Pasture intensification is insufficient to relieve pressure on conservation priority areas in open agricultural markets

Agricultural expansion is a leading driver of biodiversity loss across the world, but little is known on how future land‐use change may encroach on remaining natural vegetation. This uncertainty is, in part, due to unknown levels of future agricultural intensification and international trade. Using an economic land‐use model, we assessed potential future losses of natural vegetation with a focus on how these may threaten biodiversity hotspots and intact forest landscapes. We analysed agricultural expansion under proactive and reactive biodiversity protection scenarios, and for different rates of pasture intensification. We found growing food demand to lead to a significant expansion of cropland at the expense of pastures and natural vegetation. In our reference scenario, global cropland area increased by more than 400 Mha between 2015 and 2050, mostly in Africa and Latin America. Grazing intensification was a main determinant of future land‐use change. In Africa, higher rates of pasture intensification resulted in smaller losses of natural vegetation, and reduced pressure on biodiversity hotspots and intact forest landscapes. Investments into raising pasture productivity in conjunction with proactive land‐use planning appear essential in Africa to reduce further losses of areas with high conservation value. In Latin America, in contrast, higher pasture productivity resulted in increased livestock exports, highlighting that unchecked trade can reduce the land savings of pasture intensification. Reactive protection of sensitive areas significantly reduced the conversion of natural ecosystems in Latin America. We conclude that protection strategies need to adapt to region‐specific trade positions. In regions with a high involvement in international trade, area‐based conservation measures should be preferred over strategies aimed at increasing pasture productivity, which by themselves might not be sufficient to protect biodiversity effectively.     

The productivity of pine plantations in relation to previous land use

Summary The improved growth of pine plantations on pasture soils compared with that on soils which previously supported native eucalypt forest is primarily explained in terms of soil phosphorus. Pasture development has resulted in a decrease in the P adsorption maximum of about 300 g g^–1 soil, a figure which agrees with the increase in total P due to the application of superphosphate. P adsorption isotherms were used to calculate additions of P to give comparable levels of soil solution P in eucalypt and pasture soils. The growth of pine seedlings in soils thus amended showed a strong N×P interaction. When P was non-limiting, addition of N raised productivity of the eucalypt soil above that of the pasture soil. It is postulated that the different nature of the N×P interaction in eucalypt and pasture soils results from differences in the nitrogen cycle in the two soils.     

Carbon Stocks in Silvopastoral Systems: A Study from Four Communities in Southeastern Ecuador

Agriculture, particularly pasture, is the second largest source of greenhouse gas emissions from tropical regions. Silvopastoral systems may increase carbon pools in pastures while maintaining productivity. Adding trees to pasture provides carbon sinks in woody biomass, and may improve degraded soils and increase the stability of soil carbon pools. In this study we quantified the biomass carbon stored in spontaneous silvopastoral systems in southeastern Ecuador. We compared the stem density, basal area, aboveground biomass, and organic carbon in the top 20 cm of soil in 100 pastures, ranging from 3 to 250 hectares, in four different communities. Aboveground live woody biomass, calculated using allometric equations and two different wood densities, varied from 10.99 to 66.1 Mg per hectare. Soil organic carbon pools ranged from 85.0 to 97.6 Mg per hectare. Stem density, basal area, and aboveground live biomass all positively correlated with pasture age. We found no relationship between pasture age or stem density and soil organic carbon pools. We measured live woody biomass carbon pools of 34–1070 Mg of carbon per farm in these silvopastoral systems. We found no effects on productivity of the herbaceous layer, suggesting that having a low density of trees in pastures could substantially increase the number of trees and the associated carbon sequestration without affecting cattle production.     

Dependence of Phytomass of Herbaceous Cenoses on Weather Factors in Anthropogenically Impacted Areas

This paper is concerned with the phytomass of herbaceous phytocenoses growing in anthropogenically impacted areas in the Middle Urals at different stages of succession along the heavy-metal pollution gradient. Cenoses of young soils of dumps have less resistance and higher sensitivity to changes in weather factors, in contrast to the phytocenoses of the deposits. It is shown by general regression models that the epiterranean and subterranean biomass of cenoses on technozems depends on Selyaninov’s hydrothermic coefficient for September and the amount of precipitation in October–November of the previous year and in January–May of the current year. The degree of this dependence for cenoses under research is determined by edaphic conditions that affect the species diversity and dominance structure.     

Effects of soil management practices and irrigation on plant water relations and productivity of chestnut stands under Mediterranean conditions

The effects of different soil management practices and irrigation on plant water relations, physiological response and productivity of chestnut stands in Northeastern Portugal were assessed during four growing seasons (2003 to 2006). Treatments were: conventional soil tillage up to 15–20 cm depth with a tine cultivator thrice a year (CT); no tillage with spontaneous herbaceous vegetation (NV); no tillage with rainfed seeded pasture (NP); and no tillage with irrigated seeded pasture (NIP). Results suggest that soil water availability was the most critical parameter for chestnut productivity over the study period. In all treatments, high predawn leaf water potentials (-0.40 to -0.55 MPa) were observed during the dry seasons of 2003, 2004 and 2006, showing no critical conditions for plant productivity, which is ascribed to water availability in deep soil layers. In contrast, in 2005, an extremely dry year, water potentials decreased and varied from -1.46 to -1.72 MPa in late summer, showing unfavourable conditions for nut production. Maintenance of spontaneous herbaceous vegetation without irrigation enhanced productivity of chestnut stands as compared with the conventional tillage system and the no tillage system with seeded pasture. Productivity in the soil watering system (NIP treatment) was not significantly different from that observed in the NV treatment. Therefore, studies on the irrigation strategy should be developed, in order to increase its efficiency especially in stands with young trees.     

Zooplankton in Monospecies and Mixed Phytocenoses of <Emphasis Type="Italic">Stratiotes aloides</Emphasis> L. and <Emphasis Type="Italic">Sagittaria sagittifolia</Emphasis> L. under Experimental Conditions

Aquatic plants differing in morphology and metabolic products make unequal changes in the habitat of hydrobionts. The development of zooplankton in monospecies and mixed phytocenoses of the water soldier Stratiotes aloides L. and arrowhead Sagittaria sagittifolia L. has been studied in microcosms. In monospecies phytocenoses of different plants, the preferential development of one or another species of littoral Cladocera is found. The number of predators and species diversity increase in zooplankton as the spatial organization becomes more complex. Zooplankton in the phytocenosis, formed simultaneously by two species of plants, has features characteristic of monospecies phytocenoses, as well as its own peculiarities, primarily related to the development of euplankton species. It is assumed that aquatic plants indirectly affect zooplankton via changes in the quantitative ratio of different groups of food organisms.     

放牧对沙质草地生态系统组分的影响

对内蒙古科尔沁沙质草地5年的放牧试验结果表明,过牧对草地生态系统的危害很大,连续5年过牧使草地生物多样性、植被盖度、高度和初级生产力分别较禁牧区低87．9％、82．1％、94．0％和57．0％,草地现存生物量仅为禁牧区的2．1％,土壤粘粒、C、N含量和微生物、小型动物数量也较之降低6．0％、31．9％、25．0％、95．0％和75．9％,地表紧实度提高274．0％,特别是次级生产力从第3年转为负增长,使草地产出功能完全破坏,封育对沙质草地十分有益,封育5年草地各项指标均有大幅度增加,轻牧和中牧下的植被盖度、高度、土壤状况处于禁牧区和重牧区之间,其中轻牧区植被情况要好于中牧区,但次级生产力低于中牧区,根据多年调查和本次试验结果可以认为,内蒙古东部半干旱沙质草地牧草的利用率应为45％～50％,草地载畜量以3～4羊单位·hm^-2比较适宜。     

The productivity of pine plantations in relation to previous land use

Summary Differences in the productivity of establishedP. radiata plantations on pasture and forest soils were found to be reproducible withP. radiata seedlings in a glasshouse environment. The growth of seedlings on pasture soil exceeded that of seedlings on native forest soil (the ‘primary pasture effect’). After a history of pine on both native and pasture soils a residual effect of pasture on seedling growth was evident (the ‘secondary pasture effect’). However, the effect of a history of pine plantation (the ‘pine effect’) was to decrease the productivity of both native and pasture soil as assessed by seedling growth. These effects were not related to changes due to land management in mycorrhizal infection or in soil structure. The analysis of seedling growth leads to the conclusion that soil fertility, particularly the availability of nitrogen and phosphorus, has changed.     

Contrasting effects of manure and green waste biochars on the properties of an acidic ferralsol and productivity of a subtropical pasture

Background and Aim

We hypothesised that amending an acidic ferralsol with biochar would improve the productivity of a subtropical dairy pasture via reducing soil acidity related constraints and result in improved nitrogen use efficiency. We examined two contrasting biochars with different carbon, nutrient content and acid neutralising values.

Methods

Field plots were amended with one of three biochar treatments (Nil, feedlot manure biochar [FM], green waste biochar [GW]) in combination with presence or absence of NPK fertiliser and presence or absence of liming. The FM and GW biochars had a carbon content of 44 and 76 %, available phosphorous of 5,960 and 93 mg kg^?1, and liming values of 13 and 5.6 %, respectively. The pasture was managed to supply year round high quality feed for dairy production.

Results

The FM biochar increased total pasture productivity by 11 % and improved the agronomic nitrogen use efficiency by 23 %. It also reduced soil acidity but did not significantly affect the pH dependent soil cation exchange capacity. The GW biochar did not improve pasture productivity. Both biochars resulted in an increase in the soil carbon density.

Conclusions

The high available phosphorous content of FM biochar makes it an effective amendment for acidic ferralsols. Greenwaste biochar did not have sufficient acid neutralising capacity or phosphorous content to reduce soil acidity constraints. Both biochars enhance soil carbon storage in pasture systems on ferralsol.     

Habitat requirements of the <Emphasis Type="Italic">Charetum intermediae</Emphasis> phytocoenoses in lakes of western Poland

The study presents habitat and phytosociological analyses of the Chara intermedia phytocenoses, rare described in Europe. 16 physico-chemical water parameters were analysed, coming from the samples taken in 20 phytocenoses of 13 lakes located in western Poland. The analysed community appeared in naturally shallow lakes representing last stages of the disappearance of glacial water basins. The study attempts to estimate the bioindicative value of the charophyta meadow Charetum intermediae in relation to its habitat. A particular attention has been paid to the determination of the habitat trophic condition, and to the concentration of elements connected with the hardness of water and the content of humic substances. The study shows crucial habitat gradients of the C. intermediae association, taking into account also the species composition of phytocenoses.     

Structure and dynamics of organic matter pools in clearings in the lichen pine forests of middle taiga subzone of Yenisei Siberia

This paper studies the structure and dynamics of the major pools of organic matter in clearings in the lichen pine forests of the middle taiga subzone of Yenisei Siberia, in the range of measurements of the international observatory Zotto, a high-tech research platform for long-term (>30 years) monitoring of the atmosphere and climate changes. The contribution of phytocenoses at different stages of post-clearing succession in the process of deposition of atmospheric carbon is analyzed. In conjunction with the data on atmospheric measurements of a wide range of greenhouse gases carried out at the base of the observatory, the results of this work will be used for modeling the stocks and flows of carbon in forest ecosystems of Central Siberia.     

Impacts of Rotational Grazing on Soil Carbon in Native Grass-Based Pastures in Southern Australia

Rotational grazing management strategies have been promoted as a way to improve the sustainability of native grass-based pasture systems. From disturbance ecology theory, rotational grazing relative to continuous grazing can increase pasture productivity by allowing vegetation to recover after short intense grazing periods. This project sought to assess whether soil organic carbon (SOC) stocks would also increase with adoption of rotational grazing management. Twelve pairs of rotationally and continuously grazed paddocks were sampled across a rainfall gradient in South Australia. Pasture productivity approximated as the normalized difference vegetation index (NDVI) was on average no different between management categories, but when the data from all sites were aggregated as log response ratios (rotational/continuous) a significant positive trend of increasing NDVI under rotational grazing relative to continuous grazing was found (R² = 0.52). Mean SOC stocks (0–30 cm) were 48.3 Mg C ha^-1 with a range of 20–80 Mg C ha^-1 across the study area with no differences between grazing management categories. SOC stocks were well correlated with rainfall and temperature (multiple linear regression R² = 0.61). After removing the influence of climate on SOC stocks, the management variables, rest periods, stocking rate and grazing days, were found to be significantly correlated with SOC, explaining 22% of the variance in SOC, but there were still no clear differences in SOC stocks at paired sites. We suggest three reasons for the lack of SOC response. First, changes in plant productivity and turnover in low-medium rainfall regions due to changes in grazing management are small and slow, so we would only expect at best small incremental changes in SOC stocks. This is compounded by the inherent variability within and between paddocks making detection of a small real change difficult on short timescales. Lastly, the management data suggests that there is a gradation in implementation of rotational grazing and the use of two fixed categories (i.e. rotational v. continuous) may not be the most appropriate method of comparing diverse management styles.     

Model estimates of climate change impact on habitats of zonal vegetation for the plain territories of Russia

Possible changes in the habitats of zonal phytocenoses for the plain territories of Russia under a 1°C increase in the annual mean global surface temperature are estimated by simulation with the atmosphere-ocean general circulation models ECHAM4/OPYC3 and HadCM3 and the intermediate-complexity climate model of the Institute of Atmospheric Physics for anthropogenic scenarios of greenhouse gas changes. The response of the phytocenotic habitats to possible climate changes is estimated from the changes in net primary production for the considered climatic scenarios. The obtained data allowed us to recognize the zonal phytocenoses most sensitive to climate changes.     

Effect of time at pasture combined with restricted indoor feeding on production and behaviour in dairy cows

Extremely high nutrient loads have been reported in grazed grassland regimes compared with cutting regimes in some dairy systems that include the use of supplemental feeding. The aim of this study was, therefore, to investigate the effects on productivity and behaviour of high-yielding dairy cows with limited access to indoor feed and restriction in the time at pasture in a continuous stocking system. During a 6-week period from the start of the grazing season 2005, an experiment was conducted with the aim of investigating the effect of restrictive indoor feeding combined with limiting the time at pasture on the productivity and behaviour of high-yielding dairy cows (31.0 ± 5.4 kg energy-corrected milk) in a system based on continuous stocking. The herd was split into three groups allocated to three treatments consisting of 4, 6.5 and 9 h at pasture, respectively. Each group of cows grazed in separate paddocks with three replicates and was separately housed in a cubicle system with slatted floor during the rest of the day. All cows were fed the same amount of supplement, adjusted daily to meet the ad libitum indoor intake of the cows at pasture for nine hours. The herbage allowance was 1650 kg dry matter (DM) per ha, and the intake of supplemental feed was 9.1 kg DM per cow daily. The limitation of the time at pasture to 4 h in combination with restrictive indoor feeding reduced the daily milk, fat and protein yield and live weight compared with 9 h of access to pasture. The proportion of time during which the cows were grazing while at pasture increased from 0.64 to 0.86 and the estimated herbage intake per h at pasture decreased from 2547 g DM to1398 g DM, when time at pasture changed from 4 to 9 h. It can be concluded, that in systems with a high herbage allowance, the cow was able to compensate for 0.8 of the reduction in time at pasture by increasing the proportion of time spent grazing and presumably also both the bite rate and mass, although the latter two have not been directly confirmed in the present study.     

Dynamics of structure and biological productivity of post-fire larch forests in the Northern Mongolia

Peculiarities of forming and growth of post-fire larch (Larix sibirica Ledeb.) forests at the southern range of their distribution in the Northern Mongolia were studied. Regularities of the stand structure and dynamics of biological productivity are analyzed and discussed in the paper. It has been proved that the structure of the organic mass of the post-fire herb-carex type larch tree stands at the southern border of forest vegetation distribution is closely related to their biometric indices as-age, density, and productivity. In comparison with tree stands from the other areas of forest vegetation, the total phytomass stock of larch phytocenoses appropriately increases by zonal gradient from forest-tundra border to the Transbaikalian southern taiga and northern regions of Mongolia. Regeneration of forest cover by edificator and formation of the original larch coenopopulation is a positive trend from an environmental point of view, because the Siberian larch in young and middle-age period in the area has a sufficiently high growth energy and rate of phytomass production, with more than twice exceeding mature forests in fixed carbon of the atmosphere and has positive values of carbon balance and total destruction of organic matter by the “input-output” parameters.     

Land-Use Change and Biogeochemical Controls of Methane Fluxes in Soils of Eastern Amazonia

Tropical soils account for 10%–20% of the 15–35 Tg of atmospheric methane (CH₄) consumed annually by soils, although tropical deforestation could be changing the soil sink. The objectives of this study were (a) to quantify differences in soil CH₄ fluxes among primary forest, secondary forest, active pasture, and degraded pasture in eastern Amazonia; and (b) to investigate controlling mechanisms of CH₄ fluxes, including N availability, gas-phase transport, and soil respiration. At one ranch, Fazenda Vitória, annual uptake estimates (kg CH₄ha⁻¹ y⁻¹) based on monthly measurements were: primary forest, 2.1; secondary forest, 1.0; active pasture, 1.3; degraded pasture, 3.1. The lower annual uptake in the active pasture compared with the primary forest was due to CH₄ production during the wet season in the pasture soils, which is consistent with findings from other studies. In contrast, the degraded pasture was never a CH₄ source. Expressing uptake as a negative flux and emission as a positive flux, CH₄ fluxes were positively correlated with CO₂ fluxes, indicating that root and microbial respiration in the productive pastures, and to a lesser extent in the primary forest, contributed to the formation of anaerobic microsites where CH₄ was produced, whereas this productivity was absent in the degraded pasture. In all land uses, uptake rates of atmospheric CH₄ were greater in the dry season than in the wet season, indicating the importance of soil water content and gas transport on CH₄ fluxes. These clay soils had low annual uptake rates relative to reported rates on sandy soils, which also is consistent with gas transport within the soil being a limiting factor. Nitrogen availability indices did not correlate with CH₄ fluxes, indicating that inhibition of CH₄ oxidation was not an important mechanism explaining differences among land uses. At another ranch, Fazenda Agua Parada, no significant effect of pasture age was observed along a chronosequence of pasture ages. We conclude that land-use change can either increase or decrease the soil sink of CH₄, depending on the duration of wet and dry seasons, the effects of seasonal precipitation on gas-phase transport, and the phenology and relative productivity of the vegetation in each land use.     

Exploitation ecosystems and trophic cascades in non‐equilibrium systems: pasture – red kangaroo – dingo interactions in arid Australia

The exploitation ecosystems hypothesis (EEH) proposes that 1) plant biomass reflects the primary productivity of an ecosystem modified by the regulating effect of herbivory, and 2) herbivore abundance reflects the productivity of plants modified by the regulating effect of predation. Primary productivity thus determines the number of trophic levels in an ecosystem and the extent to which bottom–up and top–down regulation influence the biomass ratios of adjacent and non‐adjacent trophic levels (i.e. trophic cascading). We constructed an interactive model of plant (pasture), herbivore (red kangaroo Macropus rufus) and predator (dingo Canis lupus dingo), a system in which trophic cascades have been suggested to occur, and used it to test the effects of increasing stochastic variation in primary productivity and dingo culling on predictions of the EEH. The model contained four feedback loops: the predator–herbivore and herbivore–plant feedback loops, and the predator and plant density‐dependent feedback loops. The equilibrium conditions along the primary productivity gradient reproduced the three zones of trophic dynamics predicted by the EEH, plus an additional zone at productivities above which the maximum density of a predator is achieved due to social regulation: that zone is characterized by increasing herbivore density and decreasing plant biomass. Culling dingoes produced trophic cascades that were strongly attenuated at primary productivities below which the maximum density of dingoes was attained. Results were robust to uncertainty in kangaroo off‐take by dingoes and to the efficacy of dingo culling, but prey switching by dingoes from red kangaroos to reptiles would weaken trophic cascades. We conclude that social regulation of carnivores has important implications for expression of the EEH and trophic cascades, and that attenuation of trophic cascades increases with increasing stochasticity in primary productivity. Our model also provides a framework for understanding the conditions in which dingo‐mediated trophic cascades might be expected to occur, and generates testable predictions about the effects of higher dingo densities (e.g. by stopping culling or reintroduction to former range) on kangaroo and pasture dynamics.     

The use of aquatic vegetation in lake assessment: testing the sensitivity of macrophyte metrics to anthropogenic pressures and water quality

The relationships between aquatic vegetation, anthropogenic pressures and water quality in 83 Polish lowland lakes were analysed in order to select the best responding macrophyte metrics to be used in ecological status assessment. Several metrics describing the syntaxonomic composition, abundance and spatial structure of macrophytes were tested in three morphological lake types (deep regular-shaped, deep ribbon-shaped and shallow) separately by using the Spearman rank correlation coefficients. Among all the parameters tested, only some anthropogenic pressure parameters (the percentage share of urban areas and forests in a catchment, the pollution load from point sources) and all the water quality indicators (TP, TN, Chla, SD) were significantly correlated with most of the macrophyte metrics, although for different lake types the strength and significance of relationships varied substantially. The macrophyte metrics which best responded to anthropogenic pressures and water quality changes were: (i) in deep regular-shaped lakes: the percentage share of Chara phytocenoses and rush phytocenoses in the total phytolittoral area, the maximum depth of plant distribution and the colonisation index; (ii) in deep ribbon-shaped lakes: the hydrophytes/helophytes area ratio, the percentage share of submerged and rush phytocenoses in the total phytolittoral area; (iii) in shallow lakes: the percentage share of Chara phytocenoses and rush phytocenoses in the total phytolittoral area, and the hydrophytes/helophytes area ratio. These metrics can then be used when elaborating new or refining existing macrophyte-based methods of ecological status assessment.     

Effects of fertilization and irrigation on productivity, plant nutrient contents and soil nutrients in southern Mongolia

The study attempts to evaluate the effect of fertilization and irrigation on steppe productivity in dry southern Mongolian desert-steppes. We conducted an irrigation- and NPK fertilization experiment, irrigating at levels of +100 mm and fertilizers at amounts equivalent to 20 gN (m² year)^?1 in a factorial design. We tested the effects on soil nutrients and biomass production. Nutrients in plant tissue were analysed for Stipa krylovii and S. gobica, and for mixed sub-samples of total above- and belowground biomass. Available P and K and total K increased in the soil after fertilization while irrigation reduced total N. Biomass yield almost tripled and inflorescence numbers increased by factors of 4?C8 due to fertilization while irrigation alone had very restricted effects and only increased biomass of Agropyron cristatum. Nutrient content of biomass was elevated on fertilized plots. Results indicate that steppe productivity is severely restricted by nutrient availability even under ambient precipitation levels, raising the question whether nutrient withdrawal caused by current land use practices has detrimental effects on pasture productivity. The anticipated beneficial effect of increasing water availability however could not be confirmed. Whether there is an improvement in productivity due to increasing rainfall, as predicted by some climate change models, will depend on the distribution and intensity of rain events.     

An experimental investigation into the effects of flooding on the ixodid tick Boophilus microplus (Canestrini)

Summary The effect of water immersion on the non-parasitic stages of Boophilus microplus were investigated both under laboratory and field conditions. Survival of engorged female ticks was influenced by their age and the temperature of the water. Eggs and larvae were more resistant to submerison than were engorged females and their survival was increased at low temperatures and in water with high oxygen content. The persistence of this tick in areas prone to flooding was attributed to the survival of parasitic stages and to larvae on the pasture. Heavy rains produce favourable pasture conditions for tick reproduction so that a large increase in population size may be expected to follow such rain.