Nitrogen uptake : Apparent pattern during old field succession in Southeastern U.S.

Nitrogen uptake from applied nutrient solutions was evaluated in two old fields, in a pine plantation, and in a hardwood stand, to test the idea that plant communities become more efficient trappers and retainers of plant nutrients during succession. Uptake was estimated as the difference between nutrient concentrations in water collected from beneath soil profiles with and without roots by lysimeters within each successional stage. Results suggest that nitrate uptake decreased while ammonia uptake increased with succession. This apparent shift from a nitrate to an ammonia nitrogen economy during succession has been reported by other workers and is evolutionarily significant as an energy, nitrogen, and cation saving mechanism.

Rehabilitation of the painful upper extremity.

Therapy for the painful upper extremity is a challenge. This article focuses on various assessment tools and techniques that are reflective of the painful status. The author reviews several research articles that discuss validating treatment options and outlines rehabilitation for the painful upper extremity as it relates to peripheral nerve irritation and compression.

Association of carbon disulfide with plants in the family Fabaceae.

We examined 40 taxa from nine genera within the subfamily Mimosoideae; 29 (73%) from six genera produced carbon disulfide (CS2). In addition, 19 of 40 taxa (48%) produced carbonyl sulfide (OCS). Of nine mimosoid taxa that produced CS2, all possessed a djenkolic acid and a cysteine lyase. Of three mimosoid taxa that did not produce CS2, two lacked a cysteine lyase and one lacked both a lyase and a djenkolic acid. Of 16 taxa from 14 genera from the other two subfamilies of the Fabaceae, the Caesalpinioideae and Papilionoideae, none produced CS2. The results suggest that CS2 production is common in the Mimosoideae and uncommon in the Caesalpinioideae and Papilionoideae and that plants in the Mimosoideae that do produce CS2 must possess both a djenkolic acid and a cysteine lyase for this production to occur.