Dynamics of soil organic matter in primary and secondary forest succession on sandy soils in The Netherlands: An application of the ROMUL model

We applied the simulation model ROMUL of soil organic matter dynamics in order to analyse and predict forest soil organic matter (SOM) changes following stand growth and also to identify gaps of data and modelling problems. SOM build-up was analysed (a) from bare sand to forest soil during a primary succession in Scots pine forest and (b) on mature forest soil under Douglas fir plantations as an example of secondary succession in The Netherlands. As some of the experimental data were unreliable we compiled a set of various scenarios with different soil moisture regime, initial SOM pools and amount and quality of above and below ground litter input. This allowed us to find the scenarios that reflect the SOM dynamics more realistically. In the Scots pine forest, total litter input was estimated as 0.50 kg m⁻² year⁻¹. Two scenarios were defined for the test runs: (a) forest floor moisture regimes—‘dry, mesic and hydric’ and (b) augmenting a root litter pool with three ratios of needles and branches to roots: 1:1, 1:1.5 and 1:2.0. The scenario finally compiled had the following characteristics: (a) climate for dry site with summer drought and high winter moisture of forest floor; (b) a litter input of 0.25 kg m⁻² year⁻¹ above ground and 0.50 kg m⁻² year⁻¹ below ground; (c) a low nitrogen and ash content in all litter fall fractions. The test runs for the estimation of the initial SOM pools and the amount and proportion of above and below ground litter fall were also performed in the Douglas fir plantation. The inputs of above ground litter tested in various combinations were 0.30 and 0.60 kg m⁻² year⁻¹, and below ground litter 0.30, 0.60 and 0.90 kg m⁻² year⁻¹. The scenario that fitted the experimental data had an SOM pool of 20–25 kg m⁻², an aboveground litter input of 0.6 kg m⁻² year⁻¹and a below ground litter input of 0.9 kg m⁻² year⁻¹. The long-term simulation corresponded well with the observed patterns of soil organic matter accumulation associated with the forest soil development in primary and secondary succession. During primary succession in Scots pine forest on dry sand there is a consistent accumulation of a raw humus forest floor. The soil dynamics in the Douglas fir plantation also coincide with the observed patterns of SOM changes during the secondary succession, with SOM decreasing significantly under young forest, and SOM being restored in the older stands.     

Metabolic specialization of mitochondria from scallop phasic muscles

In fast, glycolytic muscles, oxidative phosphorylation presumably facilitates recuperation from exhaustive exercise and supports growth and maintenance metabolism. Given the shifts in pH with extensive glycolytic activity, the pH optima of mitochondrial processes should indicate whether mitochondria are adapted for recuperation from exercise or for growth and maintenance. We examined this question using mitochondria from the phasic adductor muscle of the scallop, Euvola (Pecten) ziczac, collected from the Golfo de Cariaco, Venezuela in 1992 and 1993. Scallop muscle mitochondria showed well coupled oxidation of glutamate and pyruvate at pH 7.0 and 6.4. The preferred substrates (glutamate, pyruvate and succinate) were oxidized at approximately 40 nmol O₂ min^-1 mg^-1 mitochondrial protein at 25°C, while malate and glutamine were oxidized at 75% and proline at 30% of these rates. Neither palmitoyl carnitine nor aspartate were oxidized. Succinate oxidation was not coupled to ADP utilization at pH 7.0 but was somewhat coupled at pH 6.4. Generally, State 3 rates of oxygen uptake were similar at pH 7.0 and 6.4. Maximal rates of oxidation of glutamate and pyruvate showed broad pH optima. For both glutamate and pyruvate, the highest respiratory control ratio (RCR) values were found at pH 6.5. The saturation curves of scallop muscle mitochondria for pyruvate, glutamate and ADP were well described by the Michaelis-Menten equation. The affinity for pyruvate was greater at pH 6.4 (apparent K _{m, app}=0.013 mM) than at pH 7.0 (K _{m, app}=0.026 mM) while the affinity for ADP (K _{m, app}=0.015 mM) and that for glutamate (K _{m, app}=0.55 mM) changed little with pH. The ADP affinity was the same whether pyruvate or glutamate was the carbon substrate. The combination of maintenance of sensitivity to ADP with an enhanced affinity for pyruvate at acidic pH values should facilitate recuperation from bouts of glycolytic activity. Scallops harvested in September and those harvested in January differed in the maximal rates of glutamate and pyruvate oxidation.     

Cadmium bioaccumulation in organs of the scallopMizuhopecten yessoensis

Cadmium and Zinc content was determined in organs of the Japanese scallopMizuhopecten yessoensis, collected in 1984 from the Sea of Japan and aged between 1 and 8 yr. Under conditions of background Cd, Cd concentration in hepatopancreas and kidney increased linearly with age from 39 to 400µg g^?1 dry wt in hepatopancreas, and from 100 to 640µg g^?1 dry wt in kidney. Such a pattern was not determined for Zn. Cd concentration in muscle, mantle and gill did not exceed 6µg g^?1 dry wt in the oldest scallops. In subcellular fractions of the hepatopancreas, cytosolic Cd accounted for 71.7% in 1-yr-old scallops and 98.8% in 8-yr-olds. A similar ratio was established for gills, although gill Cd content was an order of magnitude lower. Analysis of Cd distribution in cytoplasmic proteins (of different molecular weight) in the hepatopancreas, showed that the amount of Cd bound to metallothionein-like proteins increases with scallop growth. A considerable amount of Cd also was detected in high molecular weight proteins. Thus, Cd accumulation, with age, in organs of the Japanese scallop is due to metal binding by cytoplasmic proteins.     

Intra-familial dispersion patterns in white-footed mice,Peromyscus leucopus

Summary Spatial relationships of white-footed mouse (Peromyscus leucopus) dams and their offspring and of littermates post-weaning were determined to evaluate if their dispersion was sufficient to prevent inbreeding. Mothers tended to leave their first nest site and establish another nest site within or near their original home range. Daughters inherited part of the maternal home range but sons dispersed. During the following breeding season, sons were not in proximity to their mothers or sisters. Daughters, however, frequently attained sexual maturity and bred within the home range of males that could have been their fathers. Differential dispersal of male and female juveniles reduces the probability of mother-son and brother-sister matings, but there is no obvious dispersal-related mechanism to prevent father-daughter matings.     

Survival and productivity benefits to social nesting in the sweat bee <Emphasis Type="Italic">Megalopta genalis</Emphasis> (Hymenoptera: Halictidae)

Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests. After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures, M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate of solitary nest productivity.     

Differential responses of honeybee (<Emphasis Type="BoldItalic">Apis mellifera</Emphasis>) patrilines to changes in stimuli for the generalist tasks of nursing and foraging

Which task a social insect worker engages in is influenced by the worker’s age, genotype and the colony’s needs. In the honeybee, Apis mellifera, genotype influences both the age a worker switches tasks and its propensity of engaging in specialist tasks, such as water collecting, which only some workers will perform. In this study, we used colonies with natural levels of genetic diversity and manipulated colony age demography to drastically increase the stimuli for the generalist tasks of foraging and nursing, which all workers are thought to engage in at some point in their lives. We examined the representation of worker patrilines engaged in nursing and foraging before and after the perturbation. The representation of patrilines among foragers and nurses differed from that of their overall colony’s population. In the case of foraging, over- and underrepresentation of some patrilines was not simply due to differences in rates of development among patrilines. We show that replacement foragers tend to be drawn from patrilines that were overrepresented among foragers before the perturbation, suggesting that there is a genetic component to the tendency to engage in foraging. In contrast, the representation of patrilines in replacement nurses differed from that in the unperturbed nursing population. Our results show that there is a genetic influence on even the generalist tasks of foraging and nursing, and that the way patrilines in genetically diverse colonies respond to increases in task stimuli depends upon the task. The possible significance of this genetic influence on task allocation is discussed. Electronic supplementary material Supplementary material is available in the online version of this article at doi: and is accessible to authorized users.     

Contribution of the Natura 2000 Network to Biodiversity Conservation in Italy

Abstract:  The Natura 2000 network is the most important conservation effort being implemented in Europe. Nevertheless, no comprehensive and systematic region—or nationwide evaluation of the effectiveness of the network has been conducted. We used habitat suitability models and extent of occurrence of 468 species of vertebrates to evaluate the contribution of the Natura 2000 network to biodiversity conservation in Italy. We also estimated the population size of 101 species inside the Natura 2000 network to assess its capacity to maintain or improve the population status of listed species. In general the Italian Natura 2000 did not seem to integrate existing protected areas well. The Natura 2000 network increased from 11% to 20% the area devoted to conservation in Italy and the coverage provided to areas with high biodiversity. Nevertheless, some areas with high numbers of species were devoid of conservation areas, and more than 50% of the highly irreplaceable areas were not considered in the system. Moreover, the Natura 2000 network cannot maintain 44–80% (depending on the taxa considered) of the species in a "favorable conservation status" under World Conservation Union Red List criteria. The Natura 2000 network is probably stronger than the results of our analyses suggest. The system is based on a site-specific expert-based strategy and is driven by direct and detailed knowledge of local diversity. Nevertheless, if Natura 2000 is taken to represent the final point of all the EU conservation policies, it will inevitably fail. Its role in conservation could be enhanced by integrating the Natura 2000 system into a more general strategy that considers natural processes and the ecological and evolutionary mechanisms underlying these processes.     

Metals and organic pollutants in snow surrounding an iron factory

To estimate air pollution snow samples were collected in March 2001 at six sites in the vicinity of the Kostomuksha factory in Karelia. Seventy-two chemical elements and more than 200 individual organic compounds were identified by inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography mass spectrometry (GC-MS). It was found that the levels of Li, B, Al, Fe, Ni, Cu, Zn, Hg, Mn, Mo as well as hydrocarbons, phthalates and phenols exceeded the existing maximum allowable concentrations. A list of toxicants emitted with the factory exhausts and a list of priority pollutants for Kostomuksha were compiled. The impact of the exhausts of the Kostomuksha factory on the environment in Finland is relatively small. Electronic Publication     

Bioaccessibility of arsenic in soils developed over Jurassic ironstones in eastern England

Jurassic ironstones outcropping over parts of eastern England give rise to soils with arsenic concentrations in excess of the UK soil guideline value of 20 mg kg⁻¹ for residential areas. Total arsenic concentrations were determined for 73 ironstone derived soils and bioaccessible arsenic determined using an in vitro physiologically based extraction test. The bioaccessible arsenic concentration for these soils was found to be well below the soil guideline value with a mean concentration of 4 mg kg⁻¹ and a range of 2–17 mg kg⁻¹. The bioaccessible fraction ranges from 1.2 to 33%. Data from a sequential extraction test based on the use of aqua regia as the main extractant is presented for a subset of 20 of the soils. Chemometric data reduction is used to demonstrate that the bioaccessible arsenic is mainly contained within calcium iron carbonate (sideritic) assemblages and only partially iron aluminosilicates, probably berthierine, and iron oxyhydroxide phases, probably goethite. It is suggested that the bulk of the non-bioaccessible arsenic is bound up with less reactive iron oxide phases.     

Three party symbiosis: acoelomorph worms,corals and unicellular algal symbionts in Eilat (Red Sea)

Epizoic worms were found to occur on certain coral colonies from reefs off the coast of Eilat (Red Sea). We identified 14 coral species infested by acoelomorph worms at a depth range of 2–50 m. The host corals were all zooxanthellate and included both massive and branching stony corals and a soft coral. Worms from all hosts were identified as belonging to the genus Waminoa and contained two distinct algal symbionts differing in size. The smaller one was identified as Symbiodinium sp. and the larger one is presumed to belong to the genus Amphidinium. Worm-infested colonies of the soft coral, Stereonephthya cundabiluensis, lacked a mucus layer and exhibited distinct cell microvilli, a phenotype not present in colonies lacking Waminoa sp. In most cases, both cnidarian and Acoelomorph hosts displayed high specificity for genetically distinctive Symbiodinium spp. These observations show that the epizoic worms do not acquire their symbionts from the “host” coral.