Dry conditions and disturbance promote liana seedling survival and abundance

Abstract

Species composition and community structure in Neotropical forests have been severely affected by increases in climate change and disturbance. Among the most conspicuous changes is the proliferation of lianas. These increases have affected not only the carbon storage capacity of forests but also tree dynamics by reducing tree growth and increasing mortality. Despite the importance of lianas in Neotropical forests, most of the studies on lianas have focused on adult stages, ignoring dynamics at the seedlings stage. Here, we asked whether observed increases in liana abundance are associated with a demographic advantage that emerges early in liana ontogeny and with decreased precipitation and increased disturbance. To test this, we compared patterns of growth and survival between liana seedlings and tree seedlings using a long‐term data set of seedling plots from a subtropical wet forest in Puerto Rico, USA. Then, we examined the effect of precipitation and land use history on these demographic variables. We found evidence for liana seedling survival advantage over trees, but no growth advantages. This survival advantage exhibited significant temporal variation linked with patterns of rainfall, as well as differences associated with land‐use history in the study area. Furthermore, we found that neighborhood density has a negative effect on liana survival and growth. Our results indicate that liana proliferation is likely related to a survival advantage that emerges in early stages and is influenced by climatic conditions and past disturbance. Predicted climatic changes in rainfall patterns, including more frequent and severe droughts, together with increases in disturbance, could have a significant effect on seedling tropical communities by favoring lianas.

OCO-2 Solar-Induced Chlorophyll Fluorescence Variability across Ecoregions of the Amazon Basin and the Extreme Drought Effects of El Niño (2015–2016)

“…However, at the community level, we observed positive and negative ER-SIF 757 variations. We hypothesize that the variations could also be related to drought-driven ecological dynamics with potential for compelling the ERs' community demography to express a higher or lower Φ F and Ω C (e.g., the proliferation of tropical plants that increase tree mortality [27], a decrease in pollinators resulting in decreased natality of specific plant species [77], or a decrease in the fauna's floristic resources, thereby affecting the fauna composition [78,79] and leading to changes in Φ F by limiting the plants' N availability [16] from manure and urine stock flows). Nevertheless, similar to previous results [7], we found a widespread SIF 757 reduction during the El Niño 2015-2016 phenomena in which the positive and negative ER-SIF 757 variations suggest that both physiological responses and mortality may be taking place with a higher frequency in ERs with higher SIF 757 variations.…”

“…A reduced CO 2 uptake limits photosynthetic activity and results in lower SIF values. Drought can also cause mortality via carbon starvation, hydraulic failure, and phloem transport failure [23], which alter the ecological balance by shifting the composition of vegetation communities [24][25][26][27].…”

Large‐ and small‐seeded species have contrasting functional neighborhoods in a subtropical forest

“…Lianas constitute an important component of Neotropical forests (Schnitzer and Bongers , , Umaña et al. ) and are particularly abundant in the seedling community of the LFDP (Umaña et al. ).…”

“…) and are particularly abundant in the seedling community of the LFDP (Umaña et al. ). Although trait data for lianas are scarce, previous studies have suggested that lianas exhibit a similar range of life‐history strategies than tree species (Gilbert et al.…”

“…Liana species are very common at the seedling stage in this forest (Umaña et al. ), but our trait collection was based on tree species. Our trait dataset contained 70% of the woody species and 46% of the woody individuals found in the seedling plots.…”