Productivity Of Natural Vegetation Research Articles

Assessment of the impact of the degrees of degradation of pastures on the desert alluvial meadow soils of the village of Zhambyl

The article considers the features of the structure, chemical composition and physical properties of alluvial meadow soils of the pastures of the desert zone of the village of Zhambyl. These soils were formed in the sandy and sandy alluvial deposits of the Shu River. The soils of the floodplain of the river are mainly characterized by high fertility potential. But one of the factors limiting the growth of their potential fertility is the salinity of the soil image and the degree of degradation of pastures. The assessment of soil and plant indicators of pasture degradation in the Zhambyl base area is given. Previously, the area was irrigated and fertilized, and now it is used as a pasture. But due to overgrazing, the alluvial meadow soils of the desert near the village of Zhambyl and the vegetation on their surface have undergone anthropogenic degradation. Studies have shown that as the degradation of pastures increases, the thickness of the humus layer (A+B1) thinns, and the content of humus and nutrients in the soil decreases. The species and botanical composition of plants is undergoing changes, reducing their protection of the soil surface and the productivity of pasture feed. The results obtained are the theoretical foundations for the development of measures to increase soil fertility and productivity of natural vegetation on degraded pastures in the desert zone.

Seed Productivity of Natural Vegetation at UoD Campus as Affected by Mowing Frequency

Since 2000, there has been a noticeable increase of overgrazing in Kurdistan region of Iraq, particularly in Duhok governorate, as a result of the widespread movement of livestock (sheep and goats) by animal breeders from the middle of Iraq, particularly from the Nineveh steppes, to graze in Kurdistan region constantly from early spring to late summer. In addition to local livestock, tens of thousands of animals contributed to increased grazing frequencies, overgrazing, and degradation of rangelands in countless and extensive patches. The occasional fires, droughts, and overgrazing over the past three decades have all contributed significantly to that same degradation of rangeland in Iraq, specifically in the Kurdistan region, by depleting the soil seed bank, which is the fundamental source of natural vegetation restoration. As a result, this study was carried out in the spring of 2016 in Duhok Governorate to ascertain the impact of mowing frequencies (as consequences of grazing) on the seeds productivity of natural vegetation cover (total seeds, grasses seeds, legumes seeds, and other seeds productivity), and to determine the appropriate mowing frequencies to improve vegetation cover and make rangelands more sustainable. Four treatments —no mowing, once, twice, and three times— with five replications in (RCBD) experiment were implemented. The findings showed that the productivity of all seeds declined as mowing was repeated (once, twice, and three times), with the exception of (other seeds group), whose productivity improved when mowed twice in comparison to once. Natural vegetation cover can be utilized (mowed) or grazed even twice if the plant growth season has not yet exceeded the middle stage.

Limited role of soil texture in mediating natural vegetation response to rainfall anomalies

Evidence suggests that the response of rainfed crops to dry or wet years is modulated by soil texture. This is a central tenet for certain agronomic operations in water-limited regions that rely on spatial distribution of soil texture for guiding precision agriculture. In contrast, natural vegetation in climatic equilibrium evolves to form a dynamic assemblage of traits and species adapted to local climatic conditions, primarily precipitation in water-limited regions. For undisturbed landscapes, we hypothesize that natural vegetation responds to rainfall anomalies irrespectively of local soil texture whereas rainfed crops are expected to respond to texture-mediated plant available water. Earth system models (ESMs) often quantify vegetation response to drought and water stress based on traditional agronomic concepts despite fundamental differences in composition and traits of natural vegetation and crops. We seek to test the hypothesis above at local and regional scales to differentiate natural vegetation and rainfed crops response to rainfall anomalies across soil types and better link them to water and carbon cycles. We employed field observations and remote sensing data to systematically examine the response of natural and rainfed cropped vegetation across biomes and scales. At local scales (field to ∼0.1 km), we used crop yields from literature data and natural vegetation productivity as gross primary productivity (GPP) from adjacent FLUXNET sites. At regional scales (∼102 km), we rely exclusively on remote-sensing-based GPP. Results confirm a lack of response of natural vegetation productivity to soil texture across biomes and rainfall anomalies at all scales. In contrast, crop yields at field scale exhibit correlation with soil texture in dry years (in agreement with conventional agronomic practices). These results support the hypothesis that natural vegetation is decoupled from soil texture, whereas rainfed crops retain dependency on soil texture in dry years. However, the observed correlation of crops with soil texture becomes obscured at larger scales by spatial variation of topography, rainfall, and uncertainty in soil texture and GPP values. The study provides new insights into what natural vegetation’s climatic equilibrium might mean and reveals the role of scale in expressing such sensitivities in ESMs.

Fresh litter acts as a substantial phosphorus source of plant species appearing in primary succession on volcanic ash soil

Plants have difficulty absorbing phosphorus from volcanic ash soils owing to the adsorption of phosphorus by aluminum and iron in the soils. Thus, on volcanic ash soils, the phosphorus source for natural vegetation is expected to be organic matter, however, there is a lack of experimental evidence regarding this occurrence. Here, we studied the effect of organic matter on plant growth of some species that occur in primary successions of volcanic ash soil ecosystems, based on growth experiments and chemical analyses. We found that a large amount of inorganic phosphorus (but only a limited amount of inorganic nitrogen) is leached from fresh leaf litter of the pioneer spices Fallopia japonica at the initial stage of litter decomposition. Phosphorus from the fresh litter specifically activated the growth of subsequently invading nitrogen-fixing alder when immature volcanic soil was used for cultivation. In contrast, old organic matter in mature soil was merely a minor source of phosphorus. These results suggest that fresh litter of F. japonica is essential for growth of nitrogen-fixing alder because the litter supplies phosphorus. We consider that rapid phosphorus cycles in fresh litter-plant systems underlie the productivity of natural vegetation even in mature ecosystems established on volcanic ash soils.

Effect of Climate Change on Climate-induced Potential Productivity of Natural Vegetation in Heilongjiang

Effect of Climate Change on Climate-induced Potential Productivity of Natural Vegetation in Heilongjiang

Some thoughts on the biogeochemical cycling of potassium in terrestrial ecosystems

Potassium presents a conundrum for biogeochemists. Potassium is cycled wastefully at the plant level, but it appears to be conserved in the nutrient budgets of entire ecosystems, where it sometimes limits net primary productivity. An increasing demand for K fertilizer may accompany the expansion of agriculture into highly weathered tropical soils, where limited supplies of K may control the distribution and productivity of natural vegetation. However, the molar ratios of 4.6 for N/K in herbaceous plants, 17.3 in current global fertilizer applications, and 0.33 in the commodity price of fertilizer suggest that N is vastly overused and K is vastly over-priced in modern agriculture.

Long-term effects of climatic and hydrological variation on natural vegetation production and characteristics in a semiarid watershed: The northern Negev, Israel

Climate models for semiarid and arid regions predict increasing average temperatures and reduced amounts of total annual rainfall. This warming and drying trend could have critical, adverse effects on natural vegetation activity and survival in arid and semiarid zones. We investigated the long-term effects of climate change and surface-runoff variations on the production of natural vegetation in a dry, undisturbed, first-order watershed in the northern Negev, Israel. Vegetation dynamics were estimated by normalized difference vegetation index. Yearly annual vegetation cover varied greatly during the monitoring period (2000−2013), but a significant positive regression was found with annual rainfall and runoff amounts, suggesting a strong relationship between annual vegetation dynamics and rainfall amount in a given year. A significant positive linear regression was found between annual ET0 values and year of measurement (1994–2013), with no corresponding decrease in vegetation condition. Surface runoff in the watershed affected the vegetation's water source. Large variation in annual runoff amounts was observed for 1994–2011, averaging 22.3 and 9 mm for the first (2000–2006) and second (2007–2013) vegetation-monitoring subperiods, respectively. Perennial vegetation was less sensitive to drought years than annual vegetation, likely due to differences in water-source availability. Perennials also benefited from the arrival of nutrients, organic matter, and fertile soil flowing with the surface runoff and eroded soil into their growing area.

The dynamics of soil moisture balance components and their relations with the productivity of natural vegetation in an arid region of northwestern China

Precipitation and groundwater are important water source in soil and are vital for the survival and growth of natural vegetation in arid regions. Analyses on the dynamics of soil water balance components and their relations with plant growth are usually restricted by the lack of continuous measurement of deep soil moisture at a local or regional scale. By monitoring monthly soil water contents in the 0–3 m soil profiles, we analyzed the contributions of precipitation and groundwater to the growth of natural vegetation in an arid region of northwestern China from 2011 to 2013. The results showed that the 0–3 m desert soil and the 0–1.8 m grassland soil exhibited moderate spatial variability in the soil water contents (θ). Temporal variability of spatial mean θ decreased with depth in the soils of the desert and grassland. The profile-average of spatial mean θ maintained 0.11 cm3 cm−3 in the desert and varied from 0.37 to 0.44 cm3 cm−3 in the grassland over time. The evapotranspiration after calibration gave accurate estimation of water available for plants (402.0 and 532.4 mm year−1 in the desert and grassland, respectively). Annual mean net primary productivity of the grassland (233.4 g C m−2) was 3.8 times that of the desert. Water exchange in the desert soils was dominated by recharge into the 0–1 m soil from layers deeper than 3 m, with annual mean value of 303.4 mm. Recharge alternated with discharge events in grassland soils. Annual mean recharge and discharge amounts were 494.2 and 50.1 mm for the 0–1 m layer and 641.1 and 228.9 mm for the 0–3 m soil profile, respectively. Water supply into soil was totally consumed by evapotranspiration. Precipitation use efficiency increased when groundwater level became shallow (0.04 and 0.11 g C m−2 mm−1 in the desert and grassland, respectively). Groundwater supplied about 75% of water requirement for natural vegetation, and its use efficiencies were 0.12 and 0.33 g C m−2 mm−1 in the desert and grassland, respectively. Seedling of herbaceous species with trichomes at the interspace and under the canopy of shrubs can guarantee great utilization of precipitation in the desert. Transplanting of shrubs with large amounts of shallow lateral roots and shrubs with deep rooting systems can effectively utilize the shallow and deep soil water or groundwater. Reducing the irrigation consumption of groundwater and controlling the expansion of oasis cropland are foremost to guarantee the ecological water requirement and maintain the sustainability of natural ecosystems. Keep or increase current area and layout of the grassland may benefit the water cycle and carbon sequestration in the arid regions.

Economy-pollution nexus model of cities at river basin scale based on multi-agent simulation: A conceptual framework

Rapid urbanization greatly accelerated economic and social development in key river basins of China, but also created numerous environmental problems, from the local to the global scale, including increased air and water pollution and decreased water supply, local climate alteration and increased energy demands, as well as a major reduction in natural vegetation production and carbon storage/sequestration. The correlation analysis between urban economy and pollution transfer among cities in river basins has become one of highlights in current researches. Based on the Netlogo software platform, this paper establishes a correlation model among cities in the same river basin from the point of view of multi-agent simulation. Moreover, it assesses the relationship between urban economic development and pollution transfer from three aspects: network concentration; network size; link intensity. The influence of network concentration and link intensity on the total economic size and pollution transfer of the entire river basin is similar. In parallel, the influence of network size on the two modelled variables shows an opposite trend, demonstrating that network size has a greater impact on the city. By comparing the trend of economic size and pollution transfer with the change of network concentration in the context of different economic transfer thresholds, results demonstrate that, with the increase of network concentration, the influence becomes more pronounced. Appropriate error analysis was used to validate the simulation results. In particular, according to it, the error between 10-time and 20-time steps simulation is less than 10%. Consequently, the simulation results are valid. This paper, deepening the research on the correlation among river basin cities, lays the foundation for further research on the directional transmission of the economy and pollution.

Assessment of Ecological Water Discharge from Volgograd Dam in the Volga River Downstream Area, Russia

Water release from reservoirs to improve the environmental condition of floodplains is of great relevance. Thus, the aim of this study was to propose a method to assess ecological drawdowns from power station reservoirs. An example of its application for the Volga River downstream area is presented. The efficiency of the quantitative assessment of ecological water discharge from the reservoir of the Volgograd hydroelectric power station is analyzed and discussed in relation to the improvement of the environmental condition of the Volga-Akhtuba floodplain, which covers an area of 6.1 × 103 km2. It is shown that a decrease of spring-summer flooding worsened significantly its environmental condition, i.e. biodiversity decreased by 2-3 times, soil fertility declined by 25%, floodplain relief deformation occurred and the productivity of semi-migratory fish decreased by more than 3 times. The economic benefit accumulated from river flow regulation was » 300 × 106 USD in 2011, and economic damage related to the deterioration of the ecological situation was estimated at » 400 × 106 USD in the same year. It is impossible to fully satisfy the needs of all the participants in the water-economic complex in the assessment of the environmental flows. Priority should be given to environmental requirements. It was found that assessing the ecological drawdowns confirmed the possibility of improving the floodplain environment by reducing between 15-20% the electricity production. This would allow conserving the region’s biodiversity and increasing about 60-80% the natural vegetation productivity. This will prevent deformation of the floodplain relief and doubling the productivity of semi-migratory fish.

Estimación de biomasa y cobertura aérea usando radiometría e imágenes digitales a nivel de campo en pastizales y matorrales.

Para analizar la relación entre las reflectancias de la vegetación obtenidas mediante el uso de sensores ópticos con la cobertura aérea y producción de biomasa de la misma, en el 2007 se realizó una campaña de muestreo en los estados de Jalisco, Zacatecas, Coahuila, Durango, Querétaro y Estado de México, usando radiómetros multiespectrales en condiciones de campo. Adicionalmente a la toma de datos radiométricos se tomaron fotografías digitales para la estimación de la cobertura aérea usando métodos de clasif icación supervisada. En aproximadamente el 15% de los puntos de medición se realizaron muestreos de biomasa aérea. Con el esquema de muestreo utilizado se analizaron las relaciones entre el índice de vegetación (NDVIcp, IVCP y β) con la biomasa y cobertura aérea, estableciendo una relación entre estas variables biofísicas. La estimación de la biomasa y cobertura vegetal de una manera más rápida, como se menciona, permite hacer estimaciones sobre la condición, tendencia o producción de la vegetación natural en pastizales y matorrales, haciendo posible la toma de decisiones sobre el manejo de la misma de manera más ef iciente y expedita. El modelo utilizado para obtener la producción de biomasa en pastizal y matorral, a través de datos radiométricos y cobertura vegetal, considerando que los datos procesados corresponden a la fase lineal de crecimiento de la etapa vegetativa, da resultados óptimos para este tipo de vegetación (R2 = 0.98).

Impacts of land use on climate and ecosystem productivity over the Amazon and the South American continent

The Amazon basin is characterized by a strong interplay between the atmosphere and vegetation. Anthropogenic land use and land cover change (LULCC) affects vegetation and the exchange of energy and water with the atmosphere. Here we have assessed potential LULCC impacts on climate and natural vegetation dynamics over South America with a regional Earth system model that also accounts for vegetation dynamics. The biophysical and biogeochemical impacts from LULCC were addressed with two simulations over the CORDEX-South America domain. The results show that LULCC imposes local and remote influences on South American climate. These include significant local warming over the LULCC-affected area, changes in circulation patterns over the Amazon basin during the dry season, and an intensified hydrological cycle over much of the LULCC-affected area during the wet season. These changes affect the natural vegetation productivity which shows contrasting and significant changes between northwestern (around 10% increase) and southeastern (up to 10% decrease) parts of the Amazon basin caused by mesoscale circulation changes during the dry season, and increased productivity in parts of the LULCC-affected areas. We conclude that ongoing deforestation around the fringes of the Amazon could impact pristine forest by changing mesoscale circulation patterns, amplifying the degradation of natural vegetation caused by direct, local impacts of land use activities.

The mutual importance of anthropogenically and climate‐induced changes in global vegetation cover for future land carbon emissions in the MPI‐ESM CMIP5 simulations

AbstractBased on the Max Planck Institute Earth System Model simulations for the Coupled Model Intercomparison Project Phase 5 and on simulations with the submodel Cbalone we disentangle the influence of natural and anthropogenic vegetation changes on land carbon emissions for the years 1850 until 2300. According to our simulations, climate‐induced changes in distribution and productivity of natural vegetation strongly mitigates future carbon (C) emissions from anthropogenic land‐use and land cover change (LULCC). Depending on the assumed scenario, the accumulated carbon emissions until the year 2100 are reduced between 22 and 49% and until 2300 between 45 and 261%. The carbon storage due to climate‐induced vegetation change is generally stronger under the presence of LULCC. This is because the natural vegetation change can reestablish highly productive extratropical forests that are lost due to LULCC. After stopping anthropogenic vegetation changes in the year 2100 the refilling of depleted C pools on formerly transformed land takes (dependent on the scenario) time scales of centuries.

Recovery of natural vegetation and ecological functions of pasture ecosystems in arid steppes of the Cisural region

The results are presented that have been obtained in studies on changes in the species composition, geobotanical characteristics, and productivity of natural vegetation in arid steppes of the Cisural region during the past few decades (1977–2012). Consideration is given to the significance of the soil factor in the processes of transformation of zonal vegetation. The increasing role of arid steppes as a natural barrier to desertification is demonstrated.

Detecting land use-water quality relationships from the viewpoint of ecological restoration in an urban area

Urbanization increases impervious area, generates pollution and transforms the configuration, composition and context of land covers and thus has direct or indirect impacts on aquatic systems. Detecting land use-water quality relationships is of significance for both urban sustainable development and environmental risk management. We first selected suitable landscape metrics at landscape and class levels as well as productivity as land use indicators; second, we integrated ten water quality indicators into a comprehensive pollution index (CPI) that serves as the primary water quality indicator for measuring the effects of diffusive pollution in an urban area; finally, taking water quality indicators as dependent variables and land use indicators as independent variables, we detected land use-water quality relationships using both ordinary least squares (OLS) and geographically weighted regression (GWR) models. The main findings are (1) the CPI is a good water quality indicator for detecting land use-water quality relationships and the performance of the GWR model is superior to that of the OLS model and (2) landscape metrics have potential for predicting water quality; however, improving the productivity of natural vegetation is a more tangible and reliable way to promote water resources restoration than rearranging the configuration of land use types.

Modern climate changes of biosphere productivity in Russia and adjacent countries

The tendencies in the response of the annual plant productivity and soil organic carbon content in Russia and adjacent countries to climate changes, observed for the last 30 years, are analyzed. It is shown that the changes observed in the air temperature and atmospheric precipitation promote an increase in natural vegetation productivity over approximately 88% of the territory. Minor centers of decreased productivity of ecosystems are found in the central and northeastern districts of European Russia, in the south of Eastern Siberia, and in the Far East. A tendency to climatogenic growth of the soil organic carbon content is detected almost everywhere in the forest, forest-steppe, and steppe Russian zones.

The impact of vegetation restoration on erosion-induced sediment yield in the middle Yellow River and management prospect

According to the characteristics of water and erosion environments of different natural zones on the Loess Plateau, this paper studies changes of vegetation types, distribution boundaries of forest and grass as well as restoration capacity of vegetation in different natural zones in the middle Yellow River. The annual precipitation of 530 mm is the critical annual precipitation for forest and grass distribution in the middle Yellow River. Among the zonal and azonal envi-ronmental factors affecting watershed sediment yield, the intermediate diameter D 50 (mm) of suspended load and forest coverage ( V , %) play the leading role. Of them the effect weight of forest coverage ( V , %) on catchments sediment yield is only 3.4% less than the role of the in-termediate diameter ( D 50 , mm), they are almost the same. To effectively control soil erosion in semiarid, especially in hilly-gullied areas and make sediment transport modulus reduce to less than 6000 t/km 2 , it is rather difficult by merely relying on natural restoration of forest. In the process of cultivated land conversion into forest land and grassland, measures suiting local conditions should be adopted in tree species selection and artificial afforestation (grass planting) based on management with biological measures for slopeland and engineering measures for hilly-gullied areas, so that watershed forest coverage in key counties can reach at least over 30%. Compared with the standard period of precipitation prior to the 1960s, with the decrease of an-nual precipitation at various periods, plant productivities decline to different degrees under natural conditions. The main reason accountable for the low survival rate of new seedlings and grass over years is due to precipitation decrease. In light with regression models of annual pre-cipitation and natural vegetation productivities, it is possible to obtain estimated values of wa-tershed natural vegetation productivity and eco-water consumption needed for the restoration to the standard period respectively for the present time or arbitrary period since the 1970s, thus providing a scientific basis for forest and grassland restoration in the middle Yellow River and the management prospect.

Estimated Biomass and Productivity of Natural Vegetation on the Tibetan Plateau

Estimated Biomass and Productivity of Natural Vegetation on the Tibetan Plateau

The potential, variety, and nutrient content of natural vegetation as feedstuffs grown under cashewnut plantation

Ruminant production is limited by the quality, the sufficiency and the continuation of feed supply, especially during the dry season. The objective of the study was to find out the potency, type and quality of natural vegetation grown under cashewnut plantation. The study was carried out by exploration of existing natural vegetation resources in cashewnut plantation area. Results showed that native pasture growing under cashewnut plantation area comprised of dry-tolerant grasses and legumes, such as Setaria sp ., Themeda sp ., Calopogonium mucunoides , and Desmodium sp . The fresh yield and the dry matter production of natural vegetation grown under less than eight years old of cashewnut plantation was lower compared to those grown under cashewnut plantation of more than eight years old. This may be due to shading by the tree crop, which is known to reduce the photosynthetically active radiation reaching the ground of vegetation. It seems that, light is the critical factor affecting the growth of vegetation underneath tree canopies. Carrying capacity of native forages grown under cashewnut plantation was only 0.5 animal unit of ruminant/ha/year. Key words: Natural vegetation, cashewnut plantation, carrying capacity

Why tree-crop interactions in agroforestry appear at odds with tree-grass interactions in tropical savannahs

This paper describes recent research findings on resource sharing between trees and crops in the semiarid tropics and attempts to reconcile this information with current knowledge of the interactions between savannah trees and understorey vegetation by examining agroforestry systems from the perspective of succession. In general, productivity of natural vegetation under savannah trees increases as rainfall decreases, while the opposite occurs in agroforestry. One explanation is that in the savannah, the beneficial effects of microclimatic improvements (e.g. lower temperatures and evaporation losses) are greater in more xeric environments. Mature savannah trees have a high proportion of woody above-ground structure compared to foliage, so that the amount of water 'saved' (largely by reduction in soil evaporation) is greater than water 'lost' through transpiration by trees. By contrast, in agroforestry practices such as alley cropping where tree density is high, any beneficial effects of the trees on microclimate are negated by reductions in soil moisture due to increasing interception losses and tree transpira- tion. While investment in woody structure can improve the water economy beneath agroforestry trees, it inevitably reduces the growth rate of the trees and thus increases the time required for improved understorey productivity. Therefore, agroforesters prefer trees with more direct and immediate benefits to farmers. The greatest opportunity for simultaneous agroforestry practices is therefore to fill niches within the landscape where resources are currently under-utilised by crops. In this way, agroforestry can mimic the large scale patch dynamics and successional progression of a natural ecosystem.