Browse results

Changting Wang, Genxu Wang, Yong Wang, Hongbiao Zi, Manuel Lerdau and Wei Liu

Climate change is likely to alter the relative abundances of plant functional groups and the interactions between plants and soil microbes that maintain alpine meadow ecosystems. However, little is known about how warming-induced alterations to aboveground biomass (AGB) affect soil nutrients and microbial communities. We investigated plant community characteristics in 2002–2009 and analyzed soil properties and the soil microbial community in 2007–2009 to study the effects of warming in Qinghai Province, China. Sampling involved the use of warmed open top chambers, the monitoring of plant community characteristics, the quantification of total and available amounts of soil nutrients, and the evaluation of microbial community composition using phospholipid fatty acid (PLFA) analysis. Experimental warming initially significantly increased the number of plant functional groups and plant community AGB; however, plant community diversity and species richness decreased. Nevertheless, all these variables stabilized over time. Fungal and bacterial abundance, total nitrogen, available nitrogen and soil organic matter increased with warming, while microbial PLFAs decreased. These findings demonstrated that climate change drivers and their interactions may cause changes in soil nutrients and the abundance and content of soil microbial PLFAs. Elevated temperature has strong effects on aboveground grass biomass. Surface conditions and disturbance affect the soil microbial communities of deep soil layers.

Royi Zidon, Hagar Leschner, Uzi Motro and David Saltz

Reintroduction of herbivores may play a vital role in restoring ecosystem functions. Here we describe the role of the Persian fallow deer (Dama mesopotamica), reintroduced into Israel, as a vector of seed dispersal by endozoochory. Persian fallow deer have a wide diet both from grazing and browsing. From fecal samples, we found that more than 30 species of plants germinated from the deer pellets. Four of the more common species are considered as ruderal. Of the trees, carob (Ceratonia siliqua) seeds were the only intact seeds found in the fecal samples. We found that ingestion by the deer has a positive effect on expediting the germination of carob seeds – a factor of ecological importance in the reintroduction environment, as it contributes to plant genetic diversity by long-range seed dispersal and to community diversity.

Huan-Huan Xu, Xing-Lan Chen, Yuan-Hao Yang, Xi Zhou and Jia-Xin Yang

Paraquat and juglone generate reactive oxygen species (ROS) and are widely used to investigate defense mechanisms against ROS in model animals. We cloned cDNA encoding hsp70 from the rotifer Asplanchna brightwelli. The full-length cDNA was 2134 bp and had an open reading frame of 1929 bp encoding 642 amino acids. The deduced amino acid sequence indicated that the Asphsp70 was a cytoplasmic protein and has the highest similarity 87% with Mus musculus, 86% identity with orthologs of Danio rerio, 84% with Apis mellifera and 81% with Xenopus laevis. Expression of Asphsp70 was analyzed under 1.25, 2.5, 5 and 10 mg/L paraquat and 6.25, 12.5, 25 and 50 μg/L juglone. With paraquat, mRNA expression of Asphsp70 significantly increased immediately after exposure for 1 h (P < 0.05). Expression of Asphsp70 temporarily increased after exposure to 2.5 mg/L for 3 and 6 h, and after 10 mg/L for 3 h (P < 0.05). With exposure to 6.25 μg/L juglone, mRNA for Asphsp70 significantly increased at 1, 3 and 12 h; with 12.5, 25 and 50 μg/L, mRNA expression of Asphsp70 significantly increased immediately for 1 h (P < 0.05). These results indicated that the Asphsp70 gene was important in the response to oxidative stress.

Özge Özden and David J. Hodgson

Woodlice (Isopoda: Oniscidae) are known to play important roles in soil profile development and nutrient cycling in agroecosystems. The aim of the present work was to understand the impact of different management regimes on woodlouse fauna in Mediterranean olive groves. The olive groves were located along the Kyrenia mountain range towards the north-west of Cyprus at two different elevations. We used pitfall trapping to compare the abundance of woodlice in groves that were (a) uncultivated at low altitude; (b) uncultivated at high altitude; (c) tilled at low altitude; (d) tilled and chemically managed at low altitude. A total of 1751 woodlice were collected and a significant effect of management regime on the abundance of woodlouse was observed. The low altitude uncultivated olive groves retained a higher number of individuals than the other three management regimes. Our results suggest that tillage alone did not impact severely on woodlouse abundance, but that tillage combined with pesticide and fertilizer application could lead to significant losses in woodlouse abundance in olive grove agroecosystems, with implications for the sustainability of soil quality and biodiversity.

Lara Redolfi De Zan, Sarah Rossi de Gasperis, Luigi Fiore, Corrado Battisti and Giuseppe Maria Carpaneto

This study explored the hole-nesting bird community for two years, in three beech forest stands of central Italy. Our experimental design involved 12 replicated sampling points in each study area for a total of 36 sampling points. Stand characteristics were measured through selected environmental variables (tree diameter, tree density, volume of dead wood, diversity of dead wood and canopy closure), to develop habitat models for describing the factors affecting the abundance of hole-nesting birds. We performed generalized linear models to determine which environmental variables better explained the presence and abundance of hole-nesting birds in the three study areas. The species that showed the highest values of abundance are the Nuthatch, the Blue Tit and the Great Tit. Within the guild of hole-nesting birds there are differences in the selection of suitable trees for nesting, roosting or foraging. Primary cavity nesters (woodpeckers) are mostly related to the presence of large trees, the volume of dead wood and tree height. The presence and abundance of secondary cavity nesters (tits, nuthatches and treecreepers) seem to be mostly influenced by diversity of dead wood. The diversity of dead wood is an important variable that influences the presence and abundance of hole-nesting birds. Maintenance of both living and standing dead wood in forest ecosystems is recommended to increase the effectiveness of conservation actions affecting the hole-nesting birds.

Marek Kowalczyk, Andrzej Jakubczak, Beata Horecka, Magdalena Gryzińska and Grażyna Jeżewska-Witkowska

Domestication of dogs involved strong artificial selection. After their introduction into the human environment, dogs were exposed to factors that were not encountered in the wild. The skin and hair are barriers separating the organism from the environment, and melanin plays a significant role in their protective function. The study compared a fragment of the sequence of the DCT gene, which is involved in melanin synthesis, between two species: the dog, which is exposed to similar carcinogenic factors as humans, and the raccoon dog, a species related to the dog but less exposed to anthropogenic factors.

A fragment of the DCT gene 443 base pairs in length was obtained. Two genotypes were distinguished within the raccoon dog population, differing in one nucleotide in the intron sequence (145A>G). Between the DNA profile of the dog and the consensus sequence of the raccoon dog, 18 polymorphic sites were found – 15 in the intron sequence and 3 in the exon sequence. One change in the exon (191G>A) caused an amino acid change (2E>K). The loss of two binding sites for factor SOX10 and one for JUN-FOS was noted in the dog sequence.

On the basis of the sequence analysed, non-coding regions were found to be more susceptible to changes. Polymorphism in introns may affect the transcription profile of the DCT gene. The loss of binding sites for factors SOX10 and JUN-FOS in the dog may be an adaptive change to a different environment with respect to the raccoon dog.

Xian-Ling Xiang, Rui-Ming Jiang, Ying-Ying Chen, Ya-Li Ge, Xin-Li Wen and Yi-Long Xi

The bdelloid rotifer is an important component of freshwater zooplankton, exhibiting the features of parthenogenesis and anhydrobiotic capability. Heat shock proteins (Hsps), acting as molecular chaperones, are a highly conserved, ubiquitously expressed family of stress response proteins. In this study, the thermal optimums for heat-shock response and the levels of Hsp70 in Rotaria rotatoria (bdelloid rotifer) under different stress conditions were evaluated using survival assays and western blotting with fluorescent detection. The results showed that: (1) The survivorship in R. rotatoria were 100% throughout the temperature range of 12°C to 40°C, and the population growth rate reached its culmination at 28°C, suggesting the retardation of growth and reproduction at the other temperatures; (2) While stressed under 40°C, the levels of Hsp70 in R. rotatoria increased significantly over time, correlating with the duration of the stress; (3) As responses to different temperatures, the synthesis of Hsp70 could be induced significantly in R. rotatoria under both of high (40°C) and low (16°C) temperatures; (4) After removal of the thermal stress and recovery at 28°C, the levels of Hsp70 continued to rise for a period of time, peaked at 12 h, and then slowly declined with the extension of recovery duration, until there is no significant difference of Hsp70 levels. Summarily, with the fluctuations of stress duration and temperature, the rotifers could adapt to the environments sensitively by regulating the synthesis of Hsp70.

Naizheng Xu and Xiao Bai

Urban areas are characterized by diverse land-use patterns and are strongly influenced by anthropogenic activities. However, few studies have examined the effects of urbanization on concentrations of soil organic carbon (SOC) and its various components or δ 13C in urban soils. The aim of this study was to assess the spatial distribution of SOC fractions and δ 13C signatures of urban soils in Shanghai, China. The results showed that SOC fractions and δ 13C compositions differ over a range of spatial scales. The concentrations of SOC, readily oxidizable organic carbon (C), black carbon (BC) and δ 13C in surface soils (0–20 cm) were 10.5, 3.5, 6.9 g kg–1 and –24.9%, respectively, and the corresponding concentrations in deep soils (20–100 cm) were 8.4, 2.8, 6.0 g kg–1 and –23.9%. In urban soils, BC accounted for a higher proportion of the SOC pools. Concentrations of SOC, readily oxidizable organic C and BC were higher, whereas the 13C ratio was much lower in the city centre. The effects of carbon isotope fractionation were also more evident in the central urban area. The results also indicated that not only the concentrations of readily oxidizable organic C and BC but also the δ 13C values were related to the time since the soils were converted to urban use. Differences in the time since urbanization and the severity of the associated environmental impacts can be assessed using SOC fractions and δ 13C isotopic compositions because observed changes in these quantities can be attributed to the strong influence of anthropogenic activities.

Douglas W. Morris

Most organisms live in heterogeneous environments. Yet we know little about how variations in scales of heterogeneity influence decisions on patch use and habitat selection, and how they impact spatial distribution and evolution. In particular, we need to know whether the choice of habitats and patches emerges from a hierarchy of decisions, whether resource consumption correlates closely with space use, and whether different types of individuals are associated with patterns of spatial distribution. I address these knowledge gaps with field experiments that manipulated the risk and quality of foraging patches exploited by male meadow voles. I used clear versus wooden covers to create risky versus safe foraging sites and added supplemental food to create rich versus poor habitats. I assessed whether the resources harvested from each tray matched its frequency of use by groups of voles expressing different temperament scores. Habitat and patch use did not fit a simple hierarchy of decisions because animals merged space use and foraging speed in a sophisticated strategy of risk management. Giving-up densities mirrored activity densities at the scale of safe versus risky patches but not at the scale of safe versus risky or rich versus poor habitats. Voles tended to prefer one habitat over another for reasons independent of the experimental manipulations. Groups of voles with different temperament scores were not linked to foraging types but were linked to habitat preference. The bias in habitat use by different behavioural types provides a potential mechanism for the evolutionary divergence of populations occupying different habitats.