Survivorship, attained diameter, height and volume of three Paulownia species after 9 years in the southern Appalachians, USA

Little is known of the tree and stand dynamics of varied species of planted Paulownia left unmanaged until harvest in the southeastern United States.We sought to remedy this lack of information needed by land managers to make informed decisions by investigating diff erences in survivorship,attained diameter breast height(DBH),diameter at ground level,total height,tree volume and standlevel volume yields of planted P.elongata,P.fortunei,and P.tomentosa in the cool-moist environment of the southern Appalachian Mountains.After 9 years,combined-species survivorship was only 27.3%.Low survivorship was likely related to several inclement weather events.P.fortunei was signifi cantly smaller in DBH and total height.Three combined-species stem(bole)volume models were developed as functions of(1)DBH squared,(2)the product DBH squared and total height,and(3)the product diameter ground line squared and total height.Mean total volume production of unmanaged stands was greatest for P.elongata and P.fortunei 4 years after planting;by the 9th year,total volume of P.elongata was greater than the other two species.Results of our study provide managers information on productivity of three species of Paulownia that can be used for estimating plantation yields.

Life cycle and masting of a recovering keystone indicator species under climate fluctuation

Ecosystem health and sustainability,to a large degree,depend on the performance of keystone or dominant species.The role of climate on population dynamics of such species has been extensively examined,especially for health indicator species.Yet the life-cycle processes and response lags for many species could complicate efforts to detect clear climate signals.Longleaf pine(Pinus palustris Mill.)is such a keystone tree species in the southeastern United States that has declined in both abundance and distribu-tion during the past century.Despite research efforts on multiple fronts,the mechanisms behind the large spatial and temporal fluctuations in cone production that affects its regeneration are largely unknown.On the basis of long-term(15-56 yr)monitoring data at 10 sites across the species’native range,we examine the spatial and temporal patterns in cone production and possible climatic effects on those patterns using the information-theoretic approach.Cone production exhibited great variation across sites and years,and long-term data revealed a weak,ca.3 yr cycle(4 in one case)across the native range.The effects of climate were rather complex,most likely due to a mismatch between the prolonged cone-production life cycle process and climatic fluctuation.Spatially,sites close to each other generally showed similar physical conditions and temporal trends in cone production.Across sites within longleaf pine’s range,moderate climate conditions appear to promote cone production.At most sites,there was an increasing trend in cone production,but how such a trend might be linked to climate change requires further investigation.