College Board AP® Environmental ScienceUNIT 5 · CED TOPIC 5.2
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CED Topic 5.2 · 知识引导
Clearcutting
EIN-2.BLearning Objective · 学习目标
Describe the effect of clearcutting on forests.
描述皆伐对森林的影响。
Clearcut slope — this is what 'no root system' looks like
ESSENTIAL KNOWLEDGE · CED 原文（2 条，点开对照）
- EIN-2.B.1Clearcutting can be economically advantageous but leads to soil erosion, increased soil and stream temperatures, and flooding.
- EIN-2.B.2Forests contain trees that absorb pollutants and store carbon dioxide. The cutting and burning of trees releases carbon dioxide and contributes to climate change.
核心要点 · What actually gets tested
- Clearcutting 皆伐 = 一次性砍光整片林子（不是择伐 selective cutting）
- 经济上有利：效率高、成本低 —— 这是它存在的理由，别只写坏处
- 后果四连：土壤侵蚀 · 土壤与溪流温度升高 · 洪水 · 碳排放
- 失去树冠 = 失去遮阴 → 溪流升温 → 溶氧下降 → 水生生物受损
- 失去根系 = 没有东西固土 → 雨水直接冲走 A 层表土
Clearcutting 皆伐：把一片林地上的树木全部砍伐移除的采伐方式。对比：selective cutting 择伐只砍特定树木，保留林冠结构和根系 —— FRQ 里常让你比较两者。
官方关键词 · Key Terms
clearcutting 皆伐selective cutting 择伐soil erosion 土壤侵蚀flooding 洪水carbon sink 碳汇stream temperature 溪流温度
AP® EXAM TIP
CED 原文明确写了 economically advantageous。答题时如果只列坏处，会被判为「分析不全面」。正确写法：短期经济收益 vs 长期环境成本，两边都要写。
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引导提问：为什么皆伐之后河里的鱼会减少？写出从「树木消失」到「鱼减少」的完整因果链（至少 4 步）。
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College Board AP® Environmental ScienceUNIT 5 · CED TOPIC 5.5
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CED Topic 5.5 · 知识引导
Irrigation Methods
EIN-2.ELearning Objective · 学习目标
Describe different methods of irrigation.
描述不同的灌溉方式。
EIN-2.FLearning Objective · 学习目标
Describe the benefits and drawbacks of different methods of irrigation.
描述不同灌溉方式的利弊。
Drip irrigation tape delivering water straight to the root zone
ESSENTIAL KNOWLEDGE · CED 原文（7 条，点开对照）
- EIN-2.E.1The largest human use of freshwater is for irrigation (70%).
- EIN-2.E.2Types of irrigation include drip irrigation, flood irrigation, furrow irrigation, drip irrigation, and spray irrigation.
- EIN-2.F.2Furrow irrigation involves cutting furrows between crop rows and filling them with water. This system is inexpensive, but about 1/3 of the water is lost to evaporation and runoff.
- EIN-2.F.3Flood irrigation involves flooding an agricultural field with water. This system sees about 20% of the water lost to evaporation and runoff. This can also lead to waterlogging of the soil.
- EIN-2.F.5Drip irrigation uses perforated hoses to release small amounts of water to plant roots. This system is the most efficient, with only about 5% of water lost to evaporation and runoff. However, this system is expensive and so is not often used.
- EIN-2.F.1Waterlogging occurs when too much water is left to sit in the soil, which raises the water table of groundwater and inhibits plants’ ability to absorb oxygen through their roots.
- EIN-2.F.4Spray irrigation involves pumping ground water into spray nozzles across an agricultural field. This system is more efficient than flood and furrow irrigation, with only 1/4 or less of the water lost to evaporation or runoff. However, spray systems are more expensive than flood and furrow…
核心要点 · What actually gets tested
- 🌍 淡水最大的人为用途是灌溉，占 70% —— 这是必背数字
- 四种方式：furrow 沟灌 · flood 漫灌 · spray 喷灌 · drip 滴灌
- 效率排序：drip 最高效（约 5% 损失） > flood（20%）> spray（≤1/4）> furrow（约 1/3）
- 但 drip 和 spray 更贵；furrow 最便宜 —— 效率与成本反向
- 三大副作用：waterlogging 渍水 · salinization 盐碱化 · aquifer depletion 地下水超采
Salinization 盐碱化：灌溉水蒸发后，溶解的盐分留在土壤中并逐年累积，最终使土壤对植物有毒。干旱区灌溉农业的头号土壤问题。
官方关键词 · Key Terms
drip irrigation 滴灌flood irrigation 漫灌furrow irrigation 沟灌spray irrigation 喷灌waterlogging 渍水salinization 盐碱化aquifer depletion 地下水超采
AP® EXAM TIP
「最高效 vs 最便宜」是本 topic 的核心矛盾，也是 MCQ 最爱挖的坑：
题目问 most efficient → 选 drip
题目问 least expensive → 选 furrow
题目问为什么用得不广 → 答 expensive
题目问 most efficient → 选 drip
题目问 least expensive → 选 furrow
题目问为什么用得不广 → 答 expensive
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引导提问：美国中部 Ogallala 含水层被抽了几十年。它属于可再生资源还是不可再生？理由是什么？
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College Board AP® Environmental ScienceUNIT 5 · CED TOPIC 5.7
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CED Topic 5.7 · 知识引导
Meat Production Methods
EIN-2.HLearning Objective · 学习目标
Identify different methods of meat production.
识别不同的肉类生产方式。
EIN-2.ILearning Objective · 学习目标
Describe the benefits and drawbacks of different methods of meat production.
描述不同肉类生产方式的利弊。
A concentrated animal feeding operation (CAFO)
ESSENTIAL KNOWLEDGE · CED 原文（7 条，点开对照）
- EIN-2.H.1Methods of meat production include concentrated animal feeding operations (CAFOs), also called feedlots, and free-range grazing.
- EIN-2.I.1Meat production is less efficient than agriculture; it takes approximately 20 times more land to produce the same amount of calories from meat as from plants.
- EIN-2.I.4Overgrazing occurs when too many animals feed on a particular area of land. Overgrazing causes loss of vegetation, which leads to soil erosion.
- EIN-2.I.5Overgrazing can cause desertification. Desertification is the degradation of low precipitation regions toward being increasingly arid until they become deserts.
- EIN-2.I.2Concentrated animal feeding operations (CAFOs) are used as a way to quickly get livestock ready for slaughter. They tend to be crowded, and animals are fed grains or feed that are not as suitable as grass. Additionally, feedlots generate a large amount of organic waste, which can contaminate ground…
- EIN-2.I.3Free range grazing allows animals to graze on grass during their entire lifecycle. Meat from free range animals tends to be free from antibiotics and other chemicals used in feedlots. Organic waste from these animals acts as fertilizer. Free range grazing requires large areas of land and the meat…
- EIN-2.I.6Less consumption of meat could reduce CO2, methane, and N2O emissions; conserve water; reduce the use of antibiotics and growth hormones; and improve topsoil.
核心要点 · What actually gets tested
- 两种方式：CAFO / feedlot 集中饲养 与 free-range grazing 散养放牧
- 🔢 核心数字：同样热量，肉类需要约 20 倍于植物的土地
- CAFO：成本低、肉价便宜，但粪便量大污染水体、需抗生素、产生甲烷
- Free-range：无抗生素、粪便作肥，但需要大面积土地、肉价更贵
- Overgrazing 过度放牧 → 植被消失 → 土壤侵蚀 → desertification 荒漠化
Desertification 荒漠化：低降水地区因过度放牧/不合理耕作而持续退化、越来越干旱，最终变成沙漠的过程。注意：它是土地退化，不是沙漠自然扩张。
官方关键词 · Key Terms
CAFO / feedlot 集中动物饲养场free-range grazing 散养放牧overgrazing 过度放牧desertification 荒漠化rotational grazing 轮牧
AP® EXAM TIP
CED 原文列了「少吃肉」的 5 条好处，FRQ 里能默写就有分：
减少 CO₂ / CH₄ / N₂O 排放 · 节约水 · 减少抗生素与生长激素使用 · 改善表土（还有一条是降低土地需求）。
减少 CO₂ / CH₄ / N₂O 排放 · 节约水 · 减少抗生素与生长激素使用 · 改善表土（还有一条是降低土地需求）。
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引导提问：营养级能量传递效率只有约 10%。用这个数字解释为什么肉类需要 20 倍土地（提示：不是正好 10 倍，想想还有哪些损耗）。
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College Board AP® Environmental ScienceUNIT 5 · CED TOPIC 5.9
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CED Topic 5.9 · 知识引导
Impacts of Mining
EIN-2.KLearning Objective · 学习目标
Describe natural resource extraction through mining.
描述采矿式的自然资源开采。
EIN-2.LLearning Objective · 学习目标
Describe ecological and economic impacts of natural resource extraction through mining.
描述采矿的生态与经济影响。
Open-pit mine — the scale of the overburden is the story
ESSENTIAL KNOWLEDGE · CED 原文（4 条，点开对照）
- EIN-2.K.1As the more accessible ores are mined to depletion, mining operations are forced to access lower grade ores. Accessing these ores requires increased use of resources that can cause increased waste and pollution.
- EIN-2.K.2Surface mining is the removal of large portions of soil and rock, called overburden, in order to access the ore underneath. An example is strip mining, which removes the vegetation from an area, making the area more susceptible to erosion.
- EIN-2.L.1Mining wastes include the soil and rocks that are moved to gain access to the ore and the waste, called slag and tailings that remain when the minerals have been removed from the ore. Mining helps to provide low cost energy and material necessary to make products. The mining of coal can destroy…
- EIN-2.L.2As coal reserves get smaller, due to a lack of easily accessible reserves, it becomes necessary to access coal through subsurface mining, which is very expensive.
核心要点 · What actually gets tested
- Surface mining 地表开采：移除大片土石（overburden 覆盖层）以取得下方矿石
- 典型形式：strip mining 露天剥离开采 —— 清除植被，使地表更易侵蚀
- 废弃物两类：slag 炉渣 和 tailings 尾矿（矿物被提取后剩下的东西）
- 品位下降定律：易采矿石耗尽 → 转向低品位矿 → 更多资源投入 + 更多废石与污染
- 煤矿尤其：破坏栖息地 · 污染地下水 · 释放粉尘与甲烷
Overburden 覆盖层：覆盖在矿体之上的土壤和岩石，必须先整体剥离才能采矿。它被移走后植被全无，是地表开采造成侵蚀的直接原因。
官方关键词 · Key Terms
surface mining 地表开采strip mining 剥离开采overburden 覆盖层slag 炉渣tailings 尾矿ore grade 矿石品位subsurface mining 井下开采
AP® EXAM TIP
slag 和 tailings 要分清：
slag 炉渣 = 冶炼过程中产生的玻璃质废渣
tailings 尾矿 = 选矿后剩下的细粒废浆
两者常一起考，混用会丢分。
slag 炉渣 = 冶炼过程中产生的玻璃质废渣
tailings 尾矿 = 选矿后剩下的细粒废浆
两者常一起考，混用会丢分。
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引导提问：为什么开采低品位矿会产生「更多」污染？如果技术进步提高了开采效率，这个趋势会反转吗？
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College Board AP® Environmental ScienceUNIT 5 · CED TOPIC 5.10
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CED Topic 5.10 · 知识引导
Impacts of Urbanization
EIN-2.MLearning Objective · 学习目标
Describe the effects of urbanization on the environment.
描述城市化对环境的影响。
Urban sprawl seen from above — pavement as far as the eye can see
ESSENTIAL KNOWLEDGE · CED 原文（4 条，点开对照）
- EIN-2.M.1Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle.
- EIN-2.M.2Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
- EIN-2.M.3Impervious surfaces are human-made structures—such as roads, buildings, sidewalks, and parking lots—that do not allow water to reach the soil, leading to flooding.
- EIN-2.M.4Urban sprawl is the change in population distribution from high population density areas to low density suburbs that spread into rural lands, leading to potential environmental problems.
核心要点 · What actually gets tested
- Impervious surfaces 不透水面：道路、建筑、人行道、停车场 —— 水到不了土壤
- 直接后果：径流增加 → 洪水，同时地下水补给减少
- Saltwater intrusion 海水入侵：超采地下水导致海水倒灌进淡水含水层
- 碳循环：化石燃料燃烧 + 垃圾填埋 → 大气 CO₂ 增加
- Urban sprawl 城市蔓延：人口从高密度区迁往低密度郊区，吞并乡村土地
Impervious surface 不透水面：人造结构（道路、建筑、人行道、停车场），阻止水分到达土壤。它同时造成两件事：径流增加（洪水）和下渗减少（地下水补给不足）。
官方关键词 · Key Terms
impervious surface 不透水面urban sprawl 城市蔓延saltwater intrusion 海水入侵urban heat island 城市热岛runoff 地表径流infiltration 下渗
AP® EXAM TIP
FRQ 常给一张城市地图让你分析径流问题。标准答案链条：
more impervious surfaces → less infiltration → more surface runoff → increased flooding + reduced groundwater recharge
还要补一句 urban heat island（城市热岛）如果题目提到温度。
more impervious surfaces → less infiltration → more surface runoff → increased flooding + reduced groundwater recharge
还要补一句 urban heat island（城市热岛）如果题目提到温度。
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引导提问：一个城市把郊区的农田改成了购物中心。用 CED 的三个 EK 分别说明：水循环、碳循环、土地分布各发生了什么变化？
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