Persistence Of Native Species Research Articles

Landscape composition is more important than local vegetation structure for understory birds in cocoa agroforestry systems

Biodiversity-friendly agricultural systems allow the maintenance of native species even in highly fragmented landscapes by providing corridors to species dispersion and offering supplementary resources for animal populations. In the tropical region, cocoa agroforestry systems are of great importance for biodiversity conservation as they maintain part of the native vegetation, and therefore can be used by the local fauna. In this system, understory of native forests is replaced by cocoa trees, which are shaded by large old-growth trees. However, the persistence of native species in cocoa agroforests depends on local vegetation characteristics but also the landscape structure in which these systems are located. Here, we investigated the influence of landscape composition (i.e. amount of forest cover, cocoa agroforestry and cattle pasture) and local vegetation structure (i.e. number of native and cocoa trees, basal area of native trees and canopy closure) on understory birds in 18 cocoa agroforestry systems located in three regions in the Brazilian Atlantic forest, presenting distinct land use contexts. Specifically, we assessed the effects of these landscape and local features in predicting richness and abundance patterns of the entire community, and also in distinct ecological groups, such as forest-dependent and non-forest-dependent birds, and insectivores, frugivores, and omnivores. Using generalized linear models and Akaike information criterion, we observed lower species richness of complete community, non-forest and omnivorous birds in the most deforested region. Also, our findings demonstrated that cocoa agroforests integrated in more forested landscapes harbor greater richness and abundance of frugivorous birds. Conversely, the increase in cattle pasture amount at the landscape had a harsh effect on all bird groups evaluated. Regarding local vegetation, we observed that the increase of canopy closure leads to greater abundance of insectivorous birds in cocoa agroforestry systems. Similarly, abundance of non-forest species increased in agroforests with higher number of cocoa trees. Our study demonstrated that cocoa agroforestry systems can provide complementary habitats for many species, including forest birds, and therefore can mitigate the effects of habitat loss. However, this key benefit for bird conservation will be more effective when these agroforestry systems are located in more forested landscapes, with low amount of cattle pastures. Our findings therefore reinforce the alarming need to maintain and recover landscape-scale forest amount to ensure species persistence of birds in anthropogenic landscapes, even in those comprising biodiversity-friendly land uses such as cocoa agroforestry systems.

CO-OCCURRENCE OF CHIRICAHUA LEOPARD FROGS (LITHOBATES CHIRICAHUENSIS) WITH SUNFISH (LEPOMIS)

Invasive species are a major threat to the persistence of native species, particularly in systems where ephemeral aquatic habitats have been replaced by permanent water and predators, such as fish, have been introduced. Within the Altar Valley, Arizona, the invasive American bullfrog, Lithobates catesbeianus (formerly Rana catesbeianus), has been successfully eradicated to help recover Chiricahua leopard frogs (Lithobates chiricahuensis). However, other nonnative predators including sunfish (Lepomis) are present in some permanent water bodies. During four consecutive years (2014–2017), we detected both the federally threatened Chiricahua leopard frog and sunfish at one permanent water body in the Altar Valley. This suggests that despite the potential negative effect of predatory fish on amphibians, there may be conditions where the Chiricahua leopard frog can co-occur with this nonnative predator. A better understanding of rare situations of co-occurrence with nonnative predators may contribute to our understanding of why co-occurrence happens in some, but not all, systems and whether conservation strategies can be developed in situations where eradication of nonnative predators is infeasible.

Foraging innovation in a large-brained Meliphagidae: Blue-faced Honeyeaters (Entomyzon Cyanotis) open sugar packets

ABSTRACT Behavioral innovations are likely to contribute to the persistence of native species in developed areas. Innovativeness has been well-studied in birds, and the frequency with which they in...

Hybridization, coexistence, and possible reproductive interference between native Oxalis corniculata and alien O. dillenii in Japan

Hybridization with alien species can affect the reproduction and persistence of native species. Native Oxalis corniculata and alien O. dillenii are distributed in human-made habitats in Japan, and they coexist with their putative hybrid. We examined the origin of the putative hybrid and the possibility of introgression and reproductive interference between these species by analyzing their morphological, cytological, genetic, and reproductive characteristics. The flower morphology of the putative hybrid was similar to the alien species. The chromosome complement and the amount of nuclear DNA of the putative hybrid were intermediate between the two species. Genotyping of the nuclear ITS region showed the putative hybrid was invariably heterozygous for native and alien alleles. Haplotyping of the chloroplast trnS–trnG region showed that 22 and four hybrids had their maternal origin in the alien and native species, respectively. The ovules of the putative hybrid were sterile. When pollen of the putative hybrid was applied to flowers of the parental species, the fruit set was very low, suggesting that their pollen is only marginally viable. Based on these results, we conclude that the putative hybrid is an F1 hybrid between native and alien Oxalis species. The hybrid is virtually sterile, indicating that hybridization led to a waste of gametes and may result in reproductive interference between the two parental species. The capacity for selfing and/or asexual reproduction may weaken reproductive interference between the species; alternatively, their apparent coexistence may be maintained by dispersal from different parental habitats.

Habitat selection and reproduction of newts in networks of fish and fishless aquatic patches

The spatial distribution of organisms in patchy environments can be determined by the relationship between habitat quality and animal behaviour. In species with complex life cycles, such as pond-breeding amphibians, the selection of a suitable wetland is crucial. While the traditional view of amphibian ecology suggests strong site fidelity and low vagility, more recent research highlights mechanisms involving active site choice through avoidance behaviour and bet-hedging strategies in heterogeneous environments. The introduction of fish to the aquatic environment is one of the factors that may alter site selection and lead to local dispersal. In this context, we investigated the habitat choice of Alpine newts, Ichthyosaura alpestris, in networks of fish (Carassius auratus) and fishless aquatic patches. Using a laboratory design consisting of aquaria divided into two water tanks connected by a terrestrial platform, we assessed newt distribution and movement between patches. During the breeding period, we compared the reproductive success of individuals in two types of networks. We found that newts escaped fish by rapidly changing aquatic patches and then aggregating in safe aquatic patches that were free of fish. In the fish network, newts maintained reproduction, but the high local abundance resulted in decreased sexual activity and egg production and increased use of the terrestrial habitat. However, in the fishless network, newts moved between aquatic patches several times, exhibited more courtship behaviour and laid more eggs than they did in the fish networks. Our results showed both adaptive habitat switching due to environmental risks in the fish network and habitat supplementation (i.e. use of alternative resources) in the fishless network. Such studies on movement behaviour and habitat selection have conservation implications in showing that the persistence of native species in invaded networks depends on the rescue effect, with immigration to fish-free habitats potentially preventing local extinction.

Edge effects in savanna fragments: a case study in the cerrado

Background: Although impacts of edge effects on forest ecosystems are well known, their consequences on savannas have rarely been explored.Aims: To investigate the influence of edge effects on the plant community and microclimate of a cerrado fragment in south-eastern Brazil.Methods: Several plant community variables (density, basal area, richness and cover by each vegetation layer) and microclimatic variables (light, air temperature and humidity), were measured in 10 transects across a savanna fragment surrounded by exotic grasses, and were used to fit semi-parametric models relating these variables with the distance from the habitat edge.Results: Differences in microclimate and tree communities were poorly related to distance from the edge. On the other hand, there were detectable edge effects on the ground layer community (i.e. plants less than 50 cm in height). Edges had a negative effect on native plants of this layer (density and richness of all species and cover of native grasses), while favouring invasive grasses.Conclusions: Unlike reports for edge effects in forest ecosystems, microclimate does not explain changes in this cerrado fragment. The most significant edge effect threatening the conservation of cerrado vegetation is the widespread invasion by African grasses. Starting from the fragment borders, this invasion causes changes in the structure and composition of the native plant community, thus jeopardising the population dynamics and persistence of native species.

Distribution and spread of an introduced insular population of red-bellied squirrels (Sciurus aureogaster) in Florida

Introduced populations of species pose one of the greatest threats to the persistence of native species. Documentation of distribution, range expansion and habitat use of introduced populations are key components of developing effective management strategies for the control and eradication of invasive species. In 2006 and 2007, we surveyed four islands in Biscayne National Park for nests to evaluate the presence of red-bellied squirrels (Sciurus aureogaster) and the distribution and index of dispersion of their nests in the Florida Keys archipelago within the Atlantic Ocean. Red-bellied squirrels were initially introduced to Elliott Key, Florida, USA in in 1938. We documented evidence of squirrels on two additional islands, Sands Key and Old Rhodes Key, which adds to concerns of spread of this introduced squirrel to areas with endangered endemic insular mammals. Squirrel nests were documented only in mixed-hardwood forest, and nests had a clumped distribution within this forest type. Range expansion was a chief concern to the National Park Service, as continued spread could result in squirrels exiting the park, and prompted management action. Understanding nest site selection and distribution was critical for developing an eradication strategy for the introduced population of red-bellied squirrels from south Florida.

Presence of an invasive plant species alters pollinator visitation to a native

The degree to which pollinator-mediated interactions assist or impede plant invasions is currently poorly understood. Here we describe the findings of an experiment designed to investigate how pollinator-mediated interactions between invasive Lythrum salicaria (Purple loosestrife) and a closely related native North American species, Decodon verticillatus (Swamp loosestrife) are influenced by the stage of invasion (i.e., early or late). By comparing pollinator preference and constancy to plants in experimentally introduced arrays of L. salicaria and D. verticillatus in invaded and uninvaded communi- ties, we were able to simulate the ecological implica- tions of two different stages of L. salicaria invasion. Invasion status had no significant effect on pollinator visitation to L. salicaria and D. verticillatus when all pollinator taxa were considered together. However, when bumblebees, the dominant pollinator at all sites, were considered alone, we found a significant inter- action between pollinator preference and the invasion status of the site, with D. verticillatus preferred at uninvaded sites only, and no preference exhibited at invaded sites. In addition, for all pollinator taxa, we found that interspecific pollinator movements were overrepresented at uninvaded sites and underrepre- sented at invaded sites, suggesting that heterospecific pollen deposition could be a significant impediment to pollinator-mediated reproduction for both species in the early stages of an invasion. We discuss the potential consequences of our findings to the estab- lishment of animal-pollinated invasive plants and the persistence of native species in the face of invasion.

Dispersal behaviour of Brown Treecreepers predicts functional connectivity for several other woodland birds

The persistence of native species in fragmented landscapes is dependent on dispersal or foraging movements between habitat patches, which may be limited. Although corridors have been heralded as solutions, their effectiveness depends on species’ movement behaviour, which has rarely been studied. We previously analysed dispersal movements of Brown Treecreepers (Climacteris picumnus), concluding that scattered trees may provide greater connectivity than corridors, and the length of corridors and size of any gaps within may be more important than corridor width. However, conclusions from a single species may not be representative. Here, we analyse dispersal movements of two sedentary birds—Eastern Yellow Robins (Eopsaltria australis) and White-throated Treecreepers (Cormobates leucophaeus)—and foraging movements of two semi-nomadic birds—Fuscous Honeyeaters (Lichenostomus fuscus) and White-plumed Honeyeaters (L. penicillatus). Despite differences in their ecologies and purpose of movements, we found the movement strategies of these species at the local landscape scale were similar. The types of connectivity used and gap distances crossed were similar to those for Brown Treecreepers, strengthening our understanding of how to provide connectivity. We suggest that decision rules for movement have been shaped over evolutionary time by variability in the landscape, so movement behaviour may be less species-specific than previously assumed.

Can Carbon and Phosphorous Amendments Increase Native Forbs in a Restoration Process? A Case Study in the Northern Tall‐grass Prairie (U.S.A.)

In the northern Great Plains (United States), sites with less than 20% of native species are difficult to restore. We have experimented with a restoration method that shows some promise. It consists of systematically installing simulated small‐scale patches (8.0 m2 in size) over 25% of an old field and then seeding these patches with native species. The working hypothesis is that these patches will generate a constant source of propagules which in time will lead to increases in native species diversity within the surrounding grass matrix. The objective of this paper was to determine whether soil amendments should be used to facilitate the establishment and persistence of native species (primarily forbs) within these patches. We seeded the patches with a mixture of native grass and forb species and applied four soil treatments: P fertilization, C additions, C + P, and a control (no amendments). Results for the first 5 years were as follows: (1) seeded forb richness was mostly unaffected by soil amendments; (2) seeded and nonseeded forb biomass and density were substantially reduced by C additions, whereas they were unaffected or increased under P additions; (3) both seeded and non‐native grass biomass substantially increased with C additions; and (4) there was an inverse relationship between native seeded forbs and non‐native grass biomass. Our conclusions are that: (1) P amendments are a potential tool for enhancing native seeded forb biomass in simulated small‐scale disturbance patches; and (2) C additions, although enhancing seeded grass biomass do not reduce the biomass of non‐native grasses.

Population profile of an introduced species, the common wall lizard (Podarcis muralis), on Vancouver Island, Canada

Introduced species represent one of the greatest potential threats to persistence of native species. Therefore, it is important to understand the ecology of introduced species in order to develop appropriate mitigation strategies if required. In this study, using data collected in 1992–1993, we describe some fundamental population attributes of common wall lizards, Podarcis muralis (Laurenti, 1768), of Italian origin, introduced near Victoria, British Columbia, in the early 1970s. Male and female wall lizards reached similar snout–vent lengths, but males had relatively longer tails and were heavier. However, when gravid, females attained a body mass similar to that of males of equal snout–vent length. We found gravid females in all months from May to July, inclusive, but hatchlings did not appear in the field before late July. Growth rate was inversely related to body size, and lizards probably reached maturity in their second full summer. Larger lizards were more likely than smaller lizards to have experienced tail loss prior to capture, but the probability of tail loss upon capture was higher for smaller lizards than for adults. Our results suggest no fundamental differences in population characteristics between P. muralis on southern Vancouver Island and populations at sites within the species' natural range in Europe. Whether P. muralis on Vancouver Island is a threat to the native northern alligator lizard, Elgaria coerulea (Wiegmann, 1828), remains an open question.

Microsite availability and establishment of native species on degraded and reclaimed sites

Summary Restoration of native plant communities on previously disturbed land requires the identification and modification of environmental factors that impede or restrict ecosystem succession or development. One of the key factors in successful reclamation is to ensure colonization and persistence of native species within an area. Therefore, the identification of microsite types that favour colonization by native species should improve our ability to successfully reclaim degraded areas. The objectives of this study were to (i) identify and describe microsite types that were conducive to the establishment of five native plant species (Euphrasia frigida, Galium normanii, Thymus praecox, Cerastium spp. and Rumex acetosa) on degraded and reclaimed sites in Iceland; and (ii) to determine the effects of reclamation activities that included the application of manure and inorganic fertilizer on the distribution of microsite types and seedling establishment. Reclamation sites of different ages were examined on an eroded area where the target community was a grass or shrub heath. The spatial distribution of plant establishment was not random but varied among microsite types and study sites. More seedlings than expected were found in microsite types characterized by small rocks and biological soil crusts. These may have entrapped seed and provided more soil stability and moisture than other microsite types. The cover of these microsite types varied among the study sites but the pattern of seedling establishment among the five native forbs was similar. Synthesis and applications. Practical reclamation methods are improved by identifying those factors that promote successful seedling establishment by native species. Application of fertilizer without additional seeding proved to be a simple reclamation approach that increased the availability of one favourable microsite type, enhanced the establishment of native species and subsequently allowed vegetation cover to expand. Seed of native plants may be difficult to obtain commercially, but this approach can be used on degraded land where propagules are available but recovery is slowed by soil instability or nutrient limitations.

Fern Miscellany: Brooklyn

Brooklyn, of all five boroughs of Greater New York, is probably least blessed in sites suitable for the persistence of native species of ferns. While there are many hundreds of acres which have not been built upon, most of such acreage comprises either salt-marshland or regions of grading and fill. It is not impossible that there may exist some small areas of natural marshland where the Osmundas may be found. I have found O. spectabilis on one of the narrow sand strips which border the ocean side of Great South Bay (Oak Island Beach). Even Manhattan, despite is great encrustations of asphalt, brick, and cement has at least some areas of rocky outcrops, including the park section at its northern end. The Bronx has the hundreds of acres along the Bronx River included within the Botanical Garden and Zoological Park area, where woods of native hemlock and other trees offer sites for ferns. Similarly, Queens Borough, although I cannot vouch for any specific ferns, offers park reservations which carry westward the conditions under which a number of species flourish on Long Island in general. Richmond-Staten Island-is the least citified of all five boroughs from its former state. While I have made no recent visit there, its central areas must still offer sites for the persistence of Dryopteris Goldiana and other related wood ferns, and its marshy woods presumably still provide sites for the Massachusetts fern, the narrow chain fern, and others. In earlier days, the area now lying within the boundaries of Kings County (Brooklyn) must have had approximately the same fern flora as adjacent Long Island regions still offer. When road traffic permits, it is still 148