Five years of tree death in a Fagus-Magnolia forest, southeast Texas (USA)

Summary

Death of trees (>4.5 cm dbh) and saplings (1.4 m tall–4.5 cm dbh) was monitored over 5 years in a Southern Mixed Hardwood Forest to determine causes of death, death rates, and to assess the nature and direction of forest change. Most trees died standing (77%), presumably the result of pathogen attack or adverse physiological condition; knockdown by other trees (10%) and wind breakage (11%) were other common causes of death. Frequency of wind break and knockdown varied with size, but standing death did not. Most trees (64%) and some saplings (26%) died outright (complete death of the genetic individual); the others had sprouts or living residual parts. For some species, survival of residual parts was high, and so resprouting or persistence may be important in population recruitment. For others, low survival of residual parts means that sprouting does not effectively prolong the life of an individual. Most populations were stable or declining slightly. Shade-intolerant species showed higher death rates in small size classes than did the more tolerant species, so in the absence of disturbance one might expect some change in species composition toward the putative climax dominants.