Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → États-Unis → 1984 → Ephemeral plant responses to termites, water and nitrogen in a Chihuahuan Desert

New Mexico State University (1984)

Ephemeral plant responses to termites, water and nitrogen in a Chihuahuan Desert

Gutierrez, Julio R.

Titre : Ephemeral plant responses to termites, water and nitrogen in a Chihuahuan Desert

Auteur : Gutierrez, Julio R.

Université de soutenance : New Mexico State University

Grade : Doctor of Philosophy (PhD ) 1984

Résumé
The effects of subterranean termites, water supplementation and nitrogen amendment on ephemeral plant biomass, cover and density were investigated in a Chihuahuan desert ecosystem. Plants were sampled on one plot of 1200 m2 previously treated with chlordane to eliminate the termites and one untreated plot (with termites). These plots were subdivided in twelve 3 x 3 m subplots. Six of these subplots were irrigated every 15 days with 13 mm H2O and the other six received only natural rainfall (unwatered plots). Three randomly selected plots in the watered and unwatered treatments in both termite and no termite plots were fertilized with 2.5 g/m2 ammonium nitrate. Soil temperature and soil moisture in the watered and unwatered plots were measured on a regular basis. Soil nitrogen and tissue nitrogen of some selected plant species growing in the different treatments were analyzed. There were no differences in soil temperature among treatments. Soil moisture was higher in the termite than in the no-termite plots, and in the watered than in the unwatered plots during spring and summer. Soil nitrogen was higher in the no-termite than in the termite plot. Long-lived plant species such as Baileya multiradiata and Eriastrum diffusum accumulated more nitrogen in the termite and watered plots than in the no-termite and unwatered plots. Short-lived species did not exhibit differences in tissue nitrogen when the different treatments were compared. Ephemeral plant species composition differed, but neither total plant biomass nor total plant cover differed between termite and no-termite plots. Most of the species responded to the water treatments either by lengthening their growing seasons, increasing their density or increasing their biomass production. In most of the cases water amendments had a greater effect on the species abundances in the no-termite than in termite plots. In the termite plots, nitrogen amendments produced the larger effects and plant response to the treatments suggests that, in the no-termite plots, the system is shifting from one dominated by water-responsive species to another dominated by nitrogen-responsive species. Termite plots were dominated by deep-rooted water-responsive species (e.g., B. multiradiata).

Mots Clés : ephemeral plant, nutrients, , termites, nitrogen, amendment, pesticide, Chlordane, rainfall simulation

Présentation (Jornada NMSU)

Page publiée le 28 janvier 2018