Threats to Biodiversity | 生物多样性面临的威胁

📚 Threats to Biodiversity | 生物多样性面临的威胁

Biodiversity is the variety of life on Earth, from genes to species to ecosystems. It is not evenly distributed, and it is currently declining at rates far above natural background extinction. Understanding the main threats to biodiversity is essential for making evidence-based conservation decisions.

生物多样性是地球上生命的多样性，涵盖基因、物种和生态系统。它分布不均，目前正以远高于自然背景灭绝的速度下降。了解生物多样性面临的主要威胁，对于做出基于证据的保护决策至关重要。

1. Defining Biodiversity and Its Value | 生物多样性的定义与价值

Biodiversity is usually described at three levels: species diversity, genetic diversity and ecosystem diversity. Species diversity includes both species richness and evenness; genetic diversity is the variation of alleles within a population; ecosystem diversity refers to the range of habitats and ecological processes.

生物多样性通常从三个层次描述：物种多样性、遗传多样性和生态系统多样性。物种多样性包括物种丰富度和均匀度；遗传多样性是种群内等位基因的变异；生态系统多样性指生境和生态过程的范围。

High biodiversity supports ecosystem services such as pollination, nutrient cycling, soil formation and climate regulation. It also increases resilience to environmental change because more species can perform similar functional roles, providing insurance against the loss of any one species.

高生物多样性支撑传粉、养分循环、土壤形成和气候调节等生态系统服务。由于更多物种可执行相似功能，它还能提高对环境变化的恢复力，为任何单一物种的丧失提供保障。

2. Habitat Loss and Fragmentation | 栖息地丧失与破碎化

Habitat loss is the single greatest threat to terrestrial biodiversity. Clearing forest for agriculture, urban expansion, road building and mining removes the physical environment species depend on for food, shelter and reproduction.

栖息地丧失是陆地生物多样性面临的最大威胁。为农业开垦森林、城市扩张、道路建设和采矿会移除物种赖以生存的物理环境，包括食物、庇护所和繁殖场所。

Fragmentation splits large habitats into small, isolated patches. This reduces population sizes, limits gene flow between patches, increases edge effects and makes species more vulnerable to local extinction from disturbance or chance events.

破碎化将大块栖息地分割成小而孤立的斑块。这会缩小种群规模、限制斑块间的基因流动、增强边缘效应，使物种更容易因干扰或偶然事件而局部灭绝。

Deforestation for palm oil and cattle ranching / 棕榈油和养牛导致的森林砍伐
Wetland drainage for agriculture / 农业排干湿地
Urban sprawl along coastlines / 沿海城市扩张

3. Invasive Species | 外来入侵物种

Invasive species are non-native organisms that spread rapidly and harm native biodiversity. They may outcompete native species for resources, introduce diseases, or alter habitat structure such as shading out ground flora.

入侵物种是迅速扩散并危害本地生物多样性的非本地生物。它们可能争夺本地物种资源、传播疾病或改变生境结构，例如遮蔽地面植物。

Examples include the cane toad in Australia, water hyacinth in African lakes, and the grey squirrel displacing the red squirrel in Britain. Without natural predators, invasive populations can grow exponentially and dominate communities.

例子包括澳大利亚的甘蔗蟾蜍、非洲湖泊的水葫芦，以及在英国取代红松鼠的灰松鼠。由于缺乏天敌，入侵种群可呈指数增长并主导群落。

Control is expensive and often only possible before establishment. Prevention, early detection and rapid response are therefore the most cost-effective management strategies.

控制入侵物种成本高昂，而且通常只有在种群建立前才可行。因此，预防、早期发现和快速反应是最具成本效益的管理策略。

4. Overexploitation | 过度开发

Overexploitation occurs when harvesting exceeds the reproductive capacity of a population. Unsustainable fishing, hunting, logging and collection for the pet trade all reduce populations below viable levels.

过度开发指收获量超过种群的繁殖能力。不可持续的捕鱼、狩猎、伐木和宠物贸易采集都会使种群降到不可维持的水平。

Fisheries can collapse when fishing mortality exceeds recruitment. The concept of maximum sustainable yield aims to take no more than the surplus production, but illegal and unregulated harvesting often prevents this from being achieved.

当捕捞死亡率超过补充量时，渔业可能崩溃。最大可持续产量概念旨在只收获剩余生产量，但非法和无管制捕捞往往使其难以实现。

The tragedy of the commons explains why shared resources are overused: individuals gain the full benefit of harvesting, while the cost of depletion is spread across society.

公地悲剧解释了共享资源被过度使用的原因：个人获得全部收获利益，而枯竭成本却由整个社会承担。

5. Pollution | 污染

Pollution damages biodiversity through toxic chemicals, excess nutrients, plastics and noise. Pesticides and herbicides can kill non-target species, including pollinators and soil organisms, reducing ecosystem function.

污染通过有毒化学品、过量养分、塑料和噪声损害生物多样性。农药和除草剂可杀死非靶标物种，包括传粉者和土壤生物，从而降低生态系统功能。

Eutrophication from fertiliser runoff causes algal blooms; decomposition of the algae reduces dissolved oxygen and kills fish. Persistent pollutants such as heavy metals and PCBs bioaccumulate in food chains and can poison top predators.

化肥径流引起的富营养化导致藻华；藻类分解降低溶解氧并杀死鱼类。重金属和多氯联苯等持久性污染物在食物链中生物累积，可能毒害顶级捕食者。

Plastic waste causes physical harm through entanglement and ingestion. Microplastics can absorb and transport other pollutants, entering food webs at the lowest trophic levels.

塑料废物通过缠绕和误食造成物理伤害。微塑料可吸附并运输其他污染物，从最低营养级进入食物网。

6. Climate Change | 气候变化

Climate change alters temperature, precipitation and sea level. Species must move to suitable conditions, adapt genetically, or face extinction. Rapid warming exceeds the migration ability of many plants and animals.

气候变化改变温度、降水和海平面。物种必须迁移到适宜环境、遗传适应或面临灭绝。快速变暖超过许多动植物的迁移能力。

Coral bleaching occurs when elevated sea temperatures disrupt the symbiosis between corals and zooxanthellae. Ocean acidification from dissolved CO₂ reduces carbonate availability for shell-forming organisms such as molluscs and corals.

当海温升高破坏珊瑚与虫黄藻的共生关系时，会发生珊瑚白化。溶解 CO₂ 引起的海洋酸化减少了软体动物和珊瑚等造壳生物可用的碳酸盐。

Phenological mismatches arise when life cycle events, such as flowering and pollinator emergence, shift at different rates, disrupting mutualisms and food web timing.

物候错配指生活周期事件（如开花与传粉者出现）以不同速率变化，从而破坏互利关系和食物网时序。

7. Disease and Pathogens | 疾病与病原体

Emerging infectious diseases can reduce biodiversity, especially when host populations are already stressed or have low genetic diversity. Global trade and movement of animals spread pathogens to new areas where native species lack immunity.

新发传染病可降低生物多样性，尤其是宿主种群已经受到压力或遗传多样性较低时。全球贸易和动物流动将病原体传播到新地区，当地物种缺乏免疫力。

The chytrid fungus Batrachochytrium dendrobatidis has caused declines in amphibian populations worldwide. Dense populations in fragmented habitats often experience faster disease transmission, increasing mortality.

壶菌 Batrachochytrium dendrobatidis 已导致全球两栖动物种群下降。破碎化生境中的高密度种群通常疾病传播更快，死亡率增加。

Pathogens can also be transported by human activities, such as moving soil, plants or animals between regions. Biosecurity measures help reduce the risk of disease introduction.

病原体还可通过人类活动传播，例如在不同地区之间移动土壤、植物或动物。生物安全措施有助于降低疾病传入的风险。

8. Genetic Erosion and Small Populations | 遗传侵蚀与小种群

Small populations lose genetic diversity through genetic drift and inbreeding. This reduces adaptive potential and can lower fertility and survival, an effect called inbreeding depression.

小种群通过遗传漂变和近亲繁殖丧失遗传多样性。这会降低适应潜力，并可能降低生育力和存活率，称为近交衰退。

The extinction vortex describes a positive feedback loop: population decline reduces genetic diversity, which lowers fitness, causing further decline. Once entered, the vortex becomes increasingly difficult to escape.

灭绝漩涡描述正反馈循环：种群下降降低遗传多样性，从而降低适合度，导致进一步下降。一旦进入漩涡，就越来越难以逃脱。

Conservation genetics aims to maintain effective population size and gene flow. Translocations between isolated subpopulations can restore genetic variation and reduce inbreeding.

保护遗传学旨在维持有效种群大小和基因流动。在孤立亚种群之间进行个体迁移可以恢复遗传变异并减少近亲繁殖。

9. Measuring and Monitoring Threats | 威胁的测量与监测

Conservation biologists monitor biodiversity using species richness, percentage cover, and diversity indices. Simpson’s Index of Diversity is commonly used to quantify diversity:

保护生物学家使用物种丰富度、覆盖百分数和多样性指数监测生物多样性。常用辛普森多样性指数来量化多样性：

D = 1 – Σ (n / N)²

In the formula, n is the number of individuals of one species and N is the total number of individuals of all species. A value close to 1 indicates high diversity; a value close to 0 indicates low diversity.

公式中，n 是某一物种的个体数，N 是所有物种的总个体数。值越接近 1 表示多样性越高；越接近 0 表示多样性越低。

The IUCN Red List classifies species from Least Concern to Extinct based on population size, range and trend. Camera traps, environmental DNA and satellite imagery are used to detect changes in threatened species.

IUCN 红色名录根据种群大小、分布范围和趋势将物种从无危到灭绝分类。相机陷阱、环境 DNA 和卫星图像用于检测受威胁物种的变化。

IUCN category / IUCN 类别	Typical criterion / 典型标准
Endangered / 濒危	Population decline of at least 50% over 10 years or 3 generations / 10年内或3代内种群下降至少50%

10. Conservation Strategies and Evaluation | 保护策略与评估

In-situ conservation protects species in their natural habitats through protected areas, wildlife corridors and habitat restoration. Ex-situ methods include captive breeding, seed banks and botanical gardens for species that cannot survive in the wild.

就地保护通过保护区、野生动物廊道和栖息地恢复在自然生境中保护物种。迁地方法包括圈养繁殖、种子库和植物园，用于无法在野外生存的物种。

International agreements such as CITES regulate trade in endangered species. Captive breeding and reintroduction have saved species such as the Arabian oryx, but ex-situ populations often have limited genetic diversity and may not survive in the wild.

CITES 等国际协定管制濒危物种贸易。圈养繁殖和重引入已拯救阿拉伯大羚羊等物种，但迁地种群通常遗传多样性有限，可能无法在野外生存。

Effective conservation usually combines habitat protection, community involvement and sustainable resource use. Evaluating success requires long-term monitoring of population size, habitat area and ecosystem function, not just the number of individuals released.

有效保护通常结合栖息地保护、社区参与和资源可持续利用。评估成功需要长期监测种群大小、栖息地面积和生态系统功能，而不仅仅是释放的个体数量。

Published by TutorHao | Biology Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）

Threats to Biodiversity | 生物多样性面临的威胁