Effects Of Land-use Intensification Research Articles

Difficulties in using land use pressure and soil quality indicators to predict water quality

Intensive agriculture can impair river water quality. Soil quality monitoring has been used to measure the effect of land use intensification on water quality at a point and field scales but not at the catchment scale. Other farm scale land use pressures, like stocking rate and the value of land, which relate to land use intensity are now publicly available, nationally. We therefore tested whether point scale soil quality measures, together with newly available farm scale land use pressures (land valuation and stocking rate) and existing catchment and climatic characteristics could help predict the behaviour of water quality data across 192 catchments in New Zealand. We used a generalised additive model to make predictions of the change in nitrogen fractions (r2 = 0.65–0.71), phosphorus fractions (r2 = 0.51–0.70), clarity and turbidity (r2 = 0.42–0.46), and E. coli (r2 = 0.35) over 15 years. The state and trend of water quality was strongly related to a refined farm scale land use classification, and to catchment and climatic characteristics (e.g. slope, elevation, and rainfall). Relationships with point scale soil quality measures and the land use pressures were weak. The weak relationship with land use pressures may be caused by using a single snapshot in time (2022), which cannot account for lag times in water quality response but leaves room for additional temporal data to improve predictive power. The weak relationship to soil quality measures was probably caused by limited data points (n = 667 sites) that were unrepresentative of land use, and areas of catchment subject to processes like runoff or leaching. While national soil quality measures might be useful for evaluating environmental risk at the field or farm scale, without a large increase in sampling, they were not relevant at the catchment scale. Additional analyses should be performed to determine how many samples would be needed to detect a change using an environmentally focused soil test that can guide water quality management.

Species richness: A pivotal factor mediating the effects of land use intensification and climate on grassland multifunctionality

Abstract Temperate seminatural grasslands harbour unique biodiversity, support livestock farming through forage production, and deliver many essential ecosystem services (ESs) to human society; they are highly multifunctional. However, temperate grassland ecosystems are also among the most threatened ecosystems on earth due to land use and climate changes. Understanding how biodiversity, climate and land use intensification impact grassland multifunctionality through complex direct and indirect pathways is critical to better anticipate the future of these fragile ecosystems. Here, we evaluate how local plant species richness (SR) modulates the effect of land use intensification and climate on grassland multifunctionality (using six key ESs: biomass productivity and stability, forage quality, carbon storage, pollination and local plant rarity) in the French Massif Central, the largest grassland in Western Europe. We sampled 100 grasslands with contrasted fertilization rates and SR, over large elevational and latitudinal gradients related to variation in mean annual temperature (MAT), and drought severity (DS), two key climate change drivers predicted to increase in the future. Using a confirmatory path analysis, we found that SR was the main driver of multifunctionality. We also found significant SR × MAT and SR × fertilization interactions suggesting that warm climate and high fertilization rates alter the biodiversity–ecosystem multifunctionality relationships. Furthermore, increasing temperature and fertilization indirectly influenced multifunctionality by decreasing SR and consequent multifunctionality in warm lowland and highly fertilized grasslands compared to colder montane grasslands or less fertilized ones. DS only impacted some ES individually (e.g. forage quality). Synthesis and applications: We identified species richness (SR) as a pivotal factor mediating the effects of land use intensification and climate on multifunctionality through both direct and indirect pathways. Failing to account for changes in SR could thus bias any prediction of, or aggravate, the effects of land use intensification and climate change on ecosystem services delivery in temperate grassland ecosystems. Considering that SR, mean annual temperature and fertilization are major proxies of three main global change drivers (biodiversity loss, climate change and land use intensification) our study may help to better anticipate the effect of multiple interacting global change drivers on grassland ecosystems.

Effect of Land-Use Intensification on Soil Properties and Plant Species Diversity in the Mediterranean Agroecosystem

In recent decades, agriculture in Greece has undergone significant changes due to the intensification of land use. This intensification, contrary to the sustainable land management, has an impact on the healthiness of the environmental agroecosystem. This study aimed to investigate if these cultivation systems influence some of the main edaphic properties and plant species diversity and which are the main anthropogenic interventions which may have a decisive role in the changes of soil physicochemical properties and the reduction of plant species. To assess the environmental implications among different types of land-use, the most sensitive and reliable edaphic indicators were measured and plant species diversity was recorded. Three land-use types such as maize crops, alfalafa and abandoned land were selected and ten fields with an area of approximately 1 ha in each land use type were taken. The results indicate that among the edaphic parameters pH, sand, electrical conductivity (EC), soil organic matter (SOM), NO3- as well as Ca+2 and Cu+2 soil concentration presented statistically significant differences among thirty cultivated fields. Among three different land uses, the edaphic variables EC, SOM, BD, Cal & Na concentrations presented significant differences. A higher soil organic matter content was observed in abandoned land while bulk density and electric conductivity value as well as Na+ concentrations were lower compared to other land uses. In total 122 taxa belonging to 30 families were recorded, while the families with the greatest species diversity were Poaceae, Asteraceae and Fabaceae in all land uses. Therophytes was the dominant life-form, followed by the Hemicryptophytes and Geophytes. The findings of the present study imply that different agronomic practices influence soil quality parameters, which are likely to affect species diversity and the environmental implications among different land uses.

Land use intensification alters the relative contributions of plant functional diversity and soil properties on grassland productivity.

Understanding the mechanisms of grassland productivity variation is critical for global carbon cycling and climate change mitigation. Heretofore, it is unknown how different environmental factors drive small-scale spatial variation in productivity, and whether land use intensification, one of the most important global changes, can regulate the processes that drive productivity change. Here we performed an 18-year exclosure experiment across six sites with high-intensity mowing/grazing history in northern China to examine the effects of land use intensification on plant functional diversity, soil properties, and their relative contributions to above-ground net primary productivity (ANPP). We found that plant functional diversity and soil properties contributed to the variation in ANPP both independently and equally in enclosed grasslands (plant diversity: 20.6%; soil properties: 19.5%). Intensive land use significantly decreased the Rao's quadratic entropy (RaoQ) and community-weighted mean value (CWM) of plant height, and further suppressed the contributions of plant functional diversity to ANPP. In contrast, intensive land use increased soil available N, P, pH, electrical conductivity, and homogeneity of soil available P, and strengthened their contributions to ANPP (31.5%). Our results indicate that high-intensity land use practices in grasslands decrease the role of plant functional diversity, but strengthen the effects of soil properties on productivity. We, therefore, suggest that plant functional diversity can be used effectively to boost productivity in undisturbed grasslands, while soil properties might be a more critical consideration for grassland management in an areas with increased land use.

Pollinator guilds respond contrastingly at different scales to landscape parameters of land-use intensity.

Land‐use intensification is the main factor for the catastrophic decline of insect pollinators. However, land‐use intensification includes multiple processes that act across various scales and should affect pollinator guilds differently depending on their ecology. We aimed to reveal how two main pollinator guilds, wild bees and hoverflies, respond to different land‐use intensification measures, that is, arable field cover (AFC), landscape heterogeneity (LH), and functional flower composition of local plant communities as a measure of habitat quality. We sampled wild bees and hoverflies on 22 dry grassland sites within a highly intensified landscape (NE Germany) within three campaigns using pan traps. We estimated AFC and LH on consecutive radii (60–3000 m) around the dry grassland sites and estimated the local functional flower composition. Wild bee species richness and abundance was positively affected by LH and negatively by AFC at small scales (140–400 m). In contrast, hoverflies were positively affected by AFC and negatively by LH at larger scales (500–3000 m), where both landscape parameters were negatively correlated to each other. At small spatial scales, though, LH had a positive effect on hoverfly abundance. Functional flower diversity had no positive effect on pollinators, but conspicuous flowers seem to attract abundance of hoverflies. In conclusion, landscape parameters contrarily affect two pollinator guilds at different scales. The correlation of landscape parameters may influence the observed relationships between landscape parameters and pollinators. Hence, effects of land‐use intensification seem to be highly landscape‐specific.

Stability of soil organic carbon during forest conversion is more sensitive in deep soil than in topsoil in subtropical forests

Despite much research, a lot of uncertainty remains regarding the effects of forest conversion to plantation on soil organic carbon (SOC) stabilization, particularly in deep soils. After comparing the SOC content and its distribution in over 200 years old natural broadleaved of forest of Castanopsis carlesii to that in an adjacent 38 years old C. carlesii plantation, we evaluated the effect of land use intensification on soil carbon (C) storage indicators - soil aggregates, density fractions and SOC mineralization rate. The conversion of natural forest to plantation caused divergent, but seemingly progressive responses in the topsoil and deep soil. In the topsoil, SOC stocks were up to 32 % lower following the forest conversion, with a lower labile C pool, whereas the recalcitrance indices in the topsoil of the plantation forest was similar to that in the topsoil of the natural forest. In contrast, in the deep soil, SOC stocks were unaltered, but the recalcitrance indices of SOC decreased by 64 % after forest conversion. The decreased stability of deep SOC was confirmed by the observed decrease in biochemically protected C and increase in specific C mineralization (normalized for soil C content). The decline in biochemically protected C may attribute to greater physical accessibility of organic C to microbes due to soil disturbance induced by forests conversion practices. Consequently, our results supported the view that despite the variable processing rates of C in differently protected pools, all SOC pools are potentially decomposable and dynamic. Physical disturbance appears to be the key factor modifying SOC protection status and long-term stabilization.

Changing Water Management Practice in Canterbury to Address Sustainability Limits

Irrigation expansion in Canterbury has led to sustainability limits being reached for water availability and cumulative effects of land use intensification. Increasing water availability through storage was proposed, but there was strong community opposition to impacts of storage and further intensification. Effects-based institutional arrangements proved inadequate to address these issues. The regional council introduced a strategic approach based on nested adaptive systems and collaborative governance. A regional water strategy was developed through a multi-stakeholder steering group under the Canterbury Mayoral Forum and with extensive community engagement. Zone committees were established to develop zone implementation programmes. Farmer collectives are being established for operational delivery of water management targets. Farmers develop farm management plans to meet property-level outcomes, which are independently audited. Strategy investigations demonstrated that focusing on new development would not achieve sustainable development; rather, existing users also had to improve. Water use efficiency improvements were more cost-effective than new storage. Furthermore, different forms of storage, such as managed aquifer recharge, were identified to avoid adverse effects on main stems of alpine rivers. Proactive measures were needed to address water quality degradation, biodiversity loss, Mäori involvement and ecological restoration. A systems perspective and a governance change from regulatory to collaborative have improved water management. However, they also identified issues concerning affordability of proactive measures, equity in allocation, and need for a public infrastructure agency. Uneven implementation of measures has led to some groups withdrawing from the collaborative process.

Can dragonfly and damselfly communities be used as bioindicators of land use intensification?

Abstract There is a growing need to identify efficient biological indicators for assessing accelerated land use intensification, as well for understanding the effects of past environmental changes on species distributions. To address this, we used an extensive opportunistic survey dataset of 254 adult odonate (suborder Anisoptera or dragonflies; suborder Zygoptera or damselflies) species collected in nine Mexican hydrological regions during two time windows (1980–1993 and 1994–2010). We evaluated species richness, body size and individual species’ response to land use intensification over time at a national scale using Phylogenetic Bayesian Regression Mixed Models. We found that dragonfly species serve as good indicators of current land use, whereas damselfly species show time-lagged effects of land use intensification. Large species could thus be used as a proxy of recent reduction of original vegetation, whereas small species provide information on historic habitat modification. Odonate body size seems to be a better variable for measuring the integrity of original vegetation than the more commonly used species richness. Finally, the use of individual species as bioindicators at broad spatial and temporal scales is not encouraged, as it does not reflect the degree of ecological integrity, and only the occurrence of some species combinations can indicate environmental degradation.

FIVE DECADES OF DECLINE FOR OLD-GROWTH INDICATOR LICHENS IN SCOTLAND

Systematic data collection for direct statistical analysis of biodiversity trends tends to be focused on charismatic fauna and flora such as birds or vascular plants. When subsequently applied by conservation agencies in summary metrics tracking habitat and species protection, these patterns in biodiversity loss or gain can fail to capture outcomes for groups that have a prominent importance in habitat composition, diversity and ecological function, such as algae, bryophytes, lichens and other fungi. Such species are primarily recorded on an ad hoc basis by taxonomic specialists, yielding noisy data that present problems in robustly identifying trends. This study explored the use of ad hoc field-recorded data as a potential source of biodiversity information, by comparing the pattern of recording for carefully selected indicator species with those for benchmark or control species as a proxy for recording effort. Focusing on Scotland’s internationally important epiphytic lichens, and especially ‘old-growth’ indicator species, British Lichen Society data revealed a decline in the extent of these species in Scotland, relative to recording effort, over a period of five decades. A recent slowing in the rate of decline is observed but remains to be confirmed. The long-term decline is consistent with the effect of land use intensification, resulting in small and isolated populations that are vulnerable to extinction debt. We caution that remedial protection and monitoring for such populations remains vital as a complement to Scotland’s larger scale ambition for increased woodland extent and connectivity.

Effects of Land Use Intensification on Avian Predator Assemblages: A Comparison of Landscapes with Different Histories in Northern Europe

Land use and landcover change alter the ability of habitat networks to maintain viable species populations. While their effects on the quality, amount and patterns of landcover patches are commonly studied, how they affect ecological processes, such as predation on focal species remains neglected. This macroecological study tests the hypothesis that predator assemblages are affected by land use intensity linked to different socio-economic contexts. We measured the distribution and abundance of two avian predator groups (generalist corvid birds and specialist raptors), and proxy variables that mirror their food resources, at three spatial scales in northern Europe’s West and East. In total, we made 900 survey counts for avian predators and their resources in six landcover strata throughout five landscapes and analyzed their relationships. The abundance of omnivorous corvid birds was associated with the number of anthropogenic food resources. Thus, corvid birds were most common in the urban and agricultural landcovers, and where forest cover was low. Corvid bird abundance, and availability of their resources, increased with increasing land use intensity. Raptors were less abundant than corvid birds and most common in semi-natural grasslands. The number of raptor species increased with decreasing land use intensity. This study shows that the abundance and composition of avian predator species must be understood to maintain functional habitat networks.

Can Intensification of Cattle Ranching Reduce Deforestation in the Amazon? Insights From an Agent-based Social-Ecological Model

Deforestation in the Amazon with its vast consequences for the ecosystem and climate is largely related to subsequent land use for cattle ranching. In addition to conservation policies, proposals to reduce deforestation include measures to intensify cattle ranching. However, the effects of land-use intensification on deforestation are debated in the literature. This paper introduces the abacra model, a stylized agent-based model to study the interplay of deforestation and the intensification of cattle ranching in the Brazilian Amazon. The model combines social learning and ecological processes with market dynamics. In the model, agents adopt either an extensive or semi-intensive strategy of cattle ranching based on the success of their neighbors. They earn their income by selling cattle on a stylized market. We present a comprehensive analysis of the model with statistical methods and find that it produces highly non-linear transient outcomes in dependence on key parameters like the rate of social interaction and elasticity of the cattle price. We show that under many environmental and economic conditions, intensification does not reduce deforestation rates and sometimes even has a detrimental effect on deforestation. Anti-deforestation policies incentivizing fast intensification can only lower deforestation rates under conditions in which the local cattle market saturates.

Belowground Tritrophic Food Chain Modulates Soil Respiration in Grasslands

Edaphic biota significantly affects several essential ecological functions such as C-storage, nutrient turnover, and productivity. However, it is not completely understood how belowground animal contribution to these functions changes in grasslands subject to different land use types. A microcosm experiment was carried out to test the effect of a tritrophic food chain on CO2 release from grassland soils. Soil was collected from three differently managed grassland systems (meadow, pasture, and mown pasture) located in three distinct German regions that cover a north-south gradient of approximately 500 km. The tritrophic food chain comprised natural edaphic microflora, nematodes, and predatory gamasid mites. The experimental design involved a full factorial combination of the presence and absence of nematodes and gamasid mites. Nematodes significantly increased the CO2 emissions in most treatments, but the extent of this effect varied with land use type. The fact that grazing by nematodes stimulated the metabolic activity of the edaphic microflora over a wide range of grassland soils highlighted the critical impact of the microfauna on ecosystem services associated with soil organic matter dynamics. Gamasids slightly amplified the effect of nematodes on microbial metabolic activity, but only in the pastures. This effect was most probably due to the control of nematode abundance. The fact that gamasid addition also augmented the impact of environmental conditions on nematode-induced modulation of soil respiration highlighted the need for including land use differences while evaluating soil fauna contribution to soil processes. To conclude, the differential response of the investigated tritrophic food chain to different grassland management systems suggests that adverse effects of land use intensification on important soil processes such as atmospheric C-release could potentially be reduced by using management methods that preserve essential features of the belowground food web.

Effects of landuse intensification on stream basal resources and invertebrate communities

AbstractHuman population growth and development have degraded freshwater ecosystems through direct negative effects on basal resources and higher trophic levels. Knowledge of how basal resources are influenced by anthropogenic activities is needed to examine foodweb responses and to evaluate negative effects of human disturbance. We combined quantitative sampling of all putative resources and consumers and naturally occurring stable isotopes of resource C and N to investigate how land use influences characteristics of basal resources (leaf litter, fine particulate organic matter [FPOM] suspended in water, FPOM deposited in pools, and epilithon) and the invertebrate communities in 9 streams of British Columbia (Canada) on a seasonal basis. Study streams were grouped as forest, cropland, and urban, based on percentages of land use in their catchments. We tested for seasonal and spatial differences in biomass, isotopic variability, and overlap of different basal resources and their relationships with inverte...

Sediment-associated organic carbon and nitrogen inputs from erosion and irrigation to rice fields in a mountainous watershed in Northwest Vietnam

Maintaining indigenous nutrient supply and positive nutrient balances are key factors in sustaining rice yields. Irrigation systems act as conveyers for water, sediments and nutrients throughout landscapes, especially in mountainous, cultivated tropical areas where erosivity is usually high. Contributions of erosion and irrigation to the nutrient balance of paddy fields, however, are rarely assessed. In this study, a turbidity-based method was used to quantify sediment-associated organic carbon and nitrogen as well as dissolved nitrogen inputs from erosion and irrigation to a 13 ha rice area in Northwest Vietnam. The irrigation source is a surface reservoir, and both reservoir and irrigation channel are surrounded by permanent upland maize cultivation on the steep slopes. Additionally, organic carbon and nitrogen loads in paddy outflow were determined to obtain nutrient budgets. Irrigation contributed 90 % of sediment-associated organic carbon inputs and virtually all nitrogen inputs. Analysis of ammonium and nitrate in total nitrogen loads showed that 24 % of the total N inputs from irrigation to the rice area, or 0.28 Mg ha−1 a−1, were plant-available. Loads measured at the outlet of rice fields showed that paddies were a trap for sediment-associated nutrients: balancing inputs and outflow, a net load of 1.09 Mg ha−1 a−1 of sediment-associated organic carbon and 0.68 Mg ha−1 a−1 of sediment-associated nitrogen remained in the rice fields. Sediment-associated organic carbon and nitrogen inputs thus form an important contribution to the indigenous nutrient supply of rice in these maize-paddy systems, while the rice fields simultaneously capture nutrients, protecting downstream areas from the effects of land use intensification on surrounding slopes. These results underscore the importance of upland-lowland linkages in tropical, mountainous, erosion-prone areas.

Soil conditions and land use intensification effects on soil microbial communities across a range of European field sites

Intensive land use practices necessary for providing food and raw materials are known to have a deleterious effect on soil. However, the effects that such practices have on soil microbes are less well understood. To investigate the effects of land use intensification on soil microbial communities we used a combined T-RFLP and pyrosequencing approach to study bacteria, archaea and fungi in spring and autumn at five long term observatories (LTOs) in Europe; each with a particular land use type and contrasting levels of intensification (low and high). Generally, due to large gradients in soil variables, both molecular methods revealed that soil microbial communities were structured according to differences in soil conditions between the LTOs, more so than land use intensity. Moreover, variance partitioning analysis also showed that soil properties better explained the differences in microbial communities than land use intensity effects. Predictable responses in dominant bacterial, archaeal and fungal taxa to edaphic conditions (e.g. soil pH and resource availability) were apparent between the LTOs. Some effects of land use intensification at individual field sites were observed. However, these effects were manifest when land use change affected soil conditions. Uniquely, this study details the responses of different microbial groups to soil type and land use intensification, and their relative importance across a range of European field sites. These findings reinforce our understanding of drivers impacting soil microbial community structure at both field and larger geographic scales.

Effects of Land-Use Intensification on Distribution and Diversity of Fusarium Species in Machakos County, Kenya

Land-use intensification has a significant influence on occurrence of soil microorganisms. The effect of this phenomenon on Fusarium species is poorly characterized. One hundred soil samples were obtained from 3 replicated land- use types (LUT) in Mwala and Kauti irrigation regions in Machakos County. These included two intensive land-uses under irrigation and rain-fed agriculture and undisturbed lands. Mwala irrigated lands were divided into four blocks based on history of cultivation. Using soil dilution plate technique, 1,546 isolates of Fusarium were recovered and identified into twelve species namely; F. oxysporum, F. solani, F. nygamai, F. equiseti, F. chlamydosporum, F. beomiforme, F. verticillioides, F. proliferatum, F. acuminatum, F. compactum, F. semitectum, and F. merismoides. Fusarium oxysporum was the most abundant and diverse Fusarium species. Fusarium semitectum, F. compactum and F .merismoides had the least distribution being isolated from only one LUT. Fusarium beomiforme and F. acuminatum were recovered from irrigated farmlands only while F. verticillioides, F. proliferatum and F. acuminatum were restricted to disturbed lands only. The difference in abundance of Fusarium between the three LUTs was significant (P = 0.047) with irrigated lands having the highest abundance. Mwala block A had the highest abundance, richness and diversity of Fusarium. Lands with a higher intensity of disturbance had a higher abundance and richness of Fusarium than the less undisturbed lands. This may have severe implication on crop production as most species of Fusarium isolated are pathogenic. Sustainable ways of controlling these potential crop pathogens should be sought.

Impact of land use on occupancy and abundance of terrestrial mammals in the Drakensberg Midlands, South Africa

Better management and knowledge regarding the effect of land use intensification on mammal abundance and occupancy is crucial for species conservation. This is particularly true in dynamic forest-farmland mosaics subjected to rapid human-induced habitat alterations for agricultural practices. We conducted camera-trap surveys at 44 locations across farmland use gradients between October 2012 and January 2013. We estimated occupancy and relative abundance of 10 terrestrial mammals in response to farmland use in the Drakensberg Midlands, South Africa. Occupancy modelling revealed the importance of available forest and wetland to several mammals. Occupancy estimates for Leptailurus serval were lower in cropland than for Herpestes ichneumon, Atilax paludinosus and Potamochoerus larvatus. Occupancy of Leptailurus serval and Redunca rundinu increased with relative human abundance while the relationship was inverse for Hystrix cristata and Potamochoerus larvatus. Livestock-related activity influenced occupancy of Potamochoerus larvatus positively and Hystrix cristata negatively. Pesticide usage had a negative impact on detection of several mammals, and occupancy of Atilax paludinosus. Commercial plantation influenced occupancy of Tragelaphus scriptus and Potamochoerus larvatus positively. Plantation supported the abundance of five species positively. Wetland influenced relative abundance of Leptailurus serval positively. Pesticide use significantly decreased relative abundance of Leptailurus serval and Atilax paludinosus. Livestock and human relative abundance were positively associated with relative abundance of Leptailurus serval and Canis mesomelas and negatively for other species. Our models proved the sensitivity of some mammals towards the natural habitat loss due to agricultural practices while others appeared to be tolerant to such human-modified habitats. We suggest feasible management implications for conserving diverse mammalian assemblages in farmland mosaics.

Effect of land use intensification on specialization in plant–floral visitor interaction networks in the Pampas of Argentina

Land use intensification reduces natural areas and alters landscape heterogeneity diminishing species richness and changing ecosystem functionality. The analysis of interaction networks is a useful tool for estimating the degree of change experienced by ecosystems. Here, plant–floral visitor networks from fragments of grassland restored by agricultural activities discontinued over a long time were compared with networks from agriculturalized fragments nearby. The hypothesis evaluated was that land use intensification changes the structure of the original networks by modifying species richness and the network degree of specialization. The study was carried out at three sites located over a 700km transect across the provinces of Buenos Aires and La Pampa, Argentina. At each site, four fragments were selected (two restored and two agricultural). Five monthly samplings were taken between November and March along three consecutive years. Entomophilous plants and their floral visitors were identified and all plant–floral visitor interactions were recorded. With these data, richness of plants and visitors were calculated, interaction networks were constructed and the degree of specialization was calculated for each network. Land use intensification caused changes in the community composition and degree of specialization. When cropping was the predominant farming enterprise, richness of floral visitors and plants decreased as compared to restored fragments. When cattle production was the predominant land use, richness of floral visitors remained stable. However, at one of the sites plants richness was 48% higher in the grazed fragments than in those restored. In the agricultural fragments, the abundance of units of floral attraction due to exotic plants increased, but the visitation rates were the same as in the restored fragments. The networks in the agricultural fragments were more generalist than in restored fragments, in agreement with previous studies on the effect of land use intensification on natural systems.

Soil–vegetation interaction on slopes with bush encroachment in the central Alps – adapting slope stability measurements to shifting process domains

AbstractIn the European Alps many high mountain grasslands which were traditionally used for summer pasturing and haying have been abandoned during recent decades. Abandonment of mown or grazed grasslands causes a shift in vegetation composition and thus a change in landscape ecology and geomorphology. Alpine areas are very fragile ecosystems and are highly sensitive to changing environmental conditions, which can affect the geomorphic regime of these high energy environments. The effect of land use intensification on erosion rates is well documented, whereas the effect of land abandonment on erosion rates is still discussed controversially, particularly in relation to its short‐term and long‐term consequences. Generally, an established perennial vegetation cover improves the mechanical anchoring of the soil and the regulation of the soil water budget, including run‐off generation and erosion. However, changing vegetation composition affects many other above‐ and below‐ground properties like root density, diversity and geometry, soil structure, pore volume and acidity. Each combination of these properties can lead to a distinct scenario of dominating surface processes. The study of soil properties along a chronosequence of green alder (alnus viridis) encroachment on the Unteralptal in central Switzerland revealed that shrub encroachment changes soil and vegetation properties towards an increase of resistance to run‐off related erosion processes, but a decrease of slope stability against shallow landslides. Copyright © 2014 John Wiley & Sons, Ltd.

Nitrogen leaching losses from forests in New Zealand

Regional governing organisations in New Zealand are developing new policies to assess and manage the effects of land use intensification on water quality. Such policies require an assessment to be made of potential nitrogen leaching losses from different land uses, particularly where land use may be becoming more intensive. This review compiles the information on nitrogen concentrations and fluxes in stream and soil water drainage from indigenous and planted forests in New Zealand. Nitrogen concentrations and losses in streams from undisturbed indigenous forests and from planted forests established on land that has not been developed for agriculture are low. Nitrogen concentrations and losses in streams draining forests established on pasture land are commonly higher than in streams from indigenous forests and from forests planted on non-agricultural land, however most of the values for planted forests on pasture land were influenced by high volcanic nitrogen inputs. The impact of afforestation of pasture land on nitrogen leaching is described, as are the effects of planted forest management practices including fertilisation, harvesting and herbicide use. Nitrogen leaching is generally not greatly affected by forest management practices, however fertilisation can cause large leaching losses in coastal sand forests. While nitrogen leaching from planted forests is normally less than from other major land uses, there are key times during the forest rotation when nitrogen leaching may occur, particularly in forests planted on coastal sands or pasture land. It is advantageous to minimise leaching at these key stages to limit adverse effects on the environment and maintain nitrogen in the soil for the benefit of crop nutrition. Measures to reduce nitrogen leaching losses in forests are discussed, as are practices to minimise nitrogen leaching of forest plantings in catchments with high nitrogen soils, where forests may be planted specifically to reduce nitrogen loss to sensitive waterways.