Global importance of large‐diameter trees
Authors: Lutz James A. , Furniss Tucker J. , Johnson Daniel J. , Davies Stuart J. , Allen David , Alonso Alfonso , Anderson‐Teixeira Kristina J. , Andrade Ana , Baltzer Jennifer , Becker Kendall M. L. , Blomdahl Erika M. , Bourg Norman A. , Bunyavejchewin Sarayudh , Burslem David F. R. P. , Cansler C. Alina , Cao Ke , Cao Min , Cárdenas Dairon , Chang Li‐Wan , Chao Kuo‐Jung , Chao Wei‐Chun , Chiang Jyh‐Min , Chu Chengjin , Chuyong George B. , Clay Keith , Condit Richard , Cordell Susan , Dattaraja Handanakere S. , Duque Alvaro , Ewango Corneille E. N. , Fischer Gunter A. , Fletcher Christine , Freund James A. , Giardina Christian , Germain Sara J. , Gilbert Gregory S. , Hao Zhanqing , Hart Terese , Hau Billy C. H. , He Fangliang , Hector Andrew , Howe Robert W. , Hsieh Chang‐Fu , Hu Yue‐Hua , Hubbell Stephen P. , Inman‐Narahari Faith M. , Itoh Akira , Janík David , Kassim Abdul Rahman , Kenfack David , Korte Lisa , Král Kamil , Larson Andrew J. , Li YiDe , Lin Yiching , Liu Shirong , Lum Shawn , Ma Keping , Makana Jean‐Remy , Malhi Yadvinder , McMahon Sean M. , McShea William J. , Memiaghe Hervé R. , Mi Xiangcheng , Morecroft Michael , Musili Paul M. , Myers Jonathan A. , Novotny Vojtech , de Oliveira Alexandre , Ong Perry , Orwig David A. , Ostertag Rebecca , Parker Geoffrey G. , Patankar Rajit , Phillips Richard P. , Reynolds Glen , Sack Lawren , Song Guo‐Zhang M. , Su Sheng‐Hsin , Sukumar Raman , Sun I‐Fang , Suresh Hebbalalu S. , Swanson Mark E. , Tan Sylvester , Thomas Duncan W. , Thompson Jill , Uriarte Maria , Valencia Renato , Vicentini Alberto , Vrška Tomáš , Wang Xugao , Weiblen George D. , Wolf Amy , Wu Shu‐Hui , Xu Han , Yamakura Takuo , Yap Sandra , Zimmerman Jess K. 
Published: May 2018

Aim

To examine the contribution of large‐diameter trees to biomass, stand structure, and species richness across forest biomes.

Location

Global.

Time period

Early 21st century.

Major taxa studied

Woody plants.

Methods

We examined the contribution of large trees to forest density, richness and biomass using a global network of 48 large (from 2 to 60 ha) forest plots representing 5,601,473 stems across 9,298 species and 210 plant families. This contribution was assessed using three metrics: the largest 1% of trees ≥ 1 cm diameter at breast height (DBH), all trees ≥ 60 cm DBH, and those rank‐ordered largest trees that cumulatively comprise 50% of forest biomass.

Results

Averaged across these 48 forest plots, the largest 1% of trees ≥ 1 cm DBH comprised 50% of aboveground live biomass, with hectare‐scale standard deviation of 26%. Trees ≥ 60 cm DBH comprised 41% of aboveground live tree biomass. The size of the largest trees correlated with total forest biomass (r2 = .62,p < .001). Large‐diameter trees in high biomass forests represented far fewer species relative to overall forest richness (r2 = .45,p < .001). Forests with more diverse large‐diameter tree communities were comprised of smaller trees (r2 = .33,p < .001). Lower large‐diameter richness was associated with large‐diameter trees being individuals of more common species (r2 = .17,p = .002). The concentration of biomass in the largest 1% of trees declined with increasing absolute latitude (r2 = .46,p < .001), as did forest density (r2 = .31,p < .001). Forest structural complexity increased with increasing absolute latitude (r2 = .26,p < .001).

Main conclusions

Because large‐diameter trees constitute roughly half of the mature forest biomass worldwide, their dynamics and sensitivities to environmental change represent potentially large controls on global forest carbon cycling. We recommend managing forests for conservation of existing large‐diameter trees or those that can soon reach large diameters as a simple way to conserve and potentially enhance ecosystem services.