Wardle, D. A.; Bonner, K. I.; Barker, G. M. 2002. Linkages between plant litter decomposition, litter quality, and vegetation responses to herbivores. Functional Ecology 16: 585–595.
To predict possible effects of deer and goats on the decomposer subsystem, litter from several understorey plant species were collected from 28 forested locations throughout New Zealand. At each location exclosure plots were used to determine effects of browsing mammals on each plant species. Litters from those species which were reduced by browsers decomposed more rapidly, and had lower concentrations of phenolics, tannins, lignin and fibre than those promoted by browsers; litter N and P concentrations did not differ between these two types of plants. This suggests that browsing results in understorey domination by plant species that impair decomposer processes.
02 December, 2002
Sessions and Kelly (2002): Predator-mediated apparent competition between an introduced grass and a native fern.
Sessions, L.A. & Kelly, D. 2002. Predator-mediated apparent competition between an introduced grass (Agrostis capillaris) and a native fern Botrychium australe (Ophioglossaceae) in New Zealand. Oikos 96: 102-109.
A 1995 wildfire burnt a population of Botrychium which had been studied since 1986. The fern survived the fire well, but from 1997 on suffered very high levels of herbivory which prevented reproduction, reduced plant size and increased mortality. Exclusion experiments identified the introduced slug Deroceras reticulatum as the culprit; the slug increased due to greater shelter from Agrostis which increased after the fire. Therefore this is an example of apparent competition: the introduced grass negatively affected the native fern by harbouring an introduced invertebrate herbivore. The future for this population of Botrychium looks bleak.
A 1995 wildfire burnt a population of Botrychium which had been studied since 1986. The fern survived the fire well, but from 1997 on suffered very high levels of herbivory which prevented reproduction, reduced plant size and increased mortality. Exclusion experiments identified the introduced slug Deroceras reticulatum as the culprit; the slug increased due to greater shelter from Agrostis which increased after the fire. Therefore this is an example of apparent competition: the introduced grass negatively affected the native fern by harbouring an introduced invertebrate herbivore. The future for this population of Botrychium looks bleak.
Schauber et al. (2002): Synchronous and asynchronous masting by 18 New Zealand plant species.
Schauber, E.M., Kelly, D., Turchin, P., Simon, C., Lee, W.G., Allen, R.B., Payton, I.J., Wilson, P.R., Cowan, P.E. & Brockie, R.E. 2002. Synchronous and asynchronous masting by 18 New Zealand plant species: the role of temperature cues and implications for climate change. Ecology 83: 1214-1225.
This paper tests for synchrony in seed crops in 34 datasets from 18 NZ plant species from Fiordland to Wellington, in Chionochloa, Nothofagus, Phormium, Elaeocarpus, and Dacrydium. All species except rimu were highly correlated across years within and between genera. Heavy seeding years came one year after warm summers, and were also related to high values of the Southern Oscillation Index (La Nina). The synchrony is apparently not driven by selective benefits (e.g. shared seed predators) but instead by incidental sharing of the same climate cue. Global warming could alter the pattern of high seed crops, with widespread community effects.
This paper tests for synchrony in seed crops in 34 datasets from 18 NZ plant species from Fiordland to Wellington, in Chionochloa, Nothofagus, Phormium, Elaeocarpus, and Dacrydium. All species except rimu were highly correlated across years within and between genera. Heavy seeding years came one year after warm summers, and were also related to high values of the Southern Oscillation Index (La Nina). The synchrony is apparently not driven by selective benefits (e.g. shared seed predators) but instead by incidental sharing of the same climate cue. Global warming could alter the pattern of high seed crops, with widespread community effects.
Sanders and Maloney (2002): Causes of mortality at nests of ground-nesting birds in the Upper Waitaki Basin, New Zealand: a five-year video study.
Sanders, M.D.; Maloney, R.F. 2002. Causes of mortality at nests of ground-nesting birds in the Upper Waitaki Basin, New Zealand: a five-year video study. Biological Conservation 106: 225-236.
This study used video cameras to obtain definitive evidence of the causes of mortality at nests of three species of ground-nesting birds. Unlike most video studies, this study videoed sufficient nests to draw conclusions about the relative impacts of various predators. Seventy-seven lethal events were recorded at 172 nests. Cats, ferrets, and hedgehogs accounted for 43, 19, and 18% of mortality at nests. Cats were the only predator to take adult birds. Stoats, avian predators, and other causes of mortality each accounted for <4% of lethal events. The paper also reports on the duration and diurnal timing of predation.
This study used video cameras to obtain definitive evidence of the causes of mortality at nests of three species of ground-nesting birds. Unlike most video studies, this study videoed sufficient nests to draw conclusions about the relative impacts of various predators. Seventy-seven lethal events were recorded at 172 nests. Cats, ferrets, and hedgehogs accounted for 43, 19, and 18% of mortality at nests. Cats were the only predator to take adult birds. Stoats, avian predators, and other causes of mortality each accounted for <4% of lethal events. The paper also reports on the duration and diurnal timing of predation.
Joy and Death (2002): Predictive modelling of freshwater fish as a biomonitoring tool in New Zealand.
Joy, M. K.; Death, R. G. 2002. Predictive modelling of freshwater fish as a biomonitoring tool in New Zealand. Freshwater Biology 47: 2261–2275.
The paper describes the first application of a regional predictive model using freshwater fish for bioassessment in New Zealand. Fish assemblages were surveyed at 200 reference sites in the Manawatu–Wanganui region. These “reference sites” represent the best available conditions covering the full range of stream types in the region. They were used to predict the fish assemblages to be expected in the absence of impacts using multivariate analysis based on environmental variables. Test site fish assemblages were compared with expected assemblages using weighted probabilities from reference sites using an observed over ex-pected (O/E) ratio.
The paper describes the first application of a regional predictive model using freshwater fish for bioassessment in New Zealand. Fish assemblages were surveyed at 200 reference sites in the Manawatu–Wanganui region. These “reference sites” represent the best available conditions covering the full range of stream types in the region. They were used to predict the fish assemblages to be expected in the absence of impacts using multivariate analysis based on environmental variables. Test site fish assemblages were compared with expected assemblages using weighted probabilities from reference sites using an observed over ex-pected (O/E) ratio.
Lord et al. (2002): Have frugivores influenced the evolution of fruit traits in New Zealand?
Lord, J.M.; Markey, A.; Marshall, J. 2002. Have frugivores influenced the evolution of fruit traits in New Zealand? In D. Levey, WR Silva and M Galetti (eds.) Seed dispersal and Frugivory: Ecology, Evolution and Conservation. CABI Publishing, Wallingford, Oxfordshire, U.K.
The chapter summarises information on fruit size and colour in NZ then looks at the influence of three frugivore guilds (non-volant birds, volant birds, reptiles) on fruit evolution. Flightless birds, including moa, ate fruit, but there is no evidence of fruit "adapted" to dispersal by these species. The smaller size of NZ fruit reflects the smaller sizes of volant frugivorous birds (c.f. Australia), indicating that fruit evolution in NZ has been influenced by the characteristics of this guild. Frugivory by reptiles may have played a part in the evolution of pale fruit colours in small leaved shrubs.
The chapter summarises information on fruit size and colour in NZ then looks at the influence of three frugivore guilds (non-volant birds, volant birds, reptiles) on fruit evolution. Flightless birds, including moa, ate fruit, but there is no evidence of fruit "adapted" to dispersal by these species. The smaller size of NZ fruit reflects the smaller sizes of volant frugivorous birds (c.f. Australia), indicating that fruit evolution in NZ has been influenced by the characteristics of this guild. Frugivory by reptiles may have played a part in the evolution of pale fruit colours in small leaved shrubs.
Leathwick (2002): Intra-generic competition among Nothofagus in New Zealandís primary indigenous forests.
Leathwick, J. R. 2002. Intra-generic competition among Nothofagus in New Zealandís primary indigenous forests. Biodiversity and Conservation 11: 2177–2187.
This paper extends the analysis described in Leathwick & Austin (2001) by considering competitive interactions within the genus Nothofagus. Species responses to environment were first assessed using multiple regressions, to which were added terms to assess changes in both overall abundance and species responses to annual temperature with increasing numbers of congeners. Results indicate that variation in abundance along the annual temperature gradient is strongly influenced by the competitive context provided by the remaining congeners. Red and silver beech also appear to behave in a mutualistic fashion, reaching greater abundance when growing together than when growing with other species.
This paper extends the analysis described in Leathwick & Austin (2001) by considering competitive interactions within the genus Nothofagus. Species responses to environment were first assessed using multiple regressions, to which were added terms to assess changes in both overall abundance and species responses to annual temperature with increasing numbers of congeners. Results indicate that variation in abundance along the annual temperature gradient is strongly influenced by the competitive context provided by the remaining congeners. Red and silver beech also appear to behave in a mutualistic fashion, reaching greater abundance when growing together than when growing with other species.
Holzapfel et al. (2002): Genetic variation of the endangered holoparasite Dactylanthus taylorii (Balanophoraceae) in New Zealand.
Holzapfel, S., Faville, M. & Gemmill, C.E.C. 2002. Genetic variation of the endangered holoparasite Dactylanthus taylorii (Balanophoraceae) in New Zealand. Journal of Biogeography 29: 663–676.
Genetic variation among seventeen populations from the entire known range of the endemic root parasite Dactylanthus taylorii is studied using RAPDs. Markers show that all sampled populations are unique and can be grouped into two main clusters, corresponding to an eastern and western distribution separated by the Taupo Volcanic Zone. Observed genetic variation is predomi-nantly among as opposed to within populations and is not correlated with geographical distance below the regional scale. Results indicate long isolation and restricted gene flow among populations and are interpreted mainly as characteristics of the species. The role of vegetation disturbance through volcanism is discussed.
Genetic variation among seventeen populations from the entire known range of the endemic root parasite Dactylanthus taylorii is studied using RAPDs. Markers show that all sampled populations are unique and can be grouped into two main clusters, corresponding to an eastern and western distribution separated by the Taupo Volcanic Zone. Observed genetic variation is predomi-nantly among as opposed to within populations and is not correlated with geographical distance below the regional scale. Results indicate long isolation and restricted gene flow among populations and are interpreted mainly as characteristics of the species. The role of vegetation disturbance through volcanism is discussed.
Miller (2002): Conservation of riparian forest remnants, West Coast, New Zealand.
Miller, C. 2002. Conservation of riparian forest remnants, West Coast, New Zealand. Landscape Research 27: 125-140.
This paper presents data on the spatial extent and distribution of intact and fragmented riparian forest on the South island’s West Coast. The implications of ecological processes and land-management practises are discussed, and three conservation priorities are identified.
This paper presents data on the spatial extent and distribution of intact and fragmented riparian forest on the South island’s West Coast. The implications of ecological processes and land-management practises are discussed, and three conservation priorities are identified.
Gillman et al. (2002): Use of artificial seedlings to estimate damage of forest seedlings due to litterfall and animals.
Gillman, L.N., Wright, S.D., & Ogden, J. 2002. Use of artificial seedlings to estimate damage of forest seedlings due to litterfall and animals. Journal of Vegetation Science 13: 635–640.
Artificial seedlings are often used to estimate seedling mortality due to non-trophic micro-disturbance such as litterfall and up-rooting. This study evaluated the use of artificial seedlings in five New Zealand forests. It was concluded that artificial seedlings could not be used to estimate mortality, and were vulnerable to a novelty response by animals. The value, however, of artificial seedlings is that they provide a good measure of litterfall disturbance potential that is independent of natural seedling clumping within litterfall safe-sites, and independent of species specific resistance to damage. Thus, they can be used to compare litterfall damage risk among microsites and forests.
Artificial seedlings are often used to estimate seedling mortality due to non-trophic micro-disturbance such as litterfall and up-rooting. This study evaluated the use of artificial seedlings in five New Zealand forests. It was concluded that artificial seedlings could not be used to estimate mortality, and were vulnerable to a novelty response by animals. The value, however, of artificial seedlings is that they provide a good measure of litterfall disturbance potential that is independent of natural seedling clumping within litterfall safe-sites, and independent of species specific resistance to damage. Thus, they can be used to compare litterfall damage risk among microsites and forests.
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