Understory vegetation accounts for a large proportion of floral diversity. It provides various ecosystem functions and services, such as productivity, nutrient cycling, organic matter decomposition and ecosystem self-regeneration. This review summarizes the available literature on the current status and progress of the ten most studied branches of understory vegetation on both its structural and functional aspects based on global climate change and forest management practices. Future research directions and priorities for each branch is suggested, where understory vegetation in response to the interplay of multiple environmental factors and its long-term monitoring using ground-based surveys combined with more efficient modern techniques is highlighted, although the critical role of understory vegetation in ecosystem processes individually verified in the context of management practices or climate changes have been extensively investigated. In summary, this review provides insights into the effective management of the regeneration and restoration of forest ecosystems, as well as the maintenance of ecosystem multilevel structures, spatial patterns, and ecological functions.

Wildfire is essential in altering land ecosystems’ structures, processes, and functions. As a critical disturbance in the China–Mongolia–Russia cross-border area, it is vital to understand the potential drivers of wildfires and predict where wildfires are more likely to occur. This study assessed factors affecting wildfire using the Random Forest (RF) model. No single factor played a decisive role in the incidence of wildfires. However, the climatic variables were most critical, dominating the occurrence of wildfires. The probability of wildfire occurrence was simulated and predicted using the Adaptive Network-based Fuzzy Inference System (ANFIS). The particle swarm optimization (PSO) model and genetic algorithm (GA) were used to optimize the ANFIS model. The hybrid ANFIS models performed better than single ANFIS for the training and validation datasets. The hybrid ANFIS models, such as PSO-ANFIS and GA-ANFIS, overcome the over-fitting problem of the single ANFIS model at the learning stage of the wildfire pattern. The high classification accuracy and good model performance suggest that PSO-ANFIS can be used to predict the probability of wildfire occurrence. The probability map illustrates that high-risk areas are mainly distributed in the northeast part of the study area, especially the grassland and forest area of Dornod Province of Mongolia, Buryatia, and Chita state of Russia, and the northeast part of Inner Mongolia, China. The findings can be used as reliable estimates of the relative likelihood of wildfire hazards for wildfire management in the region covered or vicinity.

In the Gulf of Mexico coastal region, prescribed fire has been increasingly used as a management tool to restore declining native ecosystems, but it also increases the threat posed by biological invasion, since the treated sites are more susceptible to invasive species such as Chinese tallow (Triadica sebifera). We chose Mississippi Sandhill Crane National Wildlife Refuge (MSCNWR), a fire-managed landscape, to examine the potential effect of prescribed fire and landscape/community features on tallow invasion and spread. We took a complete survey of roadways and fire lines for tallow and measured a systematic sample of 144 10 × 3 m² rectangular plots along two selected roadways and a simple random sample of 56 0.04-ha circular plots across burn units. We used pair correlation function for marked point pattern data, zero-inflated negative binomial models for count data, as well as multivariate Hotelling’s T² test, to analyze the effect of prescribed fire and landscape/community characteristics on tallow invasion and spread along habitat edges and into interiors. Our results show that tallow spread along habitat edges and into interiors in a spatially clustered pattern. Tallow invasion risk decreases with the distance to seed trees and shrub coverage, and with the time since last fire if seed trees are outside the effective seed dispersal range (~300 m), but increases with the time since last fire if seed trees are within the effective seed dispersal range. Tallow seedling (≤2 years old) densities increase with the time since last fire and with increasing overstory tree basal area, but decrease with the distance to seed trees. Tallow-invaded interior plots have significantly shorter mean fire return intervals (2.7 years), lower shrub coverage (8.6%), and are closer to edges (20.3 m) than non-invaded plots (4.3 years, 18.4%, 167.6 m, respectively).

Invasive tree species cause increasing damage to the environment and local economies. Previous studies have seldom treated the presence and abundance of invasive species as different phenomena. Using Classification and Regression Trees (CART) analysis, important driving factors affecting the presence and abundance of invasive tree species in Mississippi were identified. These selected factors were spatially analyzed using a spatial lag model at the county level. The empirical results from the spatial lag model showed that: (1) the presence of invasive tree species was more likely at lower elevations, private ownerships, and in counties with higher per capita annual income; and (2) the abundance of invasive tree species was related to stand age, and elevation. The odds ratio revealed that the presence was most affected by per capita mean annual income. This result might reflect impacts from intensified urban development and alteration of the landscape. As revealed by the coefficients, the abundance was most strongly affected by stand age. Thus, management prescriptions designed to monitor and control invasions should target young private forestlands at low elevations in counties with higher per capita mean annual income.

By analyzing stem map and age data of invasive tallow (Triadica sebifera) in a slash pine (Pinus elliottii) flatwood, we examined the invasion process of tallow at a local scale (stand) in the Grand Bay National Wildlife Refuge, Jackson County, Mississippi, USA. Spatially, tallow seedlings and saplings are mostly distributed in areas near the stand edge (< 20 m from the road) and underneath overstory slash pines. More tallow seedlings and saplings and tallow seeds were found around snags, particularly those in advanced decay classes, than around live trees. Thick and tall shrub layers inhibit tallow colonization and growth. The observed spatial and temporal invasion patterns of tallows suggest that the risk of tallow invasion may be greatly increased by both natural and anthropogenic disturbances that promote the foraging and nesting of tallow seed-eating birds and seed dispersal as well as create favorable site conditions for seed germination and seedling growth. Restoration of pine flatwoods and desired stand conditions such as reducing canopy openness, retaining snags, and restoring the grassy ground layer may further facilitate the invasion of tallow in areas already invaded by tallow or within the distance that tallow seeds can be dispersed by birds.