High Mortality and Low Net Change in Live Woody Biomass of Karst Evergreen and Deciduous Broad-Leaved Mixed Forest in Southwestern China

Abstract

Repeated observation based on large permanent monitoring plots is a key method for directly understanding forest regeneration dynamics. Karst forests grow slowly in adverse habitats and possess a special regeneration mode. However, no data can support these properties because no repeated observations have been performed. The mortality, recruitment, and net change in live woody biomass (NPP lw ) of a karst evergreen and deciduous broad-leaved mixed forest in Central Guizhou Province, Southwestern China, were studied on the basis of a short-term continuous monitoring (3 years) of a 2 ha plot. The species richness of individuals with a diameter at breast height (DBH) ≥ 1 cm decreased from 66 to 58 during the study period. Eight species disappeared, and no new species appeared. The individual number declined from 16,821 to 15,003 because most species indicated more deaths than recruitments. Trees presented the lowest mortality rate, and shrubs presented the highest recruitment rate among the species. Individual death number decreased with the increase in DBH classes. The estimated aboveground NPP lw was 8.41 t ha −1 year −1 . The survivors, recruitments, and deaths contributed 10.88, 0.11, and −2.58 t ha −1 year −1 , respectively. Trees (8.37 t ha −1 year −1 ), rather than shrubs (0.04 t ha −1 year −1 ) and lianas (−0.004 t ha −1 year −1 ), were the major contributors. The karst forest presented higher mortality and lower NPP lw than nonkarst forests in subtropical China and in the world.

Life form dynamics of the tree layer in evergreen and deciduous broad-leaved mixed forest during 1996–2017 in Tianmu Mountains, eastern China

“…Fig. 2 shows that the mortality of the trees with small DBH was the highest and with medium DBH was the smallest, which is consistent with the findings obtained from the evergreen and deciduous broad-leaved mixed forest in the Karst region of southwest China (Liu et al 2018) and the Tiantong National Forest Park (Wu et al 2014). Note that the trees with small DBH also showed the highest recruitment rate.…”

Stand Structure and Abiotic Factors Modulate Karst Forest Biomass in Southwest China

“…For example, the largest biomass increase in the world occurred in the South China karst region between 1999 and 2012 [10]. Other studies reported the biomass in typical karst ecosystems, or along vegetation restoration areas based on surveys of small plots [2,6,[11][12][13][14]. However, no biomass investigations have been conducted on a local scale in the karst region, especially in forests.…”

Seasonal Changes and Vertical Distribution of Fine Root Biomass During Vegetation Restoration in a Karst Area, Southwest China

“…Most of the degraded land has seen a shift from cropland or abandoned bare land to forest or other secondary vegetation. Several studies have examined the aboveground biomass in karst regions, including biomass change with vegetation restoration (Cheng et al, 2015; Liu et al, 2016, 2018; Tong et al, 2018). However, our current knowledge of belowground fine root biomass is considerably more limited than that of aboveground biomass in karst regions, and the effects of ecological restoration on fine root biomass have not been evaluated in detail in this fragile ecosystem.…”