Effects of forest management on mating patterns,pollen flow and intergenerational transfer of genetic diversity in wild Arabica coffee (Coffea arabica L.) from Afromontane rainforests

Coffea arabica, the wild ancestor of all commercial Arabica coffee cultivars worldwide, is endemic to the montane rainforests of Ethiopia. These forests, which harbour the most important C. arabica gene pool, are threatened by increasing anthropogenic disturbance, potentially altering the mating patterns, pollen dispersal and maintenance of genetic diversity in C. arabica understorey populations. We genotyped 376 adult coffee shrubs and 418 progenies from three natural unmanaged, and three highly managed coffee populations, using 24 microsatellite markers. Mating system analysis of C. arabica yielded an overall multilocus outcrossing rate of 76%, which contrasts with the common knowledge that C. arabica is a predominantly selfing species. In highly managed coffee populations, paternity could be assigned to 78% of the progenies, whereas in the unmanaged natural coffee populations, only 57% of the progenies could be assigned to a father, indicating reduced long‐distance pollen dispersal in managed forests. Furthermore, the fraction of selfed progenies was significantly higher in managed (23%) than unmanaged (10%) coffee forests. Finally, the lack of spatial genetic structure in all studied populations suggests high seed dispersal in unmanaged populations, and intense berry harvesting and coffee planting in the managed populations. Our results imply that in situ conservation of the wild gene pool of C. arabica must focus on limiting intensification of coffee forest management, as decreased pollen dispersal and increased selfing in C. arabica in intensively managed populations may increase the risk of genetic erosion. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 76–88.     

Species composition and diversity of small Afromontane forest fragments in northern Ethiopia

In the highlands of northern Ethiopia, remnants of the original Afromontane forest vegetation are largely restricted to church yards and other sacred groves in a matrix of cropland and semiarid degraded savanna. To assess the potential for natural forest regeneration, species composition and diversity of all forest fragments (10) in a study area of 13,000 ha were analyzed in relation to environmental and soil variables. Using a random design and a density of approximately one plot per 2 ha in all fragments, 31 20×20 m plots were sampled. Indicator species analysis and MRPP tests yielded five communities representing two forest types and one degraded savanna habitat. The forest fragments had a species-poor tree and shrub community in which plots were rather homogeneous and most species abundant. NMDS and analysis of variance indicated that a topographical gradient correlated to soil phosphorus, soil depth, stoniness and the proximity to the river system explained the major differences in species composition and separated moist and dry Afromontane forest communities. The grazing intensity further partitioned the habitats. Present communities and their environmental correlates indicate that the secondary climax forest in the area probably consisted of dry Afromontane forest interlaced by broad strips of moist Afromontane forest along rivers and streams and not a continuous, mono-dominant Juniperus forest as is often presumed. Negative effects of the degraded matrix on forest fragments increased with decreasing patch area and increasing shape irregularity. Nevertheless, all remaining fragments are important for their role in the landscape ecology of the region as refuges and species pools and should be protected and managed accordingly. If seed dispersal from forest fragments into exclosures and subsequent tree recruitment are both successful, the vegetation type most likely to establish is Afromontane savanna woodland, and if managed properly, eventually dry Afromontane forest may arise. Increasing the size of small patches and placing forest plantations and exclosures in the vicinity of small forest fragments is expected to yield the most immediate results. This approach may increase the likelihood of patch colonisation by frugivorous forest birds and thus foster the regeneration of native woody species.     

Leaf area index development in temperate oak and beech forests is driven by stand characteristics and weather conditions

Using data from 20 even-aged and homogeneous mature beech and oak study plots in Flanders (Northern Belgium), an analysis of the empirical relationships between the rates of leaf area index (LAI) change throughout the leaf development of 2008 and stand, site and meteorological variables was performed. Species-specific multiple linear regressions were fitted between the rates of LAI change and the predictors for two distinct periods from April until August. After a sharp increase in LAI following budburst, the seasonal LAI development for both species showed a marked period of stationary LAI development over all study plots. The cause for the cessation of LAI growth was assumed to be the decline of air temperature and radiation during this period. Later on, the rate of LAI development restarted similarly in every plot. The influence of weather on LAI development was high and its effects were different between species, with beech mostly affected by radiation and oak negatively related to minimal and maximal values of air temperature. Furthermore, our analysis suggested that stand structural (tree density and stand basal area for both species) and tree growth characteristics (average tree-ring width ratio for oak) variables were major drivers of the LAI development during early spring. Later during the growth period, stand variables became less predominant in affecting LAI development. Site quality variables affected LAI development to a lesser extent. The seasonal LAI development was found very similar among stands. This study adds a more accurate and comprehensive approach to the modelling of LAI development during leaf growth of two important European temperate deciduous forest species.     

The effect of mechanical stimulation on root and shoot development of young containerised Quercus robur and Robinia pseudoacacia trees

Thigmomorphogenesis is a well-studied process in agricultural crops and coniferous trees. Nevertheless, the effects on both shoot and root characteristics for deciduous woody species received little attention so far. In this study, the objective was to understand the effect of aboveground flexing treatments on the development of structural, mechanical and physiological root and shoot characteristics for two deciduous tree species, Black locust (Robinia pseudoacacia L.) and English oak (Quercus robur L.). Flexing treatments were performed using an electromechanical device with a rotating arm touching and bending the plants at regular intervals. A wide range of stem, shoot as well as root system characteristics was measured. The different flexing treatments altered above- and belowground plant development for both species, with strongest effects on Quercus and most significant differences between the control and the unidirectional flexing treatment. Some responses are in accordance with previous findings, such as stem eccentricity and reduced shoot elongation under unidirectional flexing, but others are renewing, such as the lower stomatal density and larger epidermal cell surface for the Quercus plants under variable flexing direction. Despite some common responses, both species frequently differed in the way they were affected. Belowground, Quercus plants under unidirectional flexing invested relatively more in their first order root and deeper second order roots, whereas Robinia plants allocated relatively more to fine root biomass and horizontal shallow roots. Both strategies potentially increased pull-out as well as overturning resistance in their own way. The presented findings are valid for young trees grown in small containers. Based on practical know-how and shortcomings experienced in the course of this experiment, methodological recommendations are formulated. We finally stress the complex variability in growth responses, especially for root systems, observed in different studies and related to dissimilarity in species, soil conditions, plant history or type of mechanical perturbation.     

Impact of avian frugivores on dispersal and recruitment of the invasive <Emphasis Type="Italic">Prunus serotina</Emphasis> in an agricultural landscape

Although seed dispersal is considered to be a key process determining the spatial structure and spread of non-native plant populations, few studies have explicitly addressed the link between dispersal vector behaviour, seed distribution and seedling recruitment to gain insight into the process of exotic species invasion within a fragmented landscape context. The present study analyses the relationship between avian frugivory and spatial patterns of seed deposition and seedling recruitment for an expanding population of the invasive Prunus serotina in a hedgerow network landscape in Flanders, Belgium. We quantified fruit production, observed frugivores, and determined the spatial distribution of bird droppings and P. serotina seedlings. A relatively diverse assemblage of frugivores visited P. serotina seed trees, with Columba palumbus and Turdus merula being by far the most important dispersers. Landscape structure strongly affected dispersal vector behaviour and the spatial distribution of perching birds, droppings and seedlings. Frugivorous birds non-randomly dispersed seeds to perching sites and an association between perching birds, seed deposition and seedling recruitment was found. Results indicate that landscape structure contributes to non-random seed deposition of P. serotina by common local frugivores. Cutting the larger seed trees is proposed as the most feasible measure to slow down the invasion rate.     

Land rehabilitation and the conservation of birds in a degraded Afromontane landscape in northern Ethiopia

The few remaining Afromontane forest fragments in northern Ethiopia and the surrounding degraded, semiarid matrix form a habitat mosaic of varying suitability for forest birds. To evaluate the effect of recent land rehabilitation efforts on bird community composition and diversity, we studied bird species distributions in ten small forest fragments (0.40–20.95 ha), five grazing exclosures (10-year-old forest restoration areas without wood extraction and grazing livestock) and three grazed matrix sites during the rainy season (July–October 2004) using 277 one-hour species counts. Based on the distribution pattern of 146 bird species, sites were assigned to one of three bird communities (birds of moist forest, dry forest or degraded savanna), each occupying a well-defined position along an environmental gradient reflecting decreasing vegetation structure and density. All three communities were representative of the avifauna of Afrotropical Highland open forest and woodland with a high proportion of invasive and competitive generalist species (31%). Apart from these, exclosures shared more species with forest fragments (20%) than did the grazed matrix (5%), indicating local ecosystem recovery. By increasing habitat heterogeneity, exclosures have the potential to enhance landscape connectivity for forest birds and are, therefore, an effective instrument for conserving species in a fragmented landscape. However, 52 bird species (36%) occurred exclusively within forest patches and many forest birds that use exclosures are unlikely to maintain viable populations when forest fragments disappear, particularly as forest fragments may be a critical resource during the hot dry season. This highlights the high conservation value of small isolated forest fragments for less tolerant, forest-limited and/or biome-restricted species.     

A comparative evaluation of corneal epithelial cell cultures for assessing ocular permeability

The purpose of this study was to evaluate the potential value of different epithelial cell culture systems as in vitro models for studying corneal permeability. Transformed human corneal epithelial (HCE-T) cells and Statens Serum Institut rabbit corneal (SIRC) cells were cultured on permeable filters. SkinEthic human corneal epithelium (S-HCE) and Clonetics human corneal epithelium (C-HCE) were received as ready-to-use systems. Excised rabbit corneas (ERCs) and human corneas (EHCs) were mounted in Ussing chambers, and used as references. Barrier properties were assessed by measuring transepithelial electrical resistance, and by determining the apparent permeability of markers with different physico-chemical properties, namely, fluorescein, sodium salt; propranolol hydrochloride; moxaverine hydrochloride; timolol hydrogenmaleate; and rhodamine 123. SIRC cells and the S-HCE failed to develop epithelial barrier properties, and hence were unable to distinguish between the permeation markers. Barrier function and the power to differentiate compound permeabilities were evident with HCE-T cells, and were even more pronounced in the case of C-HCE, corresponding very well with data from ERCs and EHCs. A net secretion of rhodamine 123 was not observed with any of the models, suggesting that P-glycoprotein or similar efflux systems have no significant effects on corneal permeability. Currently available corneal epithelial cell culture systems show differences in epithelial barrier function. Systems lacking functional cell-cell contacts are of limited value for assessing corneal permeability, and should be critically evaluated for other purposes.     

Analysis of the reliability of manual and automated immunohistochemical staining procedures. A pilot study

OBJECTIVE: To study the variation in the number of stained cells and staining intensity comparing 2 immunostainers and manual staining for estrogen receptor (ER) expression in breast carcinoma. STUDY DESIGN: In 5 cases, 15 consecutive paraffin sections were investigated after simultaneous immunohistochemical ER staining. The slides were evaluated using a CM-2 TV image analysis system (Hund, Wetzlar, Germany). One viewing field, identified around a histologic structure present on all 15 sections, was analyzed. The percentage of immunoreactive cells (PP), mean grey values of the immunopositive (GVpos.) and immunonegative nuclei (GVneg.), and immunohistochemical staining intensity (SI, defined as GVneg.-GVpos.) were calculated. RESULTS: The mean PP values were higher for immunostainers A (70.2%) and B (53.8%) than for manual staining (40.8%). The results were significantly different comparing the 2 immunostainers (P = .0143) or immunostainer A and manual staining (P < .0001). Also, the mean SI values were higher for immunostainers A (24.5 +/- 2.8% [CV]) and B (18.5 +/- 31.1%) than for manual staining (10.8 +/- 33.8%). These differences revealed statistical significance comparing the immunostainers with manual staining (.0001 < P = .0048). CONCLUSION: Our results underline the higher staining quality using immunostainers in comparison with manual staining.     

Energy potential for combustion and anaerobic digestion of biomass from low-input high-diversity systems in conservation areas

In this study, we assessed the potential for bioenergy production of Low-Input High-Diversity (LIHD) systems in temperate West-European conservation areas. A wide range of seminatural ecosystems (wet and dry grasslands, marshes, tall-herb vegetation and heathlands) was sampled. Because LIHD biomass is often scattered and discontinuously available, we only considered the potential for anaerobic digestion and combustion. Both technologies are suitable for decentralized biomass utilization. The gross energy yield showed a promising range between 46–277  GJ per hectare per mowing cycle (MC). The energy efficiency of the anaerobic digestion process was rather low (10–30%) with a methane energy yield of 5.5–35.5 GJ ha⁻¹ MC⁻¹, experimentally determined by batch digestion tests. The water content, functional group composition and biochemical composition (hemicellulose, cellulose, lignin and Kjeldahl nitrogen) of the biomass were analyzed to assess the suitability of different valorization pathways. On the basis of the results, we were able to propose recommendations regarding the appropriate conversion techniques. Biomass from plant communities with ‘late’ harvest dates (August–October) or a high fraction of woody species like heathland and dune slacks, is best valorized through combustion, while herbaceous biomass of ‘early’ harvested grasslands (June–July) and tall-herb vegetation can better be digested. The main advantages of the production of bioenergy from LIHD biomass originating from conservation management are the minimization of the competition with food production and its potential to reconcile renewable energy policies and biodiversity goals.