Floristic variation and willow carr development within a southwest England wetland

Abstract. Woodland colonization on wetlands is considered to have a detrimental effect on their ecological value, even though detailed analysis of this process is lacking. This paper provides an evaluation of the ecological changes resulting from succession of poor fen (base‐poor mire) to willow wet woodland on Goss Moor NNR in Cornwall, UK. Different ages of willow carr were associated with eight understorey communities. During willow colonization, in the ground flora, there was a progressive decrease in poor fen species and an associated increase in woodland species, which appeared to be related to an increase in canopy cover and therefore shade. The most diverse community was found to be the most recent willow and was dominated by poor fen species. The oldest willow was the second most diverse and was associated with a reduction in poor fen species and an increase in woodland species. Architectural features were used successfully to assess the general condition and structure of willow. Tree height and DBH were identified as useful parameters to accurately assess willow age in the field. The implications of active intervention to remove willow in order to conserve the full range of communities within the hydrosere are discussed.     

The pair bond and divorce among Oystercatchers Haematopus ostralegus on Skokholm Island, Wales

Mate changes of Oystercatchers were followed over a 15-year period. In 8.0% of instances, the pair split up between breeding seasons even when both members bred the second season. The likelihood of divorce was highest for birds aged five years, the modal age of first breeding. After divorce birds did not select an older or younger mate when re-pairing. Low hatching success increased the chances of divorce. Divorce was not followed by significant changes in clutch-size, laying date or nesting success (although females tended to be more successful).     

The stem of Pachypteris papillosa (Thomas & Bose) Harris

Pachypteris papulosa (Thomas & Bose) Harris, leaves of a pteridosperm, are locally abundant in the Middle Jurassic of Yorkshire. Microsporophylls too are known but the stem has been represented only by a few puzzling fragments. Better-preserved stem material is now described. When young the stems were thick (up to 15 mm) and largely composed of soft parenchyma and thus succulent. The leaves are borne sparsely, each at the end of a prominent mamilla. The stem surface is covered by hemispherical emergences with a thickly cutinized epidermis which, when isolated, are beret-shaped. This cuticle is the only robust part of the young stem.
Later the stem formed a thick cylinder of wood and the surface was stretched. A new surface i presumed to be cork), was formed and the 'berets' and mamillac were lost. Branching occurs at distant intervals, when the stem divides nearly equally into widely diverging parts.
Pachypteris papillosa is pictured as a large shrub forming a mangrove-like thicket along tidal rivers.