Predictive systems ecology

Human societies, and their well-being, depend to a significant extent on the state of the ecosystems that surround them. These ecosystems are changing rapidly usually in response to anthropogenic changes in the environment. To determine the likely impact of environmental change on ecosystems and the best ways to manage them, it would be desirable to be able to predict their future states. We present a proposal to develop the paradigm of predictive systems ecology, explicitly to understand and predict the properties and behaviour of ecological systems. We discuss the necessary and desirable features of predictive systems ecology models. There are places where predictive systems ecology is already being practised and we summarize a range of terrestrial and marine examples. Significant challenges remain but we suggest that ecology would benefit both as a scientific discipline and increase its impact in society if it were to embrace the need to become more predictive.     

Diet of the gracile mouse opossum (Gracilinanus microtarsus) (Didelphimorphia: Didelphidae) in a Brazilian cerrado: patterns of food consumption and intrapopulation variation

The diet of the gracile mouse opossum Gracilinanus microtarsus was studied in a cerrado remnant in south-eastern Brazil through the analysis of faeces sampled from adult individuals. Patterns of food resource consumption were assessed using the statistics of per cent occurrence. Intrapopulation variation in the number of food items detected in faeces as a function of relevant factors was inferred using generalized linear models. The latter statistical formalism also allowed variation in the number of food items detected in faeces to be interpreted in terms of rate ratios among levels of significant factors. Insects, spiders, snails and fruits were detected in the faeces of G. microtarsus , with insects, particularly termites, beetles and ants, being the most frequently detected food resource. These food resources were consumed in proportion to their relative abundance in the cerrado, suggesting that G . microtarsus is an opportunistic forager feeding primarily on insects. The generalized linear model identified sex, season and food resource as significant factors affecting the number of food items detected in faeces, as well as interactions between sex and season and season and food resource. Rate ratios calculated between sexes within seasons showed that the number of food items detected in the faeces of males was larger than that detected in the faeces of females in the warm-wet and cool-dry seasons. Rate ratios calculated between seasons within sexes showed different trends in the number of food items detected in faeces for each significant food resource. It is suggested that differences in the number of food items detected in faeces between sexes within season and between seasons within sexes are related to energetic requirements associated with reproduction.     

Effects of sand bar openings on some limnological variables in a hypertrophic tropical coastal lagoon of Brazil

This study describes the spatial and temporal dynamics of several physical, chemical and biological variables in the Grussai lagoon, and their relationship to ephemeral sand bar openings and to a constant in natura waste water input. The spatial variation in pH, dissolved oxygen, electrical conductivity, total alkalinity and nutrients (e.g. soluble reactive silicate, soluble reactive phosphate and ammonium) was associated to the anoxic and nutrient rich groundwater discharge, the development of aquatic macrophytes, the biological activities of phytoplanktonic community and the marine influence. During the period when the sand bar was closed (isolated), the lagoon water was supersaturated with dissolved oxygen and exhibited high values of pH (8–10), total alkalinity (3.000–5.000 μeq l^-1), and chlorophyll a contents (60-300 μg l^-1), and had low values of dissolved nutrients (nearly undetectable). These suggest a biological processes dominance. When the sand bar was opened, there was an enrichment with dissolved inorganic nutrients (e.g. ammonium and soluble reactive phosphorus up to 120 and 5 μM, respectively) and a decrease in pH (below 8), total alkalinity (below 3.000 μeq l^-1) and dissolved oxygen during the initial second to eight days. Subsequently there was a period when the physical and chemical characteristics of seawater prevailed. The lagoon returned chemical to the pre-opening water conditions in a few days (∼ 10–20). This quick return implies highly efficient biological mechanisms. The high levels of chlorophyll a, total nitrogen and phosphorus in the water column indicate a high eutrophication stage in the Grussai lagoon during the sand bar closed periods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vegetation responses to landscape structure at multiple scales across a Northern Wisconsin,USA, pine barrens landscape

Increasing awareness of the importance of scale and landscape structure to landscape processes and concern about loss of biodiversity has resulted in efforts to understand patterns of biodiversity across multiple scales. We examined plant species distributions and their relationships to landscape structure at varying spatial scales across a pine barrens landscape in northern Wisconsin, U.S.A. We recorded plant species cover in 1×1 m plots every 5 m along a 3575 m transect, along with variables describing macro- and micro-landscape structure. A total of 139 understory plant species were recorded. The distributions of many species appeared to be strongly associated with landscape structural features, such as distinct management patches and roads. TWINSPAN and detrended correspondence analysis (DCA) identified three groups of species that overlapped extensively in the ordination, possibly reflecting the relatively homogeneous nature of disturbance in the pine barrens landscape. Distribution of understory plants did not reflect all of the patch types we identified along the transect; plot ordination and classification resulted in three to five plot groups that differed in niche breadth. Wavelet transforms showed varying relationships between landscape features and plant diversity indices (Shannon–Weiner, Simpson's Dominance) at different resolutions. Wavelet variances indicated that patterns of Shannon diversity were dominated by coarse resolutions ranging from 900–1500 m, which may have been related to topography. Patterns of Simpson's Dominance were dominated by 700 m resolution, possibly associated with canopy cover. However, a strong correspondence between overstory patch type and diversity was found for several patch types at ranges of scales that varied by patch type. Effects of linear features such as roads were apparent in the wavelet transforms at resolutions of about 5–1000 m, suggesting roads may have an important impact on plant diversity at landscape scales. At broad scales, landscape context appeared more important to diversity than individual patches, suggesting that changes in structure at fine resolutions could alter overall diversity characteristics of the landscape. Therefore, a hierarchical perspective is necessary to recognize potential large-scale change resulting from small-scale activities.     

Reproductive biology of Boswellia serrata, the source of salai guggul, an important gum-resin

Detailed studies were carried out on the phenology, floral biology, pollination ecology and breeding system of Boswellia serrata Roxb. (Burseraceae) the source of 'salai guggul'. The trees remain leafless during the entire period of flowering and fruiting. The inflorescence is a terminal raceme and produces up to 90 bisexual, actinomorphic flowers. On average a flower produces 10 044 ± 1259 starch-filled pollen grains. About 85% of the fresh pollen grains are viable; the pollen to ovule ratio is 3348 : 1. The stigma is of the wet papillate type. The style is hollow with three flattened stylar canals filled with a secretion product. The stylar canals are bordered by a layer of glandular canal cells. The inner tangential wall of the canal cells shows cellulose thickenings. The ovary is trilocular and bears three ovules, one in each locule. Flowers offer nectar and pollen as rewards to floral visitors. The giant Asian honey bee ( Apis dorsata ) and A. cerana var. indica (Indian honey bee) are the effective pollinators. The species is self-incompatible and the selfed pollen tubes are inhibited soon after their entry into the stigma. Self-pollen tubes develop a characteristic 'isthmus' as a result of enlargement of the tube soon after emergence through the narrow germ pore. Cross-pollinated flowers allowed normal pollen germination and pollen tube growth, and resulted in fruit- and seed-set. Under open pollination fruit-set was only about 10%. Although manual cross-pollinations increased fruit set, it was only up to about 20%. Low fruit set appears to be the result of inadequate cross-pollination and other constraints, presumably limitation of available nutrients.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 73–82.     

Landscape correlates of forest plant invasions: A high‐resolution analysis across the eastern United States

Aim

Invasive species occurrence is often related to the anthropogenic context of a given area. Quantifying the effects of roads is of particular interest as roads are a major vector for invasion. Our objective was to further quantify the effects of roads on forest plant invasion through a macroscale, high‐resolution investigation to assist effective invasion control and mitigation.

Location

Eastern United States.

Methods

Using invasive plant data from 23,039 forest inventory plots in 13 ecological provinces, we employed logistic regression to relate the odds of invasion to distance from a road, with adjustments for broadscale differences attributable to ecological provinces, and local scale differences in productivity, forest fragmentation and land use.

Results

The overall proportion (P) of invaded plots was 0.58 (0.65 for plots within 50 m of a road), and the highest odds (P/1 ? P) of invasion were found in relatively more productive, fragmented forest in landscapes with more than 10% agriculture or developed land cover. Wald chi‐square statistics indicated the best predictor of the odds of invasion was ecological province, followed by land use, productivity, forest fragmentation and distance from a road. Depending on the province, the adjusted odds of invasion decreased by up to 23% (typically 4%–10%) per 100 m distance from a road. The adjusted probability of invasion approached zero in only three provinces, for the least productive, least fragmented forest that was at least 2,000 m from a road in landscapes with less than 10% agricultural or developed land cover.

Main conclusions

In the eastern United States, the existence of a nearby road is less important than the landscape context associated with the road. A purely road‐mediated effect has little practical meaning because anthropogenic activities and roads are pervasive and confounded.

     

Avian diversity and function across the world's most populous cities

Understanding the composition of urban wildlife communities is crucial to promote biodiversity, ecosystem function and links between nature and people. Using crowdsourced data from over five million eBird checklists, we examined the influence of urban characteristics on avian richness and function at 8443 sites within and across 137 global cities. Under half of the species from regional pools were recorded in cities, and we found a significant phylogenetic signal for urban tolerance. Site-level avian richness was positively influenced by the extent of open forest, cultivation and wetlands and avian functional diversity by wetlands. Functional diversity co-declined with richness, but groups including granivores and aquatic birds occurred even at species-poor sites. Cities in arid areas held a higher percentage of regional species richness. Our results indicate commonalities in the influence of habitat on richness and function, as well as lower niche availability, and phylogenetic diversity across the world's cities.     

Ecological aspects of water quality regulation in England and Wales

The paper describes the regulatory functions of a new body set up in England and Wales for the management of water pollution, the National Rivers Authority. It outlines proposals for a new water quality classification scheme incorporating biological monitoring as an integral part, and describes other areas of pollution control where biology could be used with advantage. The derivation of statutory water quality objectives as a new concept in the management of natural waters is described, together with an indication of some of the legal mechanisms available to the NRA to ensure that the objectives are met.     

Ground predator abundance affects prey removal in highbush blueberry (<Emphasis Type="BoldItalic">Vaccinium corymbosum</Emphasis>) fields and can be altered by aisle ground covers

Habitat management to conserve natural enemies has increased biological control of insect pests in various cropping systems [Annu. Rev. Entomol. 45: 175–201, 2000]. We wanted to determine if insect predation in highbush blueberry, Vaccinium corymbosum L. (Ericales: Ericaceae), is influenced by manipulation of edaphic arthropod community and whether management of ground cover in aisles between blueberry rows enhances this community. The first question was studied in blueberry plots bounded by trenches permitting selective movement into plots (ingress) or out of plots (egress), as well as unbounded control plots. We observed a significant effect of boundary type on the arthropod communities relative abundance as measured with pitfall traps, with relative abundance highest in ingress plots, intermediate in control plots and lowest in egress plots. Effects of ground arthropod abundance on predation rates were assessed with onion fly, Delia antiqua (Meigen) (Diptera: Anthomyiidae), pupae as sentinel prey. Pupa recovery was greatest in egress boundary plots, intermediate in control plots and lowest in ingress boundary plots. Regression analyses indicate pupal recovery rate decreased as a function of carabid abundance as well as the abundance of non-insect ground predators. To determine if ground cover management influenced natural enemy abundance, aisles were clean cultivated or planted with three ground covers (clover, ryegrass, or buckwheat). Increasing ground cover had a significant effect on the relative abundance of Harpalus pensylvanicus De Geer (Coleoptera: Carabidae). In addition to conserving natural enemies for control of blueberry insect pests, we discuss additional benefits of ground covers that may increase their utility for blueberry production.