All chapters:

Introduction

Climate

Waters and water management

Ecosystems and ecoregions

Species diversity and use of biological resources

Nature conservation: econet and protected areas

Countries & cultures

Economy

Land use

International policy

Variation in natural zones in time has been  dramatic. The most recent glaciation in north Asia occurred 70-12 thousand years ago, but most of the Amur-Heilong basin was ice-free during that time, leaving refugia where southern flora and fauna could survive and adapt to the cold climate.  Formation of the cold Primorski current in the Sea of Japan allowed boreal-zone flora to extend southward to 44 degrees latitude (see Map of floristic zones), while in inland zones broadleaf forests extended northward to 51 degrees north.  The region has gone through cycles of long droughts and humid periods, the last drought occurring in eastern Mongolia and northeast China just 3,000 years ago, when Mongolian, Daurian, and Manchurian flora came in close contact.  These paleoclimatic  factors contributed to the richness, complexity and sharp contrasts in species composition of the Amur-Heilong River Basin   The shift of natural vegetation zones during the last 20,000 years is depicted in Maps of natural vegetation zones change.