Spatial and temporal variation of forest net primary productivity components on contrasting soils in northwestern Amazon

Abstract

Climate is a strong determinant of tropical forest productivity; therefore, it is often assumed that Amazonian forest growing on the same local rainfall regime responds similarly to fluctuations in rainfall, independently of soil differences among them. We evaluated intra‐ and inter‐annual variation of net primary productivity (NPP) components, and forest dynamics during 2004–2012 yr in five forests on clay, clay‐loam, sandy‐clay‐loam, sandy‐loam and loamy‐sand soils, and the same local rainfall regime in northwestern Amazonia (Colombia). The questions were as follows: (1) Do NPP components and forest dynamics respond synchronously to temporal rainfall fluctuations? (2) Are the responses between above and belowground components and forest dynamics similar for different forest stands? A slight and complex synchronicity among different NPP components in their response to temporal rainfall fluctuations were found; few plots showed that aboveground biomass (AGB) and stem growth were susceptible to rainfall fluctuations, while belowground components (fine roots) showed correlation with one‐month lagged rainfall. Furthermore, despite that northwestern Amazonia is considered relatively aseasonal, litterfall showed high seasonality in the loam‐soil forest group, as well as the fine‐root mass, particularly during the 2005 drought. Litterfall correlation with rainfall of sandy‐loam terra‐firme forest was time lagged as well as fine‐root mass of the loamy‐sand forest. The correlation between mortality and rainfall was weak, except for the loamy‐sand forest (white‐sand forest, 77%). High mortality rates occurred in the non‐flooded forests for the censuses that included the dry years (2004–2005, 2005–2006). Interestingly, litterfall, AGB increment, and recruitment showed high correlation among forests, particularly within the loam‐soil forest group. Nonetheless, leaf area index (LAI) measured in the most contrasting forests (clay and loamy‐sand soil) was poorly correlated with rainfall, but highly correlated among them, which could be indicating a phenotypic response to the incident radiation in these sites; also, LAI did not reflect the differences in NPP components and their response to rainfall. Overall, the different temporal behavior of NPP components among forests in relation to rainfall fluctuations suggests the important role that soil exerts on the responses of plant species in each site, besides their effect on forest dynamics and community composition.

Monitoring of Land Desertification Changes in Urat Front Banner from 2010 to 2020 Based on Remote Sensing Data

“…where SOL indicates the total solar radiation (gC•m −2 •month −1 ), FPRA represents the proportion of the incident photosynthetically active radiation absorbed by the vegetation layer, and the constant 0.5 denotes the ratio of solar radiation utilized by the vegetation to the total solar radiation [34,59].…”

“…In light of this, to analyze the spatial and temporal characteristics and evolution patterns of land desertification in the Urat front flag, this study created the region's "Albedo-NDVI" feature space between 2010 and 2020 using the ENVI and ArcGIS software platforms. Additionally, using Landsat remote sensing images as the primary data source, as well as dynamic attitude calculation [31], transfer matrix analysis [32], and center of gravity shift analysis [33], and in conjunction with MODIS-NDVI data, the CASA model was used to estimate the net primary productivity of vegetation between 2010 and 2020 [27,34]. To accurately and objectively evaluate the ecological environment of the study area, this paper analyzes the spatial distribution pattern and the impact of topographic factors on desertification.…”

Community structure and species diversity dynamics of a subtropical evergreen broad-leaved forest in China: 2005 to 2020

“…Forest dynamics have been extensively studied in recent decades ( Tang and Fang, 2006 ; Wang et al., 2011 ; Shen et al., 2018 ; Bugmann and Seidl, 2022 ), with several researchers emphasizing the importance of long-term repeated studies on natural forest communities ( Balvanera et al., 2006 ; Wiegand et al., 2017 ; Jimenez et al., 2020 ). These studies have shown that subtropical forests are not composed of stable and unchanging communities, as previously thought; instead, the community structure of these forests changes dynamically over time and space ( Condit et al., 1999 ; Neumann et al., 2012 ; Chisholm et al., 2014 ; Wiegand et al., 2017 ; Hedl and Chudomelova, 2020 ).…”