Abstract
The conservation of species diversity and improvement of forest structure are essential roles of the Natural Reserve Policy and the Natural Forest Protection Program (NFPP) in China. However, the long-term effects of NFPP are still not well-defined, and a natural reserve (Liangshui) and surrounding region were surveyed as a proxy of NFPP for approaching the protection effects. Our results showed that long-term conservation significantly altered the dominant species in the herb layer (80% of species), followed by shrub (58%) and tree layers (50%); there was a 1.6-8.0-fold increase in abundance in Corylus shrubs, Acer trees and Carex grass, but a 1.3–10.0-fold abundance decrease in larch trees, Athyrium herbs and Lonicera shrubs. In contrast, tree species diversity and distribution evenness increased by 31% and 23.4% in the reserve, respectively. Forest protection in the reserve also led to the forest structural alteration with the observation of larger-sized trees and shorter herbs, but relatively sparse forests (smaller tree density). Structural equation modeling manifested that the reserve directly altered forest structure, at a coefficient of 0.854, nearly two-fold higher than its impact on diversity (0.459) and dominant species (−0.445). The most affected parameters were plant size (trees and herbs) and tree density related to forest structure, tree diversity, herb richness and evenness for diversity traits, and Oxalidaceae and Rosaceae for dominant species. This study provides basic data that can be used to evaluate the impact of the nature reserve in NE China, and these findings can be used to guide the implementation of NFPP in the long-term in the future.
Highlights
The Natural Forest Protection Program (NFPP) was launched in 1998 with the initial aim of protecting natural forests, covering an area of 45 million ha in China [1]
In the case of dominant herb species, some were significantly richer in the reserve, such as an 8-fold increase in Carex pilosa (p < 0.01), the Oxalidaceae family, Oxalis genus and Oxalis corniculata increased by 6-fold; the Umbelliferae family, Aegopodium genus and Aegopodium alpestre showed a 1.8–2.6-fold increase; while some other groups showed sharp decreases in the reserve, such as Athyrium brevifrons, Athyrium genus and Athyriaceae family that decreased 2.3–3 times; and the Rosaceae family and Filipendula palmata that decreased nearly 1.7-fold (p < 0.01) (Table 1)
Nature conservation in NE China could strongly alter the vegetation-dominant composition in the herb layer and tree layer
Summary
The Natural Forest Protection Program (NFPP) was launched in 1998 with the initial aim of protecting natural forests, covering an area of 45 million ha in China [1]. Evaluations have been assessed in land use and land cover change [2], and carbon stocks and overall forest quality [3,4], indicating sharp declines in timber harvest with increasing forest area and slow increases in biomass stocks in northeast (NE) China [5]. Forests 2020, 11, 295 composition and diversity alternations as well as forest structure of plant size and forest density at different vertical layers, owing to experimental design difficulty. Good knowledge of tree sizes, stand density and the compositional features could contribute to the evaluation of forest carbon sequestration and productivity [10] and promote mechanical understanding of species coexistence in a complex community [11,12]. A statistical definition of the parameters most likely to be affected by forest protection will assist future investigation via less surveyed parameter design for the precise evaluation, while decoupling their association possibly supports the suitable management to reach standardized and accepted conclusions [13,14,15]
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