Researchers added labeled nitrogen to the soil around a population of trees. they analyzed the ratio of labeled to unlabeled nitrogen in the leaves, in the herbivore consumers, and in the soil in the subsequent season. what are possible hypotheses they are testing in their experiment? researchers added labeled nitrogen to the soil around a population of trees. they analyzed the ratio of labeled to unlabeled nitrogen in the leaves, in the herbivore consumers, and in the soil in the subsequent season. what are possible hypotheses they are testing in their experiment? humidity affects the cycling time in nitrogen cycles. respiration rates will increase with supplemental nitrogen. the inputs of nitrogen are exceeded by the amount of nitrogen re-cycled in a system. light availability improves nitrogen acquisition in plants. leaf litter removal due to heavy storms will alter nitrogen cycling in plants.