Abstract:
Afforestation is considered to be one of the leading land-use changes affecting ecosystem
function and diversity. This study investigates the impact of pine afforestation on
microclimate and soil in fragments of highly vulnerable Afromontane grassland at Groenvaly.
Three major challenges for afforestation research are identified as (i) the range and intricacy
of the impact of afforestation, (ii) differences in measurement and monitoring periods and
(iii) a lack of focus on biomes adjacent to plantations. The approach here aimed to address
these three areas. Air microclimate data were collected for 24 months within a plantation site,
a control grassland site and a grassland fragment using three Davis Vantage Pro2 weather
stations. Soil temperature data were logged on iButtonsTM for 18 months and soil samples
from four seasons were analysed for moisture content, nitrogen (N), nitrate, ammonium,
phosphorous (P), pH, sodium (Na), calcium (Ca), potassium (K), magnesium (Mg) and soil
organic carbon (SOC). All data were statistically analysed at within-site, between-site,
seasonal and mean scales and each analysis highlighted different conclusions. Results for the
chemicals properties of the individual grassland fragments did not exhibit within-site
variation except for K and P and between-site variation was only evident for N, nitrate,
moisture and SOC. Solar irradiance was reduced in the fragments only during winter while
SOC and P in the fragments only differed from the control grassland sites in summer and
autumn respectively. Mean values for P, pH, Na, Ca, K, SOC and soil moisture within the
fragments’ soil were between those of the control grassland and the plantation while N and
Mg values were closer to the plantation than the control grassland. Mean values for air
temperature, wind speed, solar irradiance and humidity within the fragment were closer to the
control grassland than the plantation. Soil temperatures at 2cm in the fragments were similar
to the control grassland, while temperatures at 10cm below the surface were lower than both
the control grassland and the plantation sites in winter. Maximum air temperatures in the
fragments were lowered in summer and raised in winter but minimum air temperatures were
raised in the fragments across all seasons. Results of this study show that there are different
impacts in different seasons while overall mean data indicate that the fragments’ soil is
affected, and microclimate is unaffected, by the plantation. The impact of the change in soil and microclimate in grassland fragments requires more investigation to determine if grassland
fragments are a suitable conservation strategy in pine plantations.
