Abstract

The changes in net primary production—aboveground (ANP), belowground (BNP), and total (NPP)—are considered for meadow, true, and dry steppes. The investigated meadow and true steppes are found between 36° and 116° E, 47° and 56° N. In Tyva, the production of dry steppes has been determined for different landscape positions: from the mountaintop to the bottom of intermontane depression. The ANP value in meadow steppes changes eastward from 10.2 to 3.1 t/ha per year; in true steppes, from 5.8 to 0.7 t/ha per year and depends on many factors, such as air temperature, precipitation, and soil properties. The latter are controlled by a set of factors, including the topographic position of ecosystem, which determines different soil moistening. The general trend of the eastward decrease in the ANP value is often disturbed both in meadow steppes and true steppes. In some cases, ANP increases rather than decreases in a series of meadow steppes, which is explained by certain changes in soil conditions. The first increase in ANP from 4.8 (63° E) to 6.1 (73° E) t/ha per year occurs with the replacement of Luvic Chernozem (Loamic) by Inclinigleyic Chernozem (Loamic) resulting from additional soil moistening. The second increase from 3.6 (75° E) to 6.6 (90° E) t/ha per year is related to the change from Tonguic Chernozem (Siltic) to Haplic Chernozem (Siltic, Pachic). Three increases in ANP are observed in true steppes, namely, when (1) Skeletic Kastanozem (Siltic) is replaced by Calcic Chernozem (Siltic); (2) Haplic Solonetz (Loamic), by Calcic Chernozem (Loamic); and (3) Mollic Leptosol (Siltic), by Calcic Chernozem (Siltic). The BNP value in the upper 30‑cm-thick soil layer of meadow and true steppes generally decreases eastward from 26.8 to 7.7 t/ha per year without any evident regular pattern. In Tyva with its different relief, the ANP of dry steppes varies from 3.7 to 1.7 t/ha per year and BNP, from 27.0 to 8.7 t/ha per year. Consequently, not only air temperature and precipitation determine the ANP value in grass ecosystems but also the soil properties, such as soil structure, C_org content, nutrients, and water availability.

中文翻译：

---

草原生态系统净初级生产及其空间分异的原因

摘要

考虑了草甸、纯草原和干燥草原的净初级生产力的变化——地上（ANP）、地下（BNP）和总量（NPP）。所调查的草甸和真正的草原位于东经 36° 至 116°、北纬 47° 至 56° 之间。在图瓦，已确定了不同景观位置的干燥草原的产量：从山顶到山间洼地的底部。草甸草原ANP值向东变化，从每年10.2吨/公顷变为3.1吨/公顷；在真正的草原上，每年 5.8 至 0.7 吨/公顷，取决于许多因素，例如气温、降水和土壤性质。后者受一系列因素控制，其中包括生态系统的地形位置，决定了不同的土壤湿润程度。无论是草甸草原还是真草原，ANP值向东下降的总体趋势常常受到干扰。在某些情况下，一系列草甸草原中的 ANP 会增加而不是减少，这是由土壤条件的某些变化来解释的。ANP 首次从每年 4.8 (63° E) 增加到 6.1 (73° E) 吨/公顷，是由于额外的土壤润湿导致用 Inclinigleyic 黑钙土 (Loamic) 取代 Luvic 黑钙土 (Loamic)。第二次从每年 3.6 (75° E) 增至 6.6 (90° E) t/ha 与从舌质黑钙土（粉质）到 Haplic 黑钙土（粉质、帕奇质）的变化有关。在真正的草原中观察到 ANP 的三种增加，即当（1）骨钙土（粉砂岩）被钙质黑钙土（粉砂岩）取代时；(2) Haplic Solonetz (Loamic)，作者：Calcic Chernozem (Loamic)；(3) Mollic Leptosol (Siltic)，由 Calcic Chernozem (Siltic) 生产。草甸和真草原上层30厘米厚土层的BNP值一般向东从每年26.8吨/公顷减少到7.7吨/公顷，没有任何明显的规律性。在地形不同的图瓦，干燥草原的 ANP 每年从 3.7 到 1.7 吨/公顷变化，BNP 每年从 27.0 到 8.7 吨/公顷变化。因此，不仅气温和降水决定了草地生态系统中的 ANP 值，而且还决定了土壤特性，如土壤结构、有机碳_含量、养分和水分可用性。