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Questions: Lianas are a conspicuous element of tropical forests but have largely been ignored in species‐level vegetation surveys. As a result, there is limited understanding of how environmental factors structure liana communities. Location: A 20‐ha forest dynamics plot in Xishuangbanna National Nature Reserve, southwestern China. Methods: We evaluated the distribution of the 50 most abundant liana species, comprising >18,000 individuals, in the 20‐ha forest plot. Ordination analysis and generalized linear mixed models were used to evaluate how species distribution and abundance are associated with soil pH, soil phosphorus (P), soil nitrogen (N), and soil potassium (K), canopy gaps and topography. We calculated the average weighted distribution as a proxy for the optimum resource condition for each species. Results: The first two axes of a canonical correspondence analysis explained 65% of the variation in liana species composition, with pH and P being the strongest drivers and highly correlated with each other. We modelled the responses of liana species to soil nutrients, and found a negative, unimodal or positive response of liana abundance with increasing soil nutrient concentrations. Forty‐six of the 50 species occurred under significantly higher or lower soil nutrient conditions than expected at random. Lianas mainly separated along the P gradient, whereas for N and K most liana species tended to occupy locations with high nutrient concentrations. Conclusions: Although lianas are thought to be notoriously light‐demanding, soil conditions were stronger drivers of liana species distribution than gaps. Species differences in distributions were mainly driven by soil gradients in pH and P, highlighting the importance of soil nutrient status for liana niche partitioning in wet tropical forests on highly weathered soils. Most liana species had high resource requirements for N, K and light, which come along with their fast growth and acquisitive resource use strategy. Hence, below‐ground resource availability plays an important role in shaping the assembly of liana communities. [ABSTRACT FROM AUTHOR]

Questions How do frequent disturbances of varying intensity affect heterogeneity of canopy openness and resulting regenerating tree diversity in subtropical rain forests? How does canopy gap pattern and regeneration time of a forest experiencing frequent but unpredictable typhoon disturbance vary over 17 yr? How is the understorey light environment influenced by canopy gaps in a forest experiencing frequent defoliation? Compared to non-gap areas, do gaps provide unique niches reflected in different seedling communities? Location Natural evergreen hardwood forest, northeastern Taiwan. Methods We examined gap characteristics, light availability and variability, and seedling diversity in both gaps and non-gaps in a subtropical forest with frequent typhoon disturbance, and compared the results to a survey at the same site conducted in 1995 following six typhoons in 1994. Results Gaps were smaller and covered a much smaller proportion of the forest in the 2012 survey (mean gap size 10 m2, 3.3% of the forest) than the 1995 survey (33 m2 and 10%). Canopy regeneration times estimated from the 2012 survey (200-400 yr) were much longer than those based on the 1995 survey (50-175 yr). Neither light availability nor variability differed between gaps and non-gaps, so gaps ostensibly did not provide a unique niche space. There were no seedling species occurring exclusively in gaps, and very high plant community similarity (>90%) between gaps and non-gaps. Conclusions In ecosystems with small canopy gaps resulting from frequent disturbance, gaps play a neutral role in understorey light environment and thus provide no unique niches and play a neutral role in plant diversity. Our study also suggests that measures of gap area, occurrence and forest turnover should be taken multiple times, during years with varying background disturbance rates. [ABSTRACT FROM AUTHOR]

Questions How do rodents with cyclic population dynamics affect seedling recruitment in alpine habitats? Does disturbance from rodents have larger implications on seedling recruitment in some plant communities than in others? Location Snowbeds and sheltered heaths in the low-alpine zone in areas of Børgefjell and Dovrefjell, Norway. Methods We recorded seedling emergence, rodent activity and cover of mosses, lichens, litter and bare ground in 270 plots in snowbeds and sheltered heaths in a rodent population peak year and in the following low-density year. Results Seedling recruitment was positively correlated with disturbances from lemmings and voles in both years. More seedlings emerged in the low-density year than in the year of the population peak. Snowbeds had higher seedling recruitment than the sheltered heaths, but both habitats were equally affected by disturbances from rodents. Conclusions Rodent activity created gaps and increased seedling emergence in these alpine plant communities, particularly in the year after the rodent peak, both in snowbeds and sheltered heath habitats. Our study therefore suggests that regeneration patterns in alpine vegetation are tightly linked to the population cycles of lemmings and voles, which peak in density at 3- to 5-yr intervals. [ABSTRACT FROM AUTHOR]

Question: (1) Which factors regulate post-fire recruitment and spread of the shrub Senecio bracteolatus in Patagonian grasslands? (2) What is the role of the grass Stipa speciosa on S. bracteolatus establishment in the post-fire succession? Location: Northwest Patagonia, Argentina. Methods: We studied the effect of fire on S. bracteolatus recruitment and density by comparing these variables between burned and unburned grasslands. In burned areas, we compared abiotic characteristics and seedling establishment under the canopy of grasses (S. speciosa) and in gaps (inter-tussock areas). Post-fire interactions between S. bracteolatus seedlings and S. speciosa were studied using field and greenhouse experiments. Results: Density of S. bracteolatus was higher in burned than in unburned areas. In burned sites, seedlings were more abundant under tussock grasses, whereas juveniles were more abundant in gaps. Tussocks generated more attenuated micro-environmental conditions than gaps during stressful summers. Gaps were more abundant in burned sites, while "under tussock" microsites were more frequent in unburned sites. In burned areas, tussocks allowed higher establishment of seedlings (facilitation), but gaps allowed more seedling growth and higher persistence of juveniles. Conclusions: Fire promoted S. bracteolatus recruitment in Patagonian grasslands by increasing the availability of favourable gap microsites. Grass protection for shrub seedlings became negative with time, probably due to competition with grasses. Gaps led to better performance and persistence of shrub plants. Six years after fire, higher shrub recruitment and adult density (observed as a trend) in burned grassland provides an opportunity for potential S. bracteolatus invasion. [ABSTRACT FROM AUTHOR]

Question: Previous interpretations of the variance plot of paired quadrat variance method (PQV) have been incomplete. The objective of this study was to clarify the interpretation of PQV, and to shed additional light on how different quadrat variance methods can be used, in concert, to measure scale in transect data. Methods: We used artificial and real data to examine how the PQV method elucidates spatial pattern. Two-term local quadrat variance (7TLQV) and new local variance (NLV) methods, together with their three-term counterparts, were also applied to the same data sets, and the results from all methods were compared. Results: When the mean gap size equalled the mean patch size along a transect, the first peak of the variance of PQV, NLV and `7TLQV corresponded with the gap size (or patch size). However, if the mean gap size and patch size were unequal, the variance plot of PQV displayed a flat-topped plateau, in which the first inflection represented the mean size of the smaller phase and the second inflection represented the mean size of the larger phase; TJ'LQV showed a clear peak and NLV displayed a distinct first peak while the second inflection was dampened. The results also indicated than the three-term versions of quadrat variance methods did not consistently outperform their two-term counterparts, and often confused the interpretation of scale. Conclusions: The quadrat variance methods associated with the patch-gap measurements were able to efficiently detect not only the size of patches, but also the size of gaps. [ABSTRACT FROM AUTHOR]