Intermediate Shade Research Articles

Instrumental and Visual Evaluation of the Chameleon Effect of Single-shaded Composite Resins.

To evaluate the shade-matching ability of single-shade resin-based composite restorations in different thicknesses using both instrumental and visual techniques. Cavities with 4 mm diameter and 2 mm (n=96) or 3 mm (n=96) depth were prepared in acrylic incisor teeth of shades A2, A3, B3, and C2 and restored with three single-shade resin composites, Omnichroma (Tokuyama Dental America, Encinitas, CA, USA [OM]), Vittra APS Unique (FGM Dental Group, Joinville, SC, Brazil [VU]), Zenchroma (President Dental, Allershausen, Germany [ZC]), and a microhybrid resin composite (Filtek 3M Z250 3M ESPE, St Paul, MN, USA [FZ]) of A2, A3, B3, and C2 shades. Readings were obtained using VITA Easyshade V spectrophotometer for the teeth and restorations. The CIEDE2000 (ΔE00) color difference formula was used, and the values were assessed using three-way analysis of variance (ANOVA). Forty-eight evaluators graded the shade match of 32 different specimens visually as (A) best shade match, (B) intermediate shade match, and (C) poor shade match. FZ material achieved satisfactory matches for both thicknesses, across all shades, and OM material demonstrated statistically significant lower shade matches than the ZC and the FZ materials (p<0.05). VU exhibited poor shade match with the highest ΔE00 value on C2 shade. According to the visual examination, the best shade matches were observed for FZ on A3-shade and ZC on C2-shade teeth. Shade matching for 2 mm and 3 mm-thick composite resin restorations is material- and tooth-shade dependent.

Effects of different shading levels on the growth of Bornmuellera emarginata, a nickel hyperaccumulator for use in agromining

AbstractThe Greek endemic Bornmuellera emarginata, known for its Ni hyperaccumulation capacity, is a promising candidate species for use in agromining. At the same time, the installation of photovoltaic systems on agricultural land has recently been increasing. Field observations that populations of this species usually occupy shaded places under shrubs or trees led us to study the effect of different shading levels on the growth of B. emarginata, with a view to combine the cultivation of the species with photovoltaic panels in the same area. The experiment was conducted under greenhouse conditions and lasted 210 days after sowing (DAS). Seeds were sown directly into 2‐L pots filled with ultramafic soil collected from the field. Three plant samplings (81, 140, and 210 DAS) were conducted during the experiment to determine a set of morphological and physiological parameters of the species (fresh and dry plant biomass, plant height, number of lateral shoots, total number of leaves, proline and chlorophyll concentrations) alongside with its nickel yield at different levels of shading (0%, 20%, 35%, 60%, and 90%). Growth of B. emarginata was only significantly affected at the highest shading level. Nickel yield of the species increased over time and was maximized at the end of the experiment. The highest nickel yield per plant was observed at the intermediate shading level (35%). Bornmuellera emarginata can be considered as a candidate nickel hyperaccumulator for cultivation in ultramafic or nickel‐polluted areas under photovoltaic panels with corresponding shading, providing important environmental benefits.

Heat stress conditions affect the social network structure of free-ranging sheep.

Extreme weather conditions, like heatwave events, are becoming more frequent with climate change. Animals often modify their behaviour to cope with environmental changes and extremes. During heat stress conditions, individuals change their spatial behaviour and increase the use of shaded areas to assist with thermoregulation. Here, we suggest that for social species, these behavioural changes and ambient conditions have the potential to influence an individual's position in its social network, and the social network structure as a whole. We investigated whether heat stress conditions (quantified through the temperature humidity index) and the resulting use of shaded areas, influence the social network structure and an individual's connectivity in it. We studied this in free-ranging sheep in the arid zone of Australia, GPS-tracking all 48 individuals in a flock. When heat stress conditions worsened, individuals spent more time in the shade and the network was more connected (higher density) and less structured (lower modularity). Furthermore, we then identified the behavioural change that drove the altered network structure and showed that an individual's shade use behaviour affected its social connectivity. Interestingly, individuals with intermediate shade use were most strongly connected (degree, strength, betweenness), indicating their importance for the connectivity of the social network during heat stress conditions. Heat stress conditions, which are predicted to increase in severity and frequency due to climate change, influence resource use within the ecological environment. Importantly, our study shows that these heat stress conditions also affect the animal's social environment through the changed social network structure. Ultimately, this could have further flow on effects for social foraging and individual health since social structure drives information and disease transmission.

How does shading mitigates the water deficit in young Hymenaea courbaril L. plants?

Information on tolerance to isolated or combined abiotic stresses is still scarce for tree species, although such stresses are normal in nature. The interactive effect of light availability and water stress has been reported for some native tree species in Brazil but has not been widely investigated. To test the hypothesis that shading can mitigate the stressful effect of water deficit on the photosynthetic and antioxidant metabolism and on the growth of young Hymenaea courbaril L. plants, we evaluated the following two water regimes: a) continuous irrigation - control (I) - 75% field capacity. and b) water deficit (S), characterized by irrigation suspension associated the two following periods of evaluation: P0 - when the photosynthetic rate of plants subjected to irrigation suspension reached values ​​close to zero, with the seedlings being re-irrigated at that moment, and REC - when the photosynthetic rate of the re-irrigated plants of each shading levels reached values ​​similar to those of plants in the control treatment, totaling four treatments: IP0, SP0, IREC, and SREC. The plants of these four treatments were cultivated under the four following shading levels: 0, 30, 50, and 70%, constituting 16 treatments. Intermediate shading of 30 and 50% mitigates the water deficit and accelerates the recovery of H. courbaril. Water deficit associated with cultivation without shading (0%) should not be adopted in the cultivation or transplantation of H. courbaril. After the resumption of irrigation in the REC, the other characteristics presented a recovery under all cultivation conditions. Key message: Intermediate shading of 30 and 50% mitigates the water deficit and accelerates the recovery of H. courbaril.

DISTRIBUTION, ECOLOGY AND REPRODUCTION OF BRYOPHYTES IN A PRESERVED REMNANT OF ATLANTIC FOREST IN SOUTH OF BAHIA, BRAZIL

The continuous and intense process of habitat loss and fragmentation has reduced the Atlantic Forest to less than 12% of its original area, with 80% of the remaining fragments smaller than 50 ha and only 9% protected within conservation units. One of the largest Brazilian Atlantic Forest remnants is protected inside the Una Biological Reserve – REBIO Una and Una Wildlife Refuge – REVIS UNA (designated here as “Una Region”). Una Region has fundamental importance to many biological groups due to their endemic species, most of them threatened, but with regard to bryophytes in Una Region there are still knowledge gaps. We carried out a bryofloristic survey in Una Region and analyzed floristic, ecological and reproductive aspects of the bryoflora. Bark, leaf and decaying wood samples were collected within 15 10 x 10 m plots resulting in the identification of 140 species (95 liverworts and 45 mosses), including five new records for Bahia State and 11 for the Northeastern region of Brazil, one endangered (EN) species, and one species recently described. Richness estimators revealed high proportions of undetected species, varying according to substrate type. The bryoflora was dominated by life forms of intermediate desiccation tolerance and shade specialists. Asexual or sexual reproductive structures were observed in nearly 60% of the species. Our results indicate that Una Region plays a fundamental role in the maintenance of the taxonomic, functional and genetic diversity of bryophytes and in the conservation of this group not only in Bahia, but also in the Atlantic Forest.

EFFECTS OF ARTIFICIAL SHADING AND IRRIGATION WITH BRACKISH WATER ON THE INITIAL DEVELOPMENT OF Anadenanthera colubrina (Vell.) Brenan PLANTS

ABSTRACT The use of management strategies or changes in the cultivation environment can reduce the impacts of irrigation water salinity on plant development. Therefore, in this research, physiological responses, initial growth, and plant quality of Anadenanthera colubrina (Vell.) Brenan (Angico Branco) were evaluated under different levels of shading and electrical conductivity of the irrigation water, seeking to identify the most favorable conditions for the development of this species using brackish water. The experiment was carried out in randomized blocks with split plots and four replications. The plots were formed by four environments with different shading levels: 0 (full sun), 30, 50, and 70%, and the subplots, formed by five increasing levels of electrical conductivity of the irrigation water: 0.4, 1.6, 2.8, 4.0, and 5.2 dS.m−1. The following variables were evaluated: substrate electrical conductivity, leaf gas exchange, plant height, biomass production, and Dickson quality index at 40 days in a nursery. The use of artificial shading favored plant development and photosynthesis rate, even when irrigated with moderate and high salinity water. The DQI showed that A. colubrina plants presented higher quality index when produced under intermediate shading (30% and 50%), with yield losses below 20% when irrigated with water with electrical conductivity up to 2.8 dS.m−1.

Stomatal size and density trade-off varies with leaf phenology and species shade tolerance in a South Asian moist tropical forest

The density and guard cell length of stomata regulate the physiological processes in plants. Yet, the variation of stomatal characteristics among different functional groups of trees is not been well understood. Particularly, a comprehensive understanding of stomatal behaviour in Bangladeshi moist forest trees is lacking. The study investigated how abaxial stomatal density (SD) and guard cell length (GCL) vary among tree functional types and leaf phenological groups in a moist tropical forest of Bangladesh. Cluster dendrogram revealed three groups of species based on SD and GCL. The independent sample t -test showed that there was a significant difference in SD between evergreen and deciduous tree species (t =4.18, P <0.001) but no significant difference in GCL between the two phenological groups. ANOVA revealed no significant difference in SD among the light demanding, intermediate shade tolerant and shade tolerant species (F =0.76, P =0.47). However, GCL significantly differed among the three functional groups (F =3.3, P <0.05). Maximum theoretical stomatal conductance (g max ) varied between evergreen and deciduous species but did not vary with species shade tolerance. In general, there was a significant trade-off between SD and GCL. However, the inverse relationship was stronger in deciduous and shade tolerant species than in evergreen and shade intolerant species. Leaf dry matter content was positively related with SD and negatively related with GCL. Specific leaf area and leaf thickness were not related to the stomatal traits. Our analyses suggest that leaf phenology and species shade tolerance need to be considered while estimating gas exchange through the stomata in tropical moist forests.

Effect of shade on the diversity of termites (Isoptera) in different cocoa agroforestry systems in the Nawa region (Côte d’Ivoire)

Termites are gradually being recognized as emerging pests and a major constraint to the sustainable production of cocoa in Côte d’Ivoire, the world’s leading cocoa producer. In order to develop environmentally compatible management strategies against the pest species, it is important to identify the termite species in these systems and have a better understanding of their functional diversity. This study was conducted to evaluate the effect of shade management on the diversity of termites in different cocoa growing systems in the Nawa area, one of the main cocoa producing areas in Côte d'Ivoire. The study also evaluated the effect of shade cover on termite damage to cocoa. Sampling was done using a modified standardized transect method, where termites were collected in 25 m x 2 m transects, placed in 30 m x 30 m quadrats. Termites sampled were identified and grouped according to feeding habits. Twenty-nine (29) termite species, in 17 genera and 7 subfamilies under 3 families were sampled. These termite species are distributed among the four feeding groups. Fungus-growers and wood-feeders were the most diversified. The intermediate shade systems were the least attacked by termites compared to the full sun system and shaded system. Shade therefore, seems to influence termite biodiversity and damage in cocoa agroforestry systems. We recommend awareness-raising and assistance from cocoa farmers on shade management and the choice of an appropriate cropping system such as an intermediate shade system that would reduce termite attacks, produce long term and preserve biodiversity.

Optimizing sexual reproduction of Montipora capitata for restoration: effects of abiotic conditions and light acclimation on juvenile survival and growth

The worldwide decline of coral reefs necessitates development of tools and methods for active conservation of reef structures and their ecological function. Aquaculture of sexually produced corals is a potential strategy for reef restoration efforts, but existing methods require greater scalability and optimization. To address these needs, we reared Montipora capitata larvae from Kāne’ohe Bay and raised them in an ex situ facility to examine patterns of growth and survivorship under different abiotic conditions, building from previous best practices and manipulating light levels during early life-history stages. Larvae were reared using different stocking densities and settled at varied densities (25, 125, and 225 larvae per plug) on conditioned plugs (1 or 4 wk). Juveniles were raised and tracked under different flow, shade, and light acclimation regimes for 135 d. Results show that recruitment increased with settlement density. Juvenile survivorship was maximized in high flow and intermediate shade levels, while growth was maximized by low shade environments in both aggregate and individual settlers. Light acclimation treatments yielded intermediate survivorship and tradeoffs between growth and survival compared to corals reared in static shade conditions. Importantly, no abiotic treatment combinations optimized growth and survivorship simultaneously. This study demonstrates interactions of abiotic factors and provides insight into how they can be manipulated to scale the sexual reproduction of corals for conservation.

Shade tree canopy cover affects coffee plant traits across elevations in coffee farms in southwest Ethiopia

Coffee is an important crop in the global south. However, ongoing changes in the climate system reinforce the need to quantify coffee plants' ecological and eco‐physiological traits to assure coffee production in the future. One way to assess how environmental changes affect coffee performance is via leaf traits, most notably leaf carbon and nitrogen concentrations (to reflect the nutrient status), leaf stable carbon isotope composition (δ13C) to determine intrinsic water use efficiency (WUEi), and specific leaf area (SLA) to describe carbon gain relative to water loss within a plant canopy as these traits are related to yields. Therefore, we sampled coffee plants growing at contrasting elevations using a space‐for‐time substitution approach for warming and superimposed a canopy cover gradient to assess whether increasing canopy cover could modulate responses to temperature. Three coffee shrubs were sampled in each of 59 coffee farms in southwest Ethiopia across elevations of 1500–2160 m a.s.l. and along canopy cover gradients from open to deep shade. Soil nutrient concentrations, light availability, soil temperature and moisture were quantified for each coffee shrub. Elevation and shade tree canopy cover significantly and interactively affected WUEi. Elevation was found to be the driving factor for microclimate and soil factors which indirectly influenced both SLA and WUEi. Both of these coffee leaf traits are moderately governed by soil temperature whereas leaf N and C:N are mainly controlled by soil temperature and soil chemical variables. As elevation increased, WUEi kept increasing at light (&lt; 35%) to intermediate shade levels (35–65%), and the values decreased at dense shade levels (65–100%) at high elevations, suggesting that coffee plants growing at high elevations with light shade can assimilate more CO2with minimum evaporative water loss. SLA declined with elevation. Leaf N and leaf C:N responded negatively and positively to shade canopy cover, respectively. In sum, elevation and canopy cover interactively determined microclimate and coffee leaf traits. Our findings are useful to adjust the intensity of shade, along with other tree‐level management tools, to modulate climate‐change effects on coffee at the farm level.

Organic Farming Practices and Shade Trees Reduce Pest Infestations in Robusta Coffee Systems in Amazonia.

Coffee agroforestry systems could reconcile agricultural and environmental objectives. While pests and diseases can reduce yield, their interactions with shade and nutrition have been rarely researched, and are particularly lacking in perennial systems. We hypothesized that intermediate shade levels could reduce coffee pests while excess shade could favor fungal diseases. We hypothesized that organic rather than mineral fertilization would better synchronize with nutrient uptake and higher nutrient inputs would be associated with reduced pest and disease damage due to higher plant vigor, yet effects would be less obvious in shaded plots as coffee growth would be light-limited. Using three-year-old trees of Coffea canephora var. Robusta (robusta coffee) in the Ecuadorian Amazon, we compared a full-sun system with four shading methods creating different shade levels: (1) Myroxylon balsamum; (2) Inga edulis; (3) Erythrina spp.; or, (4) Erythrina spp. plus Myroxylon balsamum. Conventional farming at either (1) moderate or (2) intensified input and organic farming at (3) low or (4) intensified input were compared in a split-plot design with shade as the main plot factor and farming practice as the sub-plot factor. The infestation of the following pests and disease incidences were evaluated monthly during the dry season: brown twig beetle (Xylosandrus morigerus), coffee leaf miner (Leucoptera coffeella), coffee berry borer (Hypothenemus hampei), anthracnose disease (Colletotrichum spp.), thread blight (Pellicularia koleroga), and cercospora leaf spot (Cercospora coffeicola). Coffee berry borer and brown twig beetle infestation were both reduced by 7% in intensified organic treatments compared to intensified conventional treatments. Colonization of coffee berry borer holes in coffee berries by the entomopathogenic fungus Beauveria bassiana was also assessed. Brown twig beetle infestation was significantly higher under full sun than under Inga edulis, yet no other shade effects were detected. We demonstrate for the first time how intensified input use might promote pest populations and thus ultimately lead to robusta coffee yield losses.

Water use in the growth of atlantic forest tree species seedlings under different shading levels

ABSTRACT The increase in the demand for seedlings of native tree species makes it important to determine their water and light requirements, which are important factors in their production, in terms of costs and time. Water use and productivity in the growth of seedlings of Dalbergia nigra (Vell.) Allemão ex Benth., Apuleia leiocarpa (Vogel) J.F. Macbr and Hymenaea courbaril L. were determined under four light levels (three shading levels and control), using a randomized block design with four replicates. Height, stem diameter, leaf area and biomass, as well as Dickson quality index (DQI) were evaluated. The seedlings were transplanted into 280-cm3 plugs, filled with substrate composed of pure biosolids, and irrigated by a drip system with automatic management. The highest total volumes applied were 3.1 L per D. nigra seedling (in 37 and 58% shading), 2.5 L per A. leiocarpa seedling (in 37% shading) and 3.8 L per H. courbaril seedling (in full sun). Growth indices, confirmed by the DQI, indicate that shading levels of 37 and 58% for D. nigra, 37% for A. leiocarpa, and full sun for H. courbaril are the most recommended. The highest volumes of irrigation promoted the greatest development of the species, in general for intermediate shading, which provided the highest values of DQI and irrigation water productivity.

Tree-ring δ18O climate signals vary among tree functional types in South Asian tropical moist forests

We present the first annually resolved and statistically reliable tree-ring δ18O (δ18OT) chronologies for the three South Asian tropical moist forest tree species (Chukrasia tabularis A. Juss., Toona ciliata M. Roem., and Lagerstroemia speciosa Roxb.) which differ in their shade tolerance and resistance to water stress. We found significantly higher mean δ18OT values in light-demanding T. ciliata than in intermediate shade tolerant C. tabularis and shade tolerant L. speciosa (p < 0.001). δ18OT in C. tabularis was mainly influenced by pre-monsoon vapor pressure deficit (VPD; r = −0.54, p < 0.01) and post monsoon maximum temperature (Tmax) (r = 0.52, p < 0.01). δ18OT in T. ciliata was strongly negatively correlated with a dry season drought index PDSI (r = −0.65, p < 0.001) and VPD (r = −0.58, p < 0.001). Pre-monsoon Tmax was strongly positively linked with δ18OT in L. speciosa (r = 0.65, p < 0.001), indicating that climatic influences on δ18OT are species-specific and vary among tree functional types. Although there was a week correlation between local precipitation and δ18OT in our studied species, we found a strong correlation between δ18OT and precipitation at a larger spatial scale. Linear mixed effect models revealed that multiple factors improved model performance only in C. tabularis, yielding the best model, which combined VPD and Tmax. The top models in T. ciliata and L. speciosa included only the single factors PDSI and Tmax, highlighting that the way C. tabularis interacts with climate is more complex when compared with other two species. Our analyses suggest that stable oxygen isotope composition in tree rings of South Asian tropical moist forest trees are a suitable proxy of local and regional climate variability and are an important tool for understanding the physiological mechanisms associated with the global hydrological cycle.

Change in Montane Forests of East-central West Virginia over 250 years

We compared the relative frequencies of witness trees in historical deeds to the relative frequencies of tree species found in the present forests. Changes in relative frequencies of the five dominant tree species were noted in all ecological subsections, although all species found in the past forests are represented in the present. The greatest changes across the study area were a decrease in the representation of white oak and an increase in red maple. The changes in representation by functional groups show a trend toward loss of fire-adapted species of intermediate shade intolerance with associated gains in species of high shade tolerance. Current FIA data on the species composition of trees in the sapling and seedlings size-classes indicate that the trend of reduced of oak species frequency is likely to continue into the near future. This gradual conversion from oak-dominated overstories to maple-dominated understories is a regional trend. Our findings echo a paradox found in the northeastern United States where after 400 years of land use change, forest cover has largely recovered but relative species composition has been transformed. This paradox may add to the difficulty in designing strategies and treatments for ecosystem restoration. However, as we have shown, the changes can be quantified and placed in an ecological context as support for restoration actions.

Assessing Post-Harvest Regeneration in Northern Hardwood and Mixedwood Stands: Evolution of Species Composition and Dominance within 15-Year-Old Group Selection and Patch Cutting

Multi-cohort forest management in northern hardwood stands may well be the best way to successfully regenerate tree species of intermediate shade tolerance, such as yellow birch (Betula alleghaniensis Britt.). The creation of large enough gaps in the canopy favors increased light availability within the opening, while soil scarification provides suitable germination seedbeds. Evidence of these methods’ success nonetheless remains mostly the purview of experimental studies rather than operational tests. In Quebec, Canada, the multi-cohort methods promoted include group selection cutting and patch cutting. The present study tested their implementation at an operational scale and over a large territory in both hardwood-dominated and mixedwood stands. We assessed their efficacy in promoting natural regeneration of commercial hardwood trees, notably yellow birch and sugar maple (Acer saccharum Marsh.). We conducted regeneration surveys at 2, 5, 10, and 15 years after harvest. Overall, group selection and patch cuttings were successful in regenerating the target species. Yellow birch, for instance, showed a mean stocking around 60% and a mean sapling density around 3400 stems ha−1 after 15 years. We compared several variables for measuring regeneration in early years, and found that the relative abundance, the stocking based on one stem per sampling unit, and the mean maximum height were good predictors of the relative presence of yellow birch and sugar maple in 15-year-old canopy openings. Using smaller sampling units (6.25 m2 rather than 25 m2) and waiting until year 5 may be more useful for making such predictions. In addition, there was an important turnover in vertical dominance in these openings. Non-commercial woody competitors were frequently dominant in early years but were often replaced by commercial hardwoods, notably yellow birch. We propose certain thresholds for assessing the success of post-harvest regeneration and for evaluating the need for a cleaning treatment.

The Effect of Shading and Nutrient Addition on the Microphytobenthos, Macrofauna, and Biogeochemical Properties of Intertidal Flat Sediments

Proliferation of urban structures and mangrove forests in estuaries are altering the shading of intertidal sediments. Urbanisation also tends to increase nutrient loads in estuaries, which can have numerous direct and indirect effects on estuarine flora and fauna. Mangrove canopy shades the sediment and provides nutrients to the ecosystem via leaf litter. Microphytobenthos, macrobenthos, sediment erodibility and various biogeochemical properties of sediments have been shown to differ significantly between unshaded intertidal sediment and nearby sediment under a mangrove canopy. This study tested the effects of experimental manipulation of shading and addition of nutrients on the microphytobenthos, macrobenthos, sediment erodibility and selected biogeochemical properties of exposed mudflat next to the seaward edge of a mangrove forest. In the first of two experiments, shading of plots was increased by the addition of black Perspex roofs for comparison with unshaded plots and plots with clear Perspex roofs; the addition of nutrients was done in an orthogonal design. Clear roofs were originally intended as a procedural control, but due to sedimentation on their upper surface caused intermediate levels of shading. Sediment and benthos were sampled after two weeks. Nutrients were omitted in the second experiment, with plots sampled after two weeks or three months. The only effect of nutrients was a small negative effect on chlorophyll a and colloidal carbohydrate. Intermediate shading (clear roofs) consistently increased measures of microphytobenthos biomass (e.g. Fo and chlorophyll a) and biogeochemical properties associated with microphytobenthos such as colloidal carbohydrate. Substantial shading (black roofs) decreased measures of microphytobenthos biomass and microphytobenthos associated biogeochemical properties. Effects on the fauna were much smaller and inconsistent with previous studies, after 3 months assemblages were different under black roofs compared to clear roofs and control plots, with differences primarily driven by changes in the oligochaetes. Natural or anthropogenic changes in shading at larger spatial scales are likely therefore to directly and indirectly change microphytobenthos, sediment properties, macrofauna and hence ecosystem functions; but any flow-on effects to the fauna are difficult to predict without further experiments to understand the indirect and direct responses of fauna to changing microphytobenthos and properties of intertidal sediment.

Attacks and damage of termites (Insecta: Isoptera) in different cocoa agroforestry systems (Nawa, Côte d’Ivoire).

To maintain its status of leading producer of cocoa in the world, Côte d'Ivoire must be contain the different types of threats, including the emergence of termites in cocoa farms. This study was conducted in the south-west of the country to evaluate the effect of cropping systems (full sun system, intermediate system and shaded system) on termite attacks. The study was conducted in four localities with different cocoa agroforestry systems. The sampling was made on cocoa trees in quadrats of 30mx30m and the attack rate was calculated. Eleven (11) termite species were identified. The wood-feeders groups were dominant. These termites were responsible for 41.82% of the damage on cocoa trees. Termite Attacks vary between different cropping systems. Full sun systems were most attacked comparing to intermediate shade systems that were least attacked by termites. This work shows that the shade system has an effect on termite attacks in cacao trees. The choice of right system can help to significantly reduce termite attacks in cocoa farms.

Influence of light availability and soil productivity on insect herbivory on bilberry (Vaccinium myrtillusL.) leaves following mammalian herbivory.

Vegetative parts of bilberry (Vaccinium myrtillus) are important forage for many boreal forest mammal, bird and insect species. Plant palatability to insects is affected by concentration of nutrients and defense compounds in plants. We expected that palatability of bilberry leaves to insect herbivores is influenced by light availability and soil productivity (both affecting nitrogen concentration and constitutive carbon-based defense compound concentration) and herbivory by mammals (affecting nitrogen concentration and induced carbon-based defense compound concentration). We studied bilberry leaf herbivory under different light availability, soil productivity and mammalian herbivory pressure in small sampling units (1m x 1m) in boreal forest in Norway. We used generalized linear mixed models and generalized additive mixed models to model insect herbivory on bilberry leaves as a function of shade, soil productivity and mammalian herbivory. Observed insect herbivory on bilberry leaves increased with increasing shade levels. Predicted insect herbivory increased with increasing previous mammalian herbivory at high shade levels and this response was magnified at higher soil productivity levels. At low to intermediate shade levels, this response was only present under high soil productivity levels. Our results indicate that light availability is more important for variation in bilberry leaf palatability than soil nutrient conditions.

What influences the long-term development of mixtures in British forests?

Abstract Six experiments were established between 1955 and 1962 in different parts of northern and western Britain which used replicated randomized block designs to compare the performance of two species 50:50 mixtures with pure stands of the component species. The species involved were variously lodgepole pine (Pinus contorta Dougl.), Japanese larch (Larix kaempferi Lamb. Carr.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth.), Sitka spruce (Picea sitchensis Bong. Carr.) and western hemlock (Tsuga heterophylla Raf. Sarg.). The first four species are light demanding, while Sitka spruce is of intermediate shade tolerance and western hemlock is very shade tolerant: only Scots pine and silver birch are native to Great Britain. In three experiments (Bickley, Ceannacroc, Hambleton), the mixtures were of two light-demanding species, while at the other three sites, the mixture tested contained species of different shade tolerance. The experiments were followed for around 50 years, similar to a full rotation of even-aged conifer stands in Britain. Five experiments showed a tendency for one species to dominate in mixture, possibly reflecting differences in the shade tolerance or other functional traits of the component species. In the three experiments, the basal area of the mixtures at the last assessment was significantly higher than predicted based on the performance of the pure stands (i.e. the mixture ‘overyielded’). In two of these cases, the mixture had had a higher basal area than found in the more productive pure stand indicating ‘transgressive overyielding’. Significant basal area differences were generally more evident at the later assessment date. The exception was in a Scots pine: western hemlock mixture where greater overyielding at the earlier date indicated a nursing (‘facilitation’) effect. In the remaining experiments, the performance of the mixture conformed to predictions from the growth of the component species in pure stands. Taken overall, the results suggest that functional traits can be used to interpret the performance of mixtures but prediction of the outcome will require better understanding of the interplay between species and site characteristics plus the influence of silvicultural interventions.

Effect of light intensity and water availability on plant growth, essential oil production and composition in Rosmarinus officinalis L.

The effect of light intensity (LI) and water availability (WA) on rosemary (Rosmarinus officinalis L.) plant growth, essential oil (EO) production and composition was investigated by a two-factorial field experiment, where the first factor was LI (100%, 50% or 25% of natural sunlight) and the second factor was WA (irrigation set at 85%, 70% or 55% of field capacity during plant growing). The EO obtained by steam distillation of the dried aerial part of the plant was analysed by GC/MS. Reduction of LI from 100 to 25% of natural sunlight markedly lowered plant biomass production, whereas reduction of WA from 85 to 55% had a smaller lowering effect on plant growth. High shading (25% of LI) markedly reduced EO yield on a plant basis (− 43%), whereas intermediate shading (50% of LI) increased EO yield as % content of the fresh biomass (+ 29%) when compared to full solar radiation. WA markedly influenced EO yield, as expressed on a plant basis, but only in plants exposed to 100% LI. Moreover, changes in LI and WA seemed to have an opposite effect on the relative abundance of EO constituents that are formed through the activity of two groups of enzymes, pinene synthases (α- and β-pinene, camphene and myrcene) and, respectively, bornyl diphosphate synthases (borneol, camphor and bornyl acetate). Accurate management of light conditions and water availability, in greenhouse as well as open field conditions, may allow to optimize rosemary EO yield and modulate EO profile in view of different potential uses.