Naturally Reconstructing a Grassland Cover

Beef cattle breeding Breeding Dairy cattle breeding

"Naturally" restoring a grassland cover allows to:

Not suffer but rather steer the plants that establish after degradation
Decide what to do at each stage of cover restoration
Seek a less costly and more sustainable alternative than sowing to replenish a meadow

This fact sheet proposes:

to understand the processes involved in the transition from bare soil to the return of a desired grassland cover
to set observation criteria on the vegetation of the plot at different time steps
to design, based on observations made, a set of practices to steer the succession of plant species towards what is expected.

When bare soil is observed, it is not mandatory to take out the tractor to reseed. "Naturally" restoring a forage cover that maintains itself over the years is possible. However, this does not mean waiting and relying solely on the natural capacity of meadows to recover.

Grazing practices can be a technical lever to calmly accompany the succession of plant species. They thus constitute an alternative to sowing or overseeding. The cover restoration may be longer, but more sustainable.

Above all, it will surely be more certain…

Defining a grassland cover with desired characteristics

Here, a grassland cover is defined as a plant cover that is perennial over time, diversified and dominated by a mixture of grasses (monocotyledons) and/or legumes (dicotyledons) in variable proportions. The desired characteristics are defined according to each breeder’s objectives in terms of the role of the plot in the system, the dietary needs of the herd to be covered, and the expected evolution of the vegetation.

Defining cover degradation

Here, degradation is defined as a situation materialized by the appearance of bare soil. It can result from mechanical destruction of the cover (mowing, plowing, tractor wheel passes…), damage by wild animals by trampling or rooting (wild boars, mole rats…), climatic damage (erosion by rain, severe drought…), but also from the combination of grazing or mowing practices leading to plant exhaustion (too frequent removals compared to the plants’ reserve replenishment rate, trampling…).

Promoting seedling establishment

Bare soil is a favorable ground for the initial and spontaneous establishment of seedlings. Allowing all seedlings to establish (even those that do not seem interesting in the long term) is essential to heal the cover initially.

Without sowing, or in the absence of colonization by vegetative means, a phase with pioneer plants is inevitable. It is useless to want to control which ones will develop or not. Only later will it be necessary to implement practices to steer the composition of the plant community.

Plant germination period

Species do not germinate at the same time or even in the same season. Therefore, observations should be maintained throughout the year before drawing hasty conclusions in early spring. For example, in spring, legume germination is later than that of grasses. Among dicotyledons, some species germinate year-round (Geraniums, Speedwells…), others preferentially in spring (White goosefoot, Knotweed…) or autumn (Field ryegrass…).

Observe whether seedlings are monocotyledons or dicotyledons

If the dominant seedlings are monocotyledons: Vegetation succession is already underway towards a grassland cover. In this situation, if seedling and young plant survival is allowed, cover restoration can be rapid.

If the dominant seedlings are dicotyledons: Among dicotyledons, there is a diversity of flowering plants, some called "ruderal" and generally not desired long-term in the cover (mayweed, speedwell, shepherd’s purse, mullein, thistle…). These species reflect the plot’s history. Their development strategy is: saturating the environment with seeds, rapid and early establishment, and a short life cycle. In this situation, grassland cover restoration will be longer because it must go through a succession of plant species to reach the desired monocotyledon/dicotyledon balance.

Antagonistic role of pioneer plants

Even if pioneer plants (especially annuals) are not desired long-term, it is still important to promote their establishment because it allows the future establishment of sought-after grassland plants. Indeed, the establishment of a pioneer flora provides temporary cover which can facilitate the germination of perennial grasses that need darkness to germinate but also the survival of seedlings especially during summer periods by protecting them from direct sunlight and drought.

Moreover, the rapid establishment of ruderal plants, often rosette-forming, has a role in soil stabilization and protection against erosion and reduces the risk of crusting formation after heavy rains.
This ruderal community can compromise vegetation succession because once established, ruderal flora occupies space and can compete for light with seedlings of expected grassland species. It is then necessary to exhaust them or rather to limit their development in favor of young plants with grassland value.

Check if seedlings come from vegetative or sexual reproduction

By vegetative multiplication, seedling establishment occurs from a "mother" plant still present on the plot via suckers from roots or rhizomes (rush, Carex, couch grass, feather grass…) or stolons (Creeping bentgrass, White clover…). They benefit from the mother plant’s reserves or rhizome/root residues. Thus, rapid and robust coverage of bare soil areas can be expected. These seedlings are therefore more competitive than those from sexual reproduction. Beware of possible cover homogenization due to light competition they exert on young seedlings from seeds.

By sexual reproduction, seedling establishment occurs from the germination of seeds present in the soil. All soils have a "seed bank". This consists of seeds inherited from previous years’ seed production but also seeds from the environment around the plot (brought by wind and/or animals, and/or introduced via hay and/or manure…). There is no simple observation to know the composition of the seed bank present in the soil.

Avoid seedling destruction

At this stage, all practices that could cause seedling destruction should be avoided (tool passage, grazing under low load-bearing conditions, very close grazing…)

Develop plants towards the desired cover

Once seedlings have started colonizing bare soil, the main challenge becomes to promote the survival of young plants of the desired species. It is then necessary to give them time to produce surplus energy by photosynthesis accumulated as energy reserves in specialized organs (grass sheaths, roots, rhizomes, seeds, etc.). This energy stock will make them more able to face future harsh climatic seasons (drought, heat, cold) as well as future removals (mowing or grazing).

Distinguish species by their sensitivity

It is not necessary to become a botany expert but it seems essential to distinguish species by their annual functioning. This allows identifying their sensitivity period and thus scheduling practices that favor or not their survival.

Difference in sensitivity periods between plants.

Among annual and biennial dicotyledons, the reserve level is lowest at the beginning of the growth period and at flowering onset.

Among grasses, plants are most sensitive at the beginning of growth periods (early spring, early autumn).

Among species whose reproduction mode is vegetative multiplication, a leafy stage indicates when the plant becomes able to develop without drawing on root reserves. (Thistle: 6-8 leaves, couch grass: 3-4 leaves…).

Control the proportion of pioneer plants

To exhaust plants that are not desired in the future, leaf removal must occur when their reserves are lowest. This removal forces them to draw again on reserves, causing cumulative weakening (regrowth delay, productivity decrease), even mortality. Thus, interventions must be spaced enough to allow plants to produce new shoots before another removal, but close enough to prevent full reserve replenishment.

To limit the development of young plants not desired in the future, their flowering can be blocked. Indeed, once the flowering stem is removed (by mowing or grazing), dicotyledons will not flower again that season. This stops their growth; unlike grasses, they cannot tiller. This is when it is possible to play on interspecific competition, notably for light, by letting desired species take over.

This type of intervention is delicate because it risks also affecting the reserves of other young plants that one

wants to keep.

If the practices implemented cause rapid mortality of pioneers, succession stagnates and inevitably

goes backward, to stage 1.

Destruction of young dicotyledon plants reproducing vegetatively by mechanization can have a multiplying effect by spreading rhizome or root fragments that can give rise to new plants.

How long does succession take?

There is no single simple answer to this question. It is important to determine early your objective, i.e., the desired vegetation state. The time allowed to achieve it can be greatly reduced if management strategies adapted to each restoration stage are implemented. As seen, several factors influence this succession time: origin of disturbance, seedling reproduction type, monocotyledon/dicotyledon proportion at seedling stage, implementation of practices at young plant stage that steer the transition from pioneer flora to grass flora. If practices are adapted, results can be conclusive from the first season…

Develop plants towards the desired cover

When the floristic community stabilizes, pioneers have given way, and plants have become adult, several steps are necessary to reason the practices to implement to develop the vegetation towards the desired grassland cover.

Analyze the current functioning of the meadow

At this stage, it is about observing the functioning of the meadow. Usual characteristic criteria (productivity and nutritional value) can be enriched by less usual but equally interesting criteria: aptitude for residual grazing, precocity

and annual growth profile, speed of energy reserve accumulation, earing precocity, etc.

Check if objectives are achievable on the farm

It is important to quickly verify if the set objective is achievable under the particular pedoclimatic conditions of each farm: some soils may not support demanding plants, some exposures may not host early flora, some climates may not be compatible with precocity or high productivity, etc.

Design practices to steer the flora

To develop an established grassland flora, management by adapted practices is done with some inertia, changes being slower than in the early colonization stages.

Illustration by a concrete case

© S.Mihout - SCOPELA - (photo taken in spring)

Origin of disturbance:

Former melon crop

Characteristics of the cover sought by the breeder

Diverse and balanced herbaceous cover (neither too rich nor too nitrogenous) for ewes and young lambs at the end of spring

What is observed?

Cover development stage: majority of individuals at young plant stage and some at seedling stage.

Cover composition: dominance of unwanted pioneer dicotyledons (thistles, teasels), moss, young monocotyledon plants (grass mixture).

Reproduction type: Thistle: vegetative and sexual

Teasel and grasses: sexual

Species functioning: Thistle and teasel are biennial plants. They form rosettes the first year and develop a flowering stem the second.

What to do at this stage?

The objective is to limit the development of thistles and teasels in favor of grasses and legumes. To do this:

Maintain seedling emergence observations throughout spring. Also observe autumn germinations.

Avoid any practice that would destroy young plants and inevitably revert succession progress to bare soil stage.

Put rosette plants in competition with grass in spring as soon as young forage plants (grasses and legumes) are more developed.

Promote reserve accumulation in grasses and legumes by practicing selective grazing at the end of spring (= manage timing, duration, and frequency of removal)

Keep biomass standing to protect young seedlings from summer drought

Perform optional grazing in autumn to utilize grass regrowth without close grazing to ensure good grass start in spring and maintain biomass competing for light early next spring to limit establishment of undesired new plants.

Annexes

Resources to go further

This fact sheet is part of the technical tool collection published by the Pâtur’Ajuste network highlighting breeders’ know-how around the valorization of natural meadows and pastures in Livestock systems.

Autres fiches Pâtur’Ajuste

Sources

SCOPELA, with breeders’ contribution. Technical fact sheet of the Pâtur’Ajuste network: Naturally restoring a grassland cover. SCOPELA, September 2024. Available at: https://www.paturajuste.fr/parlons-technique/ressource/ressources-generiques/reconstituer-naturellement-un-couvert-prairial
Reference guide: Giving Value by Use to Each of Your Plots. Pâtur’Ajuste Network