Stand Structure Governs the Crown Collisions of Lodgepole Pine

We investigated tree sway and crown collision behavior of even-aged lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) stands of different structure in Alberta, Canada, to examine how these factors might affect loss of leaf area as stands mature. The Two Creeks stand (TC) had high density and slender trees, while the Chickadee stand (CH) had stout trees. The TC stand was then thinned (TCT) to reduce the stand density. For each stand, simultaneous tree sways of a group of 10 trees were monitored with biaxial clinometers during wind speed of 5 m/s (canopy top). Crown collisions were reconstructed by combining sway displacement of individual trees with their respective crown dimensions. Comparing the sway statistics between stands with contrasting mean bole slenderness (TC and CH) indicated that more slender trees have greater sway displacements, faster sway speeds, and a greater depth of collision. Disturbance by thinning increased sway displacements, sway speeds, and depth of collisions at TCT. Tree sway patterns were circular in shape and not aligned with wind direction, but patterns were elongated after thinning. This demonstrates the high frequency of crown collision experienced by stands with slender trees and supports the notion that crown collisions result in empty space between crowns of trees.

Property Law

This chapter examines the economics of property rights and property law. Property law is a fundamental part of social organization and is also fundamental to the operation of the economy because it defines and protects the bundle of rights that constitute property. Property law thereby creates incentives to protect and invest in assets and establishes a legal framework within which market exchange of assets can take place. The purpose of this chapter is to show how the economics of property rights can be used to understand fundamental features of property law and related extra-legal institutions. The chapter will both examine the rationale for legal doctrine and the effects of legal doctrine regarding the exercise, enforcement, and transfer of rights. It will also examine various property rights regimes including open access, private ownership, common property and state property. The guiding questions are: How are property rights established? What explains the variation in the types of property rights? What governs the use and transfer of rights? And, how are property rights enforced?