USE OF HISTORICAL YIELD DATA TO FORECAST RANGE HERBAGE PRODUCTION
USE OF HISTORICAL YIELD DATA TO FORECAST RANGE HERBAGE PRODUCTION
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使用历史产量数据预测牧草产量范围
DOI：
10.2307/3898649
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
S. Smoliak
中科院分区：
文献类型：
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作者：
C. Hanson;J. Wight;J. Smith;S. Smoliak
对艾伯塔省东南部Manyberries Range实验农场51年草本植物产量序列的分析表明，当年的草本植物产量与前一年的产量之间存在轻微的相关性。分析表明，在低于平均产量的年份，低于平均产量的条件概率与任何给定年份低于平均产量的无条件概率大致相同。在收益率低于平均水平的一年后，收益率高于平均水平的条件概率显著低于任何一年收益率高于平均水平的无条件概率。在超过平均产量的情况下，一年后出现高于平均产量的概率明显大于无条件概率。关于干旱对植被和动物生命的影响，已经有许多研究，其摘要可以在Hounam等人中找到。(1975)。周期性干旱是牧场环境的一部分。它们的出现会极大地减少植物和动物的数量。在大平原北部，20世纪30年代的S干旱导致植物密度和可用牧草严重减少(White等人。1978年)。这样的牧草损失使牧场管理问题复杂化。干旱的发生、强度和持续时间的不可预测性进一步加剧了这些问题，对牧场资源管理者来说，干旱对牧草可获得性的遗留影响也是重要的。这篇论文的目的是确定当前和前一两年的收益率之间是否存在相关性。特别令人感兴趣的是，年牧草产量低于平均水平对随后几年产量低于平均水平的可能性的影响。
An analysis of the 51-year berbage yield series from the Manyberries Range Experimental Farm in southeastern Alberta showed that there was a slight dependency between current year’s herbage yield and previous year’s yield. The analysis showed that the conditional probability of a below-average yield following a belowaverage yield year was about the same as the unconditional probability of having a below-average yield in any given year. The conditional probability of an above-average yield following a year with a below-average yield was significantly below the unconditional probability of having an above-average yield in any year. The probability of an above-average yield following a year with an above-average yield was significantly greater than the unconditional probability. There have been numerous studies on the effects of drought on vegetation and animal life, a summary of which can be found in Hounam et al. (1975). Periodic droughts are part of the rangeland environment. Their occurrence can drastically reduce both plant and animal populations. In the northern Great Plains, the 1930’s drought resulted in severe reductions in plant density and available forage (White et al. 1978). Such forage losses complicate the problems of range management. These problems are further intensified by the unpredictability of occurrence, intensity, and duration of drought, Also of importance to range resource managers are the carryover or residual effects of drought on forage availability. The purpose of this paper was to determine if there was a dependency between current and the previous 1 or 2 years’yields. Of particular interest was the effect of below-average annual herbage yields on the probability of below-average yields in subsequent years.