DOI: 10.5281/zenodo.13362620
title: Pound Hill disturbance timing experiment, Silwood Park

description: The composition of plant communities is in part determined by seedling recruitment, which depends on seed germination and seedling survival.  Because species differ in the optimal environmental conditions for germination it is expected that variations in timing and severity of disturbances have an effect on the relative abundance of plant species and the composition of the seed bank. The Pound Hill experiment aims to assess the effect of the timing of cultivation and soil disturbance on grasslands diversity and biomass. It was established in 1991 in an area of Silwood Park that had been maintained for the conservation of arable weeds through an annual cultivation at various times of the year for at least a decade.  This regime transformed a wheat-cultivated land into a species-rich community of ruderal plants, mostly annuals. The experimental area, which is protected from rabbits' damage, is divided in plots that since October 1992 have been cultivated in March, May or October. Two data sets are available for this experiment: 

1. Data of aboveground standing biomass of each plant species present in all plots collected in July 2003 (PoundHillDist_biomass.csv)

2. Data of percentage of cover of each plant species collected in 2014, 2016, 2017, 2019-2021 (PoundHillDist_cover.csv).
description: The study site is Silwood Park Campus from Imperial College London, Buckhurst Road, Ascot, Berkshire SL5 7PY, United Kingdom.  Silwood Park campus, with 78 ha, contains acid grasslands, scrubland, ancient woodlands and few decades old oak-dominated woodlands.Silwood Park experiences an average annual rainfall of 698mm with little seasonal pattern (1987-2022).  Mean hourly temperature is 10oC with July max of 23 oC and January min of 1.4 oC (1987-2022).

A rabbit-prof fence separates an open area of 100 x 40m. Inside; four blocks (A-D) of 36 x 36m are divided into three plots of 36 x 8m, which are cultivated in March, May or October. The three cultivation treatments are then replicated four times.  Disturbance treatments consist of cutting the vegetation followed by rotovating the ground to smooth soil.

PLOTTREAT






Plot



Block



Cultivation



UK grid



Latitude



Longitude





1



A



October



SU9387569299



51.41495



-0.6515





2



A



May



SU9387069308



51.41503



-0.65157





3



A



March



SU9386869316



51.4151



-0.65159





4



B



May



SU9386569322



51.41516



-0.65163





5



B



March



SU9386469330



51.41523



-0.65165





6



B



October



SU9386169337



51.41529



-0.65168





7



C



March



SU9386169345



51.41536



-0.65168





8



C



October



SU9385969352



51.41543



-0.65171





9



C



May



SU9385669359



51.41549



-0.65175





10



D



March



SU9385369369



51.41558



-0.65179





11



D



October



SU9385269374



51.41563



-0.65181





12



D



May



SU9384969381



51.41569



-0.65184





The experiment is located at Pound Hill Field. It lies on acid, sandy soil of the Bagshot Series and is surrounded by naturally regenerated Oak, Sycamore and Birch wood.

In 1996, 1999 and 2002 all plots were treated with herbicide after the annuals seed production to control for perennial grass species.

In 2002-2003 the whole experiment was split in half and all plots were cultivated at the same time. The eastern part of each plot was ploughed and rotovated in autumn 2002, and the western half of each plot in spring 2003 (see justification in Crawley, Ecology (2004) 85: 3277–3288).

In July 2003 aboveground standing biomass was estimated in 12 50 x 25 cm quadrats located within each 36 x 8 m plot (avoiding 1-m area from plot margins). Six quadrats were chosen in the eastern half of each plot that had been cultivated in autumn 2002, and six in the western half that had been cultivated in spring 2003. All plants in each quadrat were uprooted and the roots were cut and discharged. Samples were sorted by species, dried 80°C for 24hrs and weighing to the nearest 0.01 g.

The percentage coverage of each plant species present in a plot (36 x 8 m) is estimated to the nearest 1% percent for each species rooted within the plot. If the percentage of cover is lower than 1% a qualitative score of "+", "++" or “+++” is recorded. In the data table "+" was converted to 0.1%, "++" to 0.2% and +++ to 0.3%. Total cover typically exceeds 100% because cover is estimated independently for each species.