We present a long-term analysis of the results of the Apollo butterfly Parnassius apollo recovery project in the Pieniny National Park, southern Poland, using a classical population ecology model. Six possible theoretical models of changes in population abundance were constructed and their predictions compared with current data. Models that did not take into account supplementation with captive-reared individuals provided the best fit to the population growth pattern during recovery. This was probably because of the introduction of captive-reared specimens to sites while habitat reconstruction was taking place. In addition, we provide data supporting the hypothesis that a significant reduction in the habitat's carrying capacity occurred during the restoration project, probably as a result of the population being over-supplemented with captive-reared individuals. Our analysis shows that for a recovery project to be successful, captive breeding and habitat restoration should be properly coordinated.

A general multi-type population model is considered, where individuals live and reproduce according to their age and type, but also under the influence of the size and composition of the entire population. We describe the dynamics of the population as a measure-valued process and obtain its asymptotics as the population grows with the environmental carrying capacity. Thus, a deterministic approximation is given, in the form of a law of large numbers, as well as a central limit theorem. This general framework is then adapted to model sexual reproduction, with a special section on serial monogamic mating systems.

National park management has the dual mission of protecting and conserving natural systems and providing services to visitors. These two goals are often contradictory, especially when levels of recreation and tourism increase. We studied whether and how the management of the 13 terrestrial national parks in Germany respond to increasing numbers of visitors. One to three managers from each national park completed an online questionnaire and were then interviewed by phone. We found no general strategy for managing high levels of recreational use. Adaptation to increasing visitor numbers seemed to be complex and arduous. Management options are particularly constrained by the mandatory public participation process, in which various stakeholders are involved in decision-making. Given the political pressure to make amends for restrictions imposed by designated protected areas, national park management is characterized by compromises, which results in a shift of priorities from conservation towards service provision. We argue that to maintain the balance between the dual objectives of conservation and recreation, park managers need the support of both social and biological research communities. Above all, the unique ecological merits of national parks could be more strongly highlighted to increase the general public’s acceptance of park restrictions.

In the context of determining the sustainable carrying capacity of dry-Mediterranean herbaceous rangelands, we examined the effect of animal density on cattle nutrition, which is fundamental to animal performance and welfare. The effects on dietary components of low (0.56 cows/ha; L) and high (1.11 cows/ha; H) animal densities were monitored for three consecutive years in grazing beef cows. In the dry season (summer and early autumn), cows had free access to N-rich poultry litter (PL) given as a dietary supplement. In each season, near-IR spectroscopy (NIRS) was used to predict the chemical composition of herbage samples (ash, NDF, CP, in vitro dry matter digestibility (IVDMD) and metabolizable energy (ME) content from IVDMD). Near-IR spectroscopy was applied also to faecal samples to determine the chemical composition of the diet selected by the animal, as well as the contents of ash, NDF and CP in the faeces themselves. A faecal-NIRS equation was applied to estimate the dietary proportion of PL. Seasonal categories were green, dry without PL supplementation and dry with it. We found no effects of animal density on nutrition during the green season but effects were apparent when cows consumed dry pasture. Ash content predicted by faecal NIRS was higher in the diet than in plant samples clipped from pasture, which infers that cows ingested soil. Dietary and faecal ash contents were higher (P<0.05) at the H, implying greater soil intake in these animals. During the dry period, dietary contents of ME were higher in L than in H (P<0.05). Poultry litter supplementation was associated with a marked increase (P<0.01) in dietary and faecal CP contents. Poultry litter represented 0.45 and 0.59 of the diet in treatments L and H, respectively (P<0.05). Consequently, treatment H had higher faecal protein (P<0.05). A tendency of higher dietary protein (P=0.08) and lower dietary NDF (P=0.10) in treatment H was probably related to greater PL ingestion. Given that high and sustained rates of poultry litter consumption are detrimental to animal health, the above results cast doubts on the long-term sustainability of the higher of the animal densities tested. Although it may be sustainable vis-à-vis the vegetation, treatment H may have exceeded the boundaries of what is acceptable for cow health. Chemical information revealed with NIRS can be used to evaluate whether animal densities are compatible with animal health and welfare standards and can play a role in determining the carrying capacity of Mediterranean rangelands.

Field studies were conducted to determine the effect of early-season and early- plus late-season acetolactate synthase–resistant Helianthus annuus interference on Glycine max and H. annuus growth and yield at two sites in Missouri. Helianthus annuus densities of 3 plants m−2 were established shortly after G. max emergence in all plots except the weed-free check. To study early-season interference, H. annuus were removed with postemergence glyphosate (0.84 kg ae ha−1) 2, 4, 6, and 8 wk after planting (WAP) and kept weed-free for the rest of the growing season. Glycine max yields were not different with 2, 4, 6, or 8 wk of early-season interference at either location. To study early- plus late-season interference, H. annuus densities were established at 3 plants m−2. They were then removed 2, 4, 6, or 8 WAP with glyphosate and subsequently reestablished at the same density within 2 wk after removal by newly emerging and transplanted H. annuus. These H. annuus were allowed to remain in the field for the remainder of the growing season. This provided a weed-free period of approximately 2 wk during the growing season beginning 2, 4, 6, or 8 WAP. Season-long interference and no-interference treatments were also included. Glycine max yields were reduced 47 to 72% with season-long interference. Helianthus annuus vegetative dry matter was approximately 56% lower at Columbia than at Miami. Glycine max yields tended to increase as the weed-free period was delayed into the growing season. Early-season weed-free periods (2 to 4 and 4 to 6 WAP) allowed H. annuus to become re-established before G. max formed a canopy and resulted in larger amounts of H. annuus biomass and seed production as well as G. max yield losses of 15 to 80%. Re-establishment of H. annuus in 6 to 8 WAP and 8 to 10 WAP weed-free treatments generally resulted in the plants surviving for only a few weeks after establishment and not producing seed or reducing G. max yield.

Dependence of individual reproduction upon the size of the whole population is studied in a general branching process context. The particular feature under scrutiny is that of reproduction changing from supercritical in small populations to subcritical in large populations. The transition occurs when the population size passes a critical threshold, known in ecology as the carrying capacity. We show that populations either die out directly, never coming close to the carrying capacity, or grow quickly towards the carrying capacity, subsequently lingering around it for a time that is expected to be exponentially long in terms of a carrying capacity tending to infinity.

The Critically Endangered black-faced lion tamarin Leontopithecus caissara has a restricted distribution consisting of small mainland and island populations each with distinct habitats in coastal south-eastern Brazil. The conservation action plan for the species recommends translocation to increase population size and promote genetic exchange among threatened isolated populations, measures that require an understanding of habitat and resource requirements. We investigated habitat selection by the black-faced lion tamarin, comparing habitats and examining frequency of use by two insular groups and two mainland groups. Using this understanding of habitat preferences we were able to refine current estimates of the carrying capacity (K) for this species. Habitats preferred by mainland groups were swamps and inundated areas and secondary forest. Submontane forest was avoided, as were hydromorphic lowland forest and urbanized areas. Island groups used mainly tall lowland forest and arboreal restinga (forest on sandy soil). The finding that L. caissara avoids montane forest sheds light on its restricted distribution to low elevation coastal plains. An estimate of K indicated c. 700 individuals, which could be increased to c. 1,500 with appropriate conservation management measures. Findings agree with the supposition that lion tamarins are typical of mature Atlantic forest, with little altitudinal variation but flexible in their use of successional stages. Future conservation management measures should account for differences in habitat use, selection and differences between island and mainland habitats.

Conservationists are raising concerns over high lion Panthera leo mortality and prey population declines in the area at the frontier between the Democratic Republic of Congo and Uganda. Confirming if threats to lions are severe or lion populations are disappearing requires extensive surveys on the ground because aerial detection of lions is inaccurate. Yet, ground surveys over large areas are unsafe or infeasible in the war-torn study area. We used aerial surveys of medium- to large-bodied ungulate prey to estimate lion abundance in two adjoining parks: Queen Elizabeth National Park, Uganda, and Parc National des Virunga, Democratic Republic of Congo. We validated two approaches to predict lion abundance using total counts of lions from Uganda. From this, we predict the two national parks together could have held 221 lions in 2004 and they have the potential to hold 905 lions if prey recover and lion-specific mortality is curbed. This makes the region a potential stronghold for the species in central Africa. However, a recent one third decline in lion numbers in the Ugandan Park and pervasive threats to the Congolese Park lead us to recommend immediate conservation intervention for lions and their prey. In Uganda, we recommend focused action to protect lions from poaching and retaliation, whereas in Congo, general enforcement of wildlife protection and a ground-based survey for lions are needed.

Agriculture faces a multitude of challenges in the 21st century, and new tools are needed to help determine how it should respond. Among these challenges is a need to reconcile how human food consumption patterns should change to both improve human nutrition and reduce agriculture's environmental footprint. A complete-diet framework is needed for better understanding how diet influences demand for a fundamental agricultural resource, land. We tested such a model, measuring the impact of fat and meat consumption on the land requirements of food production in New York State (NYS). Analysis was confined to this geographic area to simplify the modeling procedure and to examine the state's ability to reduce environmental impact by supplying food locally. Per capita land resource requirements were calculated with a spreadsheet model for 42 diets ranging from 0 to 381 g d−1 (0 to 12 oz d−1) of meat and eggs and 20 to 45% total calories from fat. Many of these diets meet national dietary recommendations. The potential human carrying capacity of the NYS land base was then derived, based on recent estimates of available agricultural land. A nearly fivefold difference (0.18–0.86 ha) in per capita land requirements was observed across the diets. Increasing meat in the diet increased per capita land requirements, while increasing total dietary fat increased the land requirements of low meat diets but reduced the land needed for high meat diets. Higher meat diets used a larger share of the available cropland suited only to pasture and perennial crops. Thus, only a threefold difference was observed for the potential number of people fed from the NYS land base (2.0–6.2 million). In addition, some high-fat vegetarian diets supported fewer people than lower fat diets containing 63–127 g d−1 of meat (approximately one- to two-thirds of the national average per capita consumption in the US). These results support the assertion that diet should be considered in its entirety when assessing environmental impact. To more completely understand how diet influences land requirements and potential carrying capacity, this model should be applied across a larger geographic area that encompasses a wider variety of climates and soil resources. To better understand the ability of a local region to supply more of its own food, the model should be moved into a geospatial framework.

The threatened Kirtland's warbler Dendroica kirtlandii breeds in stands of young jack pine Pinus banksiana growing on well-drained soils in Michigan, USA. We summarize information documenting the range expansion of Kirtland's warbler due to increased habitat management in the core breeding range in the Lower Peninsula of Michigan during 1990–2000. We collected records and conducted searches for the species in Michigan's Upper Peninsula and Wisconsin over 1978–2000. During that time 25 males were found in Wisconsin and 90 males in the Upper Peninsula. We documented colonization of Michigan's Upper Peninsula by six ringed males from the Lower Peninsula of Michigan. Four ringed birds also moved back to the core breeding range, including two males that made two-way movements between the core breeding range and the Upper Peninsula. Thirty-seven females were observed with males from 1995 to 2000, all in Michigan. Nesting activities were noted for 25 pairs and at least nine nests fledged young. One male ringed as a fledgling returned to breed in two subsequent years. After a 19-year period of population stability, the Kirtland's warbler population increased four-fold during 1990–2000, most likely in response to a tripling in habitat area. This increase in sightings and documented breeding may be related to habitat availability in Michigan's Upper Peninsula and to saturation of habitat in the main breeding range. The increase in extra-limital records during 1995–1999 corresponds to the time when the population went from the minimum to the maximum projected population densities, and a decline in natural wildfire habitat was just offset by new managed habitat for the Kirtland's warbler.

The elephant population of South Africa's Addo Elephant National Park increased in number from 11 elephants when the park was created in 1931, to 284 elephants in 1998. We studied management records throughout this period in conjunction with demographic data, enabling retrospective assessment of the long-term impacts of management actions. Problem animal control during the 1930s left no sexually mature bulls in the population for a period of 9 years, hindering the population's initial recovery. Population growth prior to 1954 was also limited by high mortality: between 1931 and 1954 inadequate fencing allowed elephants to stray outside their protected area resulting in elephants being shot by farmers or dying from collisions with trains. Secure elephant-proof fencing was constructed in 1954. Subsequently, there was a significant decrease in mortality (from 5.0% to 1.2%) and an increase in population growth (from 3.2% to 6.1%). However, evidence suggests that confinement might have had a negative impact on survival and social behaviour of adult males. We suggest that the concepts of social carrying capacities and behavioural conservation of populations need to be incorporated into management. The case studies described here highlight the importance of treating conservation management and research as necessary partners, and monitoring should be an integral part of any management plan.

Tourism is regarded by many countries, particularly resource-poor countries, as a potential stimulus to the economy. Yet tourism, by the nature of the activities involved, is constrained by the natural resource base and infrastructure, and by the pollution and other environmental and social impacts of tourist numbers. Tourism development strategies of national governments have been diverse in the face of this complex relationship between the economic costs and benefits of tourism. This paper examines tourist development based on concepts of open access and renewable natural resources. The experiences of two economies highly dependent on tourism, the Maldives and Nepal, are compared and contrasted. Although these countries offer very different attractions to tourists, they are faced with similar problems in terms of adverse environmental impacts of tourism. The dominant impacts in both areas are those associated with solid waste disposal and water resources, compounded by the depletion of natural resources. Both countries are currently employing 'dispersal' techniques to overcome the adverse impacts of tourism, but such strategies do not address the fundamental problem of maintaining tourism revenues whilst minimizing environmental damage. Even if an ecological carrying capacity can be defined, the experiences of these two countries indicate that impacts on local communities may well exceed so-called cultural carrying capacity.