No abstract

Despite their value, coastal ecosystems are globally threatened by anthropogenic impacts, yet how these impacts are driven by economic development is not well understood. We compiled a multifaceted dataset to quantify coastal trends and examine the role of economic growth in China's coastal degradation since the 1950s. Although China's coastal population growth did not change following the 1978 economic reforms, its coastal economy increased by orders of magnitude. All 15 coastal human impacts examined increased over time, especially after the reforms. Econometric analysis revealed positive relationships between most impacts and GDP across temporal and spatial scales, often lacking dropping thresholds. These relationships generally held when influences of population growth were addressed by analyzing per capita impacts, and when population density was included as explanatory variables. Historical trends in physical and biotic indicators showed that China's coastal ecosystems changed little or slowly between the 1950s and 1978, but have degraded at accelerated rates since 1978. Thus economic growth has been the cause of accelerating human damage to China's coastal ecosystems. China's GDP per capita remains very low. Without strict conservation efforts, continuing economic growth will further degrade China's coastal ecosystems.

No abstract

Abstract:The temporal trends of reference evapotranspiration (ET ref

Severe droughts are on the rise in many regions. But thus far, attempts to predict when drought will cause a major regime shift or when ecosystems are resilient, often using plant drought tolerance models, have been frustrated. Here, we show that pressure from natural enemies regulates an ecosystem's resilience to severe droughts. Field experiments revealed that in protected salt marshes experiencing a severe drought, plant-eating grazers eliminated drought-stressed vegetation that could otherwise survive and recover from the climate extreme, transforming once lush marshes into persistent salt barrens. These results provide an explicit experimental demonstration for the obligatory role of natural enemies across the initiation, expansion and recovery stages of a natural ecosystem's collapse. Our study highlights that natural enemies can hasten an ecosystem's resilience to drought to much lower levels than currently predicted, calling for integration into climate change predictions and conservation strategies.

No abstract

Along with the sequent completion of Manwan and Dachaoshan Dam, the river continuum of the middle and lower reaches of the Lancang River was separated into three types of segments: reservoir, below-dam segment and downstream flowing segment. The long-term series of water quality and river flow data over 20 years were analyzed in order to study the impact of dam construction and operation on water quality and water self-purification capacity of these different river segments. From pre-dam period to the first 7 years after Manwan Dam had been accomplished, the water quality of Manwan Reservoir became worse due to the accumulation of pollutants, and then to the next 5 years the water quality became better in virtue of the water self-purification of the reservoir. The cooperative operation of Manwan and Dachaoshan Dam had cumulatively positive impacts on water quality of their below-dam segment but no impacts on that of downstream flowing segment. From pre-dam period to the first 7 years after the closure of Manwan Dam, the water selfpurification capacity of Xiaowan-Manwan segment for BOD 5 , COD Mn and NH 3 -N decreased. Also, the water self-purification capacity of Manwan-Dachaoshan segment for BOD 5 and COD Mn decreased but for NH 3 -N increased. However, the water self-purification capacity of Jinghong-Ganlanba segment changed contrary to Manwan-Dachaoshan segment. In general, the construction of Manwan Dam negatively affected the water self-purification capacity of reservoir and below-dam segment but impose little impact on that of downstream flowing segment. This study suggested that it is necessary to pay attention to the effect of complicated temporal and spatial characteristics of dam on aquatic ecosystem.

Topsoil (0-20 cm) samples were collected from the edge of roads to the locations about 200 m off the roads along the four roads with different transportation periods in October 2005. Total concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn were determined using the inductively coupled plasma atomic absorption spectrometry in order to assess and compare road transportation pollution. Results showed that with the exception of As, Cu and Pb, the average concentrations of heavy metals were generally, higher than the regional elemental background values. Most soil samples were moderately or highly polluted by Cd or Ni, but the contamination index (P i ) values for As, Pb and Zn were lower than other heavy metals in all sites. Among the four roads, heavy metal pollution was heavier for Dali Road due to longer transportation periods, while low or no contamination could be observed for the other roads. However, the integrated contamination index (P c ) values showed a generally low contamination or no contamination level for all soil samples in this region, followed by the order of Dali Road [ Dabao Highway [ Road 320 [ Sixiao Highway. The same pollution source of these heavy metals was found using factor analysis.