YOUTH CLIMATE MAPPING EXTERNSHIP · 2026 COHORT

Impacts of Land Use

and Land Cover Change

on Karura Forest

2016 – 2026

A ten-year NDVI-based assessment of vegetation change, prepared as the Session 1 Group Project — Scope, Deliverables, Mapping Sprint & Output Checklist.

Prepared by Group 5 UN mappers

SESSION 1 · GROUP PROJECT BRIEF

Scope

What this project covers

Study area: Karura Forest Reserve, Nairobi County: the full gazetted boundary, including the main block and the eastern and western extensions.

Time horizon: A ten-year change window: 2016 (baseline), 2020 (mid-point), and 2026 (current), using NDVI as the indicator of vegetation conditions.

Indicator: Normalized Difference Vegetation Index (NDVI), Band 1 (Gray), used as a proxy for canopy density, greenness, and land cover integrity.

Question addressed: How have land use and land cover within and around Karura Forest changed over the decade, and where are the hotspots of vegetation loss or degradation?

PROJECT AT A GLANCE

Group

Group 5

Site

Karura Forest, Nairobi

Area extent (approx.)

26 km E–W × 17 km N–S grid frame

Years analyzed

2016 · 2020 · 2026

Data layer

NDVI, single-band raster

Scale reference

1.5 km scale bar on each map

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SESSION 1 · GROUP PROJECT BRIEF

Deliverables

01

NDVI Map Series

Three standalone NDVI maps of Karura Forest for 2016, 2020, and 2026, each with title, legend, scale bar, and north arrow.

02

Comparative Analysis

A side-by-side reading of NDVI range and spatial pattern shifts across the decade, flagging areas of gain or loss.

03

Map Output Checklist

A completed quality checklist confirming every cartographic element required by the brief is present on each map.

04

Group Presentation

This slide deck, summarizing scope, method, findings, and recommendations for the externship review session.

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SESSION 1 · GROUP PROJECT BRIEF

Mapping Sprint Instructions

Workflow followed to produce the three NDVI outputs

1

Define the study boundary

Import the Karura Forest reserve boundary and use it to clip all raster processing to a common extent.

2

Acquire imagery per year

Source cloud-free satellite imagery for 2016, 2020, and 2026 covering the same forest extent and season where possible using Copernicus.

3

Compute NDVI

Calculate NDVI (Band 1, Gray) for each year's imagery using the standard NIR–Red band ratio.

4

Symbolize consistently

Apply a comparable green-to-orange/red color ramp across all three years so visual change reads accurately.

5

Lay out the map

Add title, legend, appropriate scale bar, and north arrow to each map using the shared guidelines.

6

Export and label

Export each map as a labeled image (NDVI 2016 / 2020 / 2026) and file it under Group 5's designs.

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SESSION 1 · GROUP PROJECT BRIEF

Map Output Checklist

Verified against the three submitted NDVI maps (2016 / 2020 / 2026)

Checklist item

Verification

✓

Descriptive title on every map

Present — "KARURA FOREST NDVI (year)" on all three

✓

Legend with band and value range

Present — Band 1 (Gray) with min/max NDVI shown

✓

Scale bar

Present — 0 / 0.75 / 1.5 km bar on all three

✓

North arrow

Present — top-right on all three

✓

Study area boundary outline

Present — "Karura Forest" outline layer shown

✓

Coordinate grid

Present — gridlines at 5-unit intervals

✓

Consistent color ramp across years

Present — green (high NDVI) to orange/red (low NDVI)

✓

Author / group credit

Present — "Designs by Group 5" on all three maps

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FINDINGS · MAP 1 OF 3

NDVI — 2016 (Baseline)

NDVI RANGE

0.676105

maximum (dense canopy)

-0.142723

minimum (bare / stressed)

READING THE MAP

Wide, contiguous high-NDVI canopy across the main block; low-NDVI (orange/red) patches limited mainly to the eastern arm and river-edge clearings.

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FINDINGS · MAP 2 OF 3

NDVI — 2020 (Mid-point)

NDVI RANGE

0.648460

maximum (dense canopy)

-0.062229

minimum (bare / stressed)

READING THE MAP

Canopy remains broadly intact; a visible pale patch inside the central block and mild spread of low-NDVI clusters along the eastern boundary and river.

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FINDINGS · MAP 3 OF 3

NDVI — 2026 (Current)

NDVI RANGE

0.659508

maximum (dense canopy)

0.005169

minimum (bare / stressed)

READING THE MAP

Narrower NDVI range overall — fewer very-low outliers, but denser orange/red clustering along the eastern arm, river corridor, and western extension edges.

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FINDINGS

Comparative Analysis, 2016 – 2026

Interpretation

• The NDVI floor has risen steadily from -0.14 in 2016 to +0.005 in 2026, meaning the most degraded pixels in the reserve are less extreme than a decade ago.
• The NDVI ceiling has drifted slightly downward, from 0.676 (2016) to 0.648 (2020) to 0.659 (2026), suggesting peak canopy vigor has softened rather than intensified.
• Spatially, low-NDVI (orange/red) clusters concentrate along the eastern arm, the river corridor, and the western extension boundary in all three years and appear denser in 2026 than in 2016.
• Together, this points to a forest that is more spatially even but has more edge-zone pressure, consistent with encroachment, path/infrastructure widening, or land-use change at the reserve's margins rather than in the core.

NDVI RANGE SHIFT

2016

-0.143

0.676

2020

-0.062

0.648

2026

0.005

0.659

Left edge = minimum NDVI (bare/stressed); right edge = maximum NDVI (dense canopy). Bars show each year's full observed range on the same scale.

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SOLUTIONS

How to Address the Problem

Four intervention areas targeting the eastern arm, river corridor, and extension edges identified in the analysis

🛰

Monitor

Repeat this NDVI sprint every year on the same boundary and color ramp. Set an alert threshold so any new low-NDVI cluster at the edges triggers a field check within weeks, not years.

🚧

Protect the boundary

Reinforce and regularly patrol the eastern arm and western extension edges the two zones where low-NDVI clustering is densest and growing. Fix or fence gaps where encroachment paths have formed.

🌱

Restore degraded patches

Prioritize replanting in the river-corridor clearings and the eastern-arm hotspots with indigenous species, starting with the pixels showing the steepest NDVI decline between 2020 and 2026.

🤝

Engage neighboring communities

Work with adjacent settlements and land users on agreed buffer-zone rules and livelihood alternatives, since edge pressure typically tracks human activity at the boundary rather than the forest core.

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SOLUTIONS

Implementation Roadmap

A phased sequence turning the four intervention areas into action

NOW – 3 MONTHS

Immediate

• Field-verify the 2026 low-NDVI clusters on the eastern arm and river corridor
• Patrol and flag boundary gaps at the western extension edge
• Set the annual NDVI monitoring cadence and alert threshold

3 – 12 MONTHS

Short-term

• Begin indigenous-species replanting at the confirmed degraded patches
• Open buffer-zone discussions with adjacent communities and land users
• Repair or fence confirmed encroachment paths

1 – 3 YEARS

Medium-term

• Track NDVI recovery on restored patches against the 2026 baseline
• Formalize community buffer-zone agreements and livelihood support
• Expand monitoring to cover any newly emerging edge hotspots

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CONCLUSION & RECOMMENDATIONS

A more even, more pressured forest

What the maps show

• Karura Forest's core canopy has remained largely stable across 2016–2026, with high-NDVI cover persisting through the main and western blocks.
• The clearest change is at the margins: the eastern arm, river corridor, and extension boundaries show a denser spread of low-NDVI zones by 2026.

How the response follows through

• Four intervention areas — monitoring, boundary protection, restoration, and community engagement — target those same edge zones directly.
• A phased roadmap sequences those interventions from immediate field verification through medium-term recovery tracking.
• Success is measured the same way the problem was found: the NDVI floor should keep rising and edge-zone clusters should shrink at each annual check.

Group 5 · Youth Climate Mapping Externship, 2026 Cohort