Within-plant patchiness in nectar standing crop in Anchusa strigosa

Vegetatio ◽  
1991 ◽  
Vol 94 (2) ◽  
pp. 95-99 ◽  
Author(s):  
A. Shmida ◽  
R. Kadmon
Keyword(s):  
Standing Crop ◽  
Nectar Standing Crop

scholarly journals Notes on the flowering and pollination of the endemic grassland Aloe reitzii var. reitzii (Asphodelaceae)

Bothalia ◽  
2017 ◽  
Vol 47 (2) ◽  
Author(s):  
Craig T. Symes
Keyword(s):  
South Africa ◽  
Standing Crop ◽  
Bird Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Pollination Biology ◽  
Nectar Volume ◽  
Invertebrate Species ◽  
Nectar Standing Crop ◽  
Insight Into

Background: Aloe reitzii var. reitzii is a succulent with a restricted distribution in the montane grassland of eastern South Africa. It is a summer (late January–March) flowering succulent that grows on rocky outcrops at 1000 m–1600 m, and the conspicuous inflorescences suggest a pollination system focused towards birds.Objectives: To understand more about the pollination biology of A. reitzii var. reitzii.Methods: Nectar standing crop (flower volume and concentration) and the proportion of plants flowering were recorded. Camera traps and observations were used to record visitors to A. reitzii var. reitzii inflorescences.Results: Nectar volume was 36 μL ± 27 μL per flower (range 6 μL–93 μL; n = 27) and concentration was 16.5% ± 1.7% (range 13.5% – 19.5%). Camera trap observations, where 18.9% of all plants were observed flowering, recorded the three bird species Cape Weaver, Ploceus capensis, Malachite Sunbird, Nectarinia famosa and Greater Double-collared Sunbird, Cinnyris afer (60.4%, 27.1% and 12.5% of plant visits, respectively) visiting inflorescences.Conclusion: Because birds are important pollinators for many Aloe species, it is assumed that the bird species detected visiting A. reitzii var. reitzii are similarly important pollinators. At least 10 invertebrate species and sengi (Elephantulus sp.) were also recorded as visitors to flowers, but they may be less important pollinators than specialist and generalist avian nectarivores. This study provides further insight into the pollination biology of a diverse, and ecologically important, succulent genus in Africa.

scholarly journals Extreme Drought Affects Visitation and Seed Set in a Plant Species in the Central Chilean Andes Heavily Dependent on Hummingbird Pollination

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1553
Author(s):  
Mary T. K. Arroyo ◽  
Valeria Robles ◽  
Ítalo Tamburrino ◽  
Jaime Martínez-Harms ◽  
René D. Garreaud ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Plant Species ◽  
Standing Crop ◽  
Seed Set ◽  
Austral Summer ◽  
Flower Head ◽  
Floral Longevity ◽  
Visitation Frequency ◽  
Nectar Standing Crop ◽  
Nectar Concentration

Rising temperatures and increasing drought in Mediterranean-type climate areas are expected to affect plant–pollinator interactions, especially in plant species with specialised pollination. Central Chile experienced a mega drought between 2010 and 2020 which reached an extreme in the austral summer of 2019–2020. Based on intensive pollinator sampling and floral studies we show that the subalpine form of Mutisia subulata (Asteraceae) is a specialised hummingbird-pollinated species. In a two-year study which included the severest drought year, we quantified visitation frequency, flower-head density, flower-head visitation rates, two measures of floral longevity, nectar characteristics and seed set and monitored climatic variables to detect direct and indirect climate-related effects on pollinator visitation. Flower-head density, nectar standing crop and seed set were significantly reduced in the severest drought year while nectar concentration increased. The best model to explain visitation frequency included flower-head density, relative humidity, temperature, and nectar standing crop with highly significant effects of the first three variables. Results for flower-head density suggest hummingbirds were able to associate visual signals with reduced resource availability and/or were less abundant. The negative effect of lower relative humidity suggests the birds were able to perceive differences in nectar concentration. Reduced seed set per flower-head together with the availability of far fewer ovules in the 2019–2020 austral summer would have resulted in a major reduction in seed set. Longer and more intense droughts in this century could threaten local population persistence in M. subulata.

scholarly journals Seasonal variation in exploitative competition between honeybees and bumblebees

Oecologia ◽  
2019 ◽  
Vol 192 (2) ◽  
pp. 351-361 ◽  
Author(s):  
Veronica R. Wignall ◽  
Isabella Campbell Harry ◽  
Natasha L. Davies ◽  
Stephen D. Kenny ◽  
Jack K. McMinn ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Standing Crop ◽  
Foraging Behaviour ◽  
Competitive Exclusion ◽  
Floral Resources ◽  
Competitive Pressure ◽  
Exploitative Competition ◽  
Full Bloom ◽  
Nectar Standing Crop ◽  
Flower Choice

AbstractHoneybees (Apis mellifera) and bumblebees (Bombus spp.) often undergo exploitative competition for shared floral resources, which can alter their foraging behaviour and flower choice, even causing competitive exclusion. This may be strongest in summer, when foraging conditions are most challenging for bees, compared to other times of the year. However, the seasonal dynamics of competition between these major pollinator groups are not well understood. Here, we investigate whether the strength of exploitative competition for nectar between honeybees and bumblebees varies seasonally, and whether competitive pressure is greatest in summer months. We carried out experimental bee exclusion trials from May to late September, using experimental patches of lavender, variety Grosso, in full bloom. In each trial, we compared the numbers of honeybees (HB) foraging on patches from which bumblebees had been manually excluded (bumblebee excluded, BBE) versus control (CON) patches, HB(BBE-CON). This measure of exploitative competition varied significantly with season. As expected, mean HB(BBE-CON) was significantly greater in summer trials than in spring or autumn trials. This was despite high nectar standing crop volumes in BBE patch flowers in spring and autumn trials. Mean HB(BBE-CON) was not different between spring and autumn trials. Our results show that nectar competition between honeybees and bumblebees varies seasonally and is stronger in summer than spring or autumn, adding to current understanding of the seasonality of resource demand and competition between bee species. This information may also help to inform conservation programs aiming to increase floral resources for bees by showing when these resources are most needed.

FIRE, BEES, AND SEED PRODUCTION IN A MEDITERRANEAN KEY SPECIES SALVIA FRUTICOSA MILLER (LAMIACEAE)

1999 ◽  
Vol 47 (3) ◽  
pp. 157-163 ◽  
Author(s):  
Gidi Ne'eman ◽  
Amots Dafni
Keyword(s):  
Seed Production ◽  
Standing Crop ◽  
Solitary Bees ◽  
Burned Area ◽  
Flower Visitation ◽  
Salvia Fruticosa ◽  
Long Term Effect ◽  
Key Species ◽  
Nectar Standing Crop ◽  
Pollination Environment

The typical Mediterranean phrygana has a very rich biodiversity of plants and of solitary bees. Fire may kill the brood of soil-nesting and other solitary bees and may affect pollen and nectar sources. Such changes would be expected to influence seed production in populations of post-fire obligate seeder species and thus also their population dynamics. We compared nectar standing crop, flower visitation rate of bumble bees and solitary bees, and consequent seed production in a typical Mediterranean shrub (Salvia fruticosa Miller) growing in unburned east Mediterranean phrygana vegetation and in an adjacent burned area. The volume of nectar standing crop in the burned area was higher than in the unburned area, while the nectar concentration showed the opposite trend. The mean frequency of Bombus' visits was higher in the burned area, while solitary bees visited flowers only in the unburned habitats. The seed production of S. fruticosa was significantly lower in the burned area. This reduction might have a long-term effect on post-fire species composition and abundance due to the fact that this species is an obligate post-fire seeder. The present evidence indicates that the bee-dependent pollination environment was not re-balanced even six years after fire. This situation has important implications concerning plant species and their bee pollinator diversity.

Flowering, pollination, nectar standing crop, and nectaries ofEuterpe precatoria (Arecaceae), an Amazonian rain forest palm

1997 ◽  
Vol 206 (1-4) ◽  
pp. 71-97 ◽  
Author(s):  
Heike K�chmeister ◽  
Ilse Silberbauer-Gottsberger ◽  
Gerhard Gottsberger
Keyword(s):  
Rain Forest ◽  
Standing Crop ◽  
Nectar Standing Crop ◽  
Amazonian Rain Forest

STANDING CROP NITROGEN CONTENT (FIFE)

1994 ◽  
Author(s):  
T. G. F. KITTEL ◽  
W. J. PARTON ◽  
D. S. SCHIMEL
Keyword(s):  
Nitrogen Content ◽  
Standing Crop

Litter fall of epiphytic macrolichens in two old Picea abies forests in Sweden

1985 ◽  
Vol 63 (5) ◽  
pp. 980-987 ◽  
Author(s):  
Per-Anders Esseen
Keyword(s):  
Standing Crop ◽  
Annual Variation ◽  
Length Distribution ◽  
Forest Stand ◽  
Epiphytic Lichens ◽  
Litter Fall ◽  
Alectoria Sarmentosa ◽  
Usnea Longissima ◽  
Tree Litter ◽  
Thallus Length

The seasonal and annual variation in the litter fall of epiphytic lichens and tree litter was studied over a period of 2 to 3 years at two forested hills in the eastern part of central Sweden. Litter fall was measured using traps and for one species, Usnea longissima, by collecting specimens present on the ground. Total litter fall amounted to 2.5 and 2.8 tons ha−1 year−1 of which lichens constituted 4.6 and 5.7% at the two sites. Lichen litter fall was highest during the period from late autumn to the beginning of summer. Both the lichens and the tree litter showed significant between-year differences. Usnea longissima had an annual turnover of 7.0 and 10.0% of the standing crop at the two sites. The thallus length distribution of U. longissima was positively skewed. It is concluded that dispersal of thallus fragments by wind evidently plays an important role for many of the filamentous lichens studied. It is suggested that U. longissima disperses over a much shorter distance than Alectoria sarmentosa and Bryoria spp. within a forest stand.

scholarly journals Changes in ecosystem processes induced by land use: Human appropriation of aboveground NPP and its influence on standing crop in Austria

2001 ◽  
Vol 15 (4) ◽  
pp. 929-942 ◽  
Author(s):  
Helmut Haberl ◽  
Karl-Heinz Erb ◽  
Fridolin Krausmann ◽  
Wolfgang Loibl ◽  
Niels Schulz ◽  
...  
Keyword(s):  
Land Use ◽  
Standing Crop ◽  
Ecosystem Processes
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