Changes in the structure and composition of the ‘Mexical’ scrubland bee community along an elevational gradient

‘Mexical’ scrubland is a sclerophyllous evergreen Mediterranean-like vegetation occurring in the leeward slopes of the main Mexican mountain ranges, under tropical climate. This biome occupies an elevational range approximately from 1900 to 2600 meters above sea level, which frequently is the upper-most part of the mountains range. This puts it at risk of extinction in a scenario of global warming in which an upward retraction of this type of vegetation is expected. The Mexical remains one of the least studied ecosystems in Mexico. For instance, nothing is known about pollinator fauna of this vegetation. Our main objective is to make a first insight into the taxonomic identity of the bee fauna that inhabits this biome, and to study how it is distributed along the elevational gradient that it occupies. Our results highlight that elevation gradient negatively affects bee species richness and that this relationship is strongly mediated by temperature. Bee abundance had no significant pattern along elevational gradient, but shows a significant relationship with flower density. Interestingly, and contrary to previous works, we obtained a different pattern for bee richness and bee abundance. Bee community composition changed strongly along elevation gradient, mainly in relation to temperature and flower density. In a global warming scenario, as temperatures increases, species with cold preferences, occupying the highest part of the elevation gradient, are likely to suffer negative consequences (even extinction risk), if they are not flexible enough to adjust their physiology and/or some life-story traits to warmer conditions. Species occupying mid and lower elevations are likely to extend their range of elevational distribution towards higher ranges. This will foreseeably cause a new composition of species and a new scenario of interactions, the adjustment of which still leaves many unknowns to solve.

Contribution of Extensive Farming Practices to the Supply of Floral Resources for Pollinators

Intensification of agricultural practices leads to a loss of floral resources and drives pollinator decline. Extensive agricultural practices are encouraged in Europe and contribute to the preservation of biodiversity. We compared three agricultural landscapes without extensive farming practices with three adjacent landscapes containing organic crops and extensively managed grasslands in Belgium. Nectar resource availability and plant–pollinator interactions were monitored from April to June. Flower density per plant species and plant–pollinator interactions were recorded in different landscape elements. In April, the main nectar resources were provided by linear elements such as hedgerows and forest edges. Nectar production peaked in May, driven by intensive grasslands and mass-flowering crops. Occurrence of extensive grasslands and organic crops significantly alleviated the nectar resource gap observed in June. Our results underscore the importance of maintaining landscape heterogeneity for continuous flower resources and highlight the specific role of extensive grasslands and organic crops in June.

An efficient RGB-UAV-based platform for field almond tree phenotyping: 3-D architecture and flowering traits

Background Almond is an emerging crop due to the health benefits of almond consumption including nutritional, anti-inflammatory, and hypocholesterolaemia properties. Traditional almond producers were concentrated in California, Australia, and Mediterranean countries. However, almond is currently present in more than 50 countries due to breeding programs have modernized almond orchards by developing new varieties with improved traits related to late flowering (to reduce the risk of damage caused by late frosts) and tree architecture. Almond tree architecture and flowering are acquired and evaluated through intensive field labour for breeders. Flowering detection has traditionally been a very challenging objective. To our knowledge, there is no published information about monitoring of the tree flowering dynamics of a crop at the field scale by using color information from photogrammetric 3D point clouds and OBIA. As an alternative, a procedure based on the generation of colored photogrammetric point clouds using a low cost (RGB) camera on-board an unmanned aerial vehicle (UAV), and an semi-automatic object based image analysis (OBIA) algorithm was created for monitoring the flower density and flowering period of every almond tree in the framework of two almond phenotypic trials with different planting dates. Results Our method was useful for detecting the phenotypic variability of every almond variety by mapping and quantifying every tree height and volume as well as the flowering dynamics and flower density. There was a high level of agreement among the tree height, flower density, and blooming calendar derived from our procedure on both fields with the ones created from on-ground measured data. Some of the almond varieties showed a significant linear fit between its crown volume and their yield. Conclusions Our findings could help breeders and researchers to reduce the gap between phenomics and genomics by generating accurate almond tree information in an efficient, non-destructive, and inexpensive way. The method described is also useful for data mining to select the most promising accessions, making it possible to assess specific multi-criteria ranking varieties, which are one of the main tools for breeders.

Population Density and Habitat Characteristics of Nipa Fruticans in Degraded Mangrove Ecosystem (Case Study in Mahakam Delta, East Kalimantan)

<p>Mahakam Delta is one of the largest mangrove ecosystem areas in East Kalimantan, which is dominated by nipa (<em>Nypa fruticans</em>). This paper investigates the population density of nipa and measures habitat characteristics in the area, which represents the condition of mangrove ecosystem that has received heavy pressures as a result of the increase in human activities.A total of 30 plots, size of 100m² each plot, were sampled from six locations in the study site. In each plot, the number of individual, stalk, leaves, fruit and flower of nipa was recorded. Nipa zone adjacent to active ponds area had the density of 106 individual/ha with 913 stalks ha^-1. The leaf density was 336 leaves ha^-1, fruit density was 12 fruits ha^-1 and flower density was 12 flowers/ha. Furthermore, nipa density in locations faraway from active ponds area was 74 individual/ha with 861 stalks/ha. While the leaf density was 239 leaves/ha, fruit density in this area was 2 fruits/ha and flower density was 9 flowers/ha. Result also showed that nipa habitat in study site is characterized by high turbidity and low salinity. Among other parameters, tidal level has strongest correlation to nipa population density. This study can also be considered as a preliminary assessment to develop mangrove ecosystem rehabilitation action plans in Mahakam Delta and to consider the potential use of nipa as an alternative source of livelihood for local communities living in the vicinity of the Mahakam Delta area.</p>

HONEY CROP ESTIMATION FROM SPACE: DETECTION OF LARGE FLOWERING EVENTS IN WESTERN AUSTRALIAN FORESTS

<p><strong>Abstract.</strong> Recent studies have shown that in the spectral space there is often a better spectral separation between leaves and flowers and even between flowers of different species than between leaves of different species. In this study we assess the ability of satellite remotely sensed data to detect the flowering of Red Gum trees (<i>Corymbia calophylla</i>) in Western Australia, the state’s largest annual honey crop. Spectroradiometer measurements of flowers, leaves and groundcover from Red Gum forests were subjected to ANOVA analysis, which showed that flowers are spectrally different to their environment for 92<span class="thinspace"></span>% of the wavelengths between 350<span class="thinspace"></span>nm and 1800<span class="thinspace"></span>nm. A more detailed assessment, using the JM Distance calculation, showed that the spectra can be reliably separated using 10<span class="thinspace"></span>% of the wavelengths, with peak separation between 518<span class="thinspace"></span>nm and 557<span class="thinspace"></span>nm. To assess the ability of satellite-borne sensors to detect the presence of flowers, the spectroradiometer data were convolved with satellite instruments’ response curves to create synthetic remotely sensed datasets on which JM Distance analysis was performed. MODIS blue bands achieved a median JM Distance of greater than 1.9 and therefore should be able to detect the presence of flowers from the environment. Further assessment showed that the shortest wavelength bands for MODIS, VIIRS and Sentinel 3 all occur where the flower spectra have lower reflectance than their natural background. A sensitivity analysis of percentage flower cover for a pixel showed that the highest sensitivity was obtained by dividing the band closest to 520<span class="thinspace"></span>nm by the shortest wavelength band for data from these three sources. The MODIS band 10/band 8 metric was tested for its ability to detect flowers in real-world data using 15 years of qualitative honey harvest data from one apiary site as a proxy for flower density. This test was successful as, while there was some overlap between good, moderate and poor years, the poor years could be separated from the other years with nearly 80<span class="thinspace"></span>% accuracy.</p>

Architectural traits constrain the evolution of unisexual flowers and sexual segregation within inflorescences: an interspecific approach

ABSTRACTMale and female unisexual flowers have repeatedly evolved from the ancestral bisexual flowers in different lineages of flowering plants. This sex specialization in different flowers often occurs within inflorescences. We hypothesize that inflorescence architecture may impose a constraint on resource availability for late flowers, potentially leading to different optima in floral sex allocation and unisexuality. Under this hypothesis we expect that inflorescence traits increasing the difference in resource availability between early and late flowers would be phylogenetically correlated with a higher level of sexual specialization. To test this hypothesis, we performed a comparative analysis of inflorescence traits (inflorescence size, number of flowers and flower density) in the sunflower family, which displays an extraordinary variation in floral sexual specialization at the inflorescence level, i.e. hermaphroditic, gynomonoecious and monoecious species. We found that species with a complete sex separation in unisexual flowers (monoecy) had significantly denser inflorescences. Furthermore, those species arranging their flowers in denser inflorescences also showed greater differences in the size of early and late fruits, a proxy of resource variation between flowers. Our findings support the idea that floral sexual specialization and consequently sexual segregation may be the consequence of different floral sex allocation optima driven by the sequential development of flowers that results in a persistent resource decline from earlier to later flowers.

Effect of flower density on pollen viability and fruit set of Calceolaria tripartita Ruiz &Pav. (Scrophulariaceae) in Darjeeling Himalaya

<p>There are many populations in a 16 km east-west distribution and populations are usually small with fewer than 100 plants/clumps. The pollen biology in terms of pollen production, pollen-ovule ratio estimation, pollen viability and pollen fertility was studied to determine the impact of plant and flower density on pollen viability and fruit set of <em>Calceolaria tripartita</em> Ruiz &amp;Pav. (Scrophulariaceae) in Darjeeling Himalaya. It is revealed that higher the density of the plants and flowers, the productivity of pollens and ovules and the viability and fertility of pollen grains become higher showing a positive correlation between plant-flower density vs. pollen biology. Fruit set is higher in high dense flowering site than low ones which might be due to higher pollen fertility rate, low sterility and greater number of pollen load upon stigma. Thus, it reflects that plant and flower density has a crucial role upon the reproductive fitness of this taxon.</p>

Pollination ecology of Rhynchosia cana (Willd.) DC. (Fabaceae), an erect sub-shrub, in peninsular India

Rhynchosia cana is a perennial erect sub-shrub. It flowers during November-January with peak flowering in December. The flowers are hermaphroditic, nectariferous, self-compatible and display explosive pollination mechanism adapted for pollination by bees. They do not fruit through autonomous selfing, but rather through manipulated selfing, geitonogamy and xenogamy mediated principally by bees and occasionally by lycaenid butterflies. In the localities of this herb, weeds such as Hyptis suaveolens (Lamiaceae) and Chromolaena odorata (Asteraceae) show luxuriant growth and flower simultaneously, and their intense flowering and high flower density ensures that most flower-visiting insects visit their flowers. In this situation only two bee species, Nomia and Anthidium exhibited fidelity to R. cana flowers. Un-tripped flowers fall off while tripped ones set fruit. In open-pollinations, fruit set was 81% and seed set was 54%. Seed dispersal occurs by explosive pod dehiscence. Perennial root stock resurrects back to life and restarts its reproductive cycle during the rainy season. Seeds also germinate at the same time but their continued growth is subject to the availability of soil moisture content. This study suggests that R. cana is unable to compete with the co-flowering weed species for pollinators, and also has regeneration constraints due to nutrient-deficient rocky habitats with prolific growth of weeds.

Tolerance of Three Clovers (Trifoliumspp.) to Common Herbicides

Clover inclusion may increase the sustainability of certain low-maintenance turfgrasses. However, selective weed control within mixed turfgrass–clover swards proves problematic because of clover susceptibility to herbicides. Research was conducted to identify common turf herbicides that are tolerated by threeTrifoliumspecies, including white clover, ball clover, and small hop clover, within low-maintenance turfgrass. Leaf and flower density, as well as plant height, were measured 4 wk after treatment as indicators of clover response to 14 herbicides. The threeTrifoliumspp. were moderately tolerant of bentazon (< 35% decrease in leaf density, height, or flowering). Simazine was well tolerated by white clover (< 5% decrease in all response variables), yet moderate injury to ball clover and small hop clover was observed (> 32% decrease in leaf density and > 27% decrease in flower density). Pronamide was well tolerated by white and ball clovers, with no effect on measured response variables; however, pronamide decreased small hop clover height and flower density (38 and 42%, respectively). Imazethapyr and imazamox were moderately well tolerated by white clover and small hop clover (< 39% decrease by all response variables), yet ball clover may be more susceptible to these herbicides than was anticipated based on previously reported tolerance. The herbicides 2,4-DB, halosulfuron, and metribuzin were well tolerated by white clover, with no effect on measured response variables; however, results suggest ball and small hop clovers were less tolerant. Clopyralid, 2,4-D, glyphosate, imazaquin, metsulfuron-methyl, and nicosulfuron resulted in varying degrees of injury across clover species and response variables, but, in general, these herbicides may not be viable options when attempting to maintain any of the three clover species tested. Further research is needed to quantify long-term effects of herbicide application on sward composition and clover succession.