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1.
Analysis of arable land loss and its impact on rural sustainability in Southern Jiangsu Province of China 总被引:2,自引:0,他引:2
Rapid urbanization and industrialization in southern Jiangsu Province have consumed a huge amount of arable land. Through comparative analysis of land cover maps derived from TM images in 1990, 2000 and 2006, we identified the trend of arable land loss. It is found that most arable land is lost to urbanization and rural settlements development. Urban settlements, rural settlements, and industrial park-mine-transport land increased, respectively, by 87 997 ha (174.65%), 81 041 ha (104.52%), and 12 692 ha (397.99%) from 1990 to 2006. Most of the source (e.g., change from) land covers are rice paddy fields and dryland. These two covers contributed to newly urbanized areas by 37.12% and 73.52% during 1990–2000, and 46.39% and 38.86% during 2000–2006. However, the loss of arable land is weakly correlated with ecological service value, per capita net income of farmers, but positively with grain yield for some counties. Most areas in the study site have a low arable land depletion rate and a high potential for sustainable development. More attention should be directed at those counties that have a high depletion rate but a low potential for sustainable development. Rural settlements should be controlled and rationalized through legislative measures to achieve harmonious development between urban and rural areas, and sustainable development for rural areas with a minimal impact on the ecoenvironment. 相似文献
2.
Recent wetland area trends were estimated from the National Resources Inventory (NRI) for nonfederal rural lands for the period
1982–1987. NRI-based estimates of wetland area for states comprising the conterminous United States were highly correlated
with estimates made by the US Fish and Wildlife Service and with estimates of coastal salt marsh wetlands made by the National
Oceanic and Atmospheric Administration. Net wetland area declined by 1.1% (≈363,200 ha) during the five-year study period.
Conversion to open water, primarily caused by natural flooding in western inland basins, was responsible for altering extensive
wetland areas (≈171,400 ha). Of the human-induced wetland conversions, urban and built-up land was responsible for 48% of
the wetland loss, while agricultural development was indicated in 37% of the converted wetland area. A decrease in rural land,
and increases in both population, and urban and built-up land were associated with wetland loss among states. Potential reasons
for wetland loss were different in 20 coastal states than in 28 inland states. Proportionately, wetland loss due to development
was three times greater in coastal states than inland states, while agriculturally induced wetland losses were similar in
both groups. The proportionate declines of forested vs nonforested wetlands were not significantly different among states. 相似文献
3.
Land take and food security: assessment of land take on the agricultural production in Europe 总被引:1,自引:0,他引:1
Ciro Gardi Panos Panagos Marc Van Liedekerke Claudio Bosco Delphine De Brogniez 《Journal of Environmental Planning and Management》2015,58(5):898-912
Soil is a multifunctional, non-renewable natural resource for Europe as clearly expressed in the European Union (EU) Thematic Strategy for Soil Protection (COM (2006)231). Soil carries out multiple functions, including the support of food production. Urban development and its associated land take poses a major threat to soil and could have significant effects on agricultural production. This paper aims to evaluate the potential productivity losses in European agriculture due to land-take processes between 1990 and 2006. Agricultural land take was calculated using CORINE Land Cover maps of 1990, 2000 and 2006. For 21 of the 27 EU member states, agricultural land take was computed to be 752,973 ha for 1990–2000 and 436,095 ha for 2000–2006, representing 70.8% and 53.5%, respectively, of the total EU land take for these periods. The impact of this land take on the production capabilities of the agricultural sector for the period 1990–2006 for 19 of the 21 states was estimated to be equivalent to a loss of more than six million tonnes of wheat. The paper demonstrates that Europe's intense urbanisation has a direct impact on its capability to produce food. 相似文献
4.
Assessing farm-level agricultural sustainability over a 60-year period in rural eastern India 总被引:1,自引:1,他引:0
Agricultural sustainability is a vital parameter to be ascertained locally and globally if food security is to be achieved
and maintained. Agricultural sustainability is the combined product of social, economic and ecological sustainability. It
is also a function of temporal and spatial variations, a fact which indicates that area-specific sustainability indices need
to be designed. We present here an Agricultural Sustainability Index (ASI) for rural eastern India and use it to calculate
the ASI for 150 farms for three decades over a 60-year period, viz., 1950–1960, 1980–1990 and 2000–2010 for a representative
Indian village of Gangapur (25°83′N, 85°65′E). The ASI was calculated using 30 variables, 10 each of social, economic and
ecological sustainability. An extensive questionnaire-based survey was carried out to collect the relevant data. Our study
reveals that over a 60-year period, ASI values do not show a statistically significant change. We conclude that the agricultural
practices of the region have maintained sustainability so far although the scope for improvement in several broad areas identified
by us is immense. Increased ecological literacy and better implementation of government policies, aiming at health, education
and better scientist–farmer interactions, must target improved ASI values in coming decades. 相似文献
5.
济南市农村居民点用地分析及节约利用对策 总被引:3,自引:1,他引:3
随着城市化水平的提高以及城市规模的扩大,耕地日趋减少,城市用地需求量不断增加,用地矛盾加剧。通过对济南市农村居民点用地现状分析,指出了农村居民点用地存在的问题,土地利用程度低、土地资源浪费是农村居民点用地普遍存在的现象。在当前建设节约型社会的形势下,从提高土地利用程度等方面提出了节约用地的措施,指出平原地区是今后土地利用的重点;采取合理的经济措施,是解决农村居民点用地流转的新途径。 相似文献
6.
The Cache River of southernmost Illinois is used as a case study for developing and demonstrating an approach to quantitatively
link (1) national agricultural policy and global agricultural markets, (2) landowner's decisions on land use, (3) spatial
patterns of land use at a watershed scale, and (4) hydrologic impacts, thus providing a basis to predict, under a certain
set of circumstances, the environmental consequences of economic and political decisions made at larger spatial scales. The
heart of the analysis is an estimation, using logistic regression, of the affect of crop prices and Conservation Reserve Program
(CRP) rental rates on farmland owner's decisions whether to reenroll in the CRP or return to crop production. This analysis
shows that reasonable ranges for crop prices (80%–150% of 1985–1995 values) and CRP rental rates (0–125% of 1985–1995 rates)
result in a range of 3%–92% of CRP lands being returned to crop production, with crop prices having a slightly greater effect
than CRP rental rates. Four crop price/CRP rental rate scenarios are used to display resulting land-use patterns, and their
effect on sediment loads, a critical environmental quality parameter in this case, using the agricultural non point source
(AGNPS) model. These scenarios demonstrate the importance of spatial pattern of land uses on hydrological and ecological processes
within watersheds. The approach developed can be adapted for use by local governments and watershed associations whose goals
are to improve watershed resources and environmental quality. 相似文献
7.
Land use change and population growth in the Morobe Province of Papua New Guinea between 1975 and 2000 总被引:1,自引:0,他引:1
The relation between human population growth and land use change is much debated. Here we present a case study from Papua New Guinea where the population has increased from 2.3 million in 1975 to 5.2 million in 2000. Since 85% of the population relies on subsistence agriculture, population growth affects agricultural land use. We assessed land use change in the Morobe province (33,933 km2) using topographic maps of 1975 and Landsat TM images of 1990 and 2000. Between 1975 and 2000, agricultural land use increased by 58% and population grew by 99%. Most new agricultural land was taken from primary forest and the forest area decreased from 9.8 ha person(-1) in 1975 to 4.4 ha person(-1) in 2000. Total population change and total land use change were strongly correlated. Most of the agricultural land use change occurred on Inceptisols in areas with high rainfall (>2500 mm year(-1)) on moderate to very steep slopes (10-56%). Agricultural land use changes in logged-over areas were in the vicinity of populated places (villages), and in close proximity to road access. There was considerable variation between the districts but districts with higher population growth also had larger increases in agricultural areas. It is concluded that in the absence of improved farming systems the current trend of increased agriculture with rapid population growth is likely to continue. 相似文献
8.
Haight RG Homans FR Horie T Mehta SV Smith DJ Venette RC 《Environmental management》2011,47(3):506-517
Economic assessment of damage caused by invasive alien species provides useful information to consider when determining whether
management programs should be established, modified, or discontinued. We estimate the baseline economic damage from an invasive
alien pathogen, Ceratocystis fagacearum, a fungus that causes oak wilt, which is a significant disease of oaks (Quercus spp.) in the central United States. We focus on Anoka County, Minnesota, a 1,156 km2 mostly urban county in the Minneapolis-Saint Paul metropolitan region. We develop a landscape-level model of oak wilt spread
that accounts for underground and overland pathogen transmission. We predict the economic damage of tree mortality from oak
wilt spread in the absence of management during the period 2007–2016. Our metric of economic damage is removal cost, which
is one component of the total economic loss from tree mortality. We estimate that Anoka County has 5.92 million oak trees
and 885 active oak wilt pockets covering 5.47 km2 in 2007. The likelihood that landowners remove infected oaks varies by land use and ranges from 86% on developed land to
57% on forest land. Over the next decade, depending on the rates of oak wilt pocket establishment and expansion, 76–266 thousand
trees will be infected with discounted removal cost of $18–60 million. Although our predictions of removal costs are substantial,
they are lower bounds on the total economic loss from tree mortality because we do not estimate economic losses from reduced
services and increased hazards. Our predictions suggest that there are significant economic benefits, in terms of damage reduction,
from preventing new pocket establishment or slowing the radial growth of existing pockets. 相似文献
9.
Electric power generating plants that use coal were among the key targets of Title IV of the 1990 Clean Air Act. Under the
first phase of the act, 110 coal-fired electric power plants were required to reduce their sulfur dioxide emissions by 1995
and nitrogen oxide emissions by 1996. Phase 2 of the act requires even greater reduction of sulfur dioxide emissions by 2000
and nitrogen oxide emissions by 2008. This study examines whether the 107 targeted plants (three plants went off-line) have
achieved the desired sulfur dioxide and nitrogen oxide emission levels.
The analysis of sulfur dioxide is based on data from 1990, 1995, and 1999. The findings show that although sulfur oxide increased
by 3% from 1995 to 1999, it decreased by 45% over the 1990–1999 period at the firm level for the targeted firms. The findings
also indicate that the overall reduction in sulfur dioxide was achieved by utilizing low sulfur coal and by purchasing emission
allowances. So far as nitrogen oxides are concerned, there has been a reduction of 14% over the 1990–1999 period, of which
7% was achieved during the 1995–1999 period. An evaluation of emissions at the plant level indicates that several plants do
not meet the emissions level for sulfur dioxide or nitrogen oxides.
These results provide a mixed scorecard for reduction in emissions both for sulfur dioxide and nitrogen oxides. Even though
there is reduction in the emissions on an overall basis at the firm level, several plants that have not been able to reduce
emissions deserve special attention to meet the goals of the act in reducing emissions. 相似文献
10.
Changes in forest and agricultural land management practices have the potential to increase carbon (C) storage by terrestrial
systems, thus offsetting C emissions to the atmosphere from energy production. This study assesses that potential for three
terrestrial management practices within the state of Virginia, USA: afforestation of marginal agricultural lands; afforestation
of riparian agricultural lands; and changing tillage practices for row crops; each was evaluated on a statewide basis and
for seven regions within the state. Lands eligible for each practice were identified, and the C storage potential of each
practice on those lands was estimated through a modeling procedure that utilized land-resource characteristics represented
in Geographic Information System databases. Marginal agricultural lands’ afforestation was found to have the greatest potential
(1.4 Tg C yr−1, on average, over the first 20 years) if applied on all eligible lands, followed by riparian afforestation (0.2 Tg C yr−1 over 20 years) and tillage conversion (0.1 Tg C yr−1 over 14 years). The regions with the largest potentials are the Ridge and Valley of western Virginia (due to extensive areas
of steep, shallow soils) and in the Mid-Atlantic Coastal Plain in eastern Virginia (wet soils). Although widespread and rapid
implementation of the three modeled practices could be expected to offset only about 3.4% of Virginia’s energy-related CO2 emissions over the following 20 years (equivalent to about 8.5% of a Kyoto Treaty–based target), they could contribute to
achievement of C-management goals if implemented along with other mitigation measures. 相似文献
11.
Observations of Atmospheric Nitrogen and Phosphorus Deposition During the Period of Algal Bloom Formation in Northern Lake Taihu,China 总被引:5,自引:1,他引:4
Cyanobacterial blooms in Lake Taihu occurred at the end of April 2007 and had crucial impacts on the livelihood of millions
of people living there. Excessive nutrients may promote bloom formation. Atmospheric nitrogen (N) and phosphorus (P) deposition
appears to play an important role in algal bloom formation. Bulk deposition and rain water samples were collected respectively
from May 1 to November 30, 2007, the period of optimal algal growth, to measure the bulk atmospheric deposition rate, wet
deposition rate, and dry deposition rate for total nitrogen (TN; i.e., all species of nitrogen), and total phosphorus (TP;
i.e., all species of phosphorus), in northern Lake Taihu, China. The trends of the bulk atmospheric deposition rate for TN
and the wet deposition rate for TN showed double peaks during the observation period and distinct influence with plum rains
and typhoons. Meanwhile, monthly bulk atmospheric deposition rates for TP showed little influence of annual precipitation.
However, excessive rain may lead to high atmospheric N and P deposition rates. In bulk deposition samples, the average percentage
of total dissolved nitrogen accounting for TN was 91.2% and changed little with time. However, the average percentage of total
dissolved phosphorus accounting for TP was 65.6% and changed substantially with time. Annual bulk atmospheric deposition rates
of TN and TP during 2007 in Lake Taihu were estimated to be 2,976 and 84 kg km−2 a−1, respectively. The results showed decreases of 34.4% and 78.7%, respectively, compared to 2002–2003. Annual bulk deposition
load of TN for Lake Taihu was estimated at 6,958 t a−1 in 2007 including 4,642 t a−1 of wet deposition, lower than the values obtained in 2002–2003. This may be due to measures taken to save energy and emission
control regulations in the Yangtze River Delta. Nevertheless, high atmospheric N and P deposition loads helped support cyanobacterial
blooms in northern Lake Taihu during summer and autumn, the period of favorable algal growth. 相似文献
12.
Coastal Aquaculture Development in Bangladesh: Unsustainable and Sustainable Experiences 总被引:1,自引:0,他引:1
Coastal aquaculture in Bangladesh consists mainly of two shrimp species (Penaeus monodon and Macrobrachium rosenbergii). Currently, there are about 16,237 marine shrimp (P. monodon) farms covering 148,093 ha and 36,109 fresh water shrimp (M. rosenbergii) farms covering 17,638 ha coastal area. More than 0.7 million people are employed in the farmed shrimp sector and in 2005–2006
the export value of shrimp was 403.5 million USD. Thus, coastal aquaculture contributes significantly to rural employment
and economy but this is overshadowed by negative social and ecological impacts. This article reviews the key issues, constraints
and opportunities of sustainable shrimp farming. In addition we present the results of two case studies from southwestern
coastal areas where shrimp farming originated and central coastal areas where shrimp farming, especially M. rosenbergii, began in recent years. Lessons learned from the review and case studies are considered in the context of recommendations
to encompass a socially equitable and ecologically sound coastal aquaculture. 相似文献
13.
The impact of anthropogenic activities on the fluctuation of nutrients along the Densu River and its tributaries was studied.
High concentrations of nutrients were observed in the study area but the river was found to be circumneutral and fresh with
pH ranging between 6.54 and 7.84. The levels of NH4
+–N ranged between 0.21 and 2.1 mg L−1 with mean concentration of 1.19 ± 0.02 mg L−1 while that of nitrate is between 0.13 and 5.21 mg L−1 with a mean concentration of 2.07 ± 0.01 mg L−1. The levels of PO4
3−–P fluctuated within the range 0.54 and 1.04 mg L−1 with a mean of 0.84 ± 0.01 mg L−1. The Densu River Basin was also found to be with organic matter with depleted dissolved oxygen. The river recorded high BOD
values ranging from 6.91 to 18.8 mg L−1. Concentration of nutrients and organic pollutants increased as a consequence of anthropogenic inputs particularly from domestic,
agricultural and municipal sources. The highly impaired sites were those located close to the urbanized, agricultural and
high-density residential areas. The relatively high concentration of nitrate and phosphate in the river indicated that it
was quite eutrophic. 相似文献
14.
Leif G. Olmanson Patrick L. Brezonik Marvin E. Bauer 《Journal of the American Water Resources Association》2014,50(3):748-761
A large 20‐year database on water clarity for all Minnesota lakes ≥8 ha was analyzed statistically for spatial distributions, temporal trends, and relationships with in‐lake and watershed factors that potentially affect lake clarity. The database includes Landsat‐based water clarity estimates expressed in terms of Secchi depth (SDLandsat), an integrative measure of water quality, for more than 10,500 lakes for time periods centered around 1985, 1990, 1995, 2000, and 2005. Minnesota lake clarity is lower (more turbid) in the south and southwest and clearer in the north and northeast; this pattern is evident at the levels of individual lakes and ecoregions. Temporal trends in clarity were detected in ~11% of the lakes: 4.6% had improving clarity and 6.2% had decreasing clarity. Ecoregions in southern and western Minnesota, where agriculture is the predominant land use, had higher percentages of lakes with decreasing clarity than the rest of the state, and small and shallow lakes had higher percentages of decreasing clarity trends than large and deep lakes. The mean SDLandsat statewide remained stable from 1985 to 2005 but decreased in ecoregions dominated by agricultural land use. Deep lakes had higher clarity than shallow lakes statewide and for lakes grouped by land cover. SDLandsat decreased as the percentage of agriculture and/or urban area increased at county and catchment levels and it increased with increasing forested land. 相似文献
15.
为全面认识新安江水资源价值,本文对河流生态系统的各项服务功能开展了定量评价。本文按照联合国千年评估对生态系统的划分方法(供给、调节、文化与支持4项服务),结合新安江流域水生态系统的特征和结构,建立了15项评估指标体系。以2013年为基准年,对新安江水生态系统服务功能及其生态经济价值进行评价。结果显示:新安江水生态系统服务总价值为73.72亿元,其中,提供产品功能价值9.58亿元、调节功能价值11.77亿元、支持功能价值24.13亿元、文化服务功能价值28.24亿元,分别占总价值的13.0%、16.0%、32.7%、38.3%。新安江单位面积提供的生态系统服务价值为0.41亿元/km~2,高于黄山市单位面积GDP产值0.28亿元/km~2。研究认为,新安江流域水生态系统对支持和保护当地经济发展具有重要作用,研究结果以期为新安江水资源有效管理和区域生态环境保护及水环境补偿提供生态学依据。 相似文献
16.
Adolfo Campos C. 《Environmental management》2010,46(2):213-224
This study addressed the effects of land use and slope position on soil inorganic nitrogen and was conducted in small watersheds.
The study covered three land use types: tropical cloud forest, grassland, and coffee crop. To conduct this research, typical
slope small watersheds were chosen in each land use type. Slopes were divided into three positions: shoulder, backslope, and
footslope. At the center of each slope position, soil sampling was carried out. Soil inorganic nitrogen was measured monthly
during a period of 14 months (July 2005–August 2006) with 11 observations. Significant differences in soil NH4
+–N and NO3
−–N content were detected for both land use and sampling date effects, as well as for interactions. A significant slope position-by-sampling
date interaction was found only in coffee crop for NO3
−–N content. In tropical cloud forest and grassland, high soil NH4
+–N and low NO3
−–N content were recorded, while soil NO3
−–N content was high in coffee crop. Low NO3
−–N contents could mean a substantial microbial assimilation of NO3
−–N, constituting an important mechanism for nitrogen retention. Across the entire land use set, the relationship between soil
temperature and soil inorganic N concentration was described by an exponential decay function (N = 33 + 2459exp−0.23T, R
2 = 0.44, P < 0.0001). This study also showed that together, soil temperature and gravimetric soil water content explained more variation
in soil inorganic N concentration than gravimetric soil water content alone. 相似文献
17.
This study utilizes remote sensing derived forest aboveground biomass (AGB) estimates and ownership information obtained from
the Protected Areas Database (PAD), combining landscape analyses and GIS techniques to demonstrate how different ownerships
(public, regulated private, and other private) relate to the spatial distribution of AGB in New England states of the USA.
“Regulated private” lands were dominated by lands in Maine covered by a Land Use Regulatory Commission. The AGB means between
all pairs of the identified ownership categories were significantly different (P < 0.05). Mean AGB observed in public lands (156 Mg/ha) was 43% higher than that in regulated private lands (109 Mg/ha), or
30% higher than that of private lands as a whole. Seventy-seven percent of the regional forests (or about 9,300 km2) with AGB >200 Mg/ha were located outside the area designated in the PAD and concentrated in western MA, southern VT, southwestern
NH, and northwestern CT. While relatively unfragmented and high-AGB forests (>200 Mg/ha) accounted for about 8% of total forested
land, they were unevenly proportioned among the three major ownership groups across the region: 19.6% of the public land,
0.8% of the regulated private land, and 11.0% of the other private land. Mean disturbance rates (in absolute value) between
1992 and 2001 were 16, 66, and 19 percent, respectively, on public, regulated private, and other private land. This indicates
that management practices from different ownerships have a strong impact on dynamic changes of landscape structures and AGB
distributions. Our results may provide insight information for policy makers on issues regarding forest carbon management,
conservation biology, and biodiversity studies at regional level. 相似文献
18.
Omotayo Rafiu Awofolu 《The Environmentalist》2006,26(4):285-293
Groundwater (well water) from a residential area within the vicinity of an industrial estate in Lagos, Nigeria were sampled
and analysed by Flame Atomic Absorption Spectroscopy for their heavy metals content. This was with a view of assessing the
quality of the water, which was being used for domestic activities, especially, drinking usually without treatment. Total
trace metal determination by mineral acid digestion of water samples was applied. This method proved to be better than an
extractive concentration technique in the quality assurance protocols with the recovery range being 90.7 ± 0.006–97.6 ± 0.003%.
Mean concentration of trace metals in water samples ranged from Fe: 0.05–0.47 mg l−1; Al: 0.1–1.54 mg l−1; Cu: 0.14–1.39 mg l−1; Zn: 0.04–0.43 mg l−1; Cd: trace–0.02 mg l−1; Pb: trace–0.03 mg l−1, Mn: 0.01–0.18 mg l−1 and Ni: 0.02–0.11 mg l−1. Physical parameters of water samples examined were within the drinking water safety limits except for conductivity. Results
generally indicate the presence of heavy metal constituents in groundwater samples. Detection of metals such as cadmium and
lead which have serious health implications above WHO and USEPA limits in drinking water gives cause for concern. 相似文献
19.
During the post-World War II era, the Mojave Desert Region of San Bernardino County, California, has experienced rapid levels
of population growth. Over the past several decades, growth has accelerated, accompanied by significant shifts in ethnic composition,
most notably from predominantly White non-Hispanic to Hispanic. This study explores the impacts of changing ethnicity on future
development and the loss of open space by modeling ethnic propensities regarding family size and settlement preferences reflected
by U.S. Census Bureau data. Demographic trends and land conversion data were obtained for seven Mojave Desert communities
for the period between 1990 and 2001. Using a spatially explicit, logistic regression-based urban growth model, these data
and trends were used to project community-specific future growth patterns from 2000 to 2020 under three future settlement
scenarios: (1) an “historic” scenario reported in earlier research that uses a Mojave-wide average settlement density of 3.76
persons/ha; (2) an “existing” scenario based on community-specific settlement densities as of 2001; and (3) a “demographic
futures” scenario based on community-specific settlement densities that explicitly model the Region’s changing ethnicity.
Results found that under the demographic futures scenario, by 2020 roughly 53% of within-community open space would remain,
under the existing scenario only 40% would remain, and under the historic scenario model the communities would have what amounts
to a deficit of open space. Differences in the loss of open space across the scenarios demonstrate the importance of considering
demographic trends that are reflective of the residential needs and preferences of projected future populations. 相似文献
20.
Quantifying Terrestrial Ecosystem Carbon Dynamics in the Jinsha Watershed, Upper Yangtze, China from 1975 to 2000 总被引:1,自引:0,他引:1
Shuqing Zhao Shuguang Liu Runsheng Yin Zhengpeng Li Yulin Deng Kun Tan Xiangzheng Deng David Rothstein Jiaguo Qi 《Environmental management》2010,45(3):466-475
Quantifying the spatial and temporal dynamics of carbon stocks in terrestrial ecosystems and carbon fluxes between the terrestrial
biosphere and the atmosphere is critical to our understanding of regional patterns of carbon budgets. Here we use the General
Ensemble biogeochemical Modeling System to simulate the terrestrial ecosystem carbon dynamics in the Jinsha watershed of China’s
upper Yangtze basin from 1975 to 2000, based on unique combinations of spatial and temporal dynamics of major driving forces,
such as climate, soil properties, nitrogen deposition, and land use and land cover changes. Our analysis demonstrates that
the Jinsha watershed ecosystems acted as a carbon sink during the period of 1975–2000, with an average rate of 0.36 Mg/ha/yr,
primarily resulting from regional climate variation and local land use and land cover change. Vegetation biomass accumulation
accounted for 90.6% of the sink, while soil organic carbon loss before 1992 led to a lower net gain of carbon in the watershed,
and after that soils became a small sink. Ecosystem carbon sink/source patterns showed a high degree of spatial heterogeneity.
Carbon sinks were associated with forest areas without disturbances, whereas carbon sources were primarily caused by stand-replacing
disturbances. It is critical to adequately represent the detailed fast-changing dynamics of land use activities in regional
biogeochemical models to determine the spatial and temporal evolution of regional carbon sink/source patterns. 相似文献