHLC, with ON greater than NL, but was reversed for CHL:CAR ratio. Tree height and volume showed a curvilinear and linear relationship to light level, respectively. Tree height showed a positive linear relationship to qP, apparent photosynthesis, chlorophyll a:b ratio, and needle N (all P < 0.001). Tree height showed a negative linear relationship to F_pc, CHL:CAR ratio, specific needle area, C:N ratio, and needle area N⁻¹ (all P < 0.001). There were modest trade-offs between weevil protection and productivity in the intermediate ST due to the compensatory physiological and morphological adaptations to the limiting light, however, the trade-off with growth at the high-shade level was severe. For NL, consideration should now be given to the introduction and mixing of seed from local seed sources with more southern mainland seed sources, which would decrease the inbreeding effect and provide wider variation for natural selection for a more fit future population.     

中国蒺藜科3种旱生植物的木材解剖适应性

从木材次生木质部特性和径向变异两方面,对中国西部区的蒺藜科的3种旱生植物(Zygophyllumxanthoxylon,Nitrariatangutorum,Tetraenamongolica)进行了对比研究。3树种具有的共同特点为:生长轮分界明显,但是霸王和四合木的年轮有时不连续,半环孔到环孔材,具单穿孔,穿孔板倾斜,导管壁间纹孔互列,木纤维无横隔膜,联合傍管轴向薄壁组织,导管壁上呈现螺纹加厚和异型射线。所选树种明显区别是导管排列方式和导管的数量化指标:四合木导管直径较小,长度较短,频率较大,水分传导安全性增加。其他2种树种之间导管指标没有多大差别,但均比沙冬青的值大。树种导管要素长和纤维要素长的水平变动不规律,树种间和同一树种个体间差异显著。并且对该树种的解剖学特征和沙漠环境的适应性进行了讨论。图19表2参24。     

Life strategies and spatial arrangement of grasses in a Mediterranean ecosystem in Greece

The temporal and spatial distribution, and the life strategies, of fifteen grass species in a Mediterranean evergreen sclerophyllous formation at Petralona (Chalkidiki, Greece) were studied in order to identify the relationships between species, and among species and the environment, which allows for the coexistence of species. The grass species were grouped into (i) early annual species that were characterized by early germination and a relatively long growth period; they did not need excessive resources and were distributed over the entire site, (ii) late annuals that were characterized by late germination and a short growth period; they required resources within this limited period and were competitive in capturing them and so were confined to the most productive sites of the site and (iii) perennial grasses that were characterized by early germination and vegetative reproduction; they were tolerant to nutrient shortages and hence maintained their distribution on the site. The spatial arrangement of species can be considered as a response to the selective pressures of the seasonal water and resource availability in a Mediterranean environment. This environment posed temporal limitations on the activity of early annual and late annual species, which restricts them in time and space. The perennial species overcame this by being flexible in their resource capture and use, because of their ability to store nutrients.     

Anatomical adaptations of three species of Chinese xerophytes （Zygophyllaceae）

Secondary xylem characteristics and horizontal variations were described in three xerophytic species, Zygophyllum xanthoxylon, Nitraria tangutorum, Tetraena mongolica of Zygophyllaceae native to western China. All the species have obvious growth ring boundaries except sometimes discontinuous in T. mongolica and Z xanthoxylum ring to semi-ring-porosity; simple perforation plate; alternate intervessel pitting; non-septate fibres; paratracheal confluent axial parenchyrna; helical thickenings and heterocellular rays. However the vessel arrangement and quantitative features of vessels were different. Vessel elements tend to be shorter and narrower and more frequent in T. mongolica than in other two species that are hardly different could lead to greater conductive safety. The variation of vessel element length and fibre length along radial direction showed irregular tendency. There was significant difference in both fibre length and vessel element length among-tree and within-tree. Furthermore, the relationships between anatomical features and adaptability to desert environments were also discussed.     

Preliminary observations on the natural variation in the endogenous rhythm of the desert Isopod Hemilepistus reaumurii

The desert woodlouse Hemilepistus reaumurii lives in monogamous pairs, together with their offspring, in self-dug burrows. Every burrow contains only one family. This animal is active on the surface from the beginning of spring to autumn. It remains in the burrow during the hottest part of the day, to avoid the heat, but is active at the surface during morning and evening. During the winter, low temperature prevents its above ground activity. Freshly collected animals, from the north of Kairouan (Tunisia) were transferred to a controlled environment cabinet in the laboratory and their locomotor activity monitored as individuals or in male/female pairs, in annular chambers equipped with an infrared activity recording system. For the first 7 days of recording, the animals were kept in a light–dark cycle in phase with the natural diel cycle. For the second 7 days, animals were maintained in constant darkness. The temperature was held constant at 18±1 °C. Analysis of preliminary data indicates that both individuals and pairs exhibit an endogenous rhythm of locomotor activity with a circadian periodicity. Activity was mostly confined to the hours of the photophase (1–7 days) or to those of subjective day (8–14 days). The activity pattern showed two main peaks, around dusk and dawn, respectively. This bimodal circadian rhythm persisted for as long as the experiments were run, and was clearer in individual recording than in pair recording. The characteristics and biological significance of the rhythm are discussed.     

不同生态适应型北美红杉的种植环境及造林地选择

北美红杉造林地选择，根据其不同种源和无性系对不同生态环境的适应能力、生长发育的相似群体归类，并按不同的类型选择相应的造林地：中亚热带至北亚热带相关的常绿阔叶林、常绿落叶阔叶混交林和暖性针叶林植被类型林地，适宜作为温暖湿润生态适应型北美红杉的造林地；中亚热带至北亚热带相关的落叶阔叶林、针阔叶混交林以及中性湿生灌丛植被类型的林地，适宜作为温暖半湿润生态适应型北美红杉的造林地；北亚热带至暖温带相关的针阔叶混交林、针叶林以及以杜鹃、野山茶、苔草等为代表的灌丛植被类型的林地，适宜作为温凉干燥生态适应型北美红杉的造林地；耐低温类型的北美红杉，已能在云南高海拔地带的暗针叶林地区生存，并有一定生长量，值得继续研究，可选择相应的云杉、冷杉，铁杉、高山栎类、桦木、花楸、槭等针阔叶林地作为高寒山地低温环境型北美红杉造林地。云南省有大面积低产林分和宜林荒山，生产潜力较大，其中有适宜不同生态适应型北美红杉造林的环境。利用这一有利条件，发展北美红杉造林，改造这些低产林分和在适宜的荒山造林，将充分利用土地资源，大大提升这些低产林和宜林荒山的经济效益和生态效益。     

Secondary Ambrosia Beetles in Apparently Healthy Trees: Adaptations, Potential Causes and Suggested Research

Some ambrosia beetles are primary attackers of healthy, living trees, but in recent years normally secondary species have been increasingly observed attacking living trees, either as exotics or in their native geographic ranges. We identified five factors that could underlie an increasing prevalence of attack by secondary ambrosia beetles on living trees: (1) early flight before the host tree has recovered the ability to resist attack in the spring, possibly associated with climate change; (2) nutritional independence from the host that may enable ambrosia beetles to feed on ambrosia fungi that live on dead tissue in a living tree; (3) potentially pathogenic fungi that could become more pathogenic with climate change or through hybridization with exotic strains; (4) cryptic behavior that facilitates international transport and the establishment of exotic species and genotypes; and (5) a complex chemical ecology that enables secondary ambrosia beetles to locate stressed living trees that may temporarily appear to be suitable hosts for secondary beetles. We propose four avenues of research that will lead to an increased understanding of attack of living trees by ambrosia beetles, and may facilitate the implementation of effective pest management strategies and tactics: (1) intensive surveys, particularly for exotic beetle species and associated fungal strains; (2) molecular genetics studies that would facilitate the identification of known and new strains and genotypes, particularly of ambrosia fungi; (3) studies of the pathogenicity of ambrosia fungi as well as other fungi that could predispose trees to attack; and (4) investigations of the chemical ecology of tree-attacking species that could lead to new pest management tools and tactics.