Bronydd Mawr National Network Site

The site is run by the Institute of Grassland and Environmental Research and Forest Research.

Site Details:

• Bronydd Mawr (51^o37'N 03^o38'W) is an upland site at 330m a.s.l. situated near Brecon, Powys.
• Average annual rainfall is 1500mm
• Mean screen temperature is 8^oC
• The soils overlie Old Red Sandstone and are predominantly well-drained acid brown earths

• There are two tree species, Sycamore (Acer pseudoplatanu)s and Hybrid larch (Larix eurolepis) planted at 3 densities; 100, 400 and 2500 stems ha^-1.
• The 2500 trees ha^-1 treatments are Farm Woodland Controls with no grazing.
• There is a sheep-grazed Agricultural Control which has no trees.
• The silvopastoral treatments are sheep grazed, trees are individually protected.
• Grazed plots are 0.6 ha in area and receive nitrogen at 160kg N ha^-1 yr^-1.
• Farm Woodland Controls are a minimum of 0.1 ha

• In addition there are sycamore and ash (Fraxinus excelsior ) planted at 400 stems ha^-1 in plots that were sown with clover and receive zero N.
• On this site, trees are planted in rows oriented North-South on all plots.
• There are three replicates of all treatments and controls.

• Beulah ewes are mated to Texel rams (Suffolk prior to 1998)
• The Beulah has an average prolificacy of 1.3 lambs born per ewe.
• Mating commences in mid-October when ewes are removed from the experimental plots.
• Ewes are off-wintered on silage with the addition of concentrates in late pregnancy.
• Twins are lambed indoors, singles outside
• Grazing on the experimental plots starts after lambing in early April.
• Lambs are weaned in late July and removed from the plots.
• Site management conforms to National Network protocols.

• Data collection conforms to National Network standards.
• Annually recorded measurements include:-
  • tree dimensions and survival,
  • stock carrying capacity,
  • lamb production,
  • ewe condition,
  • climate data (daily),
  • soil nutrient status and foliage nutrients.
• Other studies conducted at Bronydd Mawr include:-
  • bird and insect surveys,
  • microclimate studies to evaluate light levels under canopies,
  • monitoring of herbage production (quantity and quality),
  • soil compaction,
  • evaluation of tree protection systems,
  • detailed botanical assessments, root studies.

For more information on the Bronydd Mawr Agroforestry Experiment, contact Chris Duller or Max Hislop