开发区的“第三次创业”:从工业园走向新城——以苏州工业园转型为例

开发区是全球化时代出现的新产业空间。开发区在我国经济发展和改革开放中,发挥了重要作用。理论界将我国开发区发展阶段总结为一次创业和二次创业两个阶段,但是目前我国开发区普遍出现了从工业园向新城区转型的趋向。从企业家型城市的理论视角,通过对苏州工业园发展与转型的实证研究,论证开发区建设进入第三次创业的新阶段———即从工业园向城市新区的转变。在新一轮转型中,苏州工业园实施了企业家的城市策略,采取了园区再定位、创造新城市空间等企业家城市行动,园区的新城功能和第三产业得到迅速发展。同时,研究也发现园区管委会的管治体系发生了根本变化,从促进经济增长管理向社会和城市综合管理转型。该研究将对我国新一轮开发区的转型具有重要启示。     

森林转型、农地边际化与生态恢复

中国20世纪80年代迎来了国家土地利用形态的转型,即代表自然生态空间的森林面积降至低谷后反转向上,代表人类干扰较强的耕地面积从扩张到收缩.这是生态状况从整体恶化向整体改善转变的最直接原因.森林转型对应着国家经济社会发展的阶段性演进过程,存在着必然性.其直接原因,是农林交错带的农业在与森林竞争土地资源的过程中失去优势.伴随工业化和城市化的劳动力价格上升,生活水平提高带来的林木产品需求增加,是森林竞争力提高和农业竞争力下降的经济驱动力;而转型前农业扩张引起的生态退化,则是其政策驱动力.在中国森林转型初期,政策起到了关键的促进作用.随着城市化的加速发展,人口年龄结构向老年型转变,中国迎来了劳动力工资持续上涨的阶段.以坡耕地为代表的劳动力密集型农地利用方式,由于难以实现机械化,劳动生产率与平原区农业的差距将越来越大,被“边际化”的可能性越来越高.这给森林面积或自然生态空间的进一步扩张提供了机会.     

Land use change in Southern Romania after the collapse of socialism

The drastic socio-economic and political changes that occurred after the breakdown of socialism in Eastern Europe triggered widespread land use change, including cropland abandonment and forest cover changes. Yet the rates and spatial patterns of post-socialist land use change remain largely unclear. We used Landsat TM/ETM+ images to classify land cover maps and assess landscape pattern changes from 1990 to 2005 in Argeş County, Southern Romania. Cropland abandonment was the most widespread change (21.1% abandonment rate), likely due to declining returns from farming, tenure insecurity, and demographic developments during transition. Forest cover and forest fragmentation remained remarkably stable during transition, despite widespread ownership transfers. Cropland abandonment provides opportunities for increased carbon sequestration, but threatens cultural landscapes and biodiversity. Continued monitoring is important for assessing whether abandoned croplands will eventually reforest or be put back into production and to better understand the consequences of post-socialist land use change for ecosystems and biodiversity.     

The Misdiagnosis: Rethinking “Nature-deficit Disorder”

This study examines and critiques “nature-deficit disorder” (NDD), Richard Louv's popular theory of how and why children are alienated from nature. Specifically, I explore NDD within the context of one forest conservation education program that aligns with and operationalizes Louv's message. Underlying Louv's and forest educators' discourses are culturally specific assumptions about human-nature relationships. Both evoke a fall-recovery narrative—that children are separated from nature and must return—and promote science and naming to reconnect. I argue that, in the absence of deeper cultural examination and alternative practices, NDD is a misdiagnosis—a problematic contemporary environmental discourse that can obscure and mistreat the problem. I call on adults to rethink human-nature disconnectedness by returning to the psyche, digging deeper to the problem's cultural roots, and using nontraditional communication practices such as emotional expression and non-naming.     

Forest health conditions in North America

Some of the greatest forest health impacts in North America are caused by invasive forest insects and pathogens (e.g., emerald ash borer and sudden oak death in the US), by severe outbreaks of native pests (e.g., mountain pine beetle in Canada), and fires exacerbated by changing climate. Ozone and N and S pollutants continue to impact the health of forests in several regions of North America. Long-term monitoring of forest health indicators has facilitated the assessment of forest health and sustainability in North America. By linking a nationwide network of forest health plots with the more extensive forest inventory, forest health experts in the US have evaluated current trends for major forest health indicators and developed assessments of future risks. Canada and Mexico currently lack nationwide networks of forest health plots. Development and expansion of these networks is critical to effective assessment of future forest health impacts.     

Comparison of regression coefficient and GIS-based methodologies for regional estimates of forest soil carbon stocks

Estimates of forest soil organic carbon (SOC) have applications in carbon science, soil quality studies, carbon sequestration technologies, and carbon trading. Forest SOC has been modeled using a regression coefficient methodology that applies mean SOC densities (mass/area) to broad forest regions. A higher resolution model is based on an approach that employs a geographic information system (GIS) with soil databases and satellite-derived landcover images. Despite this advancement, the regression approach remains the basis of current state and federal level greenhouse gas inventories. Both approaches are analyzed in detail for Wisconsin forest soils from 1983 to 2001, applying rigorous error-fixing algorithms to soil databases. Resulting SOC stock estimates are 20% larger when determined using the GIS method rather than the regression approach. Average annual rates of increase in SOC stocks are 3.6 and 1.0 million metric tons of carbon per year for the GIS and regression approaches respectively.     

Gaseous mercury fluxes from the forest floor of the Adirondacks

The flux of gaseous elemental mercury (Hg⁰) from the forest floor of the Adirondack Mountains in New York (USA) was measured numerous times throughout 2005 and 2006 using a polycarbonate dynamic flux chamber (DFC). The Hg flux ranged between −2.5 and 27.2 ng m⁻² h⁻¹ and was positively correlated with temperature and solar radiation. The measured Hg emission flux was highest in spring, and summer, and lowest in winter. During leaf-off periods, the Hg emission flux was highly dependent on solar radiation and less dependent on temperature. During leaf-on periods, the Hg emission flux was fairly constant because the forest canopy was shading the forest floor. Two empirical models were developed to estimate yearly Hg⁰ emissions, one for the leaf-off period and one for the leaf-on period. Using the U.S. EPA's CASTNET meteorological data, the cumulative estimated emission flux was approx. 7.0 μg Hg⁰ m⁻² year⁻¹.     

Vertical distribution of organochlorine pesticides in humus along Alpine altitudinal profiles in relation to ambiental parameters

In forest soils along vertical profiles located in different parts of the Alps, concentrations of persistent organic pollutants (POPs), namely organochlorine pesticides (OCPs) like dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), heptachlor, aldrin, dieldrin and mirex, were measured. Though local characteristics of the sites are influenced by numerous factors like orographic and meteorological parameters, forest stand characteristics and humus parameters, we ascertained a marked vertical increase of concentrations of some organochlorine compounds in the soil. On the basis of climatological values of each site, we found that the contamination increase with altitude can be ascribed to a certain ‘cold condensation effect’. In addition, the perennial atmospheric deposition of POPs is controlled by precipitation. Other key parameters explaining the accumulation of POPs are the soil organic carbon stocks, the turnover times, the re-volatilisation and degradation processes, which vary with altitude.     

Emissions of PCDD and PCDF from combustion of forest fuels and sugarcane: a comparison between field measurements and simulations in a laboratory burn facility

Release of PCDD and PCDF from biomass combustion such as forest and agricultural crop fires has been nominated as an important source for these chemicals despite minimal characterisation. Available emission factors that have been experimentally determined in laboratory and field experiments vary by several orders of magnitude from <0.5 μg TEQ (t fuel consumed)⁻¹ to >100 μg TEQ (t fuel consumed)⁻¹. The aim of this study was to evaluate the effect of experimental methods on the emission factor.A portable field sampler was used to measure PCDD/PCDF emissions from forest fires and the same fuel when burnt over a brick hearth to eliminate potential soil effects. A laboratory burn facility was used to sample emissions from the same fuels. There was very good agreement in emission factors to air (EF_Air) for forest fuel (Duke Forest, NC) of 0.52 (range: 0.40-0.79), 0.59 (range: 0.18-1.2) and 0.75 (range: 0.27-1.2) μg TEQ_WHO2005 (t fuel consumed)⁻¹ for the in-field, over a brick hearth, and burn facility experiments, respectively. Similarly, experiments with sugarcane showed very good agreement with EF_Air of 1.1 (range: 0.40-2.2), 1.5 (range: 0.84-2.2) and 1.7 (range: 0.34-4.4) μg TEQ (t fuel consumed)⁻¹ for in-field, over a brick hearth, open field and burn facility experiments respectively. Field sampling and laboratory simulations were in good agreement, and no significant changes in emissions of PCDD/PCDF could be attributed to fuel storage and transport to laboratory test facilities.     

Determination of 99Tc deposited on the ground within the 30-km zone around the Chernobyl reactor and estimation of 99Tc released into atmosphere by the accident

Technetium-99 was determined in samples from the 30-km zone around the Chernobyl reactor. Concentrations of ⁹⁹Tc in soil samples taken from three forest sites ranged from 1.1 to 14.1 Bq kg⁻¹ dry weight for the organic soil layers, and from 0.13 to 0.83 Bq kg⁻¹ dry weight for the mineral soil layers. In particular, for the organic layers, the measured ⁹⁹Tc concentrations were one or two orders of magnitude higher than those due to global fallout ⁹⁹Tc. The ⁹⁹Tc depositions (Bq m⁻²), based on the sum of the depositions measured in organic and mineral layers, ranged from 130 Bq m⁻² within the 10-km zone to about 20 Bq m⁻² close to the border of the 30-km zone. Taking the corresponding measured ¹³⁷Cs depositions into account, it was found that the activity ratio of ⁹⁹TW/¹³⁷Cs ranged from 6 × 10⁻⁵ to 1.2 × 10⁻⁴. It was estimated that about 970 GBq of ⁹⁹Tc had been released by the Chernobyl accident. This figure corresponded to 2%–3% of the total ⁹⁹Tc inventory in the core.