Temporal snychrony and patterns in an exotic host-parasitoid community

We studied an imported host-parasitoid community in Hawaii, asking to what extent the species covaried in a systematic fashion even though all species were exotic to Hawaii, and occurred in an artificial agroecosystem (a commercial guava, Psidium guajava L., orchard). Using knock-down pyrethrin sprays we were able to accurately quantify numbers of the host, [oriental fruit fly, Bactrocera dorsalis (Hendel)] and its four major parasitoid species [Biosteres arisanus (Sonan), Diachasmimorpha longicaudata (Ashmead), Psyttalia incisi (Silvestri), and Bi. vandenboschi (Fullaway)] at hourly intervals. We found that the parasitoids' activity and abundance was well correlated with the activity and abundance of their host, and that all four parasitoid species covaried in concert with one another. In fact, the magnitude of correlation between the different species in this system was greater than the correlation with temperature. This show clearly that an entirely exotic community, reassembled piecemeal as a result of biocontrol efforts, can end up with patterns of temporal covariation that are highly coincident. One other interesting result concerns the speed with which sprayed trees were recolonized by the fruit fly and its parasitoids. The time that it took each species to reach its mean density prior to removal by the first pyrethrin spray at 0600 hours varied. It took 2 h for female B. dorsalis to recolonize guava trees to pre-spray levels. It took 3 h for Bi. arisanus, 4 h for D. longicaudata, 7 h for Bi. vandenboschi and 14 h for P. incisi to reach pre-spray levels. The fact that Bi. arisanus recolonized vacant trees almost as rapidly as did the fruit fly pest suggest that there is little opportunity for the fruit fly to escape in space and time by staying one step ahead of its enemies.     

长白山站的研究数据库管理系统

长白山站的研究数据库管理系统翟永华,赵士洞（中国科学院沈阳应用生态研究所１１００１５）Ｄａｔｅ－ＢａｓｅＭａｎａｇｅｍｅｎｔＳｙｓｔｅｍｉｎＣｈａｎｇｂａｉｓｈａｎＦｏｒｅｓｔＥｃｏｓｙｓｔｅｍＲｅｓｅａｒｃｈＳｔａｔｉｏｎ．￥ＺｈａｉＹｏｎｇｈｕａ...     

Wave-separation in complex systems. Application to brain-signals

A departure from single-system dynamics, that may arise in characterizing self-organized dynamics of complex systems, is dealt with by using the Karhunen-Loève expansion of the trajectory matrix to decompose an experimental signal in a sum of spectral features. For an electroencephalographic -signal, a separation of waves and extraction of additive sub-signals are achieved, each sub-signal covering a well-bounded and physiologically meaningful frequency range. From the subsignals, an attractor that vanishes on phase-randomizing the data is characterized, under conditions where none was found for the recorded signal.     

Succession and fluctuation in the aquatic vegetation of two former Rhône River channels

The vegetation dynamics in two former braided channels of the Rhône River was studied at two time scales in order to test the following hypothesis: fluctuations would occur within seasons (flood disturbances, hydrological fluctuations, phenology) while successions would occur between years. The vegetation was surveyed in 1983, 1988 and 1989 during summer for the interannual investigation, and in spring 1989, summer 1989, winter 1989 and spring 1990 for the seasonal investigation. Terrestrialization, which was observed within the same period in other braided former channels of that river, did not happen here despite the 1989 drought. However, a vegetation zone situated in the upstream part one channel seems to represent some successional trend, resulting in the establishment of Nasturtium officinale and the increasing abundance of Chara vulgaris. In disagreement with the tested hypothesis, only fluctuations are observed at the two temporal scales in the other vegetation zones. The amplitude of cyclic trajectories observed in the seasonal study depends of the degree of hydraulic disturbances (floods, drought) that affects each vegetation zone. The channel that is closer to the river is maintained at a steady state by the periodical inputs of kinetic energy during river overflows and fast floods; the disturbances wash away fine deposits and rejuvenate the vegetation mosaic. In the other former channel that is less disturbed by floods and is characterized by a thick layer of fine sediments, the groundwater inputs from numerous limnocrene springs carry away organic matter and slow down ecological successions.Abbreviations C.A. Correspondence Analysis     

Molecules and Morphology,Phylogenetics and Genetics

Various explanations can be offered for the incongruence between phylogenetic hypotheses resulting from morphological and molecular data sets. Of these, the possibility that incongruence may result from the mutation of major morphogenetic genes leading to dramatic morphological divergence unaccompanied by equivalent change of the phylogenetic marker molecule(s) used is discussed in detail. As evidence for this hypothesis, several examples for such incongruence are surveyed. It seems possible that in many cases the genetic basis of the morphological characters responsible for the incongruence found may be simple, and that the genes involved may be homologous to genes known from mutant systems. It is suggested that: 1. the systematic documentation of incongruence between molecular and morphological phylogenies may help to assess the frequency of evolutionary change through the mutation of major morphogenetic genes, and that 2. the identification of major morphological characters distinguishing closely related taxa with mutant phenotypes known from mutant systems eventually may allow an experimental approach to the problem of evolutionary change resulting from major genes. Natural taxa suspected to be the result of such processes could be changed morphologically through transformation with the relevant genes.     

Significant increase in natural disturbance impacts on European forests since 1950

Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long-term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground-based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m³ of disturbed timber volume per year over the 70-year study period. This value is likely a conservative estimate due to under-reporting, especially of small-scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m³/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long-term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes.     

The unexpected long period of elevated CH4 emissions from an inundated fen meadow ended only with the occurrence of cattail (Typha latifolia)

Drainage and agricultural use transform natural peatlands from a net carbon (C) sink to a net C source. Rewetting of peatlands, despite of high methane (CH₄) emissions, holds the potential to mitigate climate change by greatly reducing CO₂ emissions. However, the time span for this transition is unknown because most studies are limited to a few years. Especially, nonpermanent open water areas often created after rewetting, are highly productive. Here, we present 14 consecutive years of CH₄ flux measurements following rewetting of a formerly long-term drained peatland in the Peene valley. Measurements were made at two rewetted sites (non-inundated vs. inundated) using manual chambers. During the study period, significant differences in measured CH₄ emissions occurred. In general, these differences overlapped with stages of ecosystem transition from a cultivated grassland to a polytrophic lake dominated by emergent helophytes, but could also be additionally explained by other variables. This transition started with a rapid vegetation shift from dying cultivated grasses to open water floating and submerged hydrophytes and significantly increased CH₄ emissions. Since 2008, helophytes have gradually spread from the shoreline into the open water area, especially in drier years. This process was periodically delayed by exceptional inundation and eventually resulted in the inundated site being covered by emergent helophytes. While the period between 2009 and 2015 showed exceptionally high CH₄ emissions, these decreased significantly after cattail and other emergent helophytes became dominant at the inundated site. Therefore, CH₄ emissions declined only after 10 years of transition following rewetting, potentially reaching a new steady state. Overall, this study highlights the importance of an integrative approach to understand the shallow lakes CH₄ biogeochemistry, encompassing the entire area with its mosaic of different vegetation forms. This should be ideally done through a study design including proper measurement site allocation as well as long-term measurements.     

Longitudinal growth of head circumference in Punjabi infants in Chandigarh (India)

One hundred and fifty four (86 male and 68 female) Punjabi infants residing in Chandigarh (India) were longitudinally measured for head circumference at monthly age intervals during first year of life. The general pattern of growth of head circumference was characterised by initial sharp rise followed by slow gain during second half of infancy. Beyond birth male infants, possessed higher and statistically significant mean values than their female counterparts. The pattern-wise similarity between growth curves plotted for Punjabi and Western infants, may be attributed to protective effects of breast feeding. Head circumference velocity showed rapid deceleration immediately after birth up to about 4 months, thereafter, it declined slowly. Sex differences in monthly growth rates were found to be statistically significant (p<0.05) at a few of the age intervals during first year of life.     

Latent group detection in functional partially linear regression models

In this paper, we propose a functional partially linear regression model with latent group structures to accommodate the heterogeneous relationship between a scalar response and functional covariates. The proposed model is motivated by a salinity tolerance study of barley families, whose main objective is to detect salinity tolerant barley plants. Our model is flexible, allowing for heterogeneous functional coefficients while being efficient by pooling information within a group for estimation. We develop an algorithm in the spirit of the K-means clustering to identify latent groups of the subjects under study. We establish the consistency of the proposed estimator, derive the convergence rate and the asymptotic distribution, and develop inference procedures. We show by simulation studies that the proposed method has higher accuracy for recovering latent groups and for estimating the functional coefficients than existing methods. The analysis of the barley data shows that the proposed method can help identify groups of barley families with different salinity tolerant abilities.