---
title: does protecting one parcel help the land around it
canonical_url: https://ensurance.app/guide/does-protecting-one-parcel-help-the-land-around-it
markdown_url: https://ensurance.app/guide/does-protecting-one-parcel-help-the-land-around-it.md
subtitle: "mostly yes, and the reach depends on what is moving"
category: ecosystem-services
---

# does protecting one parcel help the land around it

*mostly yes, and the reach depends on what is moving*

Mostly yes. When a forest, a wetland, or a stretch of river is protected, the land around it usually gets measurably better: more vegetation, more pollinators, cooler ground near the edge, smaller floods below. Ecologists call this **ecological spillover** (not the disease sense of the word). The reach of it depends on what is moving across the boundary, and that is the part worth understanding before you buy, protect, or fund anything.

The parcel in question is a living thing before it is a line on a plat: a protected forest beside a working one, a wetland above a town. It exists whether or not anyone pays for it. [**Ensurance**](/?from=guide) is how the parcels that stand on it can pay it. It is not the parcel. When one parcel holds up far more than its own acres, this series calls it a [keystone parcel](/guide/what-is-a-keystone-parcel?from=guide).

:::johnson
**protection spills over more often than it leaks.** — Across 2,575 effective protected areas, fewer than 12% pushed deforestation onto the land around them. More than half slowed it there too.

[see which places hold others up →](/explore?from=guide)
:::

## the objection first

The usual worry runs the other way. Protect one parcel, the argument goes, and you push the logging, the grazing, or the clearing onto the parcel next door. That is called **leakage**, and it is real in some places.

Four words cover the possibilities. **Spillover** is a benefit crossing the boundary outward. **Leakage** is harm displaced across it. **Blockage** is a protected area slowing clearing on the land around it, for example by closing an access route or holding back a frontier. **Displacement** is activity that moves rather than ends. Cumming's 2025 paper in *Frontiers in Ecology and the Environment* sets out the definitions and how to measure each, and it is the clearest place to start.

A 2019 systematic review found leakage to be the exception. Across 2,575 protected areas that were effective inside their own boundaries, fewer than 12% showed deforestation leaking to the surrounding land. Over half, 54%, showed the opposite: clearing slowed on the land around them too. A third showed no measurable effect either way. Spillover, not leakage, is the common case.

These studies watch the land next door. They do not see leakage through markets, when less timber cut here means more cut somewhere else. That is a separate question, and forest economists treat it as one.

## the evidence

Two kinds of evidence sit in this table. The first two rows compare protected land with land that was not protected, and measure what protection changed next door. The other four measure what intact habitat does for its neighbors, which is what protection keeps standing. Both point the same way.

| what moves | what was measured | finding |
|---|---|---|
| Vegetation condition | 3,063 Australian protected areas, land within 5 km | 71% produced positive vegetation spillover (Cumming 2025, *Nature*) |
| Deforestation pressure | 2,575 effective protected areas worldwide | Under 12% leakage, 54% blockage, 33% no effect (Fuller et al. 2019) |
| Pollinators | 41 crop systems worldwide | Wild pollinators from adjacent habitat raised fruit set regardless of honey bee numbers (Garibaldi et al. 2013) |
| Temperature | Under forest canopy against open ground, global synthesis | Maximum temperatures about 4.1°C lower on average under canopy (De Frenne et al. 2019); how far that carries past the edge is the microclimate row in the next table |
| Flood water | Otter Creek wetlands above Middlebury, Vermont | Flood damage to the town reduced by 54–78% (Watson et al. 2016) |
| Storm surge | Coastal wetlands in Hurricane Sandy's path | An estimated $625 million in damages avoided (Narayan et al. 2017) |

[Wild bees and honey bees are not the same service](/guide/wild-bees-and-honey-bees-are-not-the-same-service?from=guide) goes deeper on the pollination row. This page does not repeat it.

## seven ways a parcel reaches past its fence

Spillover is not one thing. It is at least seven, and each travels a different distance. The table is a synthesis by the ecologist Jay Gutierrez, whose work on the structural side of this appears in [the dependency your map can't see](/guide/the-dependency-your-map-cant-see?from=guide). The distances are typical ranges, not rules.

| mechanism | what crosses the boundary | typical reach |
|---|---|---|
| Pollination and reproduction | Bees, flies, seed carriers | 600 m to 3 km |
| Trophic regulation and biocontrol | Predatory insects, birds, bats | 100 m to 5 km |
| Hydrology | Water, its timing, its sediment | Tens of meters sideways, the whole watershed downstream |
| Microclimate | Shade, humidity, wind shelter | 50 to 200 m into the open |
| Soil and belowground life | Fungal networks, organic matter, infiltration | Tens to hundreds of meters |
| Fire and disturbance | Fuel moisture, fuel continuity | 100 m to 1 km, depending on fuel |
| Genetic flow | Genes, over generations | Years to decades |

Two things follow. A parcel that sits where several of these overlap, a riparian forest, say, with water, shade, soil, and fuel moisture all crossing its edge at once, reaches further than its acreage suggests. And the hydrology row is why a headwater parcel matters to an intake it will never see: water carries the benefit along the flow path, thinning as other land drains in, rather than fading in a circle the way shade does.

## the honest part

The evidence is uneven, and a careful steward or funder should know where.

**Some mechanisms are better proven than others.** Pollination, microclimate, and riparian hydrology have strong, repeated results. Pest control by predators, fungal connectivity at landscape scale, and the services of insect-eating birds and bats are moderate. Disease dilution, the benefit of gene flow to a managed stand, and evolutionary rescue are weak or depend heavily on context.

**Context changes the sign.** A 2018 analysis of 132 studies across 6,759 sites found that pest-predator responses to the surrounding landscape were inconsistent from one system to the next. A rule of thumb that works in one valley can fail in the next.

**The bad neighbor is real.** A protected patch can harbor the pest that eats the neighbor's crop, or carry a fire run across a boundary that a plowed field would have stopped. Any serious screen checks for the harm a parcel exports, not only the help.

**The past is not a forecast.** Effect sizes were measured in the climate of recent decades. Under a different one they may shrink or grow.

**The inverse problem is open.** That protection spills over is settled. Predicting which specific parcels, if protected, deliver the most spillover to the most people is not. Marxan, Zonation, and prioritizr choose a protected set that meets representation targets at least cost; their objective is what the set contains. InVEST maps where a service is produced. ENCORE screens a sector's exposure. None was built to rank parcels by how much they hold up the land around them, at parcel grain, with a confidence band. [What is a keystone parcel](/guide/what-is-a-keystone-parcel?from=guide) names that ground, and finding it is still method, not product.

## what it means for the parcel next door

If you own the working forest, the farm, or the subdivision beside a protected place, the protection is usually working for you. What reaches you depends on what you run. A farm gets pollinators and some pest control. A town below gets a slower flood. A working forest gets a cooler, wetter edge and a seed source. It can also get costs: deer that shelter next door, a pest reservoir, unmanaged fuel, a listed species that brings rules across the fence. The studies above say help is the more common case. You still know your side of the fence better than any study.

If you steward the protected place, the same map is your case. The land you hold is producing value past its boundary, for named neighbors, at distances you can estimate from the table above. [How upstream land decides downstream water](/guide/how-upstream-land-decides-downstream-water?from=guide) shows how a small set of upstream parcels carries most of the downstream benefit. [What is a serviceshed](/guide/what-is-a-serviceshed?from=guide) turns that reach into a list of who, exactly, is inside it.

## frequently asked questions

### what is ecological spillover?

Ecological spillover is the movement of an ecological benefit across a boundary: pollinators, predators, water, shade, soil life, fuel moisture, or genes leaving a protected or intact parcel and improving the land around it.

### does protecting land cause leakage?

Sometimes. In a 2019 systematic review, fewer than 12% of effective protected areas showed deforestation leaking to the land around them, and 54% showed clearing slow on the surround as well.

### how far does spillover reach?

It depends on the mechanism. Pollination reaches 600 meters to about 3 kilometers. Microclimate reaches 50 to 200 meters. Water reaches the whole watershed below. Genes travel over decades.

### can you predict which parcel spills over most?

Not yet with confidence. The forward evidence is strong; the inverse problem, ranking parcels by how much they hold up, is still being worked on, and any claim otherwise should show its confidence bands.

## next

The next post in this series draws the reach on a map: [what is a serviceshed](/guide/what-is-a-serviceshed?from=guide).

If you steward a place whose neighbors receive what it produces, [land stewards](/solutions/land-stewards?from=guide&topic=keystone-parcels) shows the work we do beside yours. If you can already name the parcel and the neighbor, [tell us both](/contact?from=guide&topic=keystone-parcels).

## sources

[Cumming, G.S. 2025. Protected area management has significant spillover effects on vegetation. *Nature*.](https://doi.org/10.1038/s41586-025-09837-8) — 71% of 3,063 Australian protected areas showed positive vegetation spillover within 5 km.

[Cumming, G.S. 2025. Conceptualizing and measuring ecological spillover effects from protected areas. *Frontiers in Ecology and the Environment*.](https://doi.org/10.1002/fee.70008) — Spillover, leakage, blockage, and displacement defined; decay functions.

[Fuller, C., Ondei, S., Brook, B.W., Buettel, J.C. 2019. First, do no harm: a systematic review of deforestation spillovers from protected areas. *Global Ecology and Conservation* 18, e00591.](https://doi.org/10.1016/j.gecco.2019.e00591) — Under 12% leakage, 54% blockage, 33% no effect across 2,575 effective protected areas.

[Garibaldi, L.A. et al. 2013. Wild pollinators enhance fruit set of crops regardless of honey bee abundance. *Science*.](https://doi.org/10.1126/science.1230200) — Wild pollinators raised fruit set across 41 crop systems.

[De Frenne, P. et al. 2019. Global buffering of temperatures under forest canopies. *Nature Ecology & Evolution*.](https://doi.org/10.1038/s41559-019-0842-1) — Maximum temperatures about 4.1°C lower on average under canopy.

Watson, K.B. et al. 2016. Quantifying flood mitigation services: the economic value of Otter Creek wetlands and floodplains to Middlebury, VT. *Ecological Economics* 130, 16–24. — Flood damage reduced 54–78%.

[Narayan, S. et al. 2017. The value of coastal wetlands for flood damage reduction in the northeastern USA. *Scientific Reports*.](https://doi.org/10.1038/s41598-017-09269-z) — An estimated $625 million in Sandy damages avoided.

[Karp, D.S. et al. 2018. Crop pests and predators exhibit inconsistent responses to surrounding landscape composition. *PNAS*.](https://doi.org/10.1073/pnas.1800042115) — 132 studies, 6,759 sites; pest and predator responses inconsistent across systems.

## the series

1. [what is a keystone parcel](/guide/what-is-a-keystone-parcel?from=guide)
2. [does protecting one parcel help the land around it](/guide/does-protecting-one-parcel-help-the-land-around-it?from=guide)
3. [what is a serviceshed](/guide/what-is-a-serviceshed?from=guide)
4. [how to find the keystone parcels in a watershed](/guide/how-to-find-the-keystone-parcels-in-a-watershed?from=guide)
5. [the free rider is standing on a keystone parcel](/guide/the-free-rider-is-standing-on-a-keystone-parcel?from=guide)
6. [how a keystone parcel gets paid](/guide/how-a-keystone-parcel-gets-paid?from=guide)