Abstract Ecosystem structure and processes of coastal temperate rainforests of the Pacific Northwest are thought to be strongly influenced by herbivory primarily of Roosevelt elk (Cervus elaphus roosevelti) and secondarily of Columbian black‐tailed deer (Odocoileus hemionus columbianus). Two large (0.5‐ha) exclosures were built in old‐growth coniferous rainforest communities in Olympic National Park, Washington, during 1979 to study these effects. Cover of shrubs, ferns, herbs, and graminoids and numbers of tree seedlings were described over 36 yr. Results show a sequence following ungulate exclusion of early release of shrubs, ferns, and herbs followed by eventual dominance of shrubs as other vegetation layers become shaded. Short‐term responses of individual species reflected functional traits related to ability to avoid or tolerate herbivory. Over the longer term, effects reflected changing competitive relationships among vegetation layers and other ecosystem dynamics such as the provision of fallen trees in the appropriate decay class to serve as establishment substrate for tree seedlings. In aggregate, vegetation composition shifted after 36 yr from a system dominated by herbaceous cover with a major graminoid component to one dominated by shrubs (5‐ to 6‐fold absolute increase) and ferns (5–7% increase in absolute cover), less absolute herb cover (15–20% loss), and almost no graminoids (<1.5% cover remaining in any plot) after 36 yr. These changes represented a substantial loss in plant community diversity with a loss of 46 of 74 species. Elk abundance outside of the exclosures began to decline in the 1990s leading to parallel changes in plant community trajectories outside of exclosures to those initially seen inside. While this suggests plant community responses inside the exclosures were also driven by elk exclusion, the strength of this response depends on elk abundance. 
                        more » 
                        « less   
                    This content will become publicly available on March 28, 2026
                            
                            Variation of root resource acquisition and conservation strategies in a temperate forest is linked with plant growth forms
                        
                    
    
            Abstract Exploring why species of different plant growth forms can coexist in the same forest is critical for understanding the long-term community stability, but is poorly studied from root ecological strategies. The aim of this study was to explore the variation of root functional traits among different growth forms and their distribution patterns in root economics space to clarify how plant growth forms affect the root resource acquisition strategies of co-occurring species in a forest community. We sampled 115 co-occurring species with five growth forms (i.e., trees, shrubs, lianas, herbs and ferns) from a mega-plot (>50 ha) in temperate forest and measured seven root functional traits, including root morphological, anatomical and chemical traits, that are closely associated with root resource foraging and conservation strategies. We found that root specific length (SRL) and tissue density (RTD) showed wider variations than other traits among the five growth forms. Moreover, compared with clade and mycorrhizal type, variations of SRL and RTD were largely attributed to growth forms. Importantly, 115 co-occurring species were separately aggregated by growth forms along the trade-off dimension of SRL and RTD in root economics space, suggesting the diversity in root resource acquisition strategies at a local forest community is linked to plant growth forms. In particular, herbs were concentrated towards the side of high SRL and RN, by contrast, trees, shrubs and ferns were positioned at the side of high RTD and carbon/nitrogen, and lianas were located towards the middle. Diverse root resource acquisition strategies in plant growth forms allow them to occupy specific belowground ecological niches, thereby relieving the competition for the common resource. These findings advance our understanding of the mechanism for maintaining community species coexistence from a below-ground perspective. 
        more » 
        « less   
        
    
                            - Award ID(s):
- 2021898
- PAR ID:
- 10589872
- Editor(s):
- Wang, Han
- Publisher / Repository:
- Oxford Academic
- Date Published:
- Journal Name:
- Tree Physiology
- Volume:
- 45
- Issue:
- 4
- ISSN:
- 1758-4469
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
- 
            
- 
            Lianas are major contributors to tropical forest dynamics, yet we know little about their mortality. Using overlapping censuses of the lianas and trees across a 50 ha stand of moist tropical forest, we contrasted community-wide patterns of liana mortality with relatively well-studied patterns of tree mortality to quantify patterns of liana death and identify contributing factors. Liana mortality rates were 172% higher than tree mortality rates, but species-level mortality rates of lianas were similar to trees with ‘fast’ life-history strategies and both growth forms exhibited similar spatial and size-dependent patterns. The mortality rates of liana saplings (<2.1 cm in diameter), which represent about 50% of liana individuals, decreased with increasing disturbance severity and remained consistently low during post-disturbance stand thinning. In contrast, larger liana individuals and trees of all sizes had elevated mortality rates in response to disturbance and their mortality rates decreased over time since disturbance. Within undisturbed forest patches, liana mortality rates increased with increasing soil fertility in a manner similar to trees. The distinct responses of liana saplings to disturbance appeared to distinguish liana mortality from that of trees, whereas similarities in their patterns of death suggest that there are common drivers of woody plant mortality.more » « less
- 
            Abstract Plant diversity effects on community productivity often increase over time. Whether the strengthening of diversity effects is caused by temporal shifts in species-level overyielding (i.e., higher species-level productivity in diverse communities compared with monocultures) remains unclear. Here, using data from 65 grassland and forest biodiversity experiments, we show that the temporal strength of diversity effects at the community scale is underpinned by temporal changes in the species that yield. These temporal trends of species-level overyielding are shaped by plant ecological strategies, which can be quantitatively delimited by functional traits. In grasslands, the temporal strengthening of biodiversity effects on community productivity was associated with increasing biomass overyielding of resource-conservative species increasing over time, and with overyielding of species characterized by fast resource acquisition either decreasing or increasing. In forests, temporal trends in species overyielding differ when considering above- versus belowground resource acquisition strategies. Overyielding in stem growth decreased for species with high light capture capacity but increased for those with high soil resource acquisition capacity. Our results imply that a diversity of species with different, and potentially complementary, ecological strategies is beneficial for maintaining community productivity over time in both grassland and forest ecosystems.more » « less
- 
            Muller-Landau, Helene C; Wright, S Joseph (Ed.)I present the largest survey of seed germination yet for Barro Colorado Island (BCI) and central Panama, based on 1,226 seed collections from 732 species, in 103 families, including trees, shrubs, lianas, vines, herbs, and epiphytes. Most collections were germinated in both sun and shade habitats in growing houses on BCI, simulating tree fall gap and shaded understory conditions. Many ad hoc treatments were also utilized. Data were collected during the field portion (1985–1989) of the BCI Seedling Flora Project. This publication marks the public release of the entire dataset, parts of which have previously been shared with BCI colleagues. I hope that this dataset will provide background information for those needing to produce seedlings from seed for experimental studies and that it will encourage others to incorporate seed germination as an additional plant trait into community analyses.more » « less
- 
            We provide data on mean dry and wet mass of > 800 species from Yasuní National Forest, Ecuador collected between 2000 and 2014. Species include trees, shrubs, lianas and herbs. We also provide data on number of seeds per fruit for >1100 species compiled in 2016, along with information on fruit type and dispersal mode. Both of these data sets supplement previously published data on flowering and fruiting phenology from this equatorial, ever-wet rainforest in eastern Ecuador (Garwood et al. 2023). Garwood, N.C., S.J. Wright, R. Valencia, and M.R. Metz. 2023. Rainforest phenology: flower, fruit and seed production from biweekly collections of 200 traps in the Yasuní Forest Dynamics Plot, Ecuador, 2000-2018 ver 1. Environmental Data Initiative. https://doi.org/10.6073/pasta/5e6cb3d7ff741fd9d21965c4a904bc1f (Accessed 2024-03-27).more » « less
 An official website of the United States government
An official website of the United States government 
				
			 
					 
					
