The effect of simulated herbivory on growth and nutrient status of focal and neighbouring early successional woody plant species

Lagerström, Anna; Bellingham, Peter J.; Bonner, Karen I.; Wardle, David A.

doi:10.1111/j.1600-0706.2011.19468.x

Cited by 10 publications

(9 citation statements)

References 61 publications

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“…An important next step would be to disentangle direct and indirect effects, for example by including an artificial grazing treatment (see, for example, Lagerström et al . ). There is also a need for further investigation of the mechanistic basis by which below‐ground, cascading effects of invasive ungulates alter competitive interactions between palatable and unpalatable species, and may differentially affect plants that have contrasting nutrient acquisition strategies.…”

Section: Discussionmentioning

confidence: 97%

Soil‐mediated effects of invasive ungulates on native tree seedlings

et al. 2014

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Summary1. Invasive browsing ungulates can have strong impacts on the structure and composition of forest ecosystems, particularly where ungulates are not native ecosystem components as in New Zealand. Ungulate impacts on plant communities have been considered mostly from an above-ground perspective. However, understanding below-ground effects of these invasive herbivores is critical as they may drive feedbacks to above-ground ecosystem components. 2. We measured growth responses of seedlings of five common tree species in a greenhouse experiment in soils collected from 26 plots fenced to exclude invasive ungulates for at least 17 years and from paired, unfenced control plots. We then further investigated soil-mediated effects of ungulates on one tree species, Melicytus ramiflorus, by partitioning these effects into soil abiotic and biotic components, as well as measuring arbuscular mycorrhizal fungal (AMF) root infection. 3. Biomass of seedlings of all five species was greater in soils from within exclosures, although this was only significant for two species. These soil-mediated effects were partially driven by changes in physical and chemical soil properties; soil bulk densities were lower inside exclosures than in controls. 4. Effects of invasive ungulates on seedling biomass of M. ramiflorus were positively related to effects on per cent AMF root infection. The biomass of M. ramiflorus seedlings was positively related to the AMF infection of its roots, which in turn was related to greater organic matter content and lower bulk density of soils from within exclosures. Results for M. ramiflorus indicated that soilmediated effects of ungulates on seedling biomass were of abiotic origin, but were mediated by the biotic soil component, that is, through effects on AMF. 5. Synthesis. Invasive herbivores may potentially impact on plant performance and community structure not only directly but also indirectly through influencing soil abiotic and biotic properties. Our results show that shifts in plant-soil interactions and feedbacks represent important but understudied pathways by which invasive ungulates can have wide-ranging impacts on forest ecosystems. Future studies should consider the importance of soil-mediated effects of invasive ungulates relative to direct effects of herbivory.

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Section: Discussionmentioning

confidence: 97%

Soil‐mediated effects of invasive ungulates on native tree seedlings

et al. 2014

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“…Shoot biomass production throughout the course of the experiment was calculated as the aboveground mass at the time of harvest, plus (for the defoliated plants) the cumulative total mass removed during all the previous clipping events (Wardle and Peltzer , Lagerström et al. ).…”

Section: Methodsmentioning

confidence: 99%

“…This level of defoliation is similar to that used in other comparable experiments on woody plants (Mikola et al 2000, Canham et al 2004, Ayres et al 2007 as well as that which commonly results from mammalian herbivory in New Zealand forests (Nugent et al 2001, Wilson et al 2006. Moreover, experimental defoliation is a widespread method used to mimic the effects of herbivory on individual plants across a wide range of species and systems (Mikola et al 2001, Bee et al 2007, Williamson and Wardle 2007, Lagerström et al 2011, Paine et al 2012. The experiment was maintained as a randomized block design throughout, with 10 replicate blocks of all species x treatment combinations.…”

Section: Experimental Set-upmentioning

confidence: 99%

Soil fertility and disturbance interact to drive contrasting responses of co‐occurring native and nonnative species

Peltzer

Kurokawa

Wardle

2016

Ecology

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Some plant functional groups such as nonnative invasive and nitrogen (N)‐fixing plants are widely thought to have consistent, coordinated differences in their functional traits relative to other groups such as native and non ‐N‐fixing plants. Recent evidence suggests that these trait differences between groups can be context dependent, varying with environmental factors such as resource availability and disturbance. However, many previous comparisons among plant groups differing in invasion status have not standardized growth form between groups or have compared species that do not co‐occur, which could result in invasion status per se being confounded with other factors. We determined growth and leaf functional trait responses of 20 co‐occurring woody species, that is, five species within each of four functional groups (native N‐fixers, native non ‐N‐fixers, nonnative [invasive] N‐fixers and nonnative [invasive] non‐N‐fixers), to factorial combinations of soil fertility and defoliation treatments in a mesocosm experiment to test each of two hypotheses. First, we hypothesized that nonnative invasive and N‐fixing species will have functional traits associated with rapid resource acquisition whereas natives and non ‐N‐fixing species will have traits linked to resource conservation. Second, we hypothesized that plant growth and leaf traits of nonnative and N‐fixing species will be more strongly influenced by environmental factors (i.e., soil fertility and disturbance) than will natives and non‐N‐fixers. Plant growth, foliar nutrients, and leaf structural traits varied among plant functional groups in a manner consistent with our first hypothesis. Support for our second hypothesis was mixed; origin (native vs. nonnative) and soil fertility rarely interacted to determine plant growth or variation in leaf traits whereas interactions involving N‐fixing ability and soil fertility were common. Further, there were no consistent interactive effects between plant groupings and disturbance. Our results demonstrate that variation in growth and functional traits among plant species were driven primarily by the relatively large responses of nonnative N‐fixers to soil fertility, rather than by consistent differences between other plant functional groups. These findings highlight the importance of resource availability in determining trait or performance differences among plant functional groups, and provide insights into the assembly of plant functional traits in novel communities of co‐occurring native and nonnative species.

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“…Glasshouse experiments have shown that Carmichaelia can promote foliar N uptake of coexisting plant species, differentially affecting the growth of different species (Bellingham, Walker & Wardle ; Lagerström et al . ). Several regions in which Carmichaelia or other species within the genus were historically dominant have been colonized by invasive non‐native mammals, including those that feed heavily on Carmichaelia such as hares ( Lepus europeaus ) (Grüner & Norton ) and chamois ( Rupicapra rupicapra ) (Yockney & Hickling ).…”

Section: Introductionmentioning

confidence: 97%

Loss of a dominant nitrogen‐fixing shrub in primary succession: consequences for plant and below‐ground communities

et al. 2012

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Summary1. Many ecosystems are gaining some species and losing others, leading to large shifts in community composition. Plants that support nitrogen (N)-fixing symbionts (hereafter N-fixers) are major ecosystem drivers but human-induced environmental changes can lead to their loss; the impacts of this loss have seldom been studied. In New Zealand, the gain of some invasive herbivorous mammals leads to the loss of N-fixing shrubs that are pioneers during primary succession. 2. We studied primary successional surfaces caused by river floods and landslides in a remote valley in New Zealand's South Island. We set up and maintained a removal experiment over 10 years, with N-fixing Carmichaelia odorata (hereafter Carmichaelia) either left intact or removed to represent the effects that invasive herbivorous mammals could cause under high densities. 3. Above-ground effects of 10 years of Carmichaelia removal included a 7-fold reduction of woody plant biomass, but had no effect on the shorter non-woody vegetation. Foliar N concentrations of two woody species were also reduced. Carmichaelia removal reduced local or a-diversity but enhanced b-diversity of the remaining vegetation at the functional group but not the species level. 4. Below-ground effects of 10 years of Carmichaelia removal included large reductions in soil carbon (C) and N levels, and biomass or abundance of several groups of soil biota occupying three consumer trophic levels as well as the root-, bacterial-and fungal-based energy channels. Invertebrate bacterial consumers were more adversely affected than were fungal consumers. Carmichaelia loss reduced a-diversity of some below-ground groups, while b-diversity was unresponsive or enhanced. 5. Synthesis. Our results reveal that loss of a single functionally distinct plant species, such as occurs through herbivore invasion, can cause substantial effects both above-ground and below-ground. This may affect the trajectory of the ecosystem over successional time, especially in primary seres that otherwise have very low soil carbon (C) and nitrogen (N) reservoirs. More generally, our results support the view that the simultaneous gains of some organisms (e.g. invasive herbivorous mammals) and resultant losses of others (e.g. palatable N-fixing plants) are a major element of humaninduced global change that may be transforming many communities and ecosystems world-wide.

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The effect of simulated herbivory on growth and nutrient status of focal and neighbouring early successional woody plant species

Cited by 10 publications

References 61 publications

Soil‐mediated effects of invasive ungulates on native tree seedlings

Soil‐mediated effects of invasive ungulates on native tree seedlings

Soil fertility and disturbance interact to drive contrasting responses of co‐occurring native and nonnative species

Loss of a dominant nitrogen‐fixing shrub in primary succession: consequences for plant and below‐ground communities

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