Alders increase the availability of soil phosphorus [researchgate.net]
Alders are an important food plant for the caterpillars of many butterfly and moth species and also for small birds in winter.There are 90 insect species associated with this tree. [pfaf.org]
"Nitrogen fixation requires rare heavy-metal element molybdenum as a catalyst." ... "To fix 1 gram of nitrogen, an estimated 10-100 grams of glucose is required.' Most microorganisms rarely have energy resources to produce large amounts of fixed nitrogen. Higher plants can produce excess energy through photosynthesis, but they cannot produce the necessary enzyme." [oregonstate.edu]

Populus and Salix cutting propogation: Las estacas de Populus y Salix hay que prepararlas cuando no tienen hojas, a sabia parada. Igualmente, el brote que te puedan hacer ahora no estará lignificado y con el frío del invierno se puede quemar. Estas estacas enraizaran y brotaran en primavera, por lo que en invierno poco van a hacer. [Plant supplier / nursery]
A pioneer species of willow, it quickly colonizes poor soils. [wikipedia.org]
Q__ La estaca de Populus/Salix, tiene que ser del año de crecimiento o puede ser de 2/3 años? Puede ser de 2/3 años. A__ Nosotros lo hacemos en alveolo forestal, por lo que utilizamos estacas delgadas, del año, pero en campo es conveniente ponerlas más gordas para que tengan más reservas y aguanten el terreno. Q__ Y se puede enterrar/clavar la estaca muy profundo, como 40-50cm o más? Se puede pudrir? A__Sí, se puede pudrir, sobretodo si hay agua estancada durante muchos días. Yo intentaría clavarlas en febrero para que estén el menor tiempo enterradas y sin brotar. [Plant supplier / nursery][naturalea.eu]
Cuttings directly on the ground need a wide area clearing and weed suppression, use large leaves and heavy thick mulch. [Can Neret]

Elderberry cuttings take months to root. Had more success with propagation at end of summer, after the first rains wet the ground and the parent plant are hydrated. [Can Neret]

Plant near water but not on water, 2-4 plants per m2, grows on shade with deep roots, hardy. Fast growing. Allows hard pruning at end of winter. Separate rhizomes for propagation during the spring. Water purification, natural spaces rehab [Plant supplier / nursery]
Use Carex pendula to fully shade and stabilize canal. /3T: "It is very resistant to pests and diseases and supports severe pruning in late winter. You can easily reproduce it by dividing the bush in the spring and letting the rhizome regrow. Prefers spots outside the water." [Plant supplier / nursery][vivertresturons.com]

The nursery mixes male and female willows

To harvest flowers and cuttings for propagation at end of summer.

Supply nutrient-rich mulch for future vegetable garden. Harvest after flowering.