Landscape Variation in Tree Species Richness in Northern Iran Forests

Mapping landscape variation in tree species richness (SR) is essential to the long term management and conservation of forest ecosystems. The current study examines the prospect of mapping field assessments of SR in a high-elevation, deciduous forest in northern Iran as a function of 16 biophysical variables representative of the area’s unique physiography, including topography and coastal placement, biophysical environment, and forests. Basic to this study is the development of moderate-resolution biophysical surfaces and associated plot-estimates for 202 permanent sampling plots. The biophysical variables include: (i) three topographic variables generated directly from the area’s digital terrain model; (ii) four ecophysiologically-relevant variables derived from process models or from first principles; and (iii) seven variables of Landsat-8-acquired surface reflectance and two, of surface radiance. With symbolic regression, it was shown that only four of the 16 variables were needed to explain 85% of observed plot-level variation in SR (i.e., wind velocity, surface reflectance of blue light, and topographic wetness indices representative of soil water content), yielding mean-absolute and root-mean-squared error of 0.50 and 0.78, respectively. Overall, localised calculations of wind velocity and surface reflectance of blue light explained about 63% of observed variation in SR, with wind velocity accounting for 51% of that variation. The remaining 22% was explained by linear combinations of soil-water-related topographic indices and associated thresholds. In general, SR and diversity tended to be greatest for plots dominated by Carpinus betulus (involving ≥ 33% of all trees in a plot), than by Fagus orientalis (median difference of one species). This study provides a significant step towards describing landscape variation in SR as a function of modelled and satellite-based information and symbolic regression. Methods in this study are sufficiently general to be applicable to the characterisation of SR in other forested regions of the world, providing plot-scale data are available for model generation.     

Species Richness Pattern along Altitudinal Gradient in Central European Beech Forests

The unimodal species richness-altitude distribution pattern seems to be universal. To investigate the validity of this phenomenon in homogeneous substrate and vegetation conditions, we sampled beech-dominated forests in five volcanic mountain ranges in the Western Carpathians. European beech (Fagus sylvatica L.) formed monodominant closed-canopy stands at altitudes from 300 to 1,200 m. Along this gradient, the influence of beech on understory plant species richness was expected to be strong and uniform. The shape of the species richness-altitude relationship was analyzed for three datasets: herb layer, shrub layer, and both layers merged together. Contrary to prediction, the studied species richness-altitude relationship was inversely unimodal, with a minimum at intermediate altitudes. Quadratic regression models were statistically significant for all three datasets (P<0.001) and the explained variability ranged from 12 % to 20 %. The possible explanation for the observed pattern is twofold. In the central part of the altitudinal gradient, low species richness is due to strong competition by monodominant beech with accumulation of leaf litter and uptake soil resources, mainly water. This influence is somewhat released towards the margins of the gradient. Secondly, the species pool from the neighbouring communities increases species richness only in the lower parts of the altitudinal gradient.     

Plant Traits Rather than Species Richness Explain Ecological Processes in Subtropical Forests

Ecosystems - Functional traits and species richness have been used to assess variation in ecological functions in multiple ecosystems. However, biodiversity effects on ecosystem functioning could...     

赤腹松鼠在人工林中的危害特征

2008年3月～2009年3月,设置15个固定样地每月监测,对四川省洪雅县柳杉Crypotomeria fortunei和杉木Cunninghami lanceolata人工混交林中赤腹松鼠Callosciurus erythraeus的危害特征进行调查研究,结果表明:1) 2～7月是危害的主要时期,其中3、4月最高;柳杉的年平均危害株率高于杉木,但两者的年平均危害程度区别不大;2)不同龄林的危害情况不同,月平均危害株率:中林显著高于成林和幼林(P<0.05);月平均危害程度:幼林高于中林,中林高于成林,三者差异显著(P<0.05);3)林木被危害的部位主要集中在上部和中部;不同龄林危害部位的分布不同,成林和中林的危害部位比例为上部>中部>下部,而幼林是中部>上部>下部;4)啃剥树皮类型以包含木栓、木栓形成层和次生韧皮部的树皮为主,同时有少数外周皮;啃剥外周皮的现象出现在2～4月和7～11月.     

Odor Uniformity among Tomato Individuals in Response to Herbivore Depends on Insect Species

Plants produce specific volatile organic compound (VOC) blends in response to herbivory. Herbivore-induced blends may prime the plant for future attack or attract carnivorous insects; these responses have been considered adaptive for plants. If herbivores differentially modify the VOC emission among individuals within a group of plants they feed upon, then plant responses to herbivores will not only produce specific blends but also variation in odor among individuals, i.e. individuals smell the same, then having a uniform odor. We investigated the VOC emission variation or uniformity among tomato individuals (Solanum lycopersicum L. cv. Castlemart) in response to moderate wounding by (1) nymphs of the psyllid Bactericera cockerelli (Sulc.) (TP); (2) Lepidoptera chewing-feeding larvae of Fall Armyworm (Spodoptera frugiperda Smith) (FAW) and (3) of Cabbage Looper (Trichoplusia ni Hübner) (CL), and (4) mechanical damage (MD). We used a ratio-based analysis to compare the fold-change in concentration from constitutive to induced VOC emission. We also used size and shape analysis to compare the emission of damaged and non-damaged individuals. Aside of finding herbivore-specific blends in line with other studies, we found patterns not described previously. We detected constitutive and induced odor variation among individuals attacked by the same herbivore, with the induced odor uniformity depending on the herbivore identity. We also showed that the fold-change of VOCs from constitutive to induced state differed among individuals independently of the uniformity of the blends before herbivore attack. We discuss our findings in the context of the ecological roles of VOCs in plant-plant and plant-carnivore insects’ interactions.     

Climatic and Catchment-Scale Predictors of Chinese Stream Insect Richness Differ between Taxonomic Groups

Little work has been done on large-scale patterns of stream insect richness in China. We explored the influence of climatic and catchment-scale factors on stream insect (Ephemeroptera, Plecoptera, Trichoptera; EPT) richness across mid-latitude China. We assessed the predictive ability of climatic, catchment land cover and physical structure variables on genus richness of EPT, both individually and combined, in 80 mid-latitude Chinese streams, spanning a 3899-m altitudinal gradient. We performed analyses using boosted regression trees and explored the nature of their influence on richness patterns. The relative importance of climate, land cover, and physical factors on stream insect richness varied considerably between the three orders, and while important for Ephemeroptera and Plecoptera, latitude did not improve model fit for any of the groups. EPT richness was linked with areas comprising high forest cover, elevation and slope, large catchments and low temperatures. Ephemeroptera favoured areas with high forest cover, medium-to-large catchment sizes, high temperature seasonality, and low potential evapotranspiration. Plecoptera richness was linked with low temperature seasonality and annual mean, and high slope, elevation and warm-season rainfall. Finally, Trichoptera favoured high elevation areas, with high forest cover, and low mean annual temperature, seasonality and aridity. Our findings highlight the variable role that catchment land cover, physical properties and climatic influences have on stream insect richness. This is one of the first studies of its kind in Chinese streams, thus we set the scene for more in-depth assessments of stream insect richness across broader spatial scales in China, but stress the importance of improving data availability and consistency through time.     

Specialist Insect Herbivore and Light Availability Do Not Interact in the Evolution of an Invasive Plant

Release from specialist insect herbivores may allow invasive plants to evolve traits associated with decreased resistance and increased competitive ability. Given that there may be genetic trade-off between resistance and tolerance, invasive plants could also become more tolerant to herbivores. Although it is widely acknowledged that light availability affects tolerance to herbivores, little information is available for whether the effect of light availability on tolerance differ between the introduced and native populations. We conducted a common garden experiment in the introduced range of Alternanthera philoxeroides using ten invasive US and ten native Argentinean populations at two levels of light availability and in the presence or absence of a specialist stem-boring insect Agasicles hygrophila. Plant biomass (total and storage root biomass), two allocation traits (root/shoot ratio and branch intensity, branches biomass/main stem biomass) and two functional traits (specific stem length and specific leaf area), which are potentially associated with herbivore resistance and light capture, were measured. Overall, we found that A. philoxeroides from introduced ranges had comparable biomass and tolerance to specialist herbivores, lower branch intensity, lower specific stem length and specific leaf area. Moreover, introduced populations displayed higher shade tolerance of storage root biomass and lower plastic response to shading in specific stem length. Finally, light availability had no significant effect on evolution of tolerance to specialist herbivores of A. philoxeroides. Our results suggest that post-introduction evolution might have occurred in A. philoxeroides. While light availability did not influence the evolution of tolerance to specialist herbivores, increased shade tolerance and release from specialist insects might have contributed to the successful invasion of A. philoxeroides.     

Influence of Forest Management on the Species Richness and Composition of Wood-inhabiting Basidiomycetes in Swiss Forests

In order to investigate the diversity of wood-inhabiting aphyllophoroid basidiomycetes in Swiss forests, 86 plots of 50 m ² were established. They harboured a total of 3339 samples of woody debris, classified according to three categories (coarse, fine, and very fine woody debris), yielding 238 species of wood-inhabiting fungi. The selected sites cover the main forest types of Switzerland and various degrees of management intensity. A multiple linear regression analysis showed that substrate variation, i.e. differences in the quality of dead wood, including volume, age, degree of decomposition and host tree species, are the most important factors influencing diversity of wood-inhabiting fungi. In addition, a Principle Coordinate Analysis highlighted differences in the fungal communities in the different forest types. The greatest fungal species richness is found on thermophilic deciduous tree and woody shrub species. Fine and very fine woody debris, even present in intensively managed forests, often serve as important refuges for many species. Forests with a recent management intervention were found to be either species poor or species rich. Possible reasons for these differences may lay in forest size and landscape fragmentation, the distance to the nearest species pool or microclimatic factors. In Switzerland intensively managed forests harbour significantly less wood-inhabiting, aphyllophoroid fungi than non-managed or extensively managed forests. This is the case in both deciduous forests and in conifer forests. However, occasionally intensively managed forest will also harbour rare and endangered species.     

BVOC Emissions From a Subarctic Ecosystem,as Controlled by Insect Herbivore Pressure and Temperature

Ecosystems - The biogenic volatile organic compounds, BVOCs have a central role in ecosystem–atmosphere interactions. High-latitude ecosystems are facing increasing temperatures and insect...     

Spatial Coupling of Plant and Herbivore Dynamics: The Contribution of Herbivore Dispersal to Transient and Persistent "Waves" of Damage

Spatial variations in the abundance of insect herbivores and in herbivore damage are both striking an commonplace. The standard explanations for heterogeneity in herbivore attack emphasize spatial variations in plant genetype, soils, or physical environment. Here I examine an alternative hypothesis-that heterogeneity arises in plant-herbivore systems, even in homogeneous environments, as a result of the direct coupling of herbivore movement to herbivore density and plant quality. Using a mathematical model for plant quality and herbivore growth and dispersal, I demonstrate how spatial instabilities about homogeneous steady state values result in both transient and stationary waves of damage to the plant. Key herbivore movement behaviors include the tendendy for herbivores to aggregate over a range of spatial scales for increased feeding efficiency and the tendency for herbivores to move up gradients in plant quality (herbivory-taxis). My approach translates the biased "random walk" behavior of individual herbivores into a continuum partial differential equation model. Analytical and numerical methods are used to demonstrate the nature of the spatio-temporal variations in plant quality and herbivore density.     

Richness, Abundance, and Complementarity of Fruit-feeding Butterfly Species in Relict Sacred Forests and Forest Reserves of Ghana

Sacred forest groves in Ghana are centuries old protected areas that were once part of continuous forest cover but now mostly exist as relict forest patches embedded in an agropastoral landscape. We conducted a year-long survey of the fruit-feeding butterfly fauna of four sacred groves and two forest reserves in the moist semi-deciduous forest zone of Ghana to characterize resident species diversity and complementarity among communities. Joint analysis of frugivorous butterfly diversity at these six forest fragments, which ranged in size from 6 to 5000 ha, was used to evaluate the conservation potential of these ancient indigenous reserves. A total of 6836 individuals were trapped across all sites, representing 79 species and five subfamilies. Community diversity was characterized in terms of, (a) number of species accumulated versus sampling effort, (b) rarefied species richness, (c) nonparametric richness estimates, (d) species evenness, (e) Simpson’s Index of Diversity, and (f) complementarity of communities. Diversity of the fruit-feeding butterfly communities, quantified in terms of both species evenness and rarefied species richness, was higher at the larger forest reserves than at the small sacred forest groves. Additionally, although all sites had species trapped only at that site, the 5000-ha forest reserve harbored a resident community that was clearly distinctive from and more diverse than the other communities including the other forest reserve. Hence, our findings add to the burgeoning body of data that indicates large reserves are the foundation of successful conservation programs. Nonetheless, we found these small forest patches contribute to biodiversity conservation in at least three ways and these are identified and discussed. We also identify a number of species that appear more or less vulnerable to dynamics of forest fragmentation based on changes in their relative abundance across sites and we interpret these data in the context of potential indicator species and theoretical predictions of at-risk species.     

The Herbivore Assemblage, Herbivory and Leaf Chemistry of the Mangrove Kandelia obovata in Two Contrasting Forests in Hong Kong

The herbivore assemblage, intensity of herbivory and factors determining herbivory levels on the mangrove Kandelia obovata (previously K. candel, Rhizophoraceae) were studied over a 13-month period at two forests with contrasting growing conditions in Hong Kong. Mai Po was part of an eutrophic embayment in the Pearl River estuary and generally offered more favourable conditions for mangrove growth, whereas Ting Kok had a rocky substratum and oceanic salinity. Twenty-four insect herbivore species were recorded on K. obovata, with lepidopteran larvae that consume leaf lamina being the dominant species. While leaf litter production was similar at the two forests, herbivory level at Mai Po (mean = 3.9% in terms of leaf area loss) was more severe than that at Ting Kok (mean = 2.3%). Peak herbivory levels were found in summer at both locations (6.5% for Mai Po and 3.8% for Ting Kok). Young leaves of K. obovata at both locations were generally preferred by the herbivores from the period of late spring to summer. Concentrations of most feeding deterrents (ash, crude fibre, and total soluble tannins) were significantly higher in both young and mature leaves at Ting Kok, whereas leaf nutrients (total nitrogen and water) were the same at the two sites. Young leaves at Ting Kok contained about 30% more tannins than their counterparts at Mai Po. Significant differences in leaf chemistry also existed between young and mature leaves at either site. The differences were concomitant with the observed patterns of leaf herbivory on K. obovata, and suggest a potential relationship between environmental quality and plant defence against herbivory.     

Paleoethnobotany: Modern Research Connecting Ancient Plants and Ancient Peoples

Paleoethnobotany is a growing subdiscipline of archaeology that utilizes information from numerous other disciplines to show the relationships between ancient plants and ancient peoples. The two primary disciplines that underlie paleoethnobotanical research are archaeology and botany. As such, the results of ongoing botanical research on taphonomic processes, genetic identification of ancient plant types, pollen analysis, phytoliths analysis, and seed identification directly affect the strength of paleoethnobotanical models of past human behavior. Preserved seeds form a significant portion of the archaeobotanical record. They represent not only the environment that was present when they were deposited but also a connection to the activity and culture of ancient people. Using the type of archaeobotanical remains and the archeological context of the remains, paleoethnobotanists study a diverse range of topics. These topics include, but are not limited to, the use of plants in ancient cultures, the development and rise of agriculture, and the relationship between agriculture and settlement patterns.     

Bayesian Estimation of Sequence Damage in Ancient DNA

Mol. Biol. Evol. 24:1416-1422.     

Signs of Ancient and Modern Exon-Shuffling Are Correlated to the Distribution of Ancient and Modern Domains Along Proteins

Exon-shuffling is an important mechanism accounting for the origin of many new proteins in eukaryotes. However, its role in the creation of proteins in the ancestor of prokaryotes and eukaryotes is still debatable. Excess of symmetric exons is thought to represent evidence for exon-shuffling since the exchange of exons flanked by introns of the same phase does not disrupt the reading frame of the host gene. In this report, we found that there is a significant correlation between symmetric units of shuffling and the age of protein domains. Ancient domains, present in both prokaryotes and eukaryotes, are more frequently bounded by phase 0 introns and their distribution is biased towards the central part of proteins. Modern domains are more frequently bounded by phase 1 introns and are present predominantly at the ends of proteins. We propose a model in which shuffling of ancient domains mainly flanked by phase 0 introns was important in the ancestor of eukaryotes and prokaryotes, during the creation of the central part of proteins. Shuffling of modern domains, predominantly flanked by phase 1 introns, accounted for the origin of the extremities of proteins during eukaryotic evolution.     

Mitochondrial Phylogenomics of Modern and Ancient Equids

The genus Equus is richly represented in the fossil record, yet our understanding of taxonomic relationships within this genus remains limited. To estimate the phylogenetic relationships among modern horses, zebras, asses and donkeys, we generated the first data set including complete mitochondrial sequences from all seven extant lineages within the genus Equus. Bayesian and Maximum Likelihood phylogenetic inference confirms that zebras are monophyletic within the genus, and the Plains and Grevy’s zebras form a well-supported monophyletic group. Using ancient DNA techniques, we further characterize the complete mitochondrial genomes of three extinct equid lineages (the New World stilt-legged horses, NWSLH; the subgenus Sussemionus; and the Quagga, Equus quagga quagga). Comparisons with extant taxa confirm the NWSLH as being part of the caballines, and the Quagga and Plains zebras as being conspecific. However, the evolutionary relationships among the non-caballine lineages, including the now-extinct subgenus Sussemionus, remain unresolved, most likely due to extremely rapid radiation within this group. The closest living outgroups (rhinos and tapirs) were found to be too phylogenetically distant to calibrate reliable molecular clocks. Additional mitochondrial genome sequence data, including radiocarbon dated ancient equids, will be required before revisiting the exact timing of the lineage radiation leading up to modern equids, which for now were found to have possibly shared a common ancestor as far as up to 4 Million years ago (Mya).