✦ SCIENCE ACCESS LAB

00 · Interactive Unit Notebook

Human Impacts on Ecosystems

What changes when people reshape land, move materials and make conservation decisions?

Learning targets / Objetivos

1. Explain how land use and resource use can alter ecosystems. 2. Interpret runoff and water-quality evidence without overclaiming causation. 3. Evaluate conservation actions using measurable outcomes.

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01 · Land becomes a watershed

USGS urban-stream field research
Photo unavailable / Foto no disponible · USGS urban-stream field research
USGS urban land-use collection · Public Domain · Context image, not a measurement. / Imagen de contexto, no una medición.

In a city, rain can travel quickly over sealed surfaces. In a forest, more water may infiltrate into soil. Roads can also separate habitat patches. These mechanisms are not universal: soil, slope and storm intensity matter.

Conceptual model · not field data / Modelo conceptual, no datos reales

Impervious surface → less infiltration → potentially more surface runoff → possible downstream effects

02 · Follow runoff to the creek

Stormwater pipe draining into a creek
Photo unavailable / Foto no disponible · Stormwater pipe draining into a creek
USGS stormwater discharge · Public Domain · Context image, not a measurement. / Imagen de contexto, no una medición.

Stormwater can carry sediment and dissolved nutrients. Suspended sediment increases turbidity and can reduce light to submerged plants. Excess nutrients can stimulate algal blooms; respiration and decomposition may lower dissolved oxygen. A photograph cannot identify a chemical pollutant.

03 · Test conservation decisions

Hydrologically restored wetland
Photo unavailable / Foto no disponible · Hydrologically restored wetland
Kurt Kowalski / USGS · Public Domain · Context image, not a measurement. / Imagen de contexto, no una medición.

Restoration may reconnect habitats or improve water flow. Evidence of success requires repeated measurements of ecological function, ideally before and after intervention and at a reference site. A greener photo alone is not proof of recovery.

Field vocabulary / Vocabulario de campo

Impervious surface

Land cover that greatly limits water infiltration.

Runoff

Water flowing over the land surface.

Infiltration

Water entering soil or permeable ground.

Habitat fragmentation

Separation of habitat into smaller patches.

Connectivity

Opportunity for organisms to move between habitats.

Turbidity

Cloudiness caused by suspended particles.

Dissolved oxygen

Oxygen available in water for aquatic respiration.

Nutrients

Substances such as nitrogen and phosphorus that support growth.

Species richness

Number of species observed in a sampled area.

Restoration

Actions intended to recover ecological processes or habitat.

Reference site

Comparable location used to interpret change.

Tradeoff

A benefit gained while another objective may face a cost.

Scientific Thinking / Pensamiento científico

Observation: water became cloudier after rain. Inference: sediment may have arrived through runoff. To test the inference, compare matched storm events and locations, then consider alternative sources. Observation does not automatically prove cause.

Photo captions label real locations; all assessment datasets in this unit are invented for practice and are explicitly hypothetical.