Belowground interactions for water between trees and grasses in a temperate semiarid agroforestry system |
| |
| Authors: | María Elena Fernández Javier Gyenge Julian Licata Tomás Schlichter Barbara J Bond |
| |
| Institution: | (1) CONICET, Buenos Aires, Argentina;(2) INTA EEA Bariloche, Forest Ecology Group, CC 277, 8400 Bariloche, Rio Negro, Argentina;(3) Department of Forest Science, Oregon State University, Corvallis, OR 97331, USA |
| |
| Abstract: | A fundamental hypothesis of agroforestry is the complementary use of soil resources. However, productivity of many agroforestry
systems has been lower than expected due to net competition for water, highlighting the need for a mechanistic understanding
of belowground interactions. The goal of this study was to examine root–root interactions for water in a temperate semiarid
agroforestry system, based on ponderosa pines and a Patagonian grass. The hypotheses were: (a) A greater proportion of water
uptake by pines is from deeper soil layers when they are growing with grasses than when they are growing alone; (b) Growth
of grasses is improved by the use of water hydraulically lifted by pines. We used stable isotopes of O to analyze water sources
of plants, and we measured sapflow direction in pine roots and continuous soil water content with a very sensitive system.
We also installed barriers to isolate the roots of a set of grasses from pine roots, in which we measured water status, relative
growth and water sources, comparing to control plants. The results indicated that pines and grasses show some complementary
in the use of soil water, and that pines in agroforestry systems use less shallow water than pines in monoculture. We found
evidence of hydraulic lift, but contradicting results were obtained comparing growth and isotope results of the root isolation
experiment. Therefore, we could not reject nor accept that grasses use water that is hydraulically lifted by the pines, or
that this results in a positive effect on grass growth. This information may contribute to understand the complex and variable
belowground interactions in temperate agroforestry. |
| |
| Keywords: | Complementarity Hydraulic lift Patagonia Ponderosa pine Stable isotopes |
| 本文献已被 SpringerLink 等数据库收录！ |
|
