Urban-to-rural gradients

6. Urban-to-rural gradients

12. More abundant in quiet sites R2 = 0.4 p = 0.0002 White-breasted Nuthatch Red-bellied Woodpecker % change from noisy to quiet sites More abundant in noisy sites % song overlap with traffic noise Effects on bird composition

13. 38% population growth:1990-2000 About 20.5% of forest cover lost Triangle Research Initiative: economics, forest ecology, bird behavior… Fragmentation in the “Triangle”

14. Land-use change until 1920 • Mostly hardwood forest • Much of landscape cleared • Not too wet or too dry • Not too hilly

15. Farm abandonment and succession • Many farms abandoned • “Worst of the best” • Now dominated by pines • Pinus taeda • Pinus echinata • Hardwood forests changing • More red maple • Less oak

16. What is the effect of forest fragmentation on NC Piedmont forests? Where is deforestation occurring? How do edges affect abiotic and biotic processes in forests? Do patterns of fragmentation affect patterns of forest dynamics at a large scale? Fragmentation in “Triangle”-central questions

17. What are the effects of edges? • Change in abiotic conditions • For plants, big things are light, temperature • Change in biotic conditions • Increased flux of exotic species

18. 66 edges selected 30m transect All trees greater than breast height sampled within 5m All stems sampled within 1m Tree cores taken from trees > 10cm DBH Non-Forest Forest 5m Transect Temp. sensor and moisture sensor Light sensor Schematic of edge transects. Experimental design-forest dynamics

19. 8 intensive transects 50% south-facing 50% deciduous 2 light sensors at 0m and 30m 3 temp/humidity sensors are 0m,5m, and 30m Non-Forest Forest 5m Transect Temp. sensor and moisture sensor Light sensor Schematic of edge transects. Experimental design-microclimate

20. What’s the climate like near edges? • Sensor data recorded every 10 minutes • Aggregated to daily PPFD, max. and min. temp., and RH • 3-factor crossed ANOVA design: south, deciduous, month

21. Canopy closure is less near edge Light is more: +3.9molPPFD/day The magnitude of the effect varies monthly: Jan.: +6.0 mol PPFD/day Aug.: +3.5 mol PPFD/day Seasonality varies with aspect More light…

22. Higher maximum temperatures… • South-facing edges, max. temp. +3.0°C • North-facing edges, max. temp. +0.2°C • Magnitude of edge effect on max. temp. does not vary by month • No effect on minimum temperature

23. Greater swings in RH • Similar RH at night near edges • Much lower RH during the afternoon • Complicated three-way interaction: Month, South, Edge • Low R2

24. Do trees grow faster? • Over 1200 cores collected • Average 5-year growth rate calculated • Log(Growth) = f(dist. to edge, species, soil nutrients, soil moisture proxies, competition)

25. Some do…

26. No growth response from red maple and sweet gum Environmental variables measured explain about 65% of plot-level variance, and are more important than edge effects Soil variables are very important, especially Percent Base Saturation Greater TCI means a greater growth rates Only significant interaction term: for P. taeda there is a greater increase in growth rates on dry edges than on wet edges Some don’t

27. Increased Tree-of-Heaven, Princess Tree… Also increased oak abundance Reduced abundance of red maple But lot’s of exotics