Forest Structure and Projections of Avicennia germinans (L.) L. at Three Levels of Perturbation in a Southwestern Gulf of Mexico Mangrove

Mangrove forests have declined worldwide and understanding the key drivers of regeneration at different perturbation levels can help manage and preserve these critical ecosystems. For example, the Ramsar site # 1602, located at the Tampamachoco lagoon, Veracruz, México, consists of a dense forest of medium-sized trees composed of three mangrove species. Due to several human activities, including the construction of a power plant around the 1990s, an area of approximately 2.3 km2 has suffered differential levels of perturbation: complete mortality, partial tree loss (divided into two sections: main and isolated patch), and apparently undisturbed sites. The number and size of trees, from seedlings to adults, were measured using transects and quadrats. With a matrix of the abundance of trees by size categories and species, an ordination (nMDS) showed three distinct groups corresponding to the degree of perturbation. Projection matrices based on the size structure of Avicennia germinans showed transition probabilities that varied according to perturbation levels. Lambda showed growing populations except on the zone that showed partial tree loss; a relatively high abundance of seedlings is not enough to ensure stable mangrove dynamics or start regeneration; and the survival of young trees and adult trees showed high sensitivity.

A partial tree of Central Iranian

Relations within the Iranian branch of Indo-European have traditionally been modelled by a tree that is essentially composed of binary splits into sub- and sub-subbranches. The first part of this article will argue against this tree and show that it is rendered outdated by new data that have come to light from contemporary and ancient languages. The tree was also methodologically problematic from the outset, both for reasons of the isoglosses on which it is based, and for not taking into account distinctions such as shared innovations vs. shared archaisms. The second part of the paper will present an attempt at an alternative tree for Iranian by proposing a subbranch which I will call “Central Iranian”. Such a branch seems to be suggested by a set of non-trivial morphological innovations shared by Bactrian, Parthian and some neighbouring languages. The reconstruction of the nominal system of Central Iranian which will then be proposed aims to show the result one arrives at when trying to reconstruct a subbranch as strictly bottom-up as possible, i. e. using only the data from the languages under study, and avoiding profitting from Old Iranian data and from our knowledge about the proto-languages.