The Control of Vascular Branching in Coleus 2. The Corner Traces

Corner trace connections are less well defined than those ofthe side bundle in Coleus, the locations of branch points, branchpartners, and number of connections made by a corner trace beingmore variable. The auxin balance between corner traces was alteredby leaf removal and by application of exogenous auxin. Branchingof new strands was shifted toward the pre-existing strand withthe lower auxin flux, but only within a narrow range of developmentalstages and with the imposition of a large auxin imbalance. Branchingoccurred only in nodal regions, as in control plants. Thus,auxin balance can be made to control xylem strand branching,but it does not account fully for the control of vascular branchingin intact plants. In the intact pattern, corner trace branchesappear to be directed toward the pre-existing strand with thehigher auxin flux. It is proposed that, in the vicinity of astrand with high flux, auxin is transported laterally withinthe nodal vascular cambium, facilitating vessel differentiationbetween strands in the derivatives of the vascular cambium.These vessels comprise the connections between traces. Coleus, vascular differentiation, vascular anatomy, vascular branching, vascular patterns, auxin, auxin balance, node     

Probability of Detecting Band-Tailed Pigeons During Call-Broadcast Versus Auditory Surveys

Abstract: Estimates of population trend for the interior subspecies of band-tailed pigeon (Patagioenas fasciata fasciata) are not available because no standardized survey method exists for monitoring the interior subspecies. We evaluated 2 potential band-tailed pigeon survey methods (auditory and call-broadcast surveys) from 2002 to 2004 in 5 mountain ranges in southern Arizona, USA, and in mixed-conifer forest throughout the state. Both auditory and call-broadcast surveys produced low numbers of cooing pigeons detected per survey route (x̄ ≤ 0.67) and had relatively high temporal variance in average number of cooing pigeons detected during replicate surveys (CV ≥ 161%). However, compared to auditory surveys, use of call-broadcast increased 1) the percentage of replicate surveys on which ≥1 cooing pigeon was detected by an average of 16%, and 2) the number of cooing pigeons detected per survey route by an average of 29%, with this difference being greatest during the first 45 minutes of the morning survey period. Moreover, probability of detecting a cooing pigeon was 27% greater during call-broadcast (0.80) versus auditory (0.63) surveys. We found that cooing pigeons were most common in mixed-conifer forest in southern Arizona and density of male pigeons in mixed-conifer forest throughout the state averaged 0.004 (SE = 0.001) pigeons/ha. Our results are the first to show that call-broadcast increases the probability of detecting band-tailed pigeons (or any species of Columbidae) during surveys. Call-broadcast surveys may provide a useful method for monitoring populations of the interior subspecies of band-tailed pigeon in areas where other survey methods are inappropriate.