地域規模での草食動物生育能力に対する畜産の影響
M Oesterheld1, O E Sala, S J McNaughton
1Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
Nature
|March 19, 1992
まとめ
農業生態系における家畜のバイオマスは,自然生態系に比べて,たとえ初次生産性が似ているとしても,数倍も大きい. 畜産の慣行は,草食動物のバイオマスと体サイズを大幅に増加させます.
科学分野:
- エコロジー エコロジー エコロジー
- 農業科学 農業科学とは
- 動物学 動物学
背景:
- 草食動物のトロフィクレベルの性質は,陸上の生態系における一次生産性と相関しています.
- 農業と自然のシステムにおける草食動物バイオマスの理解は,生態系管理にとって極めて重要です.
研究 の 目的:
- 南米の農業生態系における家畜のバイオマスとサイズ構造を,地元の草食動物と量的に比較する.
- 地域規模で草食動物集団に対する畜産慣行の影響を評価する.
主な方法:
- 南米の農業生態系における25倍の一次生産性のグラデントで家畜のバイオマスを分析した.
- 農業対非管理の生態系における,一次生産性と草食動物バイオマス/体サイズとの関係を比較する.
主要な成果:
- 農業生態系における家畜のバイオマスは,同様の傾きを示したが,管理されていない生態系と比較して,実質的に大きなy切断を示した.
- 一次生産性単位あたりの草食動物バイオマスは,自然生態系よりも農業生態系で約10倍でした.
- 家畜の体長は,主生産性とともに増加し,自然生態系で見られるパターンを反映した.
結論:
- 畜産の慣行は,農業システムにおける草食動物バイオマスと体サイズを大幅に高めます.
- この研究は,地元の草食動物と比較して,畜産が家畜の個体数に与える影響に関する最初の地域規模の定量的な証拠を提供します.
関連する概念動画
00:48Optimal Foraging
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
01:01Production Efficiency
Net production efficiency (NPE) is the efficiency at which organisms assimilate energy into biomass for the next trophic level. Due to low metabolic rates and less energy spent on thermoregulatory processes, the NPE of ectotherms (cold-blooded animals) is 10 times higher than endotherms (warm-blooded animals).
00:51Energy Budgets and Reproductive Strategies
Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species reproduce only once in their lifetime, often investing most available resources into that single reproductive event. Iteroparous species, by contrast, reproduce multiple times over their lifetimes, typically allocating fewer resources to any single...
00:57Population Growth
Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with unlimited resources, populations can increase exponentially, which plots as a J-shaped growth rate curve of population size against time. This type of curve is characteristic of newly-introduced invasive species, or populations that have suffered catastrophic declines and are rebounding.However, realistic environmental conditions limit the number of...
02:39Predator-Prey Interactions
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.Although predation is commonly associated with carnivory, for...
01:18Amino Acid Catabolism
Microorganisms rely on proteins as an essential carbon and energy source, particularly in environments with limited polysaccharides or lipids. However, proteins are too large to cross the plasma membrane unaided, necessitating enzymatic degradation. Microbes secrete extracellular proteases and peptidases that hydrolyze proteins into peptides, which can then be transported across the membrane. Once inside the cell, intracellular proteases degrade these peptides into free amino acids, which...