The Iowa Graduated Driver Licensing program: effectiveness in reducing crashes of teenage drivers

PROBLEM: Graduated Driver Licensing (GDL) programs vary in the United States in terms of implementation and restrictions. The State of Iowa's GDL program is assessed for its effectiveness in reducing crashes among teenage drivers. METHOD: Time series analysis was used to evaluate police documented crashes involving 16-, 17-, and 18-year-old drivers over a 10 year period, with an intervention identified at the point of GDL implementation. RESULTS: After controlling for seasonal trends and auto-correlative effects, a significant reduction in the crash rate of and 16- and 17-year-old drivers was observed due to the GDL implementation. However, there were no significant reductions in crash rates for 18-year-old drivers. DISCUSSION: The analyses suggest that the Iowa GDL program is effective in reducing the crash rates of 16- and 17-year-old drivers but the effects do not sustain for 18-year-old drivers. IMPACT ON INDUSTRY: The results suggest that the program appears to be working, however further analysis is needed to determine what factors are preventing lasting effects for these teenage drivers.     

Effect of acid precipitation on leaching of nutritionsand aluminium from forest soils

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Organizational learning during policy implementation: lessons from U.S. forest planning

ABSTRACT

Learning is critical for land management agencies implementing new policies in the face of rapid social and ecological change. We investigated learning in the U.S. Forest Service as it implemented new planning regulations. Our research objectives were to: (1) identify collective learning processes and outcomes during this time, and (2) understand factors within the organization supporting or impeding learning. Based on participant observation and 25 interviews with planning personnel, we found evidence of collective learning on individual national forests and across the organization. Several factors helped the agency act as a ‘learning organization,’ including internal networks and tools for information sharing, and meetings for staff to exchange lessons learned. Learning was compromised by limited time and capacity, and lack of internal clarity about balancing the desire for innovation with the need to ensure legal compliance and meet deadlines. This work contributes to the empirical foundations of collective learning theory, allowing us to identify learning processes and outcomes at multiple levels in a public organization, and identifying topics for future research. Based on our exploration of organizational learning, we offer suggestions for how to effectively support learning during times of new policy implementation.     

林业生产经营单位安全管理创新的几点思考

分析了当前安全生产管理现状,对林业生产经营单位安全生产管理创新进行探讨,旨在进一步提高安全管理水平。     

泵串联水灭火系统在森林防火方面的应用

现阶段为了适应国际及国内防火形势,出现了以水灭火为主要形式的灭火方式,并且在实际灭火中体现出巨大的优势.其中泵串联水灭火就是一种很好的形式.林海集团设计了一套远距离接力水泵串联供水灭火系统,尝试以手抬水泵(消防泵)接力供水的方式,从有水源的地方经过消防泵的增压,通过消防水带输送到火场,为水灭火工作提供条件,以实现水灭火.     

兴安落叶松林火后对土壤养分和土壤微生物生物量的影响

以大兴安岭兴安落叶松林火后不同强度(重度、中度、轻度)及未火烧区的土壤为研究对象,于火烧结束3年后(2009年)的秋季,采用氯仿熏蒸浸提法测定了不同强度火烧后土壤的微生物生物量碳(C_mic)和微生物生物量氮(N_mic),并研究其与土壤养分因子的关系。结果表明:兴安落叶松林重度火烧区的C_mic显著高于中度、轻度和未火烧区,N_mic在不同强度火烧样地间差异不显著,但在重度火烧区出现最高值。其中重度、中度、轻度和对照的C_mic平均为692.8、499.9、428.8和498.7 mg·kg^-1,而N_mic分别为70.6、55.2、50.9和54.1 mg·kg^-1。土壤含水量、土壤pH值、土壤有机碳对C_mic和N_mic的影响显著,土壤微生物生物量与土壤含水量、pH值、土壤有机碳均呈正相关。研究将为进一步开展火干扰对北方森林土壤碳平衡影响机理研究提供科学依据。     

林地面积增加提高了农户营林积极性吗?——基于9省1 504个农户数据的倾向值匹配分析

论文利用9省1 504个农户调研数据,实证检验了新一轮集体林改后林地面积增加对农户营林积极性的因果效应。考虑到农户对林地经营面积决策的内生性问题,采用倾向值匹配方法对选择性偏差进行控制。匹配后,处理组和控制组在多个标准上均通过了平衡性检验。结果显示,林地面积增加确实促进了农户营林积极性的提高,但这是一个缓慢的动态调整过程。其中,资本投入强度在2010年以后才逐步表现为显著增加,增长率约为25%~27%,2013年进一步强化为28%~34%。资本投入强度的增加主要是由化肥和农药投入增加引起的,对种苗的投入强度并没有显著改善。这种差异说明,新一轮林改提高了农户的森林经营和管护积极性,但对造林行为的影响有限。同时农户并没有因为林地面积增加而显著提高劳动力的投入强度。这种资本对劳动的替代与农户的非农就业行为密切相关。     

生态环境影响评价中经济评价方法研究

随着中国生态环境影响评价的开展,中国正在积极推进生态经济评价预测层次上的环评,对其评价方法提出了更高的要求。当前国内外所用生态价值评价方法缺乏环境与经济相联系起来和在决策中体现生态环评结果的方法,缺乏量化评价指标体系及评价方法,没有从系统的角度考虑一个动态的、复杂系统的环境影响因素。在系统分析生态环境影响评价中经济评价方法的基础上,对吉林省三岔子林业局天然林生态系统中保持水土、涵养水源、调节气候、净化大气等生态价值进行生态环境影响经济分析、预测、评价,首先建立该区天然林生态系统服务价值评估指标体系,并结合野外调查测量及实地数据分析,初步对天然林生态系统价值进行测算;其次利用灰色系统预测分析,对2009年-2028年三岔子林业局天然林生态系统价值进行预测,最后计算出天然林生态系统带来的经济效益。     

森林保险支付意愿及影响因素分析——基于异质性营林主体视角

基于期望效用函数理论分析了异质性营林主体的森林保险支付意愿及差异,并以传统小林农和新型林业经营主体为研究对象,以福建省382户传统小林农和88户新型林业经营主体的调研数据为基础,综合运用条件估值法、卡方检验及Cox比例风险模型,对异质性营林主体的森林保险支付意愿与差异及支付意愿影响因素进行对比与分析。研究表明：传统小林农和新型林业经营主体的森林保险意愿支付水平存在显著差异,在1000~2500元/亩保障水平下,传统小林农的意愿支付水平分别为1.911元/亩、2.941元/亩、3.532元/亩及3.979元/亩,新型林业经营主体为1.632元/亩、3.971元/亩、5.809元/亩及6.864元/亩;两类营林主体的支付意愿均随保额的提高而提高,但新型林业经营主体的提升幅度远高于小林农。异质性营林主体的森林保险支付意愿影响因素也存在明显差别,这与其在森林保险认知特征、林业生产经营特征、林业灾损特征、森林保险产品评价特征等方面存在显著差异有关。此外,林地面积对两类营林主体支付意愿均具有显著影响,规模化、集约化的林业生产经营可促进林业经营主体的森林保险愿意支付水平。     

秦岭火地塘森林水质的季节性变化特征

在秦岭火地塘林区选择2个闭合小流域及2个支沟集水区,对流域出口径流及支沟集水区溪流水pH值及水化学成分进行了8 a的测试,采用机理分析方法,就森林水质的季节性变化特征进行了研究.结果表明,林区径流pH值在7.1～8.4之间,冬、春季较高,夏、秋季较低,总体上水呈弱碱性;NO-3浓度春季和初夏较高,NH 4冬季和初春较高,PO3-4冬季与夏季较高;K 浓度春、秋季较高,Na 浓度则9月最大,8月最小;Ca2 浓度以6月和10月较高,年内变化范围19.4～44.3 mg·L-1,Mg2 则3月较高,年内变化范围2.18～5.25 mg·L-1;Cd浓度随季节的变化以1～4月较高,Pb浓度12、1月较高,但Cd、Pb均以秋季较低,年内变化范围分别为0.019～0.326 5 μg稬-1和0.217～3.886 μh稬-1;Mn浓度5、12月较高,Fe浓度春季较高,Zn则以3、8月较高.林区径流水质属Ⅰ类,相对而言,水质随季节的变化以秋季较好,冬、春季较差.