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Management Information for Alpine Fescue Grasslands

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Developing management options

The majority of tussock grassland research has focussed on determining the vegetation history of the mountain lands, and how pastoral management practices have influenced vegetation succession patterns. Only recently has grassland research started to look at the issue of progressive successional changes occurring on retired land (i.e. what vegetation changes will take place when tussock grasslands are retired from grazing and burning). In addition, the majority of studies have focussed on determining the impacts of pastoral use on induced montane fescue tussock grasslands (Festuca novae-zealandiae), the most widespread type of short tussock grassland in the eastern parts of the Main Divide. There are many information gaps to be filled, some of which are currently addressed in the FRST-funded research programme "Improved Management Systems for Tussock Grasslands". For more information about this research programme and how to become involved, contact the programme leader Dr Ockie Bosch at boscho@landcare.cri.nz.

In the meantime, the suggested management options have to draw on broad principles and "best guesses" by ecologists, or observations made by people who live and work in the tussock grasslands. Such "best guesses" may be appropriate in some situations, but not others. They will be updated as and when more information becomes available.


High-altitude tussock grasslands

High-altitude tussock grasslands generally require less active management than such communities at lower altitudes. High-altitude areas tend to be less modified, as the more extreme growing environment makes such areas less attractive for pastoral development. Short tussock grasslands at high altitude are an exception. Although some occur naturally in zones of natural disturbance such as avalanche paths, most of those occurring east of the Main Divide have been induced from tall tussock grasslands as a result of pastoral management, and may be further modified by weeds.


Factors influencing the distribution and characteristics of tussock grasslands

for more information on environmental gradients that determine the distribution of tussock grassland types, or the management factors that have influenced the characteristics of tussock grasslands.

Vegetation change since human settlement

if you want further information on a generalised model for vegetation change, east of the Main Divide.

Evolution of an alpine fescue tussock grassland

Fescue tussock grasslands have been induced from tall tussock grasslands, which have been repeatedly burnt and grazed. Meurk (1982) postulates that following patch burning of the snow tussock grassland, sheep concentrate on the patch, preventing the snow tussocks from regenerating. A grazing tolerant blue tussock-herbfield results. With light grazing, alpine fescue tussocks, with or without spaniards become established with the blue tussock sward. Where wind erosion has taken place, the blue tussocks drop out, leaving an induced short tussock grassland dominated by alpine fescue tussock and spaniards.


Impacts of grazing on short tussock grassland in general

Most relevant studies have focused on the impacts of pastoral management on induced montane short tussock grasslands, primarily fescue tussock grasslands. if you want more information.



Impacts of grazing on alpine fescue tussock grassland specifically

No work has been done to determine the levels of grazing required to maintain an alpine short tussock grassland. However, Wraight (1965) in Marlborough observed that, with heavy grazing, Festuca matthewsii and associated grazing-susceptible species e.g. Oreomyrrhis rigida are eliminated. Where erosion is not extremely rapid, Celmisia spectabilis may assume dominance, or co-dominance with bristle grass (Rytidosperma setifolia). However, on steep slopes subject to rapid erosion the sward progressively disintegrates, with bristle grass and blue tussock being the last species to go.

The need for grazing to maintain an alpine short tussock grassland will be determined by the regeneration capacity of snow tussock individuals still present, and the composition and quality of the seed bank. In some instances, where ingress by snow tussocks or subalpine shrub species is minimal, no grazing may be necessary. In other areas, it will. The actual grazing frequency and level of stocking necessary to maintain an alpine fescue tussock grassland is not known. Monitoring is therefore very important.



Maintaining an alpine fescue tussock grassland

While individual alpine fecue tussocks would have always been present in snow tussock communities above the tree line, grasslands dominated by short tussock grasslands would have been induced by repeated burning and grazing of the snow tussock grassland. To stop snow tussocks or alpine shrubland species (where present) from out competing the alpine fescue tussock, active management will be necessary.

At a conservation workshop held in June1996, some participants (ecologists and land managers) indicated that continued grazing of these induced grassland may be necessary to keep them there. However, the actual goal of wanting to maintain an alpine fescue tussock was questioned by some participants.



Buffering

The relationship between an area managed for conservation purposes and its surrounding landscape is important. Ideally, the area should be surrounded by land, which will buffer it from external influences that may compromise its conservation values.

The buffer zone may:
  • act as a fire break, thereby protecting neighbouring land from wild fires occurring in dense tussock grasslands, or preventing controlled fires on pastoral land inadvertently burning an area managed for conservation;
  • protect the area from inadvertent drift of fertiliser and/or seed from neighbouring land (during aerial application);
  • help reduce the rate of spread of some weed species into the area, e.g. intensive grazing between a forest and an ungrazed tussock grassland helps reduce the establishment of wilding trees from that forest.


Weed control

Weed spread is less likely to be a problem at high altitudes, except where significant disturbance has taken place e.g. sheep camps, or at sites which are downwind of conifer stands (plantation or wilding forests). Periodic monitoring of the area is necessary to determine whether weed species are coming into the area, and whether they are reaching problem levels. An assessment of the feasibility of controlling the weeds will then have to be made.

The need to control weed species is dependent on the characteristics of the weed (e.g. will it overtop the tussocks; does its' dispersal mechanism make it an aggressive invader?) and their impact on the indigenous ecosystem in question. Tall woody weeds are considered to be the most troublesome weed in tussock grasslands, as they have the potential to overtop and shade-out the tussocks. Wilding trees are a growing problem in Otago and inland Canterbury.

for more specific information on weed control

The spread of Hieracium in short tussock grasslands

Irrespective of whether managed for pastoral use, or soley for conservation purposes, many short tussock grasslands have a significant component of hawkweed. A large number of studies have been conducted to investigate the relationship between grazing management and rate of Hieracium spread, and associated trends on vegetation composition. However, no studies have focussed specifically on alpine fescue tussock grasslands.

More information on hawkweeds:

Summary of study findings Hieracium Management Information Module


Succession in short tussock grasslands in general

if you want general information on factors influencing vegetation succession (includes model for vegetation succession).

Most research in the tussock grasslands has focussed on the vegetation changes which have taken place as a result of man-induced disturbance (grazing and burning). Future research will need to address information gaps relating to the direction and rate of vegetation change under a minimal disturbance regime. It seems likely, however, that even if burning and grazing cease, succession can be slow and uneven, because of inadequate seed sources and composition from the resident vegetation (Wardle, 1991). The prevalence of exotic plants, especially in small lowland patches of native vegetation may well result in successional pathways away from desired native stable communities. At a Conservation Workshop, Dr Alan Rose outlined five interacting factors which influence the rate and direction of plant invasion in short tussock grasslands. Short tussock grasslands (especially those in modifed environments) are highly predisposed to invasion by weeds for a number of reasons, which are detailed here.

At a conservation workshop in 1996, ecologists and land managers developed a broad brush model to show the possible successional pathways that silver tussock grasslands could take following destocking. Participants suggested that this model could be applied to other types of short tussock grassland. The direction and rate of vegetation change depends on rainfall and altitude. The most problematic weeds were considered to be those that can overtop the tussocks, especially wilding pines and broom (gorse can serve as a nurse crop).

Allowing a Festuca matthewsii grassland to succeed towards a community dominated by native species (composition determined by seed bank)

Little work has been done which can help determine the successional pathways of tussock grasslands under a no burn and no grazing regime. However, where an adequate seed source of snow tussock or alpine shrub species is present- either from adult plants or the seed bank in the soil- it is likely that the alpine fescue tussock grassland would gradually be overtopped and dominated by these other plants.

The rate of succession will be dependent, in part, on the quantity and viability of the seed source, and the climatic characteristics of the area (the rate of woody plant invasion generally increases with increasing soil moisture).

Native woody plant regeneration

The regeneration of native subalpine shrubland species is dependent on the seed source and presence of adult plants in the grassland.

Animal Pests

Hares, rabbits, deer, goats or chamois may deplete alpine fescue grasslands if grazing pressure is too high.

Monitoring

The management guidelines suggested are based on the best available information, and are often only "best guesses". To ensure that the management practices are achieving the desired management goal, it is crucial that the vegetation condition and composition, weed status, and animal pests are monitored. Management may have to be changed in response to the findings of such on-going monitoring.

for more information on monitoring in tussock grasslands

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