Movements and activities of snow leopards in Southwestern Mongolia

Four adult (2M:2F) snow leopards (Uncia uncia) were radio-monitored (VHF; one also via satellite) year-round during 1994-1997 in the Altai Mountains of southwestern Mongolia where prey densities (i.e., ibex, Capra siberica) were relatively low (∼0.9/km²). Marked animals were more active at night (51%) than during the day (35%). Within the study area, marked leopards showed strong affinity for steep and rugged terrain, high use of areas rich in ungulate prey, and affinity for habitat edges. The satellite-monitored leopard moved more than 12 km on 14% of consecutive days monitored. Home ranges determined by standard telemetry techniques overlapped substantially and were at least 13-141 km²in size. However, the satellite-monitored individual apparently ranged over an area of at least 1590 km², and perhaps over as much as 4500 km². Since telemetry attempts from the ground were frequently unsuccessful , we suspect all marked animals likely had large home ranges. Relatively low prey abundance in the area also suggested that home ranges of >500 km²were not unreasonable to expect, though these are >10-fold larger than measured in any other part of snow leopard range. Home ranges of snow leopards may be larger than we suspect in many areas, and thus estimation of snow leopard conservation status must rigorously consider logistical constraints inherent in telemetry studies, and the relative abundance of prey.     

Estimating the density of a jaguar population in the Brazilian Pantanal using camera-traps and capture-recapture sampling in combination with GPS radio-telemetry

The jaguar (Panthera onca) is the largest feline in the Americas and third largest world-wide, smaller in size only to the tiger (P. tigris) and lion (P. leo). Yet, in comparison, relatively few studies on jaguar population densities have been conducted and baseline data for management purposes are needed. Camera trapping and capture-recapture sampling methods were used to estimate the size of a jaguar population in the Pantanal’s open wet grassland habitat, an important area for the long-term survival of the species. This study is the first jaguar population estimate conducted in co-operation with a GPS-telemetry study providing an important opportunity for comparing different methods of density estimation. An accessible area within a 460 km² privately-owned ranch was sampled with equal effort during the dry seasons of 2003 and 2004. Thirty-one and twenty-five individual jaguars were identified in 2003 and 2004, respectively. Estimates of jaguar abundance were generated by program CAPTURE. Density estimates were produced according to different methods used to calculate the effectively sampled areas which ranged from 274 to 568 km². For 2003, the currently-used mean maximum distance moved (MMDM) method produced a density of 10.3 jaguars/100 km², while GPS-telemetry-based calculations produced a mean density of 6.6 jaguars/100 km². For 2004, the MMDM method produced an estimate of 11.7 jaguars/100 km² while GPS-telemetry calculations produced a density of 6.7 jaguars/100 km². Our results suggest that the widely-used MMDM method used to calculate effectively sampled areas is significantly under-reflecting maximum distances moved by jaguars and their range-use and, thereby, considerably inflating cat density estimates. This overestimation could place a population in a difficult situation by lengthening the time taken to initiate protection measures because of underestimating the risk to that population.     

Home range size and daytime habitat selection of leopards in Huai Kha Khaeng Wildlife Sanctuary, Thailand

Leopards (Panthera pardus) are endangered in South East Asia yet little is known about which resources need to be secured for their long-term conservation or what numbers of this species this region can support. This study uses radio telemetry to investigate seasonal variation in habitat selection and home range size of Leopards in Huai Kha Khaeng Wildlife Sanctuary, Thailand. Over a five year period, 3690 locations were recorded from nine individuals. The mean ± standard error of fixed kernel home range size for six adult females was 26 ± 8.2 km², for two adult males was 45.7 ± 14.8 and for two sub-adult females was 29 km² ± 5.5. Adult female wet and dry season home range sizes did not differ significantly. One adult male showed an increase in home range size from dry to wet seasons. Estimated density was 7 adult females/100 km², which suggests 195 adult female leopards living in Huai Kha Khaeng alone, thus highlighting the larger Western Forest Complex’s potential contribution to leopard conservation. Compositional analysis of second and third order habitat selection suggested mixed deciduous and dry evergreen forest types, flat slope and areas close to stream channels are important landscape features for leopards. These results can help formulate a much needed conservation strategy for leopards in the region.     

Predator-prey relationships and responses of ungulates and their predators to the establishment of protected areas: A case study of tigers, leopards and their prey in Bardia National Park, Nepal

Interactions among sympatric large predators and their prey and how they respond to conservation measures are poorly known. This study examines predictions concerning the effects of establishing a protected area in Nepal on tigers (Panthera tigris), leopards (Panthera pardus), and their ungulate prey. Within a part of the park, after 22 years the total density of wild ungulates had increased fourfold, to ca. 200 animals/km², almost exclusively due to a remarkable increase in chital deer (Axis axis). Tiger density also increased markedly to nearly 20 animals/100 km², whereas leopard density did not and was ca. 5 animals/100 km². The prediction that grazers should increase more than browsers was only partially supported. The prediction of positive density dependence in prey selection was not supported. Instead, the most abundant species (chital and hog deer, Axis porcinus) were killed less frequently than expected, whereas the lower-density wild boar (Sus scrofa) was preferred. Predictions that (i) initially rare species suffer highest predation was partially supported, that (ii) predation is highest among the most abundant prey was not supported, and that (iii) predation is highest among the most preferred prey independently of their densities was supported. Clearly, the conservation efforts adopted in Bardia were successful, as both tigers and their natural prey base increased. However, the positive numerical response of tigers limited and depressed the abundance of some prey species. Thus, conservation activities aimed at restoring large predators are likely to change in the composition of the overall mammal community, potentially eliminating rare but preferred prey species.     

Conservation status of tigers in a primary rainforest of Peninsular Malaysia

This study provided the first reliable density estimate of tigers based on photographic capture data in Taman Negara National Park, Peninsular Malaysia's most important conservation area. Estimated densities () of adult tigers ranged from 1.10 ± 0.52 to 1.98 ± 0.54 tigers/100 km² (X²=1.56, df=2, P=0.46) with the overall mean of 1.66 ± 0.21 tigers/100 km². The tiger population in the 4343-km² park was estimated to be 68 (95% CI: 52-84) adult tigers. Prey biomass estimates ranged from 266 to 426 kg/km², and wild boar were the most important potential prey species in terms of abundance, biomass, and occupancy, followed by muntjac. Both tigers and leopards were more diurnal than nocturnal, which corresponded with the activity patterns of wild boar and muntjac. No evidence of poaching of large mammals was found in the 600-km² study sites and overall human impacts on the tiger-prey community appear to be minimal, but in the long run its viability needs to be evaluated in a greater landscape context.     

Status of tiger and leopard in Rajaji-Corbett Conservation Unit, northern India

Rajaji-Corbett Tiger Conservation Unit (RCTCU), in northern India, is one of the 11 Level-I Tiger Conservation Units (TCU) identified in the Indian subcontinent for the long-term conservation of the tiger. This TCU of about 7500 km² stretches from the Yamuna River in the west to Sharda River in the east and includes portions of the Outer Himalaya and the Shivalik hills. Little less than one third of this TCU comes under protected area status (Rajaji National Park—820 km², and Corbett Tiger Reserve—1286 km²) and the rest are under 12 reserve forest divisions, five of which have largely been converted into monoculture plantations. Between November 1999 and March 2000, we evaluated the status of tiger and leopard in RCTCU by counting the number of different pug marks on 3-5 km transect walks along 52 dry stream beds (‘raus’), for a total distance of 479 km in these reserve forests and plantations. People and cattle seen along the transects, were also counted, as an index of disturbance. In this TCU, the tiger occurs in three isolated populations: between the west bank of River Ganges and River Yamuna, from the east bank of Ganges to Kathgodam-Haldwani-Lalkuan Highway and between the Highway and River Sharda. Owing to increasing biotic pressures, the tiger has become rare in Rajaji-Corbett corridor and has become extinct in four divisions. There is a growing threat of further degradation and fragmentation of its habitat. To implement a recovery programme, we suggest several management measures such as control of poaching, resettlement of local tribes (gujjars) and five villages, creation and strengthening of forest corridors, conversion of monocultures into polyculture plantations and establishment of several mini-core areas including Nandaur Valley National Park. We recommend the reliable and user-friendly method used by us to evaluate and monitor the status of leopard and tiger in this conservation unit. A suggested Greater Corbett Tiger Reserve (2000 km²) should be kept as inviolate as possible.     

Linking monitoring and intervention for improved management of tigers in the Sundarbans of Bangladesh

Baseline data on distribution and abundance of tigers in the Sundarbans is required to identify problem areas and evaluate management strategies. This paper outlines a khal (creek) bank survey of track set frequency throughout the Bangladesh Sundarbans to aid formulation of a management-driven monitoring program. Three teams of two observers surveyed a total of 1 201 km of waterways throughout the Sundarbans, recording 1 338 tiger track sets. These sets became unrecognizable as tiger sign after a mean 10 days (range 6-14). Proportion of detectable sign recorded was 0.91. Mean (±standard error) sample unit track frequency was 1.12 ± 0.86 track sets/km of khal. The mean coefficient of variance in sample unit track rate, estimated by multiple counts of six sample units, was 0.21 (range 0.06-0.34). Track frequency generally increased from northeast to southwest. Four sample units (6%) had signs of reproduction, with a mean litter size of 1.75 ± 0.5. Monte Carlo simulation suggests a monitoring program of one complete survey every two years will have power of 0.8 (α = 0.2), to detect track frequency declines of ?19% and increases of ?17%. We recommend this monitoring scheme be implemented on the Indian side of the Sundarbans to provide a standard assessment of the tiger population and to form the basis for setting management objectives and evaluating transboundary conservation initiatives.     

Where can tigers persist in the future? A landscape-scale, density-based population model for the Indian subcontinent

Despite being targeted as a conservation flagship species for several decades, the tiger (Panthera tigris) grows ever more imperiled. Debate exists as to where tiger conservation should focus: on protected nature reserves or larger landscapes. We developed a landscape scale, density-based model to assess whether reasonably effective management of current reserves is adequate to ensure the survival of tiger populations. We focused on the Indian subcontinent, the region likely to harbor most tigers. Using tiger density estimates and vegetation data, we set tiger population targets that could be attained through reasonable management of the subcontinent’s nature reserves. Depending on the quality of the surrounding landscape matrix, our model indicated that the subcontinent could potentially hold ∼3500-6500 tigers, in up to 150 reserves. Strikingly, just 21 reserves can hold most (58-95%) of this tiger capacity. These high-population target reserves were relatively insensitive to the hostility of the surrounding matrix to tigers, as their aggregate capacity varied by <10% across a wide range of matrix conditions. In contrast, the remaining 129 reserves were highly sensitive to matrix quality, as they were unable to sustain populations with a tiger-hostile matrix, even with reasonable management. Our results suggest that reasonably improved management of the subcontinent’s reserves can sustain multiple tiger populations based on two differing conservation strategies. Conservation within the 21 reserves with the largest population targets should focus primarily on the reserves themselves. In contrast, tiger conservation in the remaining reserves can succeed only with additional management of the unprotected landscapes that surround them.     

Human-wildlife conflict in the Kingdom of Bhutan: Patterns of livestock predation by large mammalian carnivores

We examined predation activity throughout Bhutan by tiger (Panthera tigris), common leopard (Panthera pardus), snow leopard (Uncia uncia) and Himalayan black bear (Ursus thibetanus) on a variety of livestock types using data gathered over the first two years (2003-2005) of a compensation scheme for livestock losses. One thousand three hundred and seventy five kills were documented, with leopards killing significantly more livestock (70% of all kills), than tigers (19%), bears (8%) and snow leopards (2%). About 50% of livestock killing were of cattle, and about 33% were of horses, with tigers, leopards and snow leopards killing a significantly greater proportion of horses than predicted from availability. Examination of cattle kills showed that leopards killed a significantly greater proportion of smaller prey (e.g., calves), whereas tigers killed a significantly greater proportion of larger prey (e.g., bulls). Overall, livestock predation was greatest in summer and autumn which corresponded with a peak in cropping agriculture; livestock are turned out to pasture and forest during the cropping season, and subsequently, are less well guarded than at other times. Across Bhutan, high horse density and low cattle and yak density were associated with high rates of livestock attack, but no relationship was found with forest cover or human population density. Several northern districts were identified as ‘predation hotspots’, where proportions of livestock lost to predation were considerable, and the ratio of reported kills to relative abundance of livestock was high. Implications of our findings for mitigating livestock losses and for conserving large carnivores in Bhutan are discussed.     

Road crossing structures for amphibians and reptiles: Informing design through behavioral analysis

Road traffic causes significant amphibian and reptile mortality, which could be mitigated through the installation of road crossing structures that facilitate safe passage, but only if reptiles and amphibians are willing to use them. Through a series of behavioral choice experiments with frogs and turtles, we examined how aperture diameter, substrate type, length, and light permeability influenced individuals’ preferences for specific attributes of crossing structures, and how individuals responded to various heights of barrier fences. Snapping turtles (Chelydra serpentina), green frogs (Rana clamitans), and leopard frogs (Rana pipiens) preferred larger diameter tunnels (>0.5 m) whereas painted turtles (Chrysemys picta) preferred tunnels of intermediate (0.5-0.6 m) diameter. Green frogs preferred soil- and gravel-lined tunnels to concrete- and PVC-lined tunnels. Painted turtles showed non-random choice of different lengths of tunnel, possibly indicating some avoidance of the longest tunnel (9.1 m); although no species preferred to exit via the longest tunnels (9.1 m), members of all four species used such tunnels. Green frogs preferred tunnels with the greatest light permeability. Fences 0.6 m in height were effective barriers to green frogs, leopard frogs, and snapping turtles, whereas 0.3 m fences excluded painted turtles. We conclude that tunnels > 0.5 m in diameter lined with soil or gravel and accompanied by 0.6-0.9 m high guide fencing would best facilitate road crossing for these and likely other frog and turtle species.     

Mineralization of forest litter nutrients by heat and combustion

Temperature dependant mineralization dynamics during fire of litter species characteristic of the New Jersey pine barrens was determined. Senescent leaf material of pitch pine (Pinus rigida), white oak (Quercus alba) and black huckleberry (Gaylusssacia baccata) were collected at the time of abscission; sorted, ground and oven-dried at 70 °C. Replicate samples were then heated for 2 h at: 70, 100, 200, 300, 400, and 550 °C. Mass loss and total nitrogen and total phosphorus concentration of the heated material were determined. Additional samples of the residual material were extracted with deionized water, and the filtrate was assayed for the anions: , , ; and cations: , K⁺, Mg⁺⁺, and Ca⁺⁺.By heating leaf litter over a range of temperatures, to simulate the heterogeneous nature of forest litter burning, we identified patterns of nutrient mineralization characteristic of specific temperatures, some of which were common to all three litter species and others unique to individual species. In general, it appears that black huckleberry leaf litter was the most nutrient rich and the most labile. In huckleberry litter, there was a large reserve of soluble nitrogen, sulfur, phosphate, calcium and magnesium that became available upon heating to 200 °C. Pitch pine litter was the most nutrient poor, and the rates of nutrient mineralization were also generally the lowest of the three species studied. White oak litter nutrient concentration and rates of mineralization along the temperature gradient were intermediate. For all three litter species examined organic and inorganic nitrogen losses due to volatilization were >99% upon heating to 550 °C, and soluble magnesium concentrations declined significantly at temperatures of 300 °C, despite having a volatilization temperature greater than 1100 °C. Under the temperature range employed, heating of leaf litter resulted in little volatilization loss of phosphorus; however, the amount of soluble phosphate phosphorus was much lower in all three litter types at temperatures of 300 °C and above. With increasing temperatures, inorganic phosphate ions presumably became bound to cations in the ash, forming insoluble metal phosphates. The dramatic increase of the ratio of total phosphorus to soluble inorganic phosphate at higher temperatures, the loss of soluble magnesium above 300 °C, and the near complete loss of nitrogen at 550 °C suggests that after intense fires availability of these minerals may be dramatically reduced.     

Degradation of tropical forest in Hainan, China, 1991-2008: Conservation implications for Hainan Gibbon (Nomascus hainanus)

The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates in the world, confined to mature natural forest in Hainan Island, China. We assessed changes in habitat condition on the island between 1991 and 2008, using vegetation maps generated by remote-sensing images. We defined forest suitable for gibbons based on composition, tree size and canopy cover. During the 17-year period, the area of suitable gibbon forest decreased by 540 km² (35%) across the whole island, and by 6.3 km² (7%) in the locality of the sole remaining gibbon population at Bawangling National Nature Reserve. The forest patches large enough (>1 km²) to support a gibbon group decreased from 754 km² to 316 km² in total area, and from 92 to 64 in number. Suitable natural forest was mainly replaced by plantations below 760 m, or degraded by logging, grazing and planting of pines above 760 m. Meanwhile, forests in former confirmed gibbon areas became more fragmented: mean area of patches decreased by 53%. We mapped the patches of natural forest in good condition which could potentially support gibbons. We recommend a freeze on further expansion of plantations between core patches at Bawangling, Jiaxi-Houmiling and Yinggeling Nature Reserves in accordance with forest protection regulations; establishment of nature reserves in currently unprotected natural forest patches elsewhere in line with the local government’s nature reserve expansion policy; and active natural-forest restoration between remaining fragments at Bawangling.     

Conflicts between Amur (Siberian) tigers and humans in the Russian Far East

In 1999, the Russian Federation created a Tiger Response Team (TRT) to investigate and intervene in human–tiger conflicts. We examined data collected on human-Amur tiger (Panthera tigris altaica) conflicts from January 2000 through February 2009 to: (1) summarize and characterize human–tiger conflicts in the area, (2) examine causes of human–tiger conflicts, and (3) attempt to evaluate the effectiveness of the TRT. The team investigated 202 conflicts. Both attacks on humans and depredations were greatest in winter (X² = 9, df = 3, P = 0.03 and X² = 64, df = 3, P < 0.001, respectively). Tiger depredation on domestic animals was the most common type of conflict reported (57%), followed by tigers near human habitations (22%), miscellaneous conflicts (12%), and attacks on humans (9%). Dogs were killed more commonly than other domestic animals (63% of 254 animals), likely because livestock were well managed. Nineteen attacks on humans were recorded resulting in 11 injuries and 2 deaths. Nearly four tigers per year (n = 32 tigers) died, were killed, or were removed from the wild, and all but 1 of 20 tigers killed or removed from the wild by the TRT were considered unfit to survive in the wild. Attacks on humans (n = 19) were most often (77%) by wounded tigers (80% of injuries were human-caused) and commonly provoked (47% of attacks). The effectiveness of interventions focused on reducing depredation on domestic animals was unclear, but data suggested that removal of injured and other unhealthy tigers from the wild by the Tiger Response Team resulted in fewer human deaths. Our recommendations include that the TRT continues to work to reduce conflict by rapidly removing debilitated tigers from the wild, explores different methods and technologies for reducing depredation on domestic animals, and increases their efforts to maintain tigers in the wild through telemetry monitoring, translocation, and rehabilitation of orphaned cubs. Further, standardized data should be collected to evaluate all interventions, with information from evaluation guiding an adaptive management component of their human–tiger conflict mitigation activities. This process should occur across tiger landscapes in Asia to allow rapid assessment of interventions.     

Conserving tigers Panthera tigris in selectively logged Sumatran forests

The response of most large carnivores to selective logging is poorly understood. On the one hand, selective logging may represent loss of important habitat, yet, on the other hand, selective logging may increase browse availability for a terrestrial ungulate prey base, thereby indirectly benefiting large carnivores. Using a camera trap-based sampling method, we estimate tiger density in two primary-selectively logged forest areas that straddle Kerinci Seblat National Park, Sumatra. We then investigate potential differences between the habitat use of tigers: within these study areas and forest types; and, within the finer-scale landscape features associated with these covariates. Across the mixed forest study areas, tiger density estimates (adult individuals/100 km² ± S.E.) of 2.95 ± 0.56 and 1.55 ± 0.34 were produced. However, within these areas, tigers showed a preference for primary over degraded forest, and this was related to the greater accessibility of degraded forest sites to people, e.g., through their proximity to roads. Presently, the majority of Sumatran tigers occur within large tracts of primary forest, but these extend outside of the island’s protected area borders, and these unprotected forests are especially at risk from the high levels of deforestation in Sumatra. As forest is cleared, previously remote, and therefore safer, tracts of primary forest become accessible and, eventually, degraded. Yet, from our study, degraded forest in combination with primary forest supported sufficiently high tiger densities and can, therefore, make an important contribution to tiger conservation. It is therefore essential to lessen the detrimental effects of accessibility through increasing law enforcement and destroying ex-logging roads.     

Survival of the biocontrol agents Coniothyrium minitans and Bacillus subtilis MBI 600 introduced into pasteurised, sterilised and non-sterile soils

The biocontrol agents Coniothyrium minitans and Bacillus subtilis MBI 600 were added separately to three soil types that had been either sterilised, pasteurised or left non-sterile. Applied as a conidial suspension of 1×10⁶ cfu g⁻¹ soil, C. minitans showed good survival in all sterilised, pasteurised and non-sterile soils, remaining at the numerical level at which it was applied for the duration of the 30 d experiment. Applied at a lower rate of 1×10³ cfu g⁻¹ soil, C. minitans proliferated in sterilised soil to numbers slightly over 1×10⁶ cfu g⁻¹ soil, whereas no increase was seen in pasteurised or non-sterile soils from this lower application rate. However, although C. minitans was not easily recovered on plates from non-sterile soil, it did survive at the lower numerical level in pasteurised soil, and was recoverable throughout the experiment at the rate at which it was applied. B. subtilis MBI 600 survived well following introduction as a cell suspension into sterilised soil at a rate of 1×10⁶ cfu g⁻¹ soil. Spores were formed rapidly and, after 14 d, the introduced microorganism survived in this form rather than as vegetative cells. However, in non-sterile soil, the introduced microorganism did not compete well and decreased in number, with spores being formed in low numbers. Survival of B. subtilis MBI 600 in pasteurised soil was variable, but resembled the survival seen in non-sterile soil more than that seen in sterilised soil. More B. subtilis MBI 600 spores were formed in pasteurised soil than in non-sterile soil, however, and may have been important for survival in pasteurised soil. In conclusion, this work has shown that the biocontrol agent C. minitans can survive well in soil irrespective of whether the soil has been pasteurised or not and shows good promise as a soil inoculant for control of Sclerotinia sclerotiorum. Although soil pasteurisation does improve establishment of B. subtilis MBI 600 compared to non-sterile soil, survival is relatively poor when applied as cells. The best survival of B. subtilis MBI 600 occurred as spores in sterilised soil, and spore applications to pasteurised soil in an integrated control strategy may allow sufficient establishment of the biocontrol agent to target pathogens causing damping-off.     

Nematode suppression with brassicaceous amendments: application based upon glucosinolate profiles

Glucosinolate profiles differ among plant species and their isothiocyanate (ITC) derivatives differ in toxicity to nematodes. Successful management of plant-parasitic nematodes by ITCs requires the incorporation of appropriate amounts of glucosinolate-containing biomass. Plant materials, containing glucosinolate-precursors of the ITCs most toxic to nematodes, were selected and applied to soil based upon ITC lethal concentration (LC) values. This provided a reliable and repeatable basis for application rates for suppression of Meloidogyne javanica and Tylenchulus semipenetrans by Brassica hirta and M. javanica by B. juncea. Sufficient biomass of B. hirta to potentially yield 0.03-0.12 μmol ml⁻¹ of glucotropeolin reduced nematode survival compared to similar amounts of broccoli (Brassica oleraceae var. botrytis). At biomass levels providing >0.37 μmol ml⁻¹ of glucotropeolin, mortality of M. javanica was 100% with B. hirta. Biomass of B. juncea potentially yielding 2.82 μmol ml⁻¹ of sinigrin reduced M. javanica survival 65% below that obtained by a similar amount of broccoli. Rates of B. juncea to yield lethal levels of allyl ITC to reduce T. semipenetrans survival underestimated the glucosinolate application rates for this amendment. Application of plant biomass to soil >2.9% w/w reduced M. javanica survival regardless of the glucosinolate concentration of the amendment material. Application of brassicaceous amendments to soil initiates complex and dynamic biological and chemical processes. Despite the inherent complexity, we find that brassicaceous amendments can be applied to achieve consistent and repeatable nematode suppression when based upon the chemistry of the incorporated material.     

Environmental correlates of Eurasian lynx occurrence in Poland - Large scale census and GIS mapping

Based on data from the National Lynx Census, carried out in Poland in 2000-2001, and using Geographic Information System, we analysed nine habitat characteristics in 56 circular sample plots (113 km² each), where lynx (Lynx lynx) have been recorded, and 118 plots with no signs of their presence. In plots with lynx the forest cover (on average 68%) was two times higher and the forest fragmentation lower than in plots with no lynx records. The plots with and without lynx differed significantly also in the number of villages and towns, length of main motorways and railways. Lynx occurrence was negatively associated to human settlements and transportation infrastructure. Logistic regression analysis showed that sufficient forest cover (>40%) and the short straight-line distance to the eastern or southern border of Poland (as a proxy of the distance to a more contiguous range of lynx in Europe) are the two most important variables explaining lynx distribution. We conclude that, in Poland, increase of forest fragmentation and transportation infrastructure may become important threats to lynx populations.     

Short-term effects of single or combined application of mineral N fertilizer and cattle slurry on the fluxes of radiatively active trace gases from grassland soil

After implementation of legislative measures for the reduction of environmental hazards from nitrate leaching and ammonia volatilisation when using organic manures and fertilizers in Europe, much attention is now paid to the specific effects of these fertilizers on the dynamics of global warming-relevant trace gases in soil. Particularly nitrogen fertilizers and slurry from animal husbandry are known to play a key role for the CH₄ and N₂O fluxes from soils. Here we report on a short-term evaluation of trace gas fluxes in grassland as affected by single or combined application of mineral fertilizer and organic manure in early spring. Methane fluxes were characterised by a short methane emission event immediately after application of cattle slurry. Within the same day methane fluxes returned to negative, and on average over the 4-day period after slurry application, only a small but insignificant trend to reduced methane oxidation was found. Nitrous oxide emissions showed a pronounced effect of combined slurry and mineral fertilizer application. In particular fresh cattle slurry combined with calcium ammonium nitrate (CAN) mineral fertilizer induced an increase in mean N₂O flux during the first 4 days after application from 10 to 300 μg N₂O-N m⁻² h⁻¹. ¹⁵N analysis of emitted N₂O from ¹⁵N-labelled fertilizer or manure indicated that easily decomposable slurry C compounds induced a pronounced promotion of N₂O-N emission derived from mineral CAN fertilizer. Fluxes after application of either mineral fertilizer or slurry alone showed an increase of less than 5-fold. The NO_x sink strength of the soil was in the range of −6 to −10 μg NO_x-N m⁻² h⁻¹ and after fertilization it showed a tendency to be reduced by no more than 2 μg NO_x-N m⁻² h⁻¹, which was a result of both, increased NO emission and slightly increased NO₂ deposition. Associated determination of the N₂O:N₂ emission ratio revealed that after mineral N application (CAN) a large proportion (c. 50%) was emitted as N₂O, while after application of slurry with easily decomposable C and predominantly -N serving as N-source, the N₂O:N₂ emission ratio was 1:14, i.e. was changed in favour of N₂. Our work provides evidence that particularly the combination of slurry and nitrate-containing N fertilizers gives rise to considerable N₂O emissions from mineral fertilizer N pool.     

Growth promoting effects of corn (Zea mays) bacterial isolates under greenhouse and field conditions

Fertilizer costs are a major component of corn production. The use of biofertilizers may be one way of reducing production costs. In this study we present isolation and identification of three plant growth promoting bacteria that were identified as Enterobacter cloacae (CR1), Pseudomonas putida (CR7) and Stenotrophomonas maltophilia (CR3). All bacterial strains produced IAA in the presence of 100 mg l⁻¹ of tryptophan and antifungal metabolites to several soilborne pathogens. S. maltophilia and E. cloacae had broad spectrum activity against most Fusarium species. The only strain that was positive for nitrogen fixation was E. cloacae and it, and P. putida, were also positive for phosphate solubilization. These bacteria and the corn isolate Sphingobacterium canadense CR11, and known plant growth promoting bacterium Burkholderia phytofirmans E24 were used to inoculate corn seed to examine growth promotion of two lines of corn, varieties 39D82 and 39M27 under greenhouse conditions. When grown in sterilized sand varieties 39M27 and 39D82 showed significant increases in total dry weights of root and shoot of 10-20% and 13-28% and 17-32% and 21-31% respectively. Plants of the two varieties grown in soil collected from a corn field had respective increases in dry weights of root and shoot of 10-30% and 12-35% and 11-19% and 10-18%. In sand, a bacterial mixture was highly effective whereas in soil individual bacteria namely P. putida CR7 and E. cloacae CR1 gave the best results with 39M27 and 39D82 respectively. These isolates and another corn isolate, Azospirillum zeae N7, were tested in a sandy soil with a 55 and 110 kg ha⁻¹ of nitrogen fertility at the Delhi research Station of Agriculture and Agri-Food Canada over two years. Although out of seven bacterial treatments, no treatment provided a statistically significant yield increase over control plots but S. canadense CR11 and A. zeae N7 provided statistically significant yield increase as compared to other bacteria. The 110 kg rate of nitrogen provided significant yield increase compared to the 55 kg rate in both years.     

Rhizosphere activity, grass species and N availability effects on the soil C and N cycles

We examined whether grass species and soil nitrogen (N) availability could enhance Carbon (C) and N turnover during root litter decay in grassland. Three species with increasing competitiveness (Festuca ovina, Dactylis glomerata and Lolium perenne) were grown at two N fertiliser levels in an undisturbed grassland soil, in which soil organic fractions derived for the last 9 years from Lolium root litter which was ¹³C-depleted. During the subsequent experimental year, the C turnover was calculated using the respective δ¹³C values of the old and new C in the root phytomass, in two Particulate Organic Matter (POM) fractions above 200 μm and in the lightest part of the aggregated soil fraction between 50 and 200 μm. Soil N availability was monitored during the regrowth periods with ion exchange resins (IER). The C decay rates of each particle size fraction were calculated with a simple mechanistic model of C dynamics. The N mineralisation immobilisation turnover (MIT) was characterised by dilution of ¹⁵N-labelled fertiliser in the N harvestThe C:N ratio and the residence time of C in the fractions decreased with particle size. The presence of a grass rhizosphere increased the decay rate of old C. Accumulation of new C in particle size fractions increased with species competitiveness and with N supply. Species competitiveness increased C turnover in the aggregated fraction, as a result of greater accumulation of new C and faster decay of old C. Fertiliser N increased N turnover and C mineralisation in the SOM. Species competitiveness decreased soil -N exchanged with the IER and increased dissolved organic C (DOC) content. The nature of the current rhizosphere is thus an important factor driving C and N transformations of the old root litter, in relation with grass species strategy. Plant competitiveness may stimulate the C and N turnover in the more evolved SOM fractions in a similar way to the mineral N supply.