Plant Dynamics of New Zealand Tussock Grassland Infested with Hieracium pilosella. I. Effects of Seasonal Grazing, Fertilizer and Overdrilling

Scott, D.; Robertson, John; Archie, W. J.

doi:10.2307/2403580

Cited by 24 publications

(18 citation statements)

References 9 publications

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“…Studies of how livestock grazing and fertilizer application affect H. pilosella establishment and spread have produced conflicting results. For example, fertilizer application has been shown to strongly limit H. pilosella abundance at some sites by increasing the dominance of introduced grasses leading to competitive exclusion (Scott, Robertson & Archie 1990). In contrast, H. pilosella has also been shown to respond more vigorously to increased nutrient supply than a dominant native grass, Festuca novae‐zealandiae , suggesting fertilizer may provide H. pilosella with a competitive advantage that facilitates its spread (Fan & Harris 1996).…”

Section: Case Study: Hieracium Pilosella Invasion In Southern New Zeamentioning

confidence: 99%

Interacting effects of management and environmental variability at multiple scales on invasive species distributions

Diez¹,

Buckley

Case

et al. 2009

Journal of Applied Ecology

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Summary 1.The distribution and abundance of invasive species can be driven by both environmental variables and land management decisions. However, understanding these relationships can be complicated by interactions between management actions and environmental variability, and differences in scale among these variables. The resulting 'context-dependence' of management actions may be well-appreciated by ecologists and land managers, but can frustrate attempts to apply general management principles. 2. In this study, we quantify the effects of land management and environmental variability at different scales on the occurrence and abundance of Hieracium pilosella, a major agricultural weed in New Zealand. We used a hierarchical study design and analysis to capture relevant scales of variation in management actions and environmental heterogeneity, and test hypotheses about how these factors interact. 3. We show that fertilizing and grazing interact with environmental gradients at the scale of management application (farm paddocks) to influence the establishment and local abundance of H. pilosella. 4. We further show that H. pilosella's relationships with fine-scale abiotic and biotic factors are consistent with expected mechanisms driven by larger-scale management actions. Using data on occurrence and local abundance, we tease apart which factors are important to establishment and subsequent local spread. 5. Synthesis and applications. A major challenge for environmental scientists is to predict how invasive species may respond to ongoing landscape modifications and environmental change. This effort will require approaches to study design and analysis that can accommodate complexities such as interacting management and environmental variables at different scales. Management actions will be more likely to succeed when they explicitly account for variation in environmental context.

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Section: Case Study: Hieracium Pilosella Invasion In Southern New Zeamentioning

confidence: 99%

Interacting effects of management and environmental variability at multiple scales on invasive species distributions

Diez¹,

Buckley

Case

et al. 2009

Journal of Applied Ecology

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“…As the most degraded grasslands have low nutrient and moisture status, it was predicted that this control agent would attain high populations and be most effective only in areas where P. officinarum was growing in fertile sites less vulnerable to erosion. Thus it would be most successful in areas where grasslands are fertilized and/or irrigated for agricultural intensification (Scott et al 1990). In a three-year trial (2001)(2002)(2003)(2004) using transects at six sites throughout the South Island, gall wasps established at three sites, but there was no measurable impact and no change in P. officinarum cover (Newell and Smith 2004).…”

Section: Discussionmentioning

confidence: 99%

Predicting possible negative impacts of weed biocontrol by artificially suppressing invasive hawkweed in New Zealand’s tussock grasslands

et al. 2011

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To test the theory that successful biocontrol of invasive hawkweeds (Pilosella and Hieracium spp.) would increase bare ground and accelerate erosion, small areas of hawkweed were suppressed with herbicide in a nine-year study. An increase in bare ground resulting from the treatments was maintained throughout. No new invasive species were recorded, and apart from a temporary increase in a perennial grass, no existing exotic species moved into the gaps created. Indigenous plants did not respond either, although at one site where mat plants were prevalent, treatments slowed their decline. As recovery of existing vegetation was minimal, it is likely that invasion of hawkweed is a consequence of degradation rather than the reverse, and if biocontrol is successful, degraded grasslands may suffer further damage, especially in areas that are grazed. The effect may be ameliorated since biocontrol agents are predicted to perform less well under conditions of low fertility and low moisture. Our results emphasize the importance of pre-release ecological studies to clarify the role of invasive plants proposed for biocontrol.

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“…In its native habitat, A. subterminalis occurs on H. pilosella inhabiting arid, nutrient-poor grasslands, poorly fertilized upland pastures, inland dunes, and man-made heaths (Ellenberg, 1988) indicating that it should be adapted to survive in dry, low-nutrient environments. Many of the areas occupied by H. pilosella in New Zealand are similarly relatively dry and low in nutrients (Scott et al ., 1990) and successful biocontrol agents will need to colonize and populate plants growing in these conditions. Results indicate that the gall wasp should be able to do this successfully.…”

Section: Methodsmentioning

confidence: 99%

“…flightless birds prior to the introduction of grazing animals from Europe in the midnineteenth century (Scott et al ., 1990). The rampant invasion of H. pilosella into grassland ecosystems has been attributed in part to its weedy characteristics in a new environment, freed from the biotic constraints present in its native Europe, and in part to the increasing degradation of grassland ecosystems as a result of overgrazing (Rose et al ., 1995).…”

Section: Introductionmentioning

confidence: 99%

Predicting the Impact of the Biocontrol AgentAulacidea subterminalis(Cynipidae) on Growth ofHieracium pilosella(Asteraceae) under Differing Environmental Conditions in New Zealand

Klöppel¹,

Smith

Syrett³

2003

Biocontrol Science and Technology

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A gall wasp, Aulacidea subterminalis, was released into the field in New Zealand in 1999 for biocontrol of the grassland weed Hieracium pilosella. To predict its likely impact in the field, the effect of the gall wasp on plant growth was measured under stress-free conditions in a shade house trial with potted plants. Plants with galls showed a reduction in stolon length of 75%. They had slightly lower total dry matter and reduced root weight. In a glasshouse experiment to measure the impact of water stress, nutrient stress, and plant competition on growth of H. pilosella and performance of the gall wasp, the number and mean diameter of gall clusters were not significantly different between treatment and control plants. However, galled plants produced more, but shorter, stolons in all stress treatments, and stolons that were more branched in nutrient-and water-stressed plants, than ungalled plants. Under the plant competition treatment, total stolon length relative to biomass was greater with, than without, wasps, indicating that stolons were thinner. Galling by A. subterminalis is likely to reduce vegetative reproduction of H. pilosella whether or not the plants are stressed, indicating that the wasp may be a successful biocontrol agent.

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Plant Dynamics of New Zealand Tussock Grassland Infested with Hieracium pilosella. I. Effects of Seasonal Grazing, Fertilizer and Overdrilling

Cited by 24 publications

References 9 publications

Interacting effects of management and environmental variability at multiple scales on invasive species distributions

Interacting effects of management and environmental variability at multiple scales on invasive species distributions

Predicting possible negative impacts of weed biocontrol by artificially suppressing invasive hawkweed in New Zealand’s tussock grasslands

Predicting the Impact of the Biocontrol AgentAulacidea subterminalis(Cynipidae) on Growth ofHieracium pilosella(Asteraceae) under Differing Environmental Conditions in New Zealand

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