Woodstown Borough: Forest Climate Risk Snapshot
Introduction
New Jersey’s trees and forests will undoubtedly be affected by changing temperatures and
precipitation patterns posed by future climate change. Warmer summers can create stress for some
species that cannot tolerate high temperatures.
Milder winters may allow some species to survive in the area that previously would have suffered freezing damage.
Warmer springs and autumn may change the timing of leaf-out, flowering, and senescence as well extend the length of the growing season.
Shifts in precipitation patterns will also affect local trees.
More heavy precipitation events may increase the frequency or severity of flooding.
Storms may break limbs or damage trees. Drier conditions in summer or fall coupled with warmer temperatures could cause soil moisture deficits.
One of the biggest implications of projected climate change is shifting plant hardiness and heat zones. Planting suitability for trees and other plants is determined by hardiness zones, which are based on minimum temperatures, and heat zones, which are based on the number of days above 86°F. Both heat and hardiness zones are projected to shift over the next century, changing recommendations on what should be planted to ensure maximum likelihood of longer term success. Some species will be more vulnerable to these changes than others.
The Historical and projected future (RCP4.5 & 8.5) climate maps were provided by the Northeast Regional Climate Center at Cornell University through their Applied Climate Information System (ACIS, http://rcc-acis.org). Historical or Baseline data represent average values from 1981 to 2010. These are also known as the “981-2010 Normals”. Representative Concentration Pathway (RCP) is a greenhouse gas concentration trajectory adopted by the IPCC, which describe different climate futures, all of which are considered possible depending on how much greenhouse gases are emitted in the years to come. Emissions in RCP 4.5 peak around 2040, then decline. In RCP 8.5, emissions continue to rise throughout the 21st century. The climate data were extracted and summarized for each municipality (median value was used).
Woodstown Borough: Forest Climate Risk Snapshot
Growing Degree Days
The length of the growing season for plants is often measured in Growing Degree Days. The number of growing degree days per year is used to estimate the growth and development of plants (or insects) during the growing season. Higher numbers of growing-degree days indicate longer and warmer growing conditions. As growth occurs only when temperature exceeds a species’ base temperature (for example, 50°F), the number of days times the number of degrees above the base indicates the duration and magnitude of growing conditions. The higher the number, the longer the growing season.
Historical Baseline 1981-2010 (Median): 3,735
| Future Projection (Median) | Change vs. Historical Baseline (Median) | |
|---|---|---|
| RCP 4.5 2050-2070 (Days) | 4,805 | 1,070 |
| RCP 4.5 2080-2090 (Days) | 5,025 | 1,290 |
| RCP 8.5 2050-2070 (Days) | 5,245 | 1,510 |
| RCP 8.5 2080-2090 (Days) | 6,135 | 2,400 |
Woodstown Borough: Forest Climate Risk Snapshot
Plant Hardiness Zones
Plant hardiness zones provide a general indication of the extent of overwinter stress experienced by plants and are based on the average annual extreme minimum temperatures. Hardiness Zones are used by horticulturists to evaluate the cold hardiness of plants. Plant hardiness zones and subzones are delineated according to the US Department of Agriculture’s definitions, which break the geography into zones by 10 °F (5.56 °C) increments of annual extreme minimum temperature. North America is divided into 11 separate planting zones; each growing zone is 10°F warmer (or colder) in an average winter than the adjacent zone. The higher the number, the longer the growing season.
Historical Baseline 1981-2010 (Median): 7
| Future Projection (Median) | Change vs. Historical Baseline (Median) | |
|---|---|---|
| RCP 4.5 2050-2070 (Days) | 8 | 1 |
| RCP 4.5 2080-2090 (Days) | 8 | 1 |
| RCP 8.5 2050-2070 (Days) | 8 | 1 |
| RCP 8.5 2080-2090 (Days) | 9 | 2 |
Woodstown Borough: Forest Climate Risk Snapshot
Heat Zone Days
Heat zones map the distribution of potential heat stress for plants and animals, including humans. The heat zones are based on the number of days each year that a given region experiences “heat days” - days with a maximum daily temperature >30 °C (86 °F). The 30 °C threshold value is set primarily for agricultural production and is a general temperature threshold at which photosynthesis can be negatively impacted for C3 plants (e.g., most species including trees). The Continental US includes 12 Plant Heat Zones from Zone 1 with less than one heat day to Zone 12 with more than 210 heat days.
Historical Baseline 1981-2010 (Median): 53
| Future Projection (Median) | Change vs. Historical Baseline (Median) | |
|---|---|---|
| RCP 4.5 2050-2070 (Days) | 89 | 36 |
| RCP 4.5 2080-2090 (Days) | 93 | 40 |
| RCP 8.5 2050-2070 (Days) | 118 | 65 |
| RCP 8.5 2080-2090 (Days) | 142 | 89 |
Woodstown Borough: Forest Climate Risk Snapshot
Seasonal Extreme Temperatures
Alternatively, one might be interested in the projected changes in seasonal extreme temperatures. For example, we have extracted the Number of Days with a Maximum temperature above 95°F or Number of Days with a Minimum Below 32°F.
Number of Days with a Maximum temperature above 95°F
Historical Baseline 1981-2010 (Median): 3
| Future Projection (Median) | Change vs. Historical Baseline (Median) | |
|---|---|---|
| RCP 4.5 2050-2070 (Days) | 19 | 16 |
| RCP 4.5 2080-2090 (Days) | 23 | 20 |
| RCP 8.5 2050-2070 (Days) | 30 | 27 |
| RCP 8.5 2080-2090 (Days) | 56 | 53 |
Number of Days with a Minimum Below 32°F
Historical Baseline 1981-2010 (Median): 86
| Future Projection (Median) | Change vs. Historical Baseline (Median) | |
|---|---|---|
| RCP 4.5 2050-2070 (Days) | 58 | -28 |
| RCP 4.5 2080-2090 (Days) | 53 | -33 |
| RCP 8.5 2050-2070 (Days) | 49 | -37 |
| RCP 8.5 2080-2090 (Days) | 32 | -54 |
Woodstown Borough: Forest Climate Risk Snapshot
Climate Change Projections for Tree Species
The US Forest Service has assessed a number of trees species for changes in species habitat suitability from climate impacts models and heat and hardiness zones. Traits that may make species more adaptable to stress, such as resistance to pests, diseases, drought, and flooding were also considered. Their work highlights which species that may be more or less vulnerable to projected changes in the climate and other stressors in the coming decades. Species vulnerability is meant to be considered along with other management goals, such as enhancing biodiversity or providing wildlife habitat. Some vulnerable species may still be an important part of the landscape; they just may require extra care or specific planting sites.
![[Climate change projections for individual tree species]](/img/forestRisk_Table1.png "Climate change projections for individual tree species - page 1")
![[Climate change projections for individual tree species]](/img/forestRisk_Table2.png "Climate change projections for individual tree species - page 2")