De Weerd N.,Wageningen University |
De Weerd N.,Ecology Group |
Van Langevelde F.,Wageningen University |
Van Oeveren H.,Wageningen University |
And 4 more authors.
PLoS ONE | Year: 2015
The increasing spatiotemporal accuracy of Global Navigation Satellite Systems (GNSS) tracking systems opens the possibility to infer animal behaviour from tracking data. We studied the relationship between high-frequency GNSS data and behaviour, aimed at developing an easily interpretable classification method to infer behaviour from location data. Behavioural observations were carried out during tracking of cows (Bos Taurus) fitted with high-frequency GPS (Global Positioning System) receivers. Data were obtained in an open field and forested area, and movement metrics were calculated for 1 min, 12 s and 2 s intervals. We observed four behaviour types (Foraging, Lying, Standing and Walking). We subsequently used Classification and Regression Trees to classify the simultaneously obtained GPS data as these behaviour types, based on distances and turning angles between fixes. GPS data with a 1 min interval from the open field was classified correctly for more than 70% of the samples. Data from the 12 s and 2 s interval could not be classified successfully, emphasizing that the interval should be long enough for the behaviour to be defined by its characteristic movement metrics. Data obtained in the forested area were classified with a lower accuracy (57%) than the data from the open field, due to a larger positional error of GPS locations and differences in behavioural performance influenced by the habitat type. This demonstrates the importance of understanding the relationship between behaviour and movement metrics, derived from GNSS fixes at different frequencies and in different habitats, in order to successfully infer behaviour. When spatially accurate location data can be obtained, behaviour can be inferred from high-frequency GNSS fixes by calculating simple movement metrics and using easily interpretable decision trees. This allows for the combined study of animal behaviour and habitat use based on location data, and might make it possible to detect deviations in behaviour at the individual level. Copyright: © 2015 de Weerd et al.
Forster D.,WIPO Inc |
Andres C.,WIPO Inc |
Verma R.,Research Division |
Zundel C.,WIPO Inc |
And 3 more authors.
PLoS ONE | Year: 2013
The debate on the relative benefits of conventional and organic farming systems has in recent time gained significant interest. So far, global agricultural development has focused on increased productivity rather than on a holistic natural resource management for food security. Thus, developing more sustainable farming practices on a large scale is of utmost importance. However, information concerning the performance of farming systems under organic and conventional management in tropical and subtropical regions is scarce. This study presents agronomic and economic data from the conversion phase (2007-2010) of a farming systems comparison trial on a Vertisol soil in Madhya Pradesh, central India. A cotton-soybean-wheat crop rotation under biodynamic, organic and conventional (with and without Bt cotton) management was investigated. We observed a significant yield gap between organic and conventional farming systems in the 1st crop cycle (cycle 1: 2007-2008) for cotton (-29%) and wheat (-27%), whereas in the 2nd crop cycle (cycle 2: 2009-2010) cotton and wheat yields were similar in all farming systems due to lower yields in the conventional systems. In contrast, organic soybean (a nitrogen fixing leguminous plant) yields were marginally lower than conventional yields (-1% in cycle 1, -11% in cycle 2). Averaged across all crops, conventional farming systems achieved significantly higher gross margins in cycle 1 (+29%), whereas in cycle 2 gross margins in organic farming systems were significantly higher (+25%) due to lower variable production costs but similar yields. Soybean gross margin was significantly higher in the organic system (+11%) across the four harvest years compared to the conventional systems. Our results suggest that organic soybean production is a viable option for smallholder farmers under the prevailing semi-arid conditions in India. Future research needs to elucidate the long-term productivity and profitability, particularly of cotton and wheat, and the ecological impact of the different farming systems. © 2013 Forster et al.
Hidding B.,Netherlands Institute of Ecology |
Brederveld R.J.,Netherlands Institute of Ecology |
Brederveld R.J.,Ecology Group |
Nolet B.A.,Netherlands Institute of Ecology
Freshwater Biology | Year: 2010
1. Bottom-dwelling charophytes have been observed to replace canopy-forming pondweeds within a few years in de-eutrophied shallow lakes. Competition for bicarbonate (HCO3 -) may explain this shift in vegetation dominance but inhibition of pondweeds by Chara spp. through direct competition has not been shown experimentally. We tested whether charophytes inhibited growth of fennel pondweed (Potamogeton pectinatus) in the absence of belowground competition by growing plants in pots in mesocosms following a replacement series experimental design. To further understand the role of bicarbonate, we studied main and interactive effects of Chara, light and bicarbonate on P. pectinatus growth in a laboratory study. Early in the mesocosm experiment, high charophyte densities had a negative effect on P. pectinatus cover at a time when bicarbonate levels were low. However, bicarbonate levels eventually converged to low levels in all treatments. At final harvest, both species exhibited lower biomasses at higher densities of conspecific pots, indicating that ultimately intraspecific competition was limiting. In a laboratory study, Chara inhibited P. pectinatus the most under a combination of high light and high bicarbonate concentrations, suggesting that Chara may negatively affect P. pectinatus by acting as a general nutrient sink. Our results suggest that Chara growth can reduce bicarbonate levels, delaying but not preventing a P. pectinatus growth pulse. Given the recorded inhibition under ample bicarbonate supply, Chara's ability to act as nutrient sink may contribute to the decline of P. pectinatus under Chara recovery in shallow lakes. © 2010 Blackwell Publishing Ltd.
Brederveld R.J.,University Utrecht |
Brederveld R.J.,Ecology Group |
Brederveld R.J.,Biodiversity and Climate Research Center |
Jahnig S.C.,University of Duisburg - Essen |
And 4 more authors.
Journal of Applied Ecology | Year: 2011
Over the past centuries, European streams have been heavily influenced by humans through pollution and regulation. As a result, the quality and diversity of freshwater riparian habitats have declined strongly, and the diversity of riparian flora and fauna has decreased. Recent restoration measures have resulted in stream habitat improvements, but biodiversity improvements have failed to follow in fragmented streams. It has been suggested that dispersal limitation could play an important role in the lack of biodiversity improvement in restored streams, but to date, there is no conclusive evidence for this assumption. In this study, we investigated whether colonization of restored streams by plants and macroinvertebrates is limited by dispersal. We hypothesized that colonization success increases with increasing availability of (nearby) source populations and with increasing ability of species to disperse over long distances. We related species composition in seven restored stream sections to species' abundances in the surroundings and to species' dispersal abilities. For both plants and macroinvertebrates, colonization success is strongly related to the abundance of species in the local and regional species pools. For plants, dispersal strategy has an additional influence on colonization success: short-lived plants with high production of small, well-dispersed seeds colonized best within the 3- to 5-year period after restoration. The existence of dispersal strategy constraints could not be confirmed in macroinvertebrates, possibly because these are limited by a lack of connectivity on larger spatial scales. On the landscape scale, beneficial effects of increased plant diversity might further improve habitat suitability for macroinvertebrates. Synthesis and applications. Dispersal appears to be a limiting factor for successful (re)colonization of restored streams in fragmented landscapes. In plants, this is attributed to limitations in seed dispersal abilities and likely to a lack of nearby source populations as well. In macroinvertebrates, lack of nearby source populations may also be a limiting factor. Hence, we suggest restoring landscape connectivity at larger spatial scales and optimizing the availability of near-natural 'source' areas in the vicinity of restoration projects, at least for plants, to improve the success of biodiversity restoration in fragmented habitats. © 2011 The Authors. Journal of Applied Ecology © 2011 British Ecological Society.
Assessment of traffic noise impact in important bird sites in Sweden - A practical method for the regional scale [Avaliação do impacto gerado pelo ruído do tráfego em importantes habitats de aves na Suécia - Um método prático para a escala regional]
Helldin J.O.,Swedish University of Agricultural Sciences |
Helldin J.O.,Calluna AB |
Collinder P.,Ecology Group |
Bengtsson D.,Ecology Group |
And 4 more authors.
Oecologia Australis | Year: 2013
Previous research has pointed out the negative impact of traffic noise on wildlife adjacent to major roads, but despite the scientific evidence, the impact of traffic noise in natural environments is rarely assessed, and even more rarely mitigated, in road planning, in Sweden as well as in most other countries. It has been argued that the reason to this shortcoming is the lack of a practical method to assess this impact on natural environments. We developed a desktop method for assessing the traffic noise impact on areas of importance for nature conservation, with special emphasis on important bird sites. The method output is a calculation of the effective habitat loss due to traffic noise for each site, based on dose-effect relationships presented in literature, available GIS data on selected habitat types, official road data, and a simplified model for noise distribution. The method has a dual purpose; to estimate the impact of traffic noise on birds at larger geographic scales, and to identify priority sites for mitigation efforts. We applied the method in two Swedish regions with relatively low or moderate road and traffic densities. The results from these case studies pointed out that i) at regional level, the impact zone covers a small part of the land area (0.6 and 3.3% of lower and higher density regions, respectively), ii) for certain important bird habitat types, >10% of sites are within the impact zone, iii) the impact from traffic noise represents an effective loss of 0.02-1.7% of the total area of the selected habitat types. The latter figures can be taken as estimates of the present conservation debt of traffic noise. The results indicate that traffic noise may have a disproportionate impact on some important bird habitats. Because bird sites are often rich also in other taxa, and in addition tend to be important areas for outdoor recreation, we argue that traffic noise may have a broad impact on nature conservation, and that mitigation efforts should be made to minimize this impact. We discuss the general applicability of the method.