Grassland Project Research Articles

Changes of Chinese forest‐grassland ecotone in geographical scope and landscape structure from 1990 to 2020

Forest–grassland ecotone (FGE) has essential ecological and economic value. Unfortunately, it is impacted greatly by environmental changes and anthropogenic disturbance, and is considered one of the most severely threatened biomes in China. To protect Chinese FGE, identifying its exact boundary and exploring its landscape structure dynamic are badly needed, especially on nationwide scale at one‐year temporal resolution. Here, we mapped the annual FGE distribution of China from 1990 to 2020, investigated its changing trends of area, location and landscape patterns, and revealed the underlying driving factors. Our results showed that FGE area over the 31 years totaled 1 011 870 km2, covering about 10.54% of China's land. The FGE area first increased from 1990 and peaked in 1999, and then kept decreasing until 2020. The FGE gravity center has moved accumulatively 590.15 km over the 31 years, with the net moving distance of 228.76 km southwestward. From 1990 to 2020, forest area increased continuously while grassland and cropland area decreased, but these three landscape types had been dominating the FGE. The increase in forest area was largely converted from grassland. The decline in grassland mainly resulted from its conversion into cropland and forest. Meanwhile, the conversion of cropland to grassland supplemented grassland loss to a certain extent. At landscape level, the total area with decreased fragmentation is larger than that with increased fragmentation. Returning Farmland to Grassland Project and land reclamation were primary drivers for changes of fragmentation in the northern and middle part of the FGE, while temperature and precipitation were primary drivers in southern part. Our results will improve the understanding into the dynamic trends of distribution and pattern of FGE at nationwide scale, and thus help to optimize the designing of ecological projects and protective schemes for FGE as a unique and integral biome.

Short-term restoration effects of ecological projects detected using the turning point method in the Three River Headwater Region, China.

The Three River Headwater Region (TRHR) is an important river source area providing important ecological functions. Decades ago, climate change and human activities severely degraded the ecosystem in the TRHR. To restore vegetation, a series of ecological projects have been implemented since 1989. Using net primary productivity (NPP) data from 1988 to 2012, a sequential Mann-Kendall trend test (SQ-MK) method was applied to identify the turning point of vegetation NPP. This approach was able to represent the critical response time of the vegetation to important disturbances. A 3-year time window was set after the implementation of one ecological project to detect and analyze its short-term effects. The ecological projects included the Yangtze River Basin Shelterbelt System Construction Project (YRCP), the TRHR Nature Reserve Construction Project (TNR), the Returning Grazing Land to Grassland Project (RGLGP), and the first phase of the Ecological Conservation and Restoration Project of the TRHR (ECRP). Our results showed that the vegetation in the TRHR responded positively to restoration: 89% of pixels showed an increasing trend and 54% of pixels underwent an abrupt change. The accelerated growth type accounted for the highest proportion among all types of detected turning points. In the ECRP's window, the positive turns rose rapidly, from 41% in 2005 to 86% in 2008, and it showed the most balanced restoration effects across grasslands. The alpine meadow and montane meadow restoration was largely influenced by the ECRP and the RGLGP (both >40%). The alpine steppe restoration was mainly attributed to the ECRP (68%). On the county scale, the positive turns in Yushu at the source of the Yangtze River mainly benefited from the RGLGP (56%), while the positive turns in Maduo at the source of the Yellow River benefited from the ECRP (77%). Nangqian, Tanggula and Zaduo County were still in need of intervention for restoration (< 3%). The results of the study can enhance our understanding of the spatio-temporal distribution of the short-term ecological benefits of different ecological projects, thus provide a scientific and timely reference for future planning and adjustment of the conservation and restoration projects.

Effect of ecological restoration projects on carbon footprint in a grassland ecosystem on the Qinghai‐Tibet Plateau

AbstractInvestigating the cost‐effective and low‐carbon pathways for grassland ecological restoration projects is vital to achieving carbon neutrality and Sustainable Development Goals. To fill the gap of incorporating ecological and socioeconomic systems of ecological restoration projects, this study established a cost‐benefit evaluation framework that integrated the carbon footprint based on life cycle assessment and a carbon price measurement model based on the Slack‐Based Measure‐Data Envelopment Analysis model. Taking a ‘Returning Grazing Land to Grassland Project’ on the Qinghai‐Tibet Plateau as a case, this study quantified the carbon footprint of three different ecological measurements, including fences construction (released 107 kgCO2‐eq·hm−2 and absorbed 322 kgCO2‐eq·hm−2), degenerated grassland improvement (released 1080 kgCO2‐eq·hm−2 and absorbed 580 kgCO2‐eq·hm−2) and artificial grassland planting (released 2540 kgCO2‐eq·hm−2 and absorbed 6540 kgCO2‐eq·hm−2). Raw material production was the largest emitter. In addition, we calculated the carbon price in the grassland ecosystem by the carbon price measurement model, at 1.06 yuan·kgCO2‐eq−1 on average during 2011–2018. In the cost‐benefit analysis, the total carbon sequestration benefits (8.90 × 106 yuan) outweighed the total carbon emission costs (4.26 × 106 yuan). Optimizing the usage and transportation of building materials and the application of fertilizer can benefit carbon emission mitigation and enhancement of carbon sequestration capacity in grassland. This study provided a theoretical basis for ecological restoration projects and grassland carbon pricing mechanisms aiming for sustainable management.

Synergistic Change and Driving Mechanisms of Hydrological Processes and Ecosystem Quality in a Typical Arid and Semi-Arid Inland River Basin, China

Global warming and human activities are complicating the spatial and temporal relationships between basin hydrologic processes and ecosystem quality (EQ), especially in arid and semi-arid regions. Knowledge of the synergy between hydrological processes and ecosystems in arid and semi-arid zones is an effective measure to achieve ecologically sustainable development. In this study, the inland river basin Ulagai River Basin (URB), a typical arid and semi-arid region in Northern China, was used as the study area; based on an improved hydrological model and remote-sensing and in situ measured data, this URB-focused study analyzed the spatial and temporal characteristics of hydrological process factors, such as precipitation, evapotranspiration (ET), surface runoff, lateral flow, groundwater recharge, and EQ and the synergistic relationships between them. It was found that, barring snowmelt, the hydrological process factors such as precipitation, ET, surface runoff, lateral flow, and groundwater recharge had a rising trend in the URB, since the 20th century. The rate of change was higher in the downstream areas when compared with what it was in the upstream and midstream areas. The multi-year average of EQ in the basin is 53.66, which is at a medium level and has an overall improving trend, accounting for 95.14% of the total area, mainly in the upstream, downstream southern, and downstream northern areas of the basin. The change in relationship between the hydrological process factors and EQ was found to have a highly synergistic effect. Temporally, EQ was consistent with the interannual trends of precipitation, surface runoff, lateral flow, and groundwater recharge. The correlation between the hydrological process factors and EQ was found to be higher than 0.7 during the study period. Spatially, the hydrological process factors had a synergistic relationship with EQ from strong to weak upstream, midstream, and downstream, respectively. In addition, ecosystem improvements were accelerated by government initiatives such as the policy of Returning Grazing Land to Grassland Project, which has played an important role in promoting soil and water conservation and EQ. This study provides theoretical support for understanding the relationship between hydrological processes and ecological evolution in arid and semi-arid regions, and it also provides new ideas for related research.

Dynamic responses of ecological vulnerability to land cover shifts over the Yellow river Basin, China

Ecological protection and high-quality development of the Yellow River Basin (YRB) aroused profound concerns from China Central Government and is now a major national strategy. However, ecological degradation is still a pressing issue for fluvial ecological conservation. Recent years witnessed widespread implementation of ecological projects such as “Grain to Green Project” (GGP) and “Return Grazing land to Grassland Project” (RGGP) which aim to improve the ecological environment of the YRB. While dynamic responses of ecological vulnerability to land cover changes are poorly understood under climate changes and human activities. Here we use the “exposure-sensitivity-resilience” sliding ecological vulnerability evaluation framework to quantify the Ecological Vulnerability Index (EVI) and scrutinize dynamic responses of EVI to land use changes over the YRB. We find slight ecological degradation with increased EVI across the YRB from 1986 to 2013, and the highest ecological vulnerability in summer. Meanwhile, regions with degraded ecological status are found mainly along the main stream of the YRB. Besides, the gravity centers of EVI cluster mainly in the central and western parts of the YRB and correspond to four ecological conditions, i.e. unstable ecological condition, moderate ecological variability, ecological restoration, and moderate ecological variability. Furthermore, we identify a higher ecological degradation rate of croplands than non-croplands, while evidently lower ecological degradation rate of grasslands than non-grasslands. The GGP and RGGP projects have improved the ecological environment of the YRB, but have not reversed the degrading tendency of the ecological environment across the YRB.

Study on the Role of Returning Grazing to Grassland Project in Restoring Grassland Ecological Function in Manasi County

Study on the Role of Returning Grazing to Grassland Project in Restoring Grassland Ecological Function in Manasi County

Drought reduces the effectiveness of ecological projects: Perspectives from the inter-annual variability of vegetation index

To alleviate grassland degradation and improve ecosystem functions, the Chinese government has implemented some ecological projects since 2004 across the Tibetan Plateau, such as ‘Return Grazing Land to Grassland Project’ and the ‘Compensation and Rewards to Herders for Natural Grassland Conservation’. Meanwhile, the frequency and intensity of drought events have strengthened in this plateau. However, how grasslands respond to these projects and drought remains controversial. Here, taking the northern Tibetan Plateau (NTP) as the study area, we first quantified the spatiotemporal changes in the annual maximum grassland NDVI (NDVImax) after the implementation of the ecological projects (2005–2015). Then, we assessed the effects of drought (Standardized Precipitation-Evapotranspiration Index, SPEI) and ecological projects on the dynamics of NDVImax. The results showed that (1) the grazing intensity decreased significantly across the NTP after the start of ecological projects, but grassland NDVImax did not increase as expected. Statistically, 53.7% of grasslands showed a decreasing NDVImax, of which 5.7% had a significant decrease (P < 0.05), mainly in the central and eastern NTP. (2) NDVImax positively correlated with SPEI at the pixel, county, and regional scales, suggesting that drought was the driving force for the decreasing NDVImax. The severe and extreme drought events in 2015 contributed to 9.4% and 17.7% reduction of grassland NDVImax, respectively. (3) The residual analysis demonstrated that there were 4.4% of the grasslands experienced human-induced degradation. However, on the whole, the effects of ecological projects on vegetation changes of the NTP were positive. Our findings suggested that the positive effects of the ecological projects on vegetation growth were relatively mitigated or offset by drought. Thus, we question the validity of evaluating the effectiveness of ecological projects only according to the trend of vegetation productivity derived from remote-sensing based vegetation index.

Public Participation in Biodiversity Conservation of Chinese Nature Reserves

Based on the Chinese National Biodiversity Strategy and Action Plan, we identified the biodiversity conservation public affairs. This study analyzed the importance of public participation in public affairs, and identified the main participants. The survey results show that the public participates in the importance of public affairs such as the implementation of the ‘grazing and returning grassland project’, ‘supervising the illegal activities of biodiversity’, ‘local traditional knowledge survey’, and ‘protection of folk biodiversity around the nature reserve’. Cognition is higher than 4.0. The percentage of cases in the public that support the implementation of various matters is ≥50%, to ensure the scope of participation of the participants; the highest value of 11.02% of the top four is higher than the percentage of cases, to encourage the scope of participation.

Assessment of climate change adaptation measures on the income of herders in a pastoral region

Climate change, characterized with global warming, created severe potential threat to natural ecosystems and sustainable development of human society. Effective adaptation measures to mitigate the negative effects of climate change would affect both the ecological environment and the social economy. In this paper, we built a positive mathematical programming model to assess adaptation measures, which were divided into four aspects, to tackle climate change based on the survey data obtained from seven counties and 32 villages in the region of Hulun Buir. The results showed that, livestock breeding improvement had a positive impact on grass yield, livestock number and especially herder's household income (the most in Ewenki (11.7%) and the least in Xinzuo (2.3%)); artificial grassland project could lead to an average growth rate of 8.4% in household income among the four counties; current policies and going out for work could also increase household income, however, not a sustainable choice. To realize sustainable development in the context of global climate change, the vitality of sustainable development of animal husbandry under the premise of protecting ecological environment should be enhanced. For example, improving the safety and quality of livestock products through influencing livestock breeding, processing technology and high quality forage, and ensuring adequate forage supplement through artificial grassland project.

Monitoring the Grassland Change in the Qinghai-Tibetan Plateau: A Case Study on Aba County

Located on the southeast edge of the Qinghai-Tibetan plateau, Aba County is the core area of the Returning Grazing Land to Grassland Project (RGLGP) on the plateau. For the purpose of monitoring the grassland change before and after the grassland protection project in Aba County, Landsat images acquired in 1996, 2003 and 2009 were analyzed. Using Spectral Mixture Analysis (SMA) model, sub-pixel fractions of land cover components were obtained: bright vegetation (BV), dark vegetation (DV), bright soil (BS), dark soil (DS) and water. Fraction images present the distribution and proportions of typical land cover components in this study. Fractions BV and BS were chosen as two indicators for grassland degradation. Thereafter, Change Vector Analysis (CVA) model was applied on the two indicators. After the performance of the CVA model, change results which consisted of both grassland degradation and vegetation re-growth were obtained, showing the change patterns of grassland degradation and vegetation re-growing in Aba County between two gaps: from 1996 to 2003 (before the RGLGP) and from 2003 to 2009 (after the RGLGP). The change patterns of grassland degradation and vegetation re-growing can effectively assist in the development of environmental restoration measures and in the RGLGP plans for the Qinghai-Tibetan plateau.

A method to the impact assessment of the returning grazing land to grassland project on regional eco-environmental vulnerability

The Chinese government has conducted the Returning Grazing Land to Grassland Project (RGLGP) across large portions of grasslands from western China since 2003. In order to explore and understand the impact in the grassland's eco-environment during the RGLGP, we utilized Projection Pursuit Model (PPM) and Geographic Information System (GIS) to develop a spatial assessment model to examine the ecological vulnerability of the grassland. Our results include five indications: (1) it is practical to apply the spatial PPM on ecological vulnerability assessment for the grassland. This methodology avoids creating an artificial hypothesis, thereby providing objective results that successfully execute a multi-index assessment process and analysis under non-linear systems in eco-environments; (2) the spatial PPM is not only capable of evaluating regional eco-environmental vulnerability in a quantitative way, but also can quantitatively demonstrate the degree of effect in each evaluation index for regional eco-environmental vulnerability; (3) the eco-environment of the Xianshui River Basin falls into the medium range level. The normalized difference vegetation index (NDVI) and land use cover and change (LUCC) crucially influence the Xianshui River Basin's eco-environmental vulnerability. Generally, in the Xianshui River Basin, regional eco-environmental conditions improved during 2000 and 2010. The RGLGP positively affected NDVI and LUCC structure, thereby promoting the enhancement of the regional eco-environment; (4) the Xianshui River Basin divides its ecological vulnerability across different levels; therefore our study investigates three ecological regions and proposes specific suggestions for each in order to assist in eco-environmental protection and rehabilitation; and lastly that (5) the spatial PPM established by this study has the potential to be applied on all types of grassland eco-environmental vulnerability assessments under the RGLGP and under the similar conditions in the Returning Agriculture Land to Forest Project (RALFP). However, when establishing an eco-environmental vulnerability assessment model, it is necessary to choose suitable evaluation indexes in accordance with regional eco-environmental characteristics.

Plant diversity effects on pollinating and herbivorous insects can be linked to plant stoichiometry

Changes in plant diversity have consequences for higher trophic levels, e.g., higher plant diversity can enhance the reproduction and fitness of plant-associated insects. This response of higher trophic levels potentially depends on diversity-related changes in both resource quantity (abundance) and quality (nutritional content). The availability of elemental nutrients in plant resources is one aspect of nutritional quality, but has rarely been addressed as a pathway relating plant diversity to associated insects. Using the experimental plant diversity gradient of a large biodiversity grassland project, the Jena-Experiment, we analysed the %C, %N and %P and the molar ratios of those elements (C:N, C:P and N:P) in a pollinating bee, Chelostoma distinctum, and an herbivorous grasshopper, Chorthippus parallelus, reared on plots of different plant diversity. Insects showed higher content of C, N and P (% dry mass), and lower C:N and C:P ratios than plants. C:N ratios were significantly higher in grasshoppers than in bees and higher in females than in males of both species. Increasing plant species richness increased the C:N ratio of male bees and female grasshoppers. In both groups, stoichiometry was positively related to plant stoichiometry (male bees: C:P and N:P; grasshoppers: C:N and N:P). Path analysis revealed that diversity-driven changes in plant elemental composition can have consequences for abundance and chemical composition of higher trophic levels, with different responses of the two functional groups.

Changes in Spatiotemporal Land Use Patterns in Selected Hydrogeomorphic Areas of China and the USA

Differences exist in land use/cover pattern and its change between the P. R. China and the USA. In order to describe those differences, land use changes in representative regions were quantitatively analyzed and compared. Xiamen City, Changzhutan region and Liupan Mountains regions were selected to represent three different hydrogeomorphic areas of eastern, central, and western China, respectively, while the Goodwin Creek Experimental Watershed (GCEW) located in the north-central part of Mississippi in the bluff hills just east of the Mississippi River floodplain was chosen in the USA. By integrating historical Landsat TM imagery and geographical information system data, the spatiotemporal land use dynamics and conversion of land use in China and the USA between 1980 and 2010 were explored and compared. Results indicated an urban sprawl in eastern and central China, which encroached upon large amount of cropland, forest land and grassland. On the other hand, western China reclaimed cropland from grassland, forest land, which led to severe soil erosion between 1990 and 2000. Goodwin Creek Watershed of the USA converted 73.3% of the lost cropland into forest land, pasture and idle land, which accounted for about 90% in 2010. Further, counter-urbanization occurs in the GCEW due to favorable eco-environment for living. Compared with the land dynamic degree of the GCEW, eastern China is greater than it; western China is smaller than it while central China is almost equal to it. And the land use intensity index of GCEW is smaller than that of China all these years. Eastern China advocated ecological civilization in 2007 to meet the serious challenges of sustainable development. Western China started the Return of Land from Farming to Forestry and Grassland Project in 2000. The Changzhutan region in central China is served as the resource-saving and environment-friendly community in 2007, which will be favorable for the sustainable land utilization and protection of ecology. From the eco-environmental view, China might use the experience of USA for future reference.

三江源牧户参与草地生态保护的意愿

Sanjiangyuan Region is the headstream area of three main rivers in Asia,i. e. Yangtze River,Yellow River,and Lancangjiang River( Mekong). It is an important ecological barrier of the local and regional environmental security and sustainable development,not only for China but also for the southeastern Asian,In recent decades,however,grasslands in Sanjiangyuan Region were seriously disturbed or destroyed by both global climate change and human activities,which led to sharp decrease of nourishing capacity of source water and serious environmental problems of the lower reaches. Since 2005,Chinese government began to implement a series of activities,e. g. ‘Returning Grazing Land to Grassland Project' and‘Ecological Migration Project',in Sanjiangyuan Region to alleviate the situation of grassland degradation,and gradually restore and protect the ecological environment. The success of such projects in Sanjiangyuan Region depends largely on local herdsman's active response,support and participation because herdsmen' s ecological protective cognition and behavior response to grassland degradation is the key to the effective implementation of ecological protection and herdsmen' s participation willingness directly influences the accomplishment efficiency and sustainability of ecological protection. In this paper we surveyed 283 Tibetan herder household and tried to explore the key influential factors of their participation willness with the binary logistic model analysis. Several conclusions can be drawn from this investigation:( 1) About 87 percent of herdsmen have realized the externality of ecological protection,but only 70 percent of herdsmen passively participated in ecological protection based on bounded rationality with government domination.( 2) Factors like government' s protection efforts,herdsmen's cognitive level of ecological protection externalities,livelihood level,the degree of contact with the outside world and career opportunities have positive affects on herdsmen's participation willingness in ecological protection,while factors like age,the distance to the towns and regional extreme climate have negative impacts on the ecological protection willness,These factors' influence coefficient are 2. 22、3. 98、1. 93、2. 26、1. 48、-1. 63、-2. 43 and-0. 92.( 3)The livelihood level,grassland degradation perception and externalities cognitive are the most important factors of herdsmen's participation willingness in ecological protection,The probability of Herdsmen' s participation willness is not only the passive response to the consideration of their own profit and the unknown risk but also the individual choices under the influence of ecological protection education and input of local governments.( 4) In order to realize regional ecological protection,the wellbeings of local herdsmen and ecological and economical sustainable development,we should basically solve the present livelihood of the herdsmen who living on the local grasslands in the Sanjiangyuan Region and emphasize on the environmental education in their religious and local livings,formulate the conservation strategies and management planning of grasslands with an emphasis on improving both human livelihood and the environmental protection. We should also build a better ecological compensation strategy which lets herdsmen enjoy the externalities effectiveness of ecological protection and then take an active part in ecological protections of Sanjiangyuan Region.

Root Ecological Niche Index and Root Distribution Characteristics of Artificial Phytocommunities in Rehabilitated Fields

In the implementation phase of the Conversion of Cropland to Forest and Grassland (CCFG) project in China, it is important, from a scientific point of view, to recognize phytocommunities’ characteristics, species compatibility, and ecological function. The ecological niche that roots occupy, their abundance and distribution, and the factors that affect them must be acknowledged. Following the methodology of community ecology, the total root mass of a phytocommunity is measured as cubic volume. Root biomass, length, and the number of roots in every diameter class, for each soil layer and for each plant species, are regarded as observation variables. In the first instance therefore, a new method to calculate the root ecological niche index (RENI) is proposed, embracing the entire phytocommunity of plantations. Using the new method, the roots of phytocommunities in Datong County, Qinghai Province (one of the counties selected for the national CCFG experiment), are dealt with in this paper. The results show that most of the vertical distributions of plant roots belong to the type wherein the roots are concentrated in the topsoil layer (0–20 cm), far more than those in the lower soil layers. The RENI of phytocommunities is higher than that of pure stands or monocultures. The distribution of RENI by root diameter can be divided into four types: J-type, inverse J-type, recumbent S-type, and U-type. RENI is positively correlated with the wet biomass of aboveground level stems, branches, and plant leaves, and with the species richness of phytocommunities. Although the RENIs of plantations in rehabilitated fields are a little lower than those of natural forests, they are higher than those of cultivated crops. The RENIs of three community types (Picea crassifolia + Hippophae rhamnoides ssp. sinensis, H. rhamnoides ssp. sinensis, and P. crassifolia) in rehabilitated fields benefit greatly from the restoration project. The implementation of the CCFG project is important for the increase in RENI and the multiple functions of plant roots.

Temperate grassland project in South Australia

Temperate grassland project in South Australia