Grassland Slope Research Articles

Runoff and erosion reduction benefits of vegetation during natural succession on fallow grassland slopes

Vegetation restoration is an effective and important measure for controlling soil erosion in arid and -arid regions. Both its aboveground and underground parts play a crucial role in controlling surface runoff and soil detachment on slopes. But how much the parts of vegetation contribute to the runoff and sediment reducing benefits of rill erosion on slopes is unclear. We used grassland slopes at four successional stages for simulated scouring experiments to observe how successional vegetation community structures, root characteristics, and soil structures contribute to erosion and sand production. Initial flow production time increased, and total runoff decreased. Under the scour intensities, the 11-year slope had the lowest flood peak and volume and the greatest runoff reduction benefit. The 25-year slope had the lowest sand peak and volume and the greatest sediment reduction benefit. As scour intensity increased, runoff reduction effect of vegetation at the successional stages decreased; the sediment reduction benefit remained high. PLS-PM analysis showed that the indirect effects of the aboveground and underground parts of vegetation on sand production were −0.364 and −0.439, respectively. Aboveground parts mainly embodied the regulation of runoff, in which stem count, humus mass, and biomass were the main factors affecting runoff and sand production. Underground parts mainly reflected their soil structure improvement, in which root volume density, root surface area density, and root mass density are the main explanatory variables. The direct effects of runoff and soil structure on slope rill erosion were 0.330 and −0.616, respectively, suggesting the stability of soil structure is the primary factor affecting the sand production, not erosion energy. The results provide a reference for scientific assessment of the key role of natural vegetation restoration in regional soil erosion control and the development of biological measures for soil and water conservation on the slopes of the Loess Plateau.

Effects of grassland vegetation roots on soil infiltration rate in Xiazangtan super large scale landslide distribution area in the upper reaches of the Yellow River, China

In order to study the infiltration characteristics of grassland soil in the super large scale landslides distribution area in the upper reaches of the Yellow River, this study selected the Xiazangtan super large scale distribution area in Jianzha County as the study area. Through experiments and numerical simulations, plant roots characteristics, soil physical properties and infiltration characteristics of naturally grazed grassland and enclosed grassland with different slope directions were compared and analyzed, and the influence of rainfall on seepage field and stability of the two grassland slopes were discussed. The results show that the highest soil moisture infiltration capacity (FIR) is found on the shady slope of the enclosed grassland (2.25), followed by the sunny slope of the enclosed grassland (1.23) and the shady slope of the naturally grazed grassland (−0.87). Correlation analysis show that soil water content, root dry weight density, total soil porosity, number of forks and root length are positively correlated with infiltration rate (P＜0.05), whereas soil dry density is negatively correlated with infiltration rate (P＜0.05). The results of stepwise regression analyses show that soil water content, total soil porosity, root length and number of forks are the main factors affecting soil infiltration capacity. And the ability of roots to increase soil infiltration by improving soil properties is higher than the effect of roots itself. After 60 min of simulated rainfall, the safety factors of the shady slopes of naturally grazed grassland and enclosed grassland are reduced by 29.56% and 19.63%, respectively, comparing to those before rainfall. Therefore, in this study, the roots play a crucial role in regulating soil infiltration and enhance slope stability by increasing soil water content, soil total porosity and shear strength while decreasing soil dry density. The results of this study provide theoretical evidence and practical guidance for the effective prevention and control of secondary geological disasters such as soil erosion and shallow landslide on the slope of river banks in the study area by using plant ecological measures.

Untangling the effects of climate variation and human interference on grassland dynamics in North China

AbstractClimatic and anthropogenic disturbances play pivotal roles in shaping the dynamics of grassland. Quantifying their impacts on grassland variation is essential to ensure sustainable grassland management. In this study, we employed the Thornthwaite Memorial and Carnegie–Ames–Stanford‐approach (CASA) models to investigate the spatiotemporal effects of these two variables on grassland variation in northern China from 2000 to 2016, using the net primary productivity (NPP) as a measure. Our findings reveal that approximately 25.92% of the grassland in northern China experienced degradation, while restored grasslands occupied 45% of the total grassland area. The average grassland actual NPP (ANPP) and human‐induced NPP decreased at rates of −0.60 and −5.62 gC m−2 a−1, respectively. Conversely, potential NPP exhibited an upward trend with an average increase of 2.27 gC m−2 a−1. Furthermore, grassland ANPP showed a projected increase in most parts of northern China. Climate change emerged as the primary driver for grassland restoration in Xinjiang, Qinghai, and Inner Mongolia, leading to an increase of 21582.79 Gg C in grassland NPP. In contrast, human activities were the dominant catalysts for grassland degradation, resulting in a reduction of 51932.3 Gg C in grassland NPP. Human‐induced grassland degradation was ubiquitous in northwest and northeast China. With the exception of slope grassland, climate change primarily influenced the restoration of most grassland types, while human activities were the primary cause of degradation. Our analysis indicated a strong correlation between temperature and grassland degradation, while precipitation played a pivotal role in grassland restoration in northern China. Human interference demonstrated both positive and negative impacts on grassland changes. In conclusion, the increase in precipitation and the implementation of ecological restoration plans have effectively promoted the restoration of grasslands in northern China.

Formation of new erosion-deposition patterns after farmland conversion: The major role of topography

The “Grain for Green” project has a profound impact on the allochthonous process of erosion sediment stripping and transportation, which in turn interferes with the distribution of erosion patterns. Therefore, understanding the changes in erosion patterns after farmland conversion and the factors controlling the new patterns of erosion distribution are essential for understanding the mechanism of slope erosion. Accordingly, this study investigated the formation of new erosion patterns and their control factors after farmland conversion by field sampling combined with nuclear tracing (137Cs) techniques, considering the “Grain for Green” project on the Loess Plateau as the study focus. We found that the implementation of the “Grain for Green” project can significantly reduce soil erosion intensity and create a new erosion-sediment source-sink pattern on the slope. The conversion of farmland to grassland can effectively store soil organic carbon as well as more environmentally sensitive active organic carbon, and the sorting effect on sediment particles is more obvious. Meanwhile, using stepwise regression, we found that the key limiting factor affecting the erosion intensity of farmland is the topography; the response of topographic factors to erosion is much higher than the physicochemical properties of the soil itself. By quantified the direct and interactive contributions to erosion intensity, we find that the direct contributions of silt and relief amplitude were 0.48 and 0.46 in farmland, while slope (0.16), Roughness (0.20) and Relief amplitude (0.33) in grassland, respectively. The interactive contributions were 0.06 and 0.30 in farmland and grassland. The conversion of farmland to grassland results in an increase in the factors that resist erosion and the factors interact more closely with each other to limit the occurrence of soil erosion. Our study provides scientific support for a deeper understanding of the slope erosion mechanism.

Effects of grazing on soil water recharge of rehabilitated grassland under natural rainfall on the Loess Pla-teau, Northwest China.

Rainfall is critical to the regulation of slope runoff and soil water recharge. Grazing affects land cover and soil structure, with consequence on slope runoff generation and soil water recharge. Little attention has been paid to the effects of rainfall on soil water recharge caused by grazing. In this study, we examined land covers and soil water contents under different grazing intensities (G1-G5: 2.2, 3.0, 4.2, 6.7, 16.7 sheep·hm-2) and no grazing sites (NG), aiming to analyze soil water recharge under natural rainfall conditions after grazing. The results showed that grazing exerted significant effects on vegetation and biocrust coverage. The vegetation coverage was decreased by 8.3%-16.4% under G1-G5 grazing, while the biocrust coverage was increased by 106.9% under G2 grazing compared to NG. The soil surface roughness under G1-G5 grazing was increased by 53.1%-152.5%, and the thickness of biocrust was decreased by 24.1% under G5. Soil wetting front velocity decreased with increasing rainfall intensity, and that of 0-5 cm layer under the G2 grazing intensity decreased by 60.0% to 83.3% under rainfall between 18.0 mm and 70.3 mm compared to NG. The effect of grazing on soil wetting front velocity was significantly related to biocrust coverage and soil bulk density of 0-5 cm soil layer. Generally, grazing did not affect soil water recharge rates of the slope grassland on the Loess Plateau. G2 grazing may prolong the migration time of soil water in the surface layer by increasing the coverage of cyanobacteria biocrusts, which may be beneficial to the restoration of soil microenvironment. Our results provided scientific basis for water management in the enclosure grassland of the Loess Plateau in the "post-conversion era".

Slope Runoff Process and Regulation Threshold under the Dual Effects of Rainfall and Vegetation in Loess Hilly and Gully Region

The rainfall in loess hilly and gully area is concentrated, and mostly comes in the form of rainstorms. The runoff on the slope caused by rainstorms is the main cause of serious soil and water loss in the loess hilly area, and the grassland vegetation has a good inhibitory effect on the runoff on the slope. Therefore, it is of great significance to reveal the role of grassland vegetation in the process of runoff generation, and the mechanisms for controlling soil erosion in this area. In this study, typical grassland slopes in hilly and gully regions of the loess plateau were taken as research objects. Through artificial rainfall in the field, the response rules of the slope rainfall-runoff process to different grass coverage were explored. The results show that: (1) With the increase in rainfall intensity, the inhibitory effect of grassland vegetation on slope runoff decreased, which was mainly reflected in the gradual decrease in runoff rate and runoff coefficient, and the time required to reach stability gradually shortened. (2) Under 60 mm/h rainfall intensity, the sensitivity of runoff coefficient to 31.5% of grass cover change is the lowest, and the cost performance of grass cover with 55% coverage is the highest. (3) Grass coverage inhibited slope runoff by changing the hydraulic characteristics of the slope, but this effect was only obvious in low rainfall intensity and early rainfall. Rainfall in the loess hilly area is characterized by intense rain. The regulating effect of grass cover on slope runoff is not particularly significant under high intensity rainfall. If only considering the regulation of grassland vegetation on slopes, more than 60% grassland coverage is more efficient in inhibiting slope runoff under medium and low intensity rainfall.

The distribution of soil C and N along the slope is regulated by vegetation type on the Loess Plateau

Soil carbon (C) and nitrogen (N) dynamics significantly contribute to greenhouse gas emissions from terrestrial ecosystems. However, uncertainty exists regarding the distribution of soil C and N along slopes of various vegetation types. To examine differences in soil C and N on the slope, this study selected three vegetation restoration types of grasslands (Artemisia sacrorum and Artemisia capillaris), shrublands (Caragana korshinskii) and forestlands (Robinia pseudoacacia) with five slope positions (top, upper, middle, lower, and foot). The results showed that the distribution of soil C and N were regulated by the vegetation type. Soil C and N stocks in grasslands and shrublands increased from the top to the foot slope, but this pattern was not observed in forestlands. The lowest coefficients of variation (CVs) of soil C and N along the slope were observed in the shrublands, with the highest soil C (17.0 Mg ha−1) and N (1.9 Mg ha−1) stocks on the entire slope. The primary factors influencing soil C and N distribution along the slope differed depending on the vegetation type. The primary factors influencing soil C and N in grassland slopes were pH and belowground biomass C/N, while those in shrublands and forestlands were pH, litter biomass C/N, and soil inorganic N (NH4+ and NO3–). Moreover, variations in mineral-associated organic C and mineral-associated organic N dominated the soil C and N dynamics. This study showed that vegetation types regulated the distribution of soil C and N throughout the slope. The shrublands were the optimal vegetation type on the entire slope, which can help in boosting soil C and N stocks in Central Loess Plateau.

Effects of multiple environmental factors and land use patterns on microplastic distribution in the topsoil of the Qinghai and Sichuan provinces of China

The ubiquity of microplastics (MPs) in the environment has raised wide concern; however, the distribution of MPs in the soils of remote areas at the Tibetan Plateau is poorly understood. In this study, 28 soil samples were collected from various land-use soil environments in the eastern part of the Tibetan Plateau, and MPs were isolated from soils by density separation and organic matter oxidation. The MP abundance identified in the samples ranged from 0 to 160 items/kg soil, and the majority shapes of MPs was film. μ-Raman spectroscopy was used to identify the MP composition and showed that polyethylene was the principal polymer. Moreover, MP concentrations decrease as the elevation increases, which most likely explains for the lack of plastic wastes produced from agricultural activities at high altitude areas. Furthermore, the MP composition among different terrain conditions at the Tibetan Plateau was presented, and the flat condition may be conducive to the accumulation of MPs compared with the slope condition. Most MP inputs in the study area were in the farmland soils (mainly plastic covering), and atmospheric deposition may have an important effect on MP distribution in grassland, especially in slope grasslands. This study provides evidence of MP distribution associated with environmental factors in the east area of the Tibetan Plateau, which promote the understanding of MPs driven by land-use patterns and topographic conditions in the plateau soil environment.

Evaluation of soil erosion rates in the hilly-gully region of the Loess Plateau in China in the past 60 years using global fallout plutonium

Soil erosion strongly threatens the sustainability of natural ecosystems over the world, especially in the Loess Plateau in China, where has suffered severe soil erosion along with extensive land reclamation and deforestation from the 1950s to the 1970s. The large-scale vegetation restoration practices are supposed to be effective for reducing soil erosion, but the quantitative evaluation of soil erosion, particularly the response of land utilization types and vegetation coverage changes on the mitigation of soil degradation is still not well understood. Plutonium isotopes in soil cores collected from the forest, grassland slope, apple orchard, and cornfield in a typical watershed in the hilly-gully region of the Loess Plateau were analyzed to estimate the soil erosion rates in different land-use types. Widespread soil erosion at rates of 5.1–40.5 t/ha/yr. in this region in the past six decades was estimated. The influences of human activities in the past decades, type of land utilization, level of vegetation coverage, and terrain on the soil erosion in this region were discussed, and the accumulation of the eroded soil in the study sites was explored. Different types of land utilization showed diverse soil erosion rates (forest (slight) < grassland (light) < apple orchard ≈ cornfield (moderate)), indicating that natural vegetation rehabilitation, particularly restoring forest with high vegetation coverage is a practically effective conservation measure for soil erosion control; convex micro-topography on sloping fields is critical in alleviating soil loss by depositing eroded soil.

Investigating causal factors of shallow landslides in grassland regions of Switzerland

Abstract. Mountainous grassland slopes can be severely affected by soil erosion, among which shallow landslides are a crucial process, indicating instability of slopes. We determine the locations of shallow landslides across different sites to better understand regional differences and to identify their triggering causal factors. Ten sites across Switzerland located in the Alps (eight sites), in foothill regions (one site) and the Jura Mountains (one site) were selected for statistical evaluations. For the shallow-landslide inventory, we used aerial images (0.25 m) with a deep learning approach (U-Net) to map the locations of eroded sites. We used logistic regression with a group lasso variable selection method to identify important explanatory variables for predicting the mapped shallow landslides. The set of variables consists of traditional susceptibility modelling factors and climate-related factors to represent local as well as cross-regional conditions. This set of explanatory variables (predictors) are used to develop individual-site models (local evaluation) as well as an all-in-one model (cross-regional evaluation) using all shallow-landslide points simultaneously. While the local conditions of the 10 sites lead to different variable selections, consistently slope and aspect were selected as the essential explanatory variables of shallow-landslide susceptibility. Accuracy scores range between 70.2 % and 79.8 % for individual site models. The all-in-one model confirms these findings by selecting slope, aspect and roughness as the most important explanatory variables (accuracy = 72.3 %). Our findings suggest that traditional susceptibility variables describing geomorphological and geological conditions yield satisfactory results for all tested regions. However, for two sites with lower model accuracy, important processes may be under-represented with the available explanatory variables. The regression models for sites with an east–west-oriented valley axis performed slightly better than models for north–south-oriented valleys, which may be due to the influence of exposition-related processes. Additionally, model performance is higher for alpine sites, suggesting that core explanatory variables are understood for these areas.

Diverse responses of grassland dynamics to climatic and anthropogenic factors across the different time scale in China

An accurate quantification in the separation of the relative contributions of climate change and human activities on grassland dynamics is crucial for controlling grassland degradation. Here, we investigated grassland dynamics in China by using net primary productivity (NPP) as an evaluation indicator from 1982 to 2016. We calculated the human-induced grassland NPP (HNPP) by subtracting the potential NPP (PNPP) from the actual NPP (ANPP) to distinguish the climatic and anthropogenic effects on grassland NPP changes across different time scales. Results indicated that the change in grassland ANPP resulted from different dominated factors in the two periods of 1982–1999 and 2000–2016. An obvious increase of grassland ANPP was observed from 1982 to 1999, which mainly due to a slight increasing trend in grassland PNPP driven by a humid-warm climate and a slight decrease in grassland HNPP from weak human activities. An overall increase in ANPP (69.576%) over its decrease portion (30.424%) was observed from 1982 to 1999. Human activities-induced ANPP increase mainly occurred in Shaanxi, Qinghai and Gansu Provinces and Tibet Autonomous Region for the grassland types of Alpine subalpine meadow, Meadow and Slope grassland. Climate-dominated decrease mainly occurred in Shanxi, Shaanxi and Heilongjiang, especially for Plain and Slope grassland. However, an overall decreasing trend of grassland ANPP was observed from 2000 to 2016, mainly attributed to a decreasing trend in grassland HNPP by human intervention and a warm-dry climate-induced negative effect on grassland growth. Overall, the grassland underwent a decrease than increase in ANPP (58.826% vs 41.174%) during 2000–2016; the contributions of climate factors to grassland ANPP increase was relatively greater than that of human factors in Xinjiang, Qinghai and Inner Mongolia. Human activities-dominated ANPP decrease occupied 23.913%, obviously higher than the decrease dominated by climate change (9.248%), which mainly occurred in Alpine subalpine meadow, Desert grassland and Alpine subalpine grassland. Overall, these findings seem to demonstrate that there are great differences in the temporal and spatial effects of climate change and human activities on different regions and different grassland types in China before and after 1999, and contribute to providing location guidance for future grassland restoration. Meanwhile, this study is expected to improve the understanding of the driving mechanisms of grassland dynamics, and provide support for scientifically evaluating and adjusting ecological restoration policies in China.

Evaluating the dynamics of grassland net primary productivity in response to climate change in China

Net primary productivity (NPP) has been considered as a direct indicator to access the terrestrial primary production. However, considerable uncertainties remain toward the response mechanism of NPP to climate change across annual and seasonal scales, especially for grassland ecosystems. In this study, the spatiotemporal dynamics of grassland NPP and its prominent climate-controlling factor were evaluated based on the CASA model and ground-based meteorological data across annual and seasonal scales in China from 1982 to 2016. Results showed that the annual mean grassland NPP was 294.58 gC·m−2·a−1 over the 35 years; the largest annual mean NPP was observed in Alpine sub-alpine meadow (235.72 ± 13.21 gC·m−2·a−1), while the smallest annual mean NPP value occurred in Desert grassland (97.27 ± 9.64 gC·m−2·a−1). Moreover, the multiyear mean grassland NPP showed a decreasing trend from the southeast to the northwest spatially. Temporally, grassland NPP exhibited a significant increasing trend (slope = 2.4 gC·m−2·a−1; p < 0.0001) over the whole study period; an abrupt change point across the grassland NPP time series was observed in 1999. Specially, 66.34% of the grassland area showed an increasing trend in NPP, and the areas with a significant increasing trend were concentrated in Qinghai-Tibet Plateau and the northern area of Xinjiang. Further climate factor analysis with NPP indicated that NPP positively correlated with precipitation and negatively correlated with temperature for the whole grassland area. In particular, the temperature was a dominant driver in NPP variations for Alpine sub-alpine meadow, Slope grassland and Alpine sub-alpine grassland, while precipitation controlled the most in NPP variations for Plain grassland and Desert grassland. The accumulation of grassland NPP in spring and autumn benefits from the increase in temperature, and precipitation promoted the accumulated NPP in summer and winter.

Response of Grassland Slope Erosion to Vegetation Characteristics

The grassland erosion research on steep slopes is the basis and difficulty, which was studied by artificial rainfall experiments. Results showed the following: (1) Decreasing the stream power (Rω) is main way to decrease the interrill erosion. (2) The regulation effect of grass on stream power and soil erodibility are mainly achieved by grass cover and root volume, separately. (3) The contribution rates of root volume (RV), and soil bulk density (SD) to RK is 73.61%-97.94, and 0.04%-0.22%.

Field studies on the influence of rainfall intensity, vegetation cover and slope length on soil moisture infiltration on typical watersheds of the Loess Plateau, China

AbstractSoil moisture is a key process in the hydrological cycle. During ecological restoration of the Loess Plateau, soil moisture status has undergone important changes, and infiltration of soil moisture during precipitation events is a key link affecting water distribution. Our study aims to quantify the effects of vegetation cover, rainfall intensity and slope length on total infiltration and the spatial variation of water flow. Infiltration data from the upper, middle and lower slopes of a bare slope, a natural grassland and an artificial shrub grassland were obtained using a simulated rainfall experiment. The angle of the study slope was 15° and rainfall intensity was set at 60, 90, 120, 150, and 180 mm/hr. The effect these factors have on soil moisture infiltration was quantified using main effect analysis. Our results indicate that the average infiltration depth (ID) of a bare slope, a grassland slope and an artificial shrub grassland slope was 46.7–73.3, 60–80, and 60–93.3 cm, respectively, and average soil moisture storage increment was 3.5–5.7, 5.0–9.4, and 5.7–10.2 mm under different rainfall intensities, respectively. Heavy rainfall intensity and vegetation cover reduced the difference of soil infiltration in the 0–40 cm soil layer, and rainfall intensity increased surface infiltration differences on the bare slope, the grassland slope and the artificial shrub grassland slope. Infiltration was dominated by rainfall intensity, accounting for 63.03–88.92%. As rainfall continued, the contribution of rainfall intensity to infiltration gradually decreased, and the contribution of vegetation cover and slope length to infiltration increased. The interactive contribution was: rainfall intensity * vegetation cover &gt; vegetation cover * slope length &gt; rainfall * slope length. In the grass and shrub grass slopes, lateral flow was found at a depth of 23–37 cm when the slope length was 5–10 m, this being related to the difference in soil infiltration capacity between different soil layers formed by the spatial cross‐connection of roots.

Shallow erosion on grassland slopes in the European Alps – Geomorphological classification, spatio-temporal analysis, and understanding snow and vegetation impacts

Erosion with the subsequent loss of soil and soil fertility is one of the urgent environmental problems worldwide. On grassland slopes from the montane to the alpine elevation zones of the European Alps, shallow erosion is a widespread and regionally increasing phenomenon. This group of mechanical denudation processes includes shallow landslides and nival abrasion (i.e., by snow gliding and avalanches), which are displacing patches of vegetation, soil and unconsolidated material. The resulting bare ground areas as well as the dislocated material are susceptible to further transport by water, snow, or wind. Our review summarizes the current knowledge on the main geomorphological processes for Alpine grassland erosion, namely shallow landslides and abrasion by snow movements as well as combinations of both processes. We shortly discuss the basic and variable controlling factors and further present a comprehensive approach for identifying and classifying shallow erosion phenomena and processes. In this context, the possibilities, limitations, and challenges for identification, classification and analysis of these processes by remote sensing are discussed in detail. Furthermore, the article focuses particularly on the role of snow-related processes, the relationship of erosion and vegetation, and the re-stabilization of affected areas by plants. Finally, we outline the discussion on the impact of land-use and climate change on these shallow erosion processes and identify the main research gaps that should be bridged in order to both better understand and deal with these erosion types on Alpine slopes.

Ефективність поверхневого поліпшення гірських схилових луків Карпат

Goal. To determine peculiarities of formation of phytocenoses, productivity, chemical composition, nutritive value, and energy content of grass forages depending on the options for surface improvement of slope meadows of the mountain forest belt of the Carpathians at different modes of use. Methods. General scientific methods (hypotheses, induction and deduction, analogy, generalization) — to select the work program, and special (field, laboratory, mathematical-statistical, calculation) — to conduct researches and their generalization. Results. Surface improvement of cereals and grasses (with 28% share of low-value in feed terms Nardus stricta) low-productive (1.39 t/ha of dry weight) slope grasslands of mountain forest belt of the Carpathians improves their species composition and chemical composition of feed increases the productivity of the land. Share of sowed cereals or legumes increases to 34 – 46%. Under the hay regime the highest efficiency as to the output from 1 ha of dry mass was fixed for reseeding mixtures of grasses on the background of N60P30K60 (4.33 t), for the multi-mow regime — reseeding of white clover on the background of P30K60 (3,71 t), that was, respectively, by 14 and 106% more than in the variants without reseeding, and by 146 and 167% more than in the variants without improvement. Among measures of surface improvement influencing forage quality by chemical composition, increasing the content of crude protein, was the introduction of N60P30K60 or 15 t/ha of manure at multi-mow use, and reseeding of white clover — on the background P30K60. Regardless of the measures of surface improvement the highest content of crude protein, the best energy content, and nutritional value of grass fodder were fixed for multi-mow (simulated pasture) mode of use than for hay-mowing. Conclusions. Surface improvement of meadows of the mountain forest belt of the Carpathians with natural grass by operating factors of the improvement of species composition and quality of grass fodder, as well as an increase of their productivity, is the annual entering of N60P30K60 or 15 t/ha of manure, or N60P30K60 + reseeding of grass mixture (Lolium pratense and Phleum pratense) for hay use, or P30K60 + reseeding of white clover for multi-mow use. The best positive effect ensures the application of mineral fertilizers in combination with the reseeding of perennial grasses.

Importance of market-oriented research for rice production in Tanzania. A review

Rice consumption in Tanzania has greatly increased since the 1960s; it is predicted to continue to increase owing to urbanization and changes in consumer preferences from traditional staples to rice. In this study, we review rice agroecology, its value chain, and price determinants, and the history of and challenges to rice research in Tanzania. Our main findings are as follows: (1) rice cultivation can be classified into three major categories: irrigated lowland, rainfed lowland, and rainfed upland. Irrigated lowland is then subdivided into the permanent river, seasonal water, dam, and groundwater subtypes, while rainfed lowland is subdivided into flood plain (fields near rivers), catchment (fields on gentle slope in catchment basin), narrow valley (fields on flat narrow valley bottoms), and plain grassland (fields on gentle slope in savannah grassland). (2) Various stakeholders are involved in production, storage, milling, wholesale, retail, and trade at local, urban, regional, and national levels, resulting in higher market prices of local rice compared to imported rice. However, consumers still choose local rice consisting of traditional cultivar because of its distinct taste and aroma. (3) Improving yield potential through the introduction of foreign elite lines/cultivars has been a major research target; however, farmers have been rejecting most of the new cultivars due to poor grain quality. (4) An integrated set of agronomic management techniques is effective in increasing the yield of traditional cultivars under irrigated lowland. Technical package effectiveness has yet to be tested in all subtypes of rainfed lowland. We propose a new research framework for rice production in Tanzania that is greatly oriented toward meeting consumer demands. In the framework, both breeding and agronomy should have specific research targets for each agroecosystem. Furthermore, genetic resources of traditional cultivars should be fully explored. This study shows the importance of multidisciplinary approach in improving rice production in Tanzania.

Characteristics of landslides in forests and grasslands triggered by the 2016 Kumamoto earthquake

AbstractWe examined the characteristics of landslides triggered by the 2016 Kumamoto earthquake (Mw = 7.0: focal depth=10.0 km) in forests and grasslands within two affected watersheds (Tokosegawa: 6.9 km2 and Nigorigawa: 6.1 km2) in southwestern Japan. We identified 190 landslides using aerial photographs and analyzed their sizes by geographic information system (GIS). Field investigations were conducted to obtain landslide depth, volume and residual sediment for 38 selected landslides (21 in forests and 17 in grasslands). The minimum area of detected landslides in grasslands (400 m2) was smaller than in forests (1000 m2), probably because of reduced detectability of landslides under tree cover. The ratio of total area occupied by landslides for a given range of slope gradient in the watersheds increased from 3.2% on gentle grassland slopes (10–15°) to 15.5% on steep (&gt;45°) slopes, whereas the maximum landslide‐area ratio in forest sites (7.4%) occurred on relatively gentle slopes (25–30°). Estimated landslide volume ranged from 27 to 9622 m3, based on mean depth of each landslide measured around individual landslide scars. Moreover, the volumetric ratio of landslide deposit volume to total landslide volume exceeded 100% for 48% of the landslides within forests and 35% of the landslides within grasslands. Our findings show that land cover had extensive and recognizable effects on the characteristics of landslides and resulting in‐channel sediment accumulations. Resetting sediment dynamics after earthquakes associated with different land cover distributions needs to be considered within watersheds. © 2019 John Wiley &amp; Sons, Ltd.

Determination of the surface-mat effect of grassland slopes as a measure for shallow slope stability

Herbaceous vegetation is an important factor for control of shallow slope failure. While roots of herbaceous vegetation rarely cross potential shear planes, they increase soil cohesion in the top soil and create a surface-mat effect. The surface-mat is a dense layer of laterally interwoven plant fibers, which create considerable horizontal tensile strength of the top soil. Through redistributing impacting forces from unstable towards stable slope areas, the surface-mat can prevent shallow slope failure.We present a method for measuring the horizontal tensile strength of the top soil, which estimates the surface-mat effect. On four montane grassland slopes in Northern Italy, grass sods were cut out from the soil and their tensile strength was measured with a traction machine. The scope of this study is to investigate potential soil physical and biological factors influencing slope stability. Generally, the surface-mat effect decreased with soil depth. Bulk density, soil moisture and aboveground vegetation parameters showed no correlation with the surface-mat effect. Root length density was weakly correlated. Soil water saturation had a marginally significant negative correlation (p < 0.1) when root length density was low, but no correlation when root concentration was high. Vegetation type and management influenced the surface-mat effect. We conclude that the low influence of wet conditions on the surface-mat effect makes it a promising strategy for shallow erosion control. In addition, our findings suggest, that specific vegetation management can increase the surface-mat effect.

Disentangling the effects of host resources, local, and landscape variables on the occurrence pattern of the dusky large blue butterfly (Phengaris nausithous) in upland grasslands

Determining the effects of local and landscape drivers on endangered species and predicting potential suitable habitats for their persistence is crucial for effective conservation management. Here, we applied a multi-scale approach to disentangle the effects of host resources, local, and landscape variables on the occurrence pattern of Phengaris (= Maculinea) nausithous in semi-natural upland grasslands. Our approach comprised the assessment of host parameters (plant cover, density, height, flower heads density, ant nest density, ant colony size), local grassland management (pasture, meadow), site conditions (area, shape, terrain attributes), and landscape variables (landscape composition, connectivity). We used ensemble of small models based on bivariate generalized linear models for explaining and predicting the butterfly occurrence pattern. Bivariate models revealed that host ant nest density, plant cover and height, local grassland management type (pasture), slope and eastness, landscape forest cover and grassland connectivity had a positive effect on the occurrence of P. nausithous (average explained deviance 20.5%). Host ant density, host plant cover, and local grassland management were the most influential factors on the ensemble predictions. The presence of P. nausithous in upland grasslands is not only determined by host resources, but also by local and landscape factors. Such factors proved to be relevant for identifying and predicting suitable grassland sites for this endangered species. Consequently, we recommend that conservation actions should include a landscape perspective to promote connectivity by facilitating coherent grazing networks enabling dispersal between semi-natural upland grasslands and thus species persistence.