Large seasonal variation in the rate of change in girth of tropical rain-forest tree species has been described, but its origin is still under debate. We tested whether this variation might be related to variation in atmospheric relative humidity through its influence on bark water content and thickness. Variation in trunk circumference of 182 adult trees was measured about twice a month in an undisturbed tropical rain forest over 18mo using dendrometers. Furthermore, a laboratory experiment was conducted to test the direct influence of relative air humidity on bark water content and thickness. In the field, most trees displayed highly positive rates of change in girth at the onset of the wet season, while a quarter of the trees displayed negative changes during long dry seasons, whatever their total annual growth. This variation was correlated with environmental conditions, particularly with atmospheric relative humidity. Trees with high bark water content and thickness displayed a stronger decrease in girth during the dry season. In the chamber experiment, desiccation induced a decrease in the diameter of the trunk sections in tandem with a decrease in bark water content. As a result, seasonal variation in the rate of change in girth of tropical rain-forest trees reflects variation in trunk biophysical properties, through the influence of relative humidity on bark properties, but not directly variation in secondary growth
For want of public regulations for organic agriculture in Morocco, stakeholders chose to develop their own label and a Participatory Guarantee System (PGS). In this paper, we present the Participatory Action Research that led to the emergence of a PGS for local markets. Theoretically, we consider this mode of governance-by delegating to the peer community the definition of what is the local norm, and the control of this one-as a type of knowledge commons. Based on an evaluation of the Participatory Action Research, we question to which extent it could lead to a common vision, influence the design, appropriation and improvement of rules for the PGS schemes and, lastly, contribute to the emergence of a commons. We applied the grammar of institutions to describe the outputs of the participatory process. Substantial results show that the different components of the knowledge commons are now available to the community and are fairly well appreciated by the participants. Operational results suggests that the PGS still faces challenges, especially when it comes to scaling-up. We finally propose a critical analysis of the participatory approach used to build this type of socioeconomic innovation as a knowledge commons and discuss the conditions required for replicating a knowledge commons in and beyond the context of Morocco.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.