Our results showed that in this study region a 30 mm rain event size is required for NDVI to increase most sharply. Feeds; … Plant distribution at both sites is patchy with variable soil properties (Table 1). Chew RM, Chew AE (1965) The primary productivity of a desert shrub (Larrea tridentata) community. SCOTT L. COLLINS. To determine the threshold and hierarchical response of rainfall event size on the Normalized Difference Vegetation Index (NDVI, a proxy for ANPP) and the … Although the fit of linear regression reached a remarkable level, the distribution of scatters reflects a threshold. percentage cover, and to investigate differences between protected and adjacent grazed areas. Despite these limitations, though, the conclusions from this research can provide a reference for field control rainfall experiments and can also contribute to the sustainability of desert ecosystems. Analyzed the data: FL WZ HL. primary productivity- primary productivity is the rate at which producers (plants) convert energy from the sun into chemical energy; desert plants lack an efficient amount of photosynthesis, therefore less carbon dioxide is produced. Relative humidity is 46%. They have hostile living conditions for plants and animals so net primary productivity is quite low. This pattern showed that NDVI in desert ecosystems responds significantly to rainfall pulses. In the dune region, a large rainfall event led to extended periods of soil moisture content, increased plant photosynthesis and increased NDVI of by about 30%, and peak production occurred in August, when a large number of annual plants appeared. Net marine primary productivity is the amount of organic material available to support the consumers (herbivores and carnivores) of the sea. why is the NPP in deserts so low? In response to lower amounts: the NDVI in the desert and dune ecosystems responded significantly at 6.4 mm of effective rainfall on 22 July 2011, but the increases here were much smaller – 0.4% and 1.46% respectively. [3] that the k values of annual plants and shallowly rooted woody plants are smaller. distribution of seeds in and above the soil surface. Performed the experiments: FL. RU is the upper threshold above which rain events than do not yield additional benefits; and (C) provides a hypothetical response curve. The entire desert ecosystem NDVI growth rate was 3%–9% when rainfall was less than 30 mm, but it reached 22.5% with more than 30 mm – a 3- to 6-fold increase. Land Life. The response of plants to precipitation pulses has been studied extensively, from individuals to ecosystems. Yes Der Begriff Primärproduktion bezeichnet in der Ökologie die Produktion von Biomasse durch die Produzenten, also Pflanzen, Algen, Cyanobakterien und andere autotrophe Bakterien, mithilfe von Licht oder chemischer Energie aus anorganischen Substanzen. When rainfall event size increased from 5 mm to 50 mm, the frequency decreased, during the growing season. Funding: This study was supported by the National Science Fund for Distinguished Young Scholars of China (41125002) and the National Natural Science Foundation of China (41071019). The error bars represent standard errors for all the pixels in the study area. A variety of models of primary productivity response to rainfall variability-the two-layer hypothesis [10], the pulse-reserve hypothesis [2], and the threshold-delay model [11]-continue to be used with various theoretical (and subsequently operational) modifications in order to generate different scales of plant response. (A) The mean NDVI of the desert study area response to rainfall pulses for Terra and Aqua satellites. On average, therefore, rainfalls supplying more than 5 mm were likely to be associated with productivity in this ecosystem, despite a slight decrease in average temperature following rainfall (Figure 7). The maximum potential response variable values (ymax) in this study were 0.1491 and 0.3554 for desert and dune habitats, respectively, indicating that the physiology and ANPP response levels of dune plants to precipitation pulses were much higher, because of biodiversity and structure differences, in particular for annual plants whose responses occurred in late growing season, and whose root systems were better able to exploit moisture. Average annual rainfall for the study area was 124 mm from 2005 to 2012, with approximately 75% of this occurring between June and September and 25% occurring from October to May (Figure 3). Rainfall is a major driver of metabolism in water-limited ecosystems [1]. Based on the threshold-delay model and statistical analysis, the results showed that the response of NDVI to rainfall pulses began at about a 5 mm event size. Conceived and designed the experiments: WZ FL HL. No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, https://doi.org/10.1371/journal.pone.0073003, http://ladsweb.nascom.nasa.gov/data/search.html. ʅ Click the checkbox to the left of the layer name, Net Primary Productivity. Dune habitats were characterized by a single, late summer productivity peak after two large rainfall events of about 43.4 mm and 37.2 mm; in contrast, deserts showed a multi-peak pattern during the growing season. An average seasonal precipitation of 90 mm supported a mean of 223 kg ha ⁻¹ in arfaj steppe in 1979–1989, whereas an average mean seasonal precipitation of 73 mm during 1983–1989 maintained a mean phytomass of 102 kg ha ⁻¹ in the remeth steppe. Different rainfall classes present significant difference, a result that support the hierarchical response, but a 30 mm rainfall event is the threshold with a large response (Figure 6).The effect of rainfall size was much larger than the dry interval of rainfall events (Table 4), a result consistent with the conclusion that the precipitation event size is most important at the driest site considered, and the spacing of events most important at the mesic site [15], [45], [46]. (c) Net primary productivity (d) Gross primary productivity Answer: (b) Secondary productivity. It is of the following two sub types: Although rates of net primary production are similar across ecosystems (Cebrian 1999), herbivorous zooplankton in lakes remove a three to four times greater proportion of primary productivity than grazers in terrestrial systems (Cyr & Pace 1993; Hairston & Hairston 1993; Cebrian 1999), and aquatic consumers can be anywhere from six to sixty times more abundant on an areal basis within … Which rain events do not stimulate a response is a change in net... That are limited by the variation in different grassland types under the same level... Differ depending on the plants not store more energy in these condtions monthly and. Of rainfall events were small, with the increase in soil properties ( Table 1 ) what rainfall would! After response were selected as the maximum response to a rainfall event size is required for NDVI to increase sharply! Improve its chance for survival the NDVI growth rate also reflected a threshold, to. 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