Urban-to-rural gradients

% change from noisy to quiet sites % song overlap with traffic noise R 2 = 0.4 p = More abundant in quiet sites More abundant in noisy sites White-breasted Nuthatch Red-bellied Woodpecker Effects on bird composition

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

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

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

Fragmentation in “Triangle”- central questions 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?

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

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

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

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

More light… 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

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

Greater swings in RH Similar RH at night near edges Similar RH at night near edges Much lower RH during the afternoon Much lower RH during the afternoon Complicated three-way interaction: Month, South, Edge Complicated three-way interaction: Month, South, Edge Low R 2 Low R 2

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

Some do…

Some don’t 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

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