Table 4 Summary of study conclusions
From: Land use change and forest management effects on soil carbon stocks in the Northeast U.S.
Finding | Confidence | Management, C accounting, & policy considerations |
|---|---|---|
1. Deforestation decreases soil C stocks | H | Soil C losses are largest at the surface of the profile and diminish with depth; declining regional forest cover in recent decades suggest land use change is having increasingly negative effects on the regional forest sector C budget |
2. Reforestation increases soil C stocks | H | Soil C gains are largest at the surface of the profile and diminish with depth; across the region, large areas of forest that were once farmed are likely on a trajectory of long-term soil C increase |
3. Soil C increases with reforestation vary by site | H | Landform, soil, and vegetation influence O horizon C gains; site-level uncertainty in rates is tied to unknown factors (potentially including past agricultural practices) |
4. Forest harvesting does not affect soil C stocks | H | Harvesting in general does not affect soil C; outcomes to the contrary are highly exceptional and not predictable based on natural factors or silvicultural practices |
5. O horizon C may be vulnerable to harvest in select settings | M | For Spodosols, northern & boreal tree communities, steep slopes, and S-facing aspects, there is some (highly limited) evidence for O horizon C losses; low-risk-tolerance management may minimize interventions in such settings while increasing them in settings with no evidence for O horizon C losses |
6. Existing management guidelines benefit soil C | M | Soil- and water-protecting practices that are already implemented most of the time as best management practices or for legal compliance are not explicitly targeting soil C protection, but are likely promoting it |
7. Partial harvest systems require further research | H | Clearcutting is studied far more frequently than it occurs; more research on more extensive partial harvests is needed to better constrain soil C outcomes |
8. Soil C is one aspect of forest climate vulnerability | M | Silviculture and soil C management can facilitate forest climate adaptation and mitigation by placing soils, topography, and tree communities in landscape context to define goals and objectives for diverse stands and settings |