Spatiotemporal variations in productivity and water use efficiency across a temperate forest landscape of Northeast China

Abstract

Background: Forests are increasingly valued for non-timber ecosystem services in place of conventional wood fiber production. Biomass carbon sequestration is one of the key ecosystem services forests are relied upon for mitigating global climate change. However, planning for large-scale tree planting and managing established forest stands for carbon sequestration require careful consideration of the gain in biomass production and tradeoff for other regulatory services. How a tradeoff between forest production and conservation of water resources is shaped by the condition of forest stand and environmental factors remains a question of broad interest in sustainable forest ecosystem management. Methods: We studied the spatiotemporal patterns of net primary productivity (NPP), evapotranspiration (ET), and water use efficiency (WUE), and their relationships with local climatic and forest stand factors over a temperate forest landscape in Changbai Mountain, Northeast China. The time series of spatial data on NPP and ET were extracted from the global remote sensing datasets for the MOD16A3 and MOD17A3 products for the period 2000-2014. The time series of spatial patterns of annual precipitation and annual mean temperature were obtained as grid maps for regional meteorological variables. Stand patches were categorized into the types of conifers, broadleaves, and mixed-wood, as well as age-classes of young, mid-age, near mature, mature, and oldgrowth stands, and by establishment into natural and planted. Information on stands and selective site variables were compiled from the Forest Inventory Datasets of China. Analyses were performed with Arc-GIS. Results: Over the study period of 2000-2014, the landscape-level annual NPP varied between 311.7 and 573.6 gC•m − 2 •a − 1 , ET between 559.9 and 603.0 mm•a − 1 , and WUE between 0.54 and 1.01 gC•m − 2 •mm − 1 . Across the forest landscape, the mean annual NPP varied between 205.0 and 639.4 gC•m − 2 •a − 1 , ET between 441.5 and 784.0 mm•a − 1 , and WUE in the range of 0.46-1.10 gC•m − 2 •mm − 1 . The spatial variations in NPP, ET, and WUE were commonly attributable to forest type, stand age class and density, establishment mode, and temperature variables, with some effects of other selective factors on ET and WUE. The three forest types were significantly (p < 0.05) differentiated in the mean annual NPP, ET, and WUE: the coniferous forests were highest in NPP (505.3 ± 1.4 gC•m − 2 •a − 1 ; n = 1041) and WUE (0.872 ± 0.004 gC•m − 2 •mm − 1 ; n = 1041), and lowest in ET (584.1 ± 1.6 mm•a − 1 ; n = 1041), followed by the mixed-wood forests (NPP: 500.5 ± 0.8 gC•m − 2 •a − 1 ; WUE: 0.856 ± 0.02 gC•m − 2 •mm − 1 ; ET: 589.3 ± 0.9 mm•a − 1 ; n = 2156); whereas the broadleaved forests were lowest in NPP (491.6 ± 0.6 gC•m − 2 •a − 1 ; n = 4428) and WUE (0.832 ± 0.02 gC•m − 2 •mm − 1 ; n = 4428), and highest in ET (594.7 ± 0.6 mm•a − 1 ; n = 4428). The mean annual NPP, ET and WUE increased with stand age typically in coniferous forests, and weakly in mixed-wood forests. The natural sta...

Estimated biomass carbon in thinned Cunninghamia lanceolate plantations at different stand-ages

“…The first-rotation density declines as the age increases over a long term, up to 50 (Xie et al 2016) or 90 years (Selvaraj et al 2017). Stand density is an influential factor that determines biomass C sequestration and consequently physiological activities in trees (Devi and Yadava 2015;Xie et al 2016;Li et al 2019;Pan et al 2019). Older stands resulted in greater tree C storage and higher partition of biomass to the root (Xie et al 2016).…”

Reconciliation of research on forest carbon sequestration and water conservation

“…Continentally and globally, climate appears to the most important factor shaping the spatial patterns of forest carbon stocks (Pan et al 2011;Zhou et al 2019), and locally and regionally, the density and partitioning of forest carbon varies with tree species, forest structure and types, stand development, management, and soil conditions (Giardina and Ryan 2000;Law et al 2004;Sun et al 2004;Li et al 2019). Marked differences can been found in forest carbon in relation to forest types, development, and site conditions regionally (Law et al 2004) and at landscape-scale (Li et al 2019), and between natural and planted forests (Yu et al 2019). Natural and anthropogenic disturbances, accidental or intentional, are all detrimental to the stock and stability of forest carbon pools.…”

“…Realizations of the vital roles of forests in environmental regulations and eco-safety have promoted the development and management of plantation forests for non-timber products and/or services in modern forestry (Haakana et al 2020;Temperli et al 2020). Increased carbon sequestration capability and effective water conservation benefits are two of the key services highly regarded for forest ecosystems (Li et al 2019). Over the decades, numerous studies have been conducted to quantify the capacity and controls of forest carbon sequestration, and to determine the regulatory roles of forests in local and regional water cycles.…”

Improved genetic distance-based spatial deployment can effectively minimize inbreeding in seed orchard

“…Inbreeding depression mainly results from either selfing or correlated mating (Jain 1976;Ritland 1989;Keller and Waller 2002). Plant pollination dynamic research has indicated that the majority of mating occurred within a certain distance between individuals, thus it is necessary to highlight the importance of separating related individuals beyond the effective pollen dispersal distance (Levin and Kerster 1974;Adams and Birkes 1991;Li et al 2019;Zhang et al 2019). The concern over inbreeding build-up in seed orchard crops necessitated the development of orchard designs aimed at separating relatives (Giertych 1975).…”