Afforestation plays an important role in soil carbon storage and water balance. However, there is a lack of information on deep soil carbon and water storage. The study investigates the effect of returning farmland to the forest on soil carbon accumulation and soil water consumption in 20-m deep soil profile in the hilly and gully region of the Chinese Loess Plateau. Four sampling sites were selected: Platycladus orientalis (Linn.) Franco forest (PO: oriental arborvitae), Pinus tabulaeformis Carr. Forest (PT: southern Chinese pine), apple orchard (AO) and farmland (FL, as a control). Soil organic carbon (SOC) and soil inorganic carbon (SIC) content were measured in 50-cm sampling intervals of 20-m soil profiles, as well as the associated factors (e.g. soil water content). The mean SOC content of PT was the highest in the 1–5 m layer and that of FL was the lowest (p < 0.05). Compared with FL, the SOC storages of PO, PT and AO increased by 2.20, 6.33 and 0.90 kg m−2 (p > 0.05), respectively, in the whole profile. The SIC content was relatively uniform throughout the profile at all land-use types and SIC storage was 9–10 times higher than SOC storage. The soil water storage of PO, PT and AO was significantly different from that of FL with a decrease of 1169.32, 1161.60 and 1139.63 mm, respectively. After the 36-yrs implementation of the “Grain for Green” Project, SOC in 20 m soil profiles increased as a water depletion cost compared with FL. Further investigation is still needed to understand the deep soil water and carbon interactions regarding ecological restoration sustainability in the Northern Loess Plateau.
Country: China
China
Ecological infrastructure refers to naturally functioning ecosystems that deliver valuable services to people, such as filtered water and disaster risk reduction. With natural resources becoming scarcer, there is a growing interest in reinvesting in naturally functioning ecosystems in the form of ecological infrastructure, with the assumption that ecological infrastructure complements engineered infrastructure. In many low- and middle-income countries, ecological infrastructure interventions are seen as a key strategy to simultaneously alleviate poverty and improve ecosystem functioning. However, the socio-economic outcomes of ecological infrastructure investments remain poorly documented. We address this knowledge gap by synthesizing research (n = 53 cases) that analyses how ecological infrastructure investments affect ten different socio-economic dimensions, such as income and food security in low- and middle-income countries. We find that ecological infrastructure investments primarily lead to positive outcomes for short-term income and natural capital, whereas positive outcomes for other socio-economic dimensions are less frequently observed. Cases with a high degree of participant involvement in the early implementation of ecological infrastructure investments are significantly more likely to capture positive outcomes across a variety of socio-economic dimensions. Analogously, cases spanning multiple methods – rather than adopting either a qualitative or a quantitative approach – report positive outcomes across more dimensions.
The production of sufficient food for an increasing global population while conserving natural capital is a major challenge to humanity. Tree-mediated ecosystem services are recognized as key features of more sustainable agroecosystems but the strategic management of tree attributes for ecosystem service provision is poorly understood. Six agroforestry and tree cover transition studies, spanning tropical/subtropical forest zones in three continents, were synthesized to assess the contribution of tree cover to the conservation of biodiversity and ecosystem services. Loss of native earthworm populations resulted in 76% lower soil macroporosity when shade trees were absent in coffee agriculture. Increased tree cover contributed to 53% increase in tea crop yield, maintained 93% of crop pollinators found in the natural forest and, in combination with nearby forest fragments, contributed to as much as 86% lower incidence for coffee berry borer. In certain contexts, shade trees contributed to negative effects resulting from increases in abundance of white stem borer and lacebugs and resulted in 60% reduction of endangered tree species compared to forest. Managing trees for ecosystem services requires understanding which tree species to include and how to manage them for different socio-ecological contexts. This knowledge needs to be shared and translated into viable options with farming communities.
To address pasture degradation on the Tibetan Plateau, the Chinese government has launched the ecological restoration project Grazing Withdrawal Program (GWP) since 2004. However, few studies have evaluated the impact of the GWP on grassland recovery. Based on monthly remote-sensed vegetation index and meteorological data from 2000 to 2012, we assessed the dynamics of annual net primary productivity (NPP) in alpine grasslands and quantified the effects of climatic factors and anthropogenic activities on NPP change by using the climate-driven NPP and the Carnegie-Ames-Stanford Approach (CASA) models. We found that there existed two distinct periods with an accelerating trend in NPP increase before and after 2004. The area percentage of NPP change induced by climatic factors increased from 41.55% to 83.75%, but that percentage caused by human activities decreased from 58.45% to 16.25% in the two periods of 2000–2004 and 2004–2012. Between 2000 and 2004, overgrazing reduced the positive effect of climate change on NPP variability, resulting in wide-scale grassland degradation. Between 2004 and 2012, grassland ecosystems gradually recovered from heavy grazing pressure, and the human induced degradation was reversed after the implementation of the GWP. Thus, temperature and solar radiation became dominant factors in driving NPP change. Our results indicated that the GWP produces a significant positive effect on the restoration of alpine grasslands by controlling livestock numbers and decreasing grazing intensity. This study provides an objective assessment of restoration actuation on grassland ecosystems, having important implications for demonstrating the effectiveness of the GWP on grassland restoration on the Tibetan Plateau.
Under a warming climate, frequent drought and water scarcity in northern China have severely disrupted agricultural production and posed a substantial threat to farmers’ livelihoods. Based on first-hand data collected through in-depth interviews with local managers and farmer households, this study evaluated the effectiveness of rural land use management in mitigating drought risk, ensuring food security and improving farmers’ livelihoods. Our findings indicate that a) reforestation on low-yield cropland not only can improve the ecoenvironment but can also prominently mitigate the production risk to local farmers; b) replacing the traditional border irrigation with sprinkler irrigation has substantially curbed agricultural water usage and increased the per unit of output; and c) in recent years, instead of planting water-intensive grain crops, local farmers cultivated more forage crops to raise animals, which greatly diversified their income sources and reduced the drought risk of agricultural production. By performing an empirical case study in drought-prone Inner Mongolia, this study provides decision-makers with insights into how to strategically adapt to drought risk and reduce rural poverty within the broader context of climate change.
Large-scale vegetation restoration and climate change triggered a significant decline in runoff in the middle reaches of the Yellow River and its tributaries. This runoff decline intensifies inherent water shortage and results in more severe water use conflicts that are threatening sustainable development in the Loess Plateau. Innovative strategies for more water-efficient land management are essential. To this end, the factors controlling runoff were investigated using the upstream area of the Jing River as an example. Runoff was found to be mainly controlled by evaporative demand, precipitation, and land cover type. Budyko’s frameworks were applied to predict the annual and long-term runoff; however, the effect of changes in land management (e.g., afforestation) on runoff cannot be assessed due to lack of vegetation factors. Therefore, an empirical analysis tool was derived based on an existing relationship for runoff estimation. This method was found to be more effective in reproducing the annual and long-term runoff than others. The incorporation of temporal changes in land cover and form in approach enables the estimation of the possible impact of soil conservation measures (e.g., afforestation or terracing). Our study highlights the importance of adaptive land management strategies for mitigating water shortage on the Loess Plateau.
Agroforestry systems, which combine annual crops with trees, are used widely in semi-arid regions to reduce wind erosion and improve resource (e.g. water) use efficiency. Limited knowledge is available on optimizing such systems by the choice of crop species with specific physiological traits (i.e. C3 vs C4, N-fixing vs non-N-fixing). In this study we quantified the light interception and utilization efficiency of trees and crops in agro-forestry systems comprising apricot trees and a C3 species (sweet potato), a C4 species (millet) or an N-fixing legume species (peanut), and used measurements in the sole stands as a reference. A significant delay in leaf growth was found in millet. Maximum LAI of millet was 17% higher in agroforestry then expected from sole crop LAI, taking into account the relative density of 2/3, while a 25% decrease in maximum LAI compared to expected was observed in peanut and sweet potato. The total light interception in agroforestry was 54% higher than in sole tree stands and 23% higher than in sole crops. The millet intercepted more light and produced more biomass in agroforestry than peanut and sweet potato. The LUE values of the crops in the mixed systems were higher than those of the sole crops, as was the photosynthetic efficiency of individual leaves, especially in plants in the border rows of the crop strips. High light capture in agroforestry made a greater contribution to productivity of understory crops than the increases in light use efficiency. We conclude that agroforestry systems with apricot trees and annual crops, especially millet, can improve light utilization in semi-arid climates and contribute to regional sustainability and adaptation to climate change.
Ecosystem and associated services in arid and semiarid areas are sensitive to climate change and human activities. Guiding human activities based on the optimization of ecosystem services can help humans adapt to climate change effectively, which is vital for regional sustainability. We evaluated the distribution of five ecosystem services: net primary productivity (NPP), soil conservation (SC), water yield (WY), water retention (WR), and livestock supply in the grassland and agro-pastoral transitional zone of China (GAPTZ) under the future climate scenarios of representative concentration pathway (RCP) 4.5 and RCP8.5 in 2050. We designed the four grazing-intensity scenarios of ungrazed (UG), lightly grazed (LG), moderately grazed (MG), and heavily grazed (HG) and analyzed the impacts of climate change and grazing on the ecosystem services. Finally, we presented the optimization schemes of grazing intensity in the GAPTZ under the objectives of “strong sustainability” and “weak sustainability”. “Strong sustainability” objective means that the total change rate of ecosystem services compared to the ungrazed scenario is maximal and should not be less than 0. “Weak sustainability” objective means that the livestock supply is preferential and the total change rate of ecosystem services compared to the ungrazed scenario is maximal but could be less than 0. The results showed that both climate change and grazing exert great influence on the supply and interrelation of ecosystem services. In the northeast of the GAPTZ, LG and MG can stimulate grassland to tiller and enlarge ecosystem services integrally. HG has the severest negative effect on ecosystem services overall. Under the “weak sustainability” objective, LG can be widely adopted in the GAPTZ. Under the “strong sustainability” objective, grazing should be limited in the northwestern and north-central GAPTZ. Reasonable planning of grazing intensity and its spatial patterns can promote effective utilization of grassland resource and realization of regional sustainability.
Extensive cultivation of rubber plantations in Xishuangbanna in southwest (SW) China has resulted in negative hydrological consequences, particularly drought, during the pronounced dry season. Although rubber-tea agroforestry is regarded as the most successful agroforestry system for improving the sustainability of rubber agriculture and environmental conservation, plant water use patterns and their related interactions have rarely been examined in such systems. How do coexisting plants compete and share water under water deficit remains to be explored. Therefore, we used stable isotope (delta D and delta O-18) methods to determine the spatial water use patterns of both rubber trees and tea trees in a rubber-tea agroforestry system during the pronounced dry season and explored the movement of soil water in this system. The results of the MixSIAR model (a Bayesian mixing model) indicated that tea trees primarily uptake water from the 5-30 cm soil layer (40.3%, on average), and rubber trees primarily uptake water from the 30-80 cm soil layer (35.3%, on average) and absorb soil water evenly along slopes during the dry season. These results suggest that rubber trees and tea trees have different but complementary water use patterns. We also observed that the soil of the uphill and downhill tea rows contained much more water; however, the collaborative hydraulic redistribution in the studied agroforestry system could redistribute the soil water along the slope and below the ground well. Therefore, soil drought on terraces can be alleviated during the dry season. Our results confirmed that the tea tree is an appropriate crop for intercropping with rubber trees when considering water sharing and water management and provided a practical analysis of water use benefits from a rubber agroforestry system during drought stress.
The northern Tibetan Plateau is the most traditional and important semi-nomadic region in Tibet. The alpine vegetation is sensitive and vulnerable to climate change and human activities, and is also important as an ecological security in protecting the headwaters of major rivers in Asia. Therefore, the Tibetan alpine grasslands have fundamental significance to both Mainland China and South Asia. The pasture degradation, however, likely threatens the livelihood of residents and the habitats of wildlife on this plateau. Since 2004, the government has launched a series of ecological restoration projects and economic compensatory payment polices. Many fences were additionally built on degraded pastures to prevent new degradation, to promote functionality recovery, and to balance the stocking rate with forage productivity. The grazed vs. fenced paired pastures across different zonal grassland communities along evident environmental gradients provide us with a natural comparative experiment platform to test the relative contributions of natural and anthropogenic factors. This study critically reviews the background, significance of and debates on short-term grazing exclusion with fences in this region. We also aim to figure out scientific and standardized workflows for assessing the effectiveness of grazing exclusion and compensatory payments in the future.
To protect the water tower’s ecosystem environment and conserve biodiversity, China has been implementing a huge payment program for ecosystem services in the three rivers source region. We explored here the dynamics of grassland degradation and restoration from 1990 to 2012 and its relationships with climate mitigation in the TRSR to provide a definite answer as to the forcing and response of grassland degradation and restoration to climate change. Then we estimated its potential of climate mitigation benefits to address the question of whether ecological restoration could be effective in reversing the decline of ecosystem carbon mitigation service. The trend of average annual temperature and precipitation observed by meteorological stations were approximately increased. Compared before and after 2004, the area of grassland degradation was increased slightly. However, nearly one-third of degraded grassland showed improvement, and the grassland vegetation coverage showed significant increase. Comparing current grassland vegetation coverage with healthy vegetation cover with the same grass type, nearly half of the area still needs to further restore vegetation cover. The grassland degradation resulted in significant carbon emissions, but the restoration to its healthy status has been estimated to be technical mitigation potential.
To mitigate impacts of sandstorms on northern China, the Chinese government launched the Beijing–Tianjin Sand Source Control Program (BTSSCP) in 2000. The associated practices (i.e., cultivation, enclosure, and aerial seeding) were expected to greatly enhance grassland carbon sequestration. However, the BTSSCP-induced soil organic carbon (SOC) dynamics remain elusive at a regional level. Using the Xilingol League in Inner Mongolia for a case study, we examined the impacts from 2000 to 2006 of the BTSSCP on SOC stocks using the IPCC carbon budget inventory method. Results indicated that over all practices SOC storage increased by 1.7%, but there were large differences between practices. SOC increased most rapidly at the rate of 0.3 Mg C·ha–1·yr–1 under cultivation, but decreased significantly under aerial seeding with moderate or heavy grazing (0.3 vs.0.6 Mg C·ha–1·yr–1). SOC increases varied slightly for grassland types, ranging from 0.10 Mg C·ha–1·yr–1 for temperate desert steppe to 0.16 Mg C·ha–1·yr–1 for temperate meadow steppe and lowland meadow. The overall economic benefits of the SOC sink were estimated to be 4.0 million CNY. Aerial seeding with no grazing was found to be the most cost-effective practice. Finally, we indicated that at least 55.5 years (shortest for cultivation) were needed for the grasslands to reach their potential carbon stocks. Our findings highlight the importance and effectiveness of BTSSCP in promoting terrestrial carbon sequestration which may help mitigate climate change, and further stress the need for more attention to the effectiveness of specific practices.
The Ecological Protection and Restoration Program (EPRP), initiated in 2005 in the Three-River Headwaters (TRH, the headwaters of the Yangtze, Yellow, and Lantsang rivers) region, is the largest project for nature reserve protection and reconstruction in China. This massive effort was expected to improve the trade-off between grassland productivity and grazing pressure in the region. However, the impacts of EPRP on forage supply and livestock carrying capacity remain poorly understood. Using the Global Production Efficiency Model and grazing pressure index, we investigated the influences of the EPRP by comparing the grassland yield and grazing pressure index before (1988-2004) and after (2005-2012) implementation of the program. Vegetation cover, represented by the annual maximum Normalized Difference Vegetation Index (NDVI), increased by 11.2% after implementation of the EPRP. The increase of NDVI, together with increasing temperature and precipitation, led to a 30.3% increase of the mean annual grassland yield in 2005-2012 relative to that in 1988-2004 (694 kg ha(-1) vs. 533 kg ha(-1) dry matter). We show that grazing pressure was largely alleviated by the EPRP due to increased grassland yield and decreased livestock number. This was indicated by a 36.1% decline of the grazing pressure index. The effects of the EPRP varied spatially. As examples, there were larger increases of grassland yield in the southeast of the region dominated by alpine meadow and greater reduction of grazing pressure in the central and eastern parts. Nevertheless, the ecological effectiveness of the EPRP may vary with the measures used and is indicated to be coupled with climate change. This calls for more detailed comparison and attribution analyses to predict the ongoing consequences of the EPRP in order to attain sustainable implementation of restoration practices in the TRH region.
The Yangtze is the largest river basin in China and home to over 400 million people. In recent history, and especially during 1950s–1970s, extensive lakes and floodplains were reclaimed as polders for agriculture and rural development. Consequently, the flood retention capacity was decreased, many lakes were disconnected from the main channel of the Yangtze by embankments and sluice gates, and eutrophication was common. It is anticipated that there will be a greater frequency of extreme floods and droughts in the basin according to climate change scenarios. WWF commenced a programme in 2002 in partnership with government agencies and local communities to reconnect three lakes (Zhangdu, Hong and Tian-e-zhou) in Hubei Province to the river by opening sluice gates seasonally and improving lake management. The resilience of the lake environment to climate change and the livelihoods of local people were enhanced. The measures assessed here highlight: (a) the need for adaptation programmes to concurrently improve livelihoods and reduce exposure to physical risks; (b) the need to build the capacity of people and institutions; and (c) the value of decentralized adaptation as compared with new infrastructure investments.
Autonomous adaptation in the water sector is assessed to derive lessons for more successful climate change adaptation from six empirical, consistently designed river management case studies based on projects of WWF. They show that when adaptation measures are considered in the context of common problems in water management, many practical ways of building resilience to climate change through mainstream programs are evident. The cases are mainly from developing countries—India, China, Mexico, Brazil, the lower Danube basin and Tanzania—where efforts to reduce environmental degradation and enhance livelihoods have directly helped to reduce vulnerability to natural hazards and climate change. The key lessons include: the benefits of concurrent measures for improving livelihoods and reducing physical vulnerability; the need to enhance and fund local institutions to mainstream adaptation programmes; and the value in implementing ‘no and low regrets’ measures despite uncertainties.
Wetlands have many important functions. To a wide range of wildlife species, they offer critically important habitats. They also act to mitigate flooding, regulate micro and macro climate changes, degrade pollutants and control erosion etc. Wetland benefits are these functions, which provide direct, indirect, and non-use values to humans. In this study, field soil data are used to calculate the flood mitigation benefits of wetland soils within the Momoge National Nature Reserve, Jilin Province, the People’s Republic of China. Calculations are based upon environmental economic assessment methods and GIS techniques. The estimated flood mitigation capacity of wetland soils within the Momoge Reserve was 7.15 × 104 m3/hm2/yr. This translated into an economic benefit of 5700 $/hm2/yr due to flood mitigation. Spatial differences in the flood mitigation ability of soils were observed across the Momoge wetlands. Benefits associated with flood mitigation were highest within the middle reaches of the Momoge wetlands and least in the East. This quantitative analysis of flood mitigation benefit, with its investigation of wetland soils, will be a useful reference both for the assessment of wetland values in the local region and also for the greater understanding wetland function and value assessment methods.
To better understand the driving forces of changes in streamflow (Q), this study analyzed the changes in the hydro-meteorological series by the Mann-Kendall, Pettitt’s test and the flow duration curve (FDC) in the Wuding River Basin (WRB), which is a typical river basin in the Loess Plateau. The response of Q variability to climate change and human activities were also quantified by the elasticity method and decomposition method based on the Budyko framework. The results showed that Q exhibited an obvious downward trend at the rate of 0.44 mm/1 with a changing point occurred in 1980. Compared with 1961–1980, the greatest reduction in monthly Q during 1981–2007 was found in April (41 %) and the low flows have more distinct decrease than high flows. The precipitation (P), potential evapotranspiration (E0) and catchment characteristics parameter n elasticity of Q are 2.40, −1.40 and −2.51, respectively, indicating that Q variability is most sensitive to human activities. The contribution of climate change and human activities to changes in Q from the two methods are 35 and 65 %, respectively. The ecological restoration (ER) measures, including channel measures and slope measures, were found to be the dominant factors responsible for the decreased Q. Furthermore, changes in Q in 1970–1990 could be mainly ascribed to channel measures while slope measures have played more important roles after 1999 when the Grain-for-Green (GFG) project was implemented. This study could provide scientific basis for how to mitigate effectively and efficiently changes in water resources and guide measures to be implemented in the region under the future climate change.
The Three-Rivers Headwater Region (TRHR) is the headwater of the Yangtze River Basin (YARB), Yellow River Basin (YRB), and Lancang River Basin (LRB); it is known as China’s ‘Water Tower’ owing to its important supply of freshwater. In order to assess ecosystem changes in the TRHR during 2000–2012, we systematically and comprehensively evaluated a combination of model simulation results and actual observational data. The results showed the following: (1) Ecosystem pattern was relatively stable during 2000–2010, with a slight decrease in farmland and desert areas, and a slight increase in grassland and wetland/water-body areas. (2) A warmer and wetter climate, and ecological engineering, caused the vegetation cover and productivity to significantly improve. (3) Precipitation was the main controlling factor for streamflow. A significant increase in precipitation during 2000–2012 resulted in an obvious increase in annual and seasonal streamflow. Glacier melting also contributed to the streamflow increase. (4) The total amount of soil conservation increased slightly from 2000 to 2012. The increase in precipitation caused rainfall erosivity to increase, which enhanced the intensity of soil erosion. The decrease in wind speed decreased wind erosion and the frequency of sandstorms. (5) The overall habitat quality in the TRHR was stable between 2000 and 2010, and the spatial pattern exhibited obvious heterogeneity. In some counties that included nature reserves, habitat quality was slightly higher in 2010 than in 2000, which reflected the effectiveness of the ecological restoration. Overall, the aforementioned ecosystem changes are the combined results of ecological restoration and climate change, and they are likely a local and temporary improvement, rather than a comprehensive and fundamental change. Therefore, more investments and efforts are needed to preserve natural ecosystems.
The Mountain-River-Lake Program (MRL) was implemented since 25 years ago in the Poyang Lake basin, southern China. It consists of series of forest restoration projects that aim to address severe soil and water losses, and improve farmer’s livelihoods. To assess the effectiveness of the program, systematic planning, integrated research and comprehensive monitoring were used to illustrate how forest restoration projects that consider both ecological, social and economic perspectives can improve both the environment and society, and eradicate the “ecological-poverty trap”. We found that the overall ecological effects of the program are beneficial, and the socioeconomic effects are mostly positive. Forest plantations covering 4.92 × 106 ha were established, which promoted increased forest coverage from a minimum of 26.98% to 60.05% at present. The amount of carbon storage in forest increased significantly, with net carbon sequestration of plantation forests increased from 2.29 TgC/year to 10.52 TgC/year. The results also indicated that the area of land affected by heavy and severe soil erosion has decreased by 55.2% and 53.6%, respectively, while the water holding capacity was 25.2% higher in 2009 than that in 1990. The net income for farmers was almost 6 times greater than that before the program, and the number of people living below the poverty line decreased from 10 million to 0.865 million. This assessment has confirmed that if we cannot improve the livelihood of local communities and encourage them to participate in such programs, we will be unable to restore and manage degraded environments. The continuing and future impacts of the program may be even greater, and will provide important lessons and experiences for other ecological restoration programs.