Climatic relationships of some New Zealand forest tree species

Abstract. A dataset of some 10 000 plots was used to describe the climatic relationships of 33 widespread New Zealand tree species. Estimates of mean annual temperature, temperature seasonality, mean annual solar radiation, and moisture balance were derived from mathematical surfaces fitted to climate station data. Plots were also categorized into five lithological classes and three drainage classes. Generalized additive models were used to examine species/environment relationships. Mean annual temperature and mean annual solar radiation are most strongly correlated with current tree distributions, followed by moisture balance, temperature seasonality, lithology, and drainage. Most broad-leaved tree species other than Nothofagus spp. reach their greatest levels of occurrence in warm, moist environments with high solar radiation. In contrast, Nothofagus spp. generally reach their greatest levels of occurrence in cooler and/or lower insolation environments, and all have lower levels of occurrence on rhyolitic substrates which have resulted from large-scale geomorphic disturbance, mostly over the past few thousand years. Although coniferous species have widely differing climatic optima, many are biased towards lithological classes characterized either by large-scale geomorphic disturbance or harsh edaphic conditions. The relevance of these results to particular synecological questions is briefly discussed. Continuing adjustments in the range of slow-dispersing Nothofagus spp. are strongly suggested, and the climatic suitability of extensive rhyolitic basins in the central North Island, from which these species are largely absent, is confirmed.     

Biotope Associations and the Decline of Bumblebees (Bombus spp.)

Much of the ecology of rare bumblebee species remains poorly understood and in need of further study. It has recently been suggested that differences in the range and rate of decline among bumblebee species may relate to differences in their degree of habitat specialization. We examine biotope use by 17 bumblebee species in the Hebrides, southern UK and South Island, New Zealand. We identify a cluster of widespread and abundant species that occur in almost all biotopes and exploit man-made environments such as gardens and arable margins, this group corresponding to the “mainland ubiquitous” species of previous studies. A second grouping of species includes those associated to varying degrees with heathland. It is notable that some species occupy markedly different biotopes in different parts of their range; for example B. soroeensis is found largely on upland heaths in the Hebrides, but on calcareous grassland in the south. Some species, such as B. subterraneus and B. distinguendus, now survive only in specific rare biotopes and could be mistaken for habitat specialists, but it is clear from their historic distributions that they formerly occupied a broader range of biotopes. Surviving populations of several of the species that have declined most (B. distinguendus, B. sylvarum, B. muscorum sladeni, B. humilis) exhibit a markedly coastal distribution, when once they were widespread inland. We suggest that this is probably simply because some coastal biotopes are less amenable to agricultural improvement, and so more have escaped the detrimental effects of intensive farming. Our results concur with previous suggestions that bumblebees are generally not habitat specialists, so that the conservation of most bumblebee species could be achieved by restoration of flower-rich unimproved meadows.     

A review of the biology of British Naididae (Oligochaeta) with emphasis on the lotic environment

SUMMARY. Naidids live in a wide range of aquatic habitats but are particularly important numerically as part of the benthic fauna of rivers with stony substrates. In general they graze on bacteria and algae although some, particularly Chaetogaster spp., are mainly predaceous, and C. limnaei vaghini is a parasite of molluscs, chiefly Gastropoda. Food selection seems to be based largely on particle size although the food quality of the particles within the appropriate size-range influences rates of growth and reproduction. Major factors determining the distribution and abundance of naidid species are the nature of the substratum and the presence and kind of vegetation. Plants with a highly dissected form, a thick growth habit, and which permit the greatest periphyton development generally support the most abundant naidid populations. The oligochaete fauna of coarse substrates (stones and gravels) is often dominated by the Naididae but both species-richness and abundance of naidid populations are generally reduced where fine substrates (silts and muds) occur. The occurrence of worms within the substratum is also determined by its nature; naidids penetrate to depths of 20–70 cm in coarse substrates but rarely penetrate below 6 cm in mud. The principal factor limiting both depth penetration and the dominance of naidids in fine substrates is probably oxygen availability. Naidids reproduce both asexually and sexually, the former method predominating for most of the year. Asexual reproduction usually involves the budding-off of zooids but a few species fragment. Sexual reproduction is often infrequent; populations of some species produce few or no sexually mature individuals. In mature worms asexual reproduction virtually ceases. In populations that produce mature individuals there is apparently one sexual generation a year, usually occurring during the summer and autumn. Adults die soon after laying their cocoons. In general, naidids are most abundant during the summer months when rates of growth and asexual reproduction are stimulated by higher temperatures and a plentiful supply of food. A few species, however, e.g. Nais elinguis and Paranais litoralis, are more abundant in the spring. The response of naidid species to different kinds of pollution is varied but generally organic enrichment of rivers which have stony substrates results in a considerable (ten- to twenty-fold) increase in naidid abundance. Nais elinguis, N. barbata, N. communis, N. variabilis, and Chaetogaster diaphanus are often abundant in such rivers, the foremost species reaching densities of 200 000 m^?2. Nais alpina, N. bretscheri, and N. pardalis appear to be relatively intolerant of organic enrichment. A substantial increase in naidid abundance is also promoted by the deposition of biologically inert particles (coal dust, china clay, sand) on the river bed. The importance of Naididae in relation to pollution surveillance of fresh waters is discussed.     

On the dendrochronological potential of Australian trees

In the last few years there has been a marked growth of interest in the recent history of climate. The evidence of secular variations in climatic parameters during the last few centuries has implications for ecologists studying forests containing long-lived species. Such species record aspects of past climate in their annual growth-rings and in their population structures. The study of annual growth rings in Australian trees is still in its infancy. The concepts and techniques of dendrochronology and its sub-fields dendroecology and dendroclimatology are outlined. A species by species account of dendrochronological studies employing Australian trees is presented. As most of the results are unpublished, the treatment is selective and intended to illustrate the potential of, or progress with, a particular tree species. The greatest potential for dendrochronology in Australia lies with the endemic Tasmanian conifers in the genera Athrotaxis, Dacrydium and Phyllocladus. Not only do these contain very long lived individuals (e.g. > 2000yr, Dacrydium franklinii) but also they have the most suitable ring characteristics. Chronologies of about 1000 yr and 780 yr are being prepared for A. cupressoides and Phyllocladus aspleniifolius respectively. There is good regional cross-dating within species, and to a lesser extent between species, giving promise of a detailed reconstruction of past climate for Tasmania. Relatively short chronologies may be developed on the mainland using Callitris. This species may provide a proxy rainfall record for semi-arid areas which would be invaluable to their future management. The possibilities for developing chronologies using long-lived tropical rain-forest species in Queensland are discussed. The most abundant tree species of the continent as a whole, in the genera Eucalyptus and Acacia, appear to be generally unsuitable for standard dendrochronological methods aimed at climatic reconstruction although there are some exceptions. For many dendroecological studies Eucalyptus will be the only species available, and it should certainly not be disregarded.     

Reproductive strategies of epialgal bryozoans

Summary

Bryozoans are common encrusting organisms in many shallow-water marine environments. Although reproducing sexually, their success as space occupiers resides largely in their capacity for colonial growth by zooidal budding (regarded by some as a form of asexual reproduction). This paper examines the reproductive strategies of several bryozoan species commonly associated with the fronds of coastal macroalgae. These range from ephemeral species that grow rapidly, reproduce and die (Electra pilosa, Celleporella hyalina, Membranipora membranacea) to more or less annual species with well-developed reproductive and growth cycles (Flustrellidra hispida, Alcyonidium spp.). Whilst many of these bryozoans brood relatively few short-lived lecithotrophic larvae, others produce large numbers of longer-lived planktotrophic larvae. The seasonal and daily patterns of larval release are described for selected species. Resource allocation to sexual and colonial functions is considered in the context of environment-genotype interactions. Reproductive strategy is especially important in determining dispersal and colonising ability, and these in turn are major determinants of ecological pattern in epialgal bryozoan communities.     

The cost of being able to fly: a study of wing polymorphism in two species of crickets

Summary The widespread occurrence of wing polymorphisms in insects suggests that the possession of wings and ability to fly adversely affect components of the insect's life characteristics that contribute to its Darwinian fitness. This hypothesis was tested by an analysis of the differences in life history parameters of the macropterous and micropterous morphs of the two cricket species G. firmus and A. fasciatus. In both species there were no differences in development time or adult survival between the two morphs. Significant differences in head width were not consistent between the two species but in both sexes of G. firmus and females of A. fasciatus (insufficient males for analysis) long-winged individuals weighed more than short-winged individuals with the same head width. In both species egg production is delayed in macropterous females. The cumulative fecundity of the micropterous morph is greater than the macropterous morph in both species but only in G. firmus is the difference statistically significant. A. fasciatus frequently loose their wings but no such loss has been observed in G. firmus. There is a significant increase in egg production after the loss of the wings. These results are in accord with those of Tanaka (1976) for the cricket, Pteronemobius taprobanensis.Breeding experiments indicate that in G. firmus the wing polymorphism is under genetic control. The decrease in fecundity is sufficiently large that genotypes producing only macropterous offspring could only persist in highly unstable environments where continuous dispersal was imperative for survival. However, the reproductive cost of a genotype producing a small percentage of macropterous individuals is slight. The fitness that accrues to a genotype producing a few dispersing offspring is likely to offset the small reproductive cost and hence wing polymorphisms should be favoured.     

On the ecology of Cephalodella

A material consisting of 66 species of Cephalodella (Rotifera), from diverse waters in south and central Sweden, was analyzed to reveal their possible relationships to substrate and habitat. Most species preferred periphytic environments. Most species have a broad ecological range, only a few being bog specialists. An artificial substrate, white cotton, was colonized by several species, even some without eyes.     

Freakish patterns – species and species concepts in apomicts

Apomict groups keep challenging taxonomists, in classifications as well as in more fundamental question about the nature of apomictic species. The latter question is not just an academic one, because the outcome influences practical decisions on biodiversity and conservation. A historical overview over the species problem shows that a period of confusion and proliferation of species concepts between 1940 and 1990 was followed by an increasing consensus at the end of the 20th century that the species category is heterogeneous. Species come in kinds, which is understandable in light of their different evolutional histories. Recently, Wilkins stated that we do not need a generally applicable species concept, because species are not an a priori category into which all biological organisms must fit, but salient phenomena that are to be explained. Not only biparental, but also asexual organisms often form such species‐as‐phenomena, explained as some combination of adaptation to an ecological niche and reproductive compatibility. The above is illustrated by historical and current studies in three well‐studied apomict groups, viz. Ranunculus cassubicus agg., Rubus subgen. Rubus and Hieracium (subgen. Hieracium and Pilosella). Species in the Ranunculus cassubicus aggregate are the few existing sexuals, which are surrounded by a hybrid swarm of only partial apomictic forms, whereas in Rubus subgen. Rubus and Hieracium s.s. sexuals as well as numerous apomicts form well defined species. How species should be circumscribed in Pilosella is yet to be clarified. Largely, the differences between these groups can be contributed to their different modes of apomixis and the associated retained sexuality. From this review it is clear that the question is not so much ‘What is a species?‘, but ‘What is a species in this particular group?‘ To answer this question a thorough knowledge and understanding of the biology of the genus in question is required.     

Environmentally‐contingent behaviour of invasive plants as drivers or passengers

Invasive plants are often regarded as drivers that actively reduce diversity and alter ecosystem processes such as succession. Alternatively, invaders may be passengers that simply colonize openings produced by anthropogenic disturbance and are present only temporarily. Here we test whether the behaviour of invasive species as drivers or passengers is contingent on disturbance and nutrient availability. We created twelve experimental environments (three levels of annual disturbance × four levels of nitrogen availability) for 18 years in a grassland at the northern edge of the North American Great Plains. Out of 19 invasive species initially present, two perennials (Bromus inermis, a grass, and Cirsium arvense, a forb) acted as drivers, maintaining or increasing dominance, maintaining low species richness, and forming an invader‐ dominated successional sequence. Behaviour as drivers was environmentally contingent: Bromus behaved as a driver only in less disturbed environments, and the tendency of Cirsium to behave as a driver increased significantly with both disturbance and nitrogen availability. Most invasive species (90%), however, consistently behaved as passengers, disappearing or becoming rare. The importance of disturbance and fertility for starting invasions is well‐known, but our study shows that these factors also contribute to the behaviour of some invaders as drivers. The emergence of drivers and invader‐dominated successional sequences suggests that, as rates of invasion, disturbance and eutrophication continue to increase with human activity, invasive species that act as drivers may form low‐diversity communities that persist for decades.     

SEROLOGICAL STUDIES IN BAPTISIA AND CERTAIN OTHER GENERA OF THE LEGUMINOSAE

Fourteen species of Baptisia were compared serologically, using antiserum against B. nuttalliana. By means of both immunoelectrophoretic and double-diffusion techniques, it was possible to disclose 11 distinct arcs plus some weaker arcs, with few reliable (definite and repeatable) differences detected among the species of Baptisia investigated. Since the individual species of Baptisia are often quite distinctive, as judged by other chemical and morphological criteria, the serological data are in this instance conservative and appear to be effective in circumscribing the genus. In contrast, striking interspecific differences in the serological properties of unicellular green algae have been obtained (reported elsewhere) by similar techniques in this laboratory. It is concluded that serological data should be regarded as adjuncts to other systematic knowledge only on the basis of empirical manifestations of their utility. There is no clear justification for regarding serological data as intrinsically either superior or inferior to other systematic criteria.     

On choice of substrate and habitat in bdelzoid rotifers

Information on the distributions of 77 bdelloid rotifers from diverse waters in south and central Sweden was analyzed to reveal their relationships to substrate and habitat. Only two species were reported from plankton, both in low frequency. An artificial substrate, white cotton, was utilized only by few bdelloids, mainly by species with eyes. Only one species occurred at higher frequency on the saprobic substrate Sphaerotilus. Most bdelloids prefer environments rich in oxygen, but some species may be found in soft-bottom sediments. Several species dwell preferentially in diverse habitats of bogs. Some bdelloids have an exceptionally broad ecological range, but even for these is it possible to distinguish a pattern of preference and avoidance.     

The occurrence of <Emphasis Type="Italic">Pisidium</Emphasis> species (Bivalvia: Sphaeriidae) in oligotrophic springs of the Blanice River catchment (Czech Republic) in relation to ecological conditions

This paper presents a part of the results obtained from extensive studies conducted on springs — remarkable freshwater habitats with many unique characteristics and a high degree of biological diversity. The abiotic conditions and fauna composition of 68 submontane permanent oligotrophic springs in the Blanice River catchment (eastern part of The Bohemian Forest, Czech Republic) were investigated with a focus on their relationship to the Pisidium species occurrence. We attempted to determine the habitat requirements of individual pea clam species. Species of genus Pisidium generally preferred unshaded springs with fine substrate, the most favourable environment were helocrene springs. Although they were the second most numerous taxonomical group in the springs, only two species were present there: Pisidium casertanum and P. personatum. The occurrence of both species strongly positively correlated with each other. Substrate type and a few chemical parameters were the main parameters, which differentiated the distribution of both species. While P. casertanum was found to be most abundant in vegetation, P. personatum preferred humolite substrate. The occurrence of P. casertanum was further influenced by nutrients compared to P. personatum, whose occurrence positively correlated with the common minerals. In general, biotope characteristics of springs were found to be more important for Pisidium species inhabiting oligotrophic mountain springs than water chemistry.     

Freshwater habitat use by a moray eel species,Gymnothorax polyuranodon,in Fiji shown by otolith microchemistry

Freshwater eels of the Anguillidae are diadromous because they migrate between ocean and freshwater environments, but other anguilliform fishes are generally considered to be strictly marine species. A few marine eels of the Muraenidae and Ophichthidae have occasionally been found in freshwater or estuaries, indicating that anguillids are not the only anguilliform eels that can use freshwater in some parts of the world. The moray eel Gymnothorax polyuranodon is one species that is known to be present in freshwater in the Indo-Pacific, but its life history is unknown. One way to evaluate what types of habitats are used by fishes is to determine the ratio of strontium (Sr) to calcium (Ca) in their otoliths, because this can show if they have used freshwater or saltwater environments. To evaluate the patterns of freshwater use by this unusual species of marine eel, the otolith Sr/Ca ratios of four G. polyuranodon (275–344 mm) caught in a freshwater stream of Fiji were analyzed. The consistently low Sr/Ca values (0–4) indicated upstream movement after settlement and freshwater or estuarine residence of all four individuals. These eels did not appear to have entered freshwater just for a short time period, which is consistent with other reports that this species is present in estuarine and freshwater habitats. This suggests that G. polyuranodon may be a catadromous species of marine eel. The similarities and differences between the life histories of anguillid eels and the few marine eels that have evolved the ability to invade freshwater habitats is discussed in relation to the evolutionary origin of diadromy in anguilliform fishes that originated in the marine environment.     

Does probability of occurrence relate to population dynamics?

Hutchinson defined species' realized niche as the set of environmental conditions in which populations can persist in the presence of competitors. In terms of demography, the realized niche corresponds to the environments where the intrinsic growth rate (r) of populations is positive. Observed species occurrences should reflect the realized niche when additional processes like dispersal and local extinction lags do not have overwhelming effects. Despite the foundational nature of these ideas, quantitative assessments of the relationship between range‐wide demographic performance and occurrence probability have not been made. This assessment is needed both to improve our conceptual understanding of species' niches and ranges and to develop reliable mechanistic models of species geographic distributions that incorporate demography and species interactions. The objective of this study is to analyse how demographic parameters (intrinsic growth rate r and carrying capacity K ) and population density (N ) relate to occurrence probability (P_occ ). We hypothesized that these relationships vary with species' competitive ability. Demographic parameters, density, and occurrence probability were estimated for 108 tree species from four temperate forest inventory surveys (Québec, western USA, France and Switzerland). We used published information of shade tolerance as indicators of light competition strategy, assuming that high tolerance denotes high competitive capacity in stable forest environments. Interestingly, relationships between demographic parameters and occurrence probability did not vary substantially across degrees of shade tolerance and regions. Although they were influenced by the uncertainty in the estimation of the demographic parameters, we found that r was generally negatively correlated with P_occ, while N, and for most regions K, was generally positively correlated with P_occ. Thus, in temperate forest trees the regions of highest occurrence probability are those with high densities but slow intrinsic population growth rates. The uncertain relationships between demography and occurrence probability suggests caution when linking species distribution and demographic models.     

First record of <Emphasis Type="Italic">Gagea szovitsii</Emphasis> in Central Europe

Morphological characters, habitat preference, and currently known distribution of the species Gagea szovitsii (A.F. Láng) Besser, a new indigenous vascular plant species of Central Europe, are presented. The plant was found in alkali grasslands of the south-eastern part of the Great Hungarian Plain (SE Hungary). Currently, this can be regarded to the westernmost occurrence of this pontic species. Both G. szovitsii and its closest relative G. bohemica are briefly characterized here with respect to their identification, ecology and distribution. Original illustrations on G. szovitsii are presented. The paper firstly emphasizes the difference of reproductive strategy between G. szovitsii and G. bohemica; the former reproduce itself primarily sexually via seeds, while the latter reproduce itself in asexual way principally by bulbils. Taking the paleo-environmental history of its habitat into consideration, the species can be regarded as an ancient, indigenous Pontic-Pannonian steppe element of Hungary.     

The distribution and decline of a widespread butterfly Lycaena phlaeas in a pastoral landscape

1. Ecological specialists are often regarded as most likely to be threatened by anthropogenic habitat changes but few relevant data are available on changes in the status of widespread species. 2. Grid square distribution maps have been used widely to measure rates of decline and target conservation resources but it is known that coarse grain mapping is not appropriate to identify declines in widespread species that initially contain numerous local populations per grid cell. Changes in the status of widespread species need to be quantified. 3. Present‐day habitat associations, determined from over 2000 transect counts, combined with data on historical and present‐day habitat distributions, reveal that the area of occupancy and population‐level rate of decline of the Small Copper butterfly Lycaena phlaeas is likely to have been of the order of 92 and 89% respectively, in 35 km² of North Wales. Similar data on the species' major host plants Rumex acetosa and R. acetosella indicate possible declines in area occupied of 48 and 91%. If a 1‐km² grid was applied to the landscape, and if L. phlaeas, R. acetosa, and R. acetosella had occupied all 1‐km² cells in the study area in 1901 (non‐limestone cells for R. acetosella only), their declines would only have been recorded as 15, 9, and 35% respectively. 4. Many declining ecological specialists are threatened with extinction because of their initial rarity. At a population level, however, they may or may not be declining faster than less specialised species. The results presented here illustrate that some widespread species may have declined as much as many of Britain's rarities.     

Microhabitat relationships among five lizard species associated with granite outcrops in fragmented agricultural landscapes of south‐eastern Australia

A fundamental part of developing effective biodiversity conservation is to understand what factors affect the distribution and abundance of particular species. However, there is a paucity of data on ecological requirements and habitat relationships for many species, especially for groups such as reptiles. Furthermore, it is not clear whether habitat relationships for particular species in a given environment are transferable to other environments within their geographical range. This has implications for the type of ‘landscape model’ used to guide management decisions in different environments worldwide. To test the hypothesis that species‐specific habitat relationships are transferable to other environments, we present microhabitat models for five common lizard species from a poorly studied habitat – insular granite outcrops, and then compared these relationships with studies from other environments in south‐eastern Australia. We recorded twelve species from five families, representing 699 individuals, from 44 outcrops in the south‐west slopes of New South Wales. Five lizard species were abundant and accounted for 95% of all observations: Egernia striolata, Ctenotus robustus, Cryptoblepharus carnabyi, Morethia boulengeri and Carlia tetradactyla (Scincidae). Linear regression modelling revealed suites of different variables related to the abundance patterns of individual species, some of which were broadly congruent with those measured for each species in other environments. However, additional variables, particular to rocky environments, were found to relate to reptile abundance in this environment. This finding means that species' habitat relationships in one habitat may not be readily transferable to other environments, even those relatively close by. Based on these data, management decisions targeting reptile conservation in agricultural landscapes, which contain rocky outcrops, will be best guided by landscape models that not only recognize gradients in habitat suitability, but are also flexible enough to incorporate intraspecies habitat variability.     

Nematodes in Scottish forest nurseries

Seven hundred soil samples from 41 forest nurseries were collected between 1972 and 1975 and examined for plant parasitic and predatory nematodes. Rotylenchus goodeyi, Trichodorus primitivus, Cephalenchus emarginatus and Tylenchus davainei occurred in most nurseries but their numbers were generally lower than those of R. robustus and Paratrichodorus pachydermus. In a glasshouse experiment as few as 10 R. robustus decreased the growth of Sitka spruce seedlings. It was estimated that Rotylenchus and trichodorid nematodes probably retarded the growth of some seedling trees in eight of the nurseries sampled. During the survey, Trichodorus sparsus was found for the first time in Great Britain and Paralongidorus maximus for only the third time. Since both these species were found in nurseries they were probably introduced and are ideally situated to be more widely disseminated.     

Life history of peracarid species in South‐western Atlantic: Comparison of population traits between native and exotic species

Life‐history traits of exotic species are important to understand the process involved in their settlement and their potential impact on native biodiversity. In this context, the seasonal density, the population structure and the reproductive patterns of exotic and native peracarid species of two natural marine environments of Southwestern Atlantic were studied in order to determine the traits that favour the invasion success of exotic species. Five samples, consisted of algal patches (0.20 × 0.20 m quadrants), were collected seasonally from 2016 to 2017 in two intertidal environments (La Estafeta and Cerro Avanzado). Both environments presented high richness of cryptogenic and exotic species (Tanais dulongii, Monocorophium insidiosum, Ampithoe valida, Melita palmata and Jassa marmorata), and only two native species were recorded (Apohyale grandicornis and Exosphaeroma lanceolatum). The comparison of life‐history traits suggested that the distribution, dominance and the highest densities of some exotic species are closely related to their continuous reproductive and recruitment periods, their capability to adapt their life‐history strategies to different environmental conditions and to a more efficient distribution of resources during reproduction; however, in native species, only A. grandicornis registered similar life‐history traits than exotic populations, suggesting that their distribution could be limited by a latitudinal gradient. We expect that these results provide essential information to understand the invasion pattern of exotic species and their potential impact on native biodiversity in Southwestern Atlantic.