Agroforestery : rural trees… …and vegetative cover for bees
The collapse of bee population concernes Bees have an important role in the maintain of biodiversity. Like other insects, they enable sexual reproduc on to many flowering by their pollina ng ac on. In Europe, we es mated that bees pollinate more than 80% of flowering plants species (wild and cul vated). In France, more than 1,000 species of pollina ng bees exist. Among them, the honey bee Apis mellifera is of great importance because it pollinates many plants.
For thirty years, bee popula ons have declined. The main sources of this decline are caused by human ac vi es in general. The intensifica on of agriculture (monoculture, land consolida on, uproo ng of trees and hedges, pes cides ...) gradually led to the fragmenta on and deple on of habitats. In fact, we now know that the abundance of bees is linked to the flowering which is itself linked to agricultural prac ces. Various studies have proved that the simplifica on of agricultural landscapes (ie the loss of habitats for wild bees) has led to the loss of flora and so to pollinator decline.
Enhance biodiversity on farm: To promote the presence of bees in agricultural areas, it is important to keep the most diverse plant species pool as possible in the countryside and during the season (linking bloom periods during the year). Agroforestry and soil cover, subtly mixes species and types of development, possible to obtain diversity in agricultural plots è Playing the card of vegetative cover and trees The presence of a diverse and permanent vegeta ve cover that fills the gap between two crops is essen al to the life of bees and pollinators, including avoiding periods of scarcity, but also the balance and protec on of the whole agroecosystem: soil, water, climate, plant and animal biodiversity ... In this equilibrium, the tree, as giant, woody plant and as a fixed and durable element, holds a special place.
A new generation of agroforestry Far from the single-species planta ons concept of walnut trees in the middle of cereals, the agroforestry developed nowaday offers a variety of species, technics, fi ngs, adjusments, and species that meet in a comprehensive manner the various challenges facing agriculture. Tree in all its forms (alignments, pollarded trees, hedges, bushes ...), assisted natural regenera on, soil cover and soil conserva on techniques planta ons are tools that can provide the food and shelter for bees and pollinators throughout the year.
Giving bed and board throughout the year To ensure the proper development and maintenance of bee popula ons, it must encounter food and water throughout the year, be properly management against diseases and pests and encounter diverse habitats as welle as shade.
A diversity of vegetation to recreate abalance The tree itself is a diverse biota , whether alive or dead , processed into wood or cork ... It brings with itself a whole plant complexe- including herbs - and maintains communica on between the ground, surface soil and the aerial parts , which offers a variety of poten al habitats for bees and other pollinators. This role is mul plied by the wide variety of forms and situa ons that make up the tree associa ons arranged in isolated trees, tree linear, near roadways, pathways, fields, houses, town places and rivers. These different configura ons allow to diversify the types of habitat, food and shelter over me . They also allow a be er flowering and frui ng through a large light exposure. Threw it’s flowering trees provide a resource that takes over herbaceous (vegeta ve cover, meadows, vegeta ve strips ... ) and allows to diversify the pollen resource. In return , the insect pollinates the flower of the tree , which enhances the produc on of fruits and ensures gene c mixing.
Hedges Hedges are o en rich of interes ng species. The hawthorn, bramble or privet are such significant resources to bees. The French Na onal Union of beekeeping (SNA) and na onal associa ons of beekeepers highlight the interest hedges. Indeed, unlike the fallow which change every year and where biodiversity doesn’t have me to stabilise, hedges have the advantage of forming more complex ecosystems that diversify over me. Note: the destruc on of an area of hedges could result in the collapse of the produc on of an apiary in a year!
Pollard trees, hollow trees Ponds Pollarded trees and dead hollow trees have the Ponds are a fundamental element for the bees, they have a advantage of providing plenty of hiding places significant need for water, especially during hot periods, that can be used for nes ng sites. which correspond to low flow streams period.
Riparians Vegeta on on the river banks is extremely rich in plant diversity, with many food resources and refuge areas. Well maintained, it can also produce wood (fuelwood, mber). Create spatial cues Trees and hedgerows are used as markers for pollinators. Bees have a highly developed communica on system, treed elements are very important markers that are used by workers to indicate the localiza on of the food.
flmgwhrsmitjc,prs,skgpzro Winter mortality of bees, especially in crop areas, may be partly related to the loss and the trivializa on of flora. The predominance of certain melliferious crops, intensively produced (such as rapeseed or sunflower) could create a phenomenon of intensive nutrient overload in a very short me and then generates a shortage when the harvest is over. Trees and shrubs provide a food supply outside the period of flowering crops.
With the willow and hazel, bees encounter an abundant source of food from the month of February. With Ivy, they will forage un l December and make a last pollen harvest before winter. Between March and November, with a spread of flowering in me, they will find their food without interrup on, allowing them to live and reproduce, thereby maintaining a stable popula on during the honey season. Herbaceous and tree layers, a highly beneficial association Woody and herbaceous strata are complementary in terms of habitats and resources, especially its availability: wet period, the herbaceous layer is rich in nectar, but during dry periods, it will be mainly in woody strata that we will find abundant nectar, because trees are capable of capturing moisture deeper into the ground, than herbaceous. Where can I find Herbaceaous? Z Neer woody plants: next to a hedge or a tree lines, there is an non- scratched area where many herbaceous species grow. It is possible to promote and support the vegeta on of field margins: avoid the chemical weeding from the edges of the fields, mowing flowering plants a er flowering, if possible, shrubs leave a cord se le, plant a hedge .... all theses ac ons provide shelter and food areas. Z Implementa on of pollen and/or nectar producing plants covered for domes c and wild bees. These vegeta ve covers can be introduced as a major crop in rota ons (alfalfa seed-hemp ...) or as an intermediate crop (phacelia, buckwheat ...)
Diversity, the best ally for pollinators A landscape where live crops and wild plants is op mal to provide resources for bees throughout the year. We know for example that in monocultures rapeseed bee diversity is 4 mes lower than that measured on with wildflowers. The supply of wildlife is par cularly important for wild bees. An ideal countryside for bees?
It is difficult to establish the ideal landscape for bees. However, Bees don’t only produce honey! a diverse landscape is more favorable to the development of Bees use nectar, a sweet liquid secreted by the flower, and the honeydew excreted by bee popula on: sucking insects and process it into honey. offering a landscape of natural grasslands, cul vated plots HOWEVER, They Also need to eat, thanks to with permanent soil cover, agroforestry, hedges, ponds, pollen. The diversity of species will allow streams, well-maintained riparian, woodland will create a bees to ensure their life cycle on the same balance for bees . area during the flowering period. Think global We es mated that there is around 10,000 foraging bees in a bee colony (one-third of 30,000 workers). Taking into account their foraging range (radius of 1,257 ha), we get about 8 bee/hectare. Bringing addi onal colonies will have a no ceable effect on pollina on of the area and the maintain of diversity. However, we know that bees can travel threw hundreds or thousands of hectares to pollinate. So, it’s important and necessary to consider a more important scale than the plot, such as a small agricultural region. It is the consistency and the even distribu on of tree elements that will ensure a func onality oh the frame (shelter, food sources ..), an ecological con nuity to maintain popula ons.
An issue that concerns us all The farmer is an actor who has a strong impact on the regula on of bee popula ons, through his prac ces. But all rural stakeholders have a role to play in everyday life: communi es, hunters, naturalists, river technicians... Z Hun ng federa ons have established contracts for melliferous fallow and wildlife: these are cultures that are implanted in spring and remain throughout the winter un l the following spring. Z It should be noted that individuals may have accesses to these contacts. Z technicians who protct the river border Z decentralized state services that manage the edges of roads, which can adapt heights and cu ng periods to maximize service to the local flora and fauna. A few interesting species during summer Besides honey, bees use and produce other products such as pollen that is par cularly rich in protein, fat, vitamins and minerals, but also propolis that has famous therapeu c proper es. It is produced by the bark of certain so wood or hardwood buds (birch, elm, alder, willow, oak, ash ...) and is collected by bees use to seal and clean the hive.
Walking in this summer period is o en synonymous of shortage, we can easily iden fy flowers species pollinated by bees. In beekeeping plants are sorted according to their polliniferous and melliferous efficiancy. Scales used range from 1 to 5 (1 = low to 5 = very good produc on). Phacelia White clover Among the plants used for intercropping we can no ce phacelia (poll.: 1; nec: 5), vetch (3, 2) or white clover (3, 5). St. John's wort (4, 0) and goldenrod (3, 3) are recognizable by their yellow flowers and have the advantage of growing everywhere, in full sun as well as in semi-shade (hypericum) and have interes ng melliferous poten al.
Finally, oregano or marjoram (2, 3) which blooms in summer and Vetch St. John's Wort grows in many sunny backgrounds, could produce up to 480kg of sugar per hectare during it’s flowering period: a er working bee, we and get up to 560kg of honey which is whorth € 4,000 poten al sales product ....
Goldenrod Marjoram In addi on to these species, there are many crops a rac ve to bees, that can set up farmers to diversify their produc on and develop underu lized areas on the farm to produce and protect: Plant cover: faba bean, alfalfa, rape, mustard, trefoil, clover Ornamental and flower crops: Aroma c and medicinal plants Fruit trees and small fruits: citrus, cherry, almond, apple, plum, pear, chestnut, quince, strawberries, raspberries, brambles, currants, blueberries Vegetable crops: cucumber, zucchini, ar choke, asparagus …
Regulatory aspects Linked with various policies of biodiversity conserva on or environmental policies (Water Act, Na onal Biodiversity Strategy ...), the Common Agricultural Policy (CAP) requires from farmers to meet compliance of condi onality. Changes include the establishment of vegetated bands along every watercourses and 3% of ecological focus area which includes hedgerows, ponds ... These requirements can result in the crea on of new spaces available for wildlife, including bees. Moreover, they also represent a poten al of produc on (fuelwood from hedgerow trimming, riparian, tadpoles trees ...)
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